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  • 201.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Differential control of spontaneous and evoked GABA release by presynaptic L-type Ca(2+) channels in the rat medial preoptic nucleus2010Inngår i: Journal of Neurophysiology, ISSN 0022-3077, E-ISSN 1522-1598, Vol. 104, nr 1, s. 200-209Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To clarify the role of presynaptic L-type Ca(2+) channels in GABA-mediated transmission in the medial preoptic nucleus (MPN), spontaneous, miniature, and impulse-evoked inhibitory postsynaptic currents (sIPSCs, mIPSCs, and eIPSCs, respectively) were recorded from MPN neurons in a slice preparation from rat brain. The effects of different stimulus protocols and pharmacological tools to detect contributions of L-type Ca(2+) channels and of Ca(2+)-activated K(+) (K(Ca)) channels were analyzed. Block of L-type channels did not affect the sIPSC and mIPSC properties (frequency, amplitude, decay time course) in the absence of external stimulation but unexpectedly potentiated the eIPSCs evoked at low stimulus frequency (0.1-2.0 Hz). This effect was similar to and overlapping with the effect of K(Ca)-channel blockers. High-frequency stimulation (50 Hz for 10 s) induced a substantial posttetanic potentiation (PTP) of the eIPSC amplitude and of the sIPSC frequency. Block of L-type channels still potentiated the eIPSC during PTP, but in contrast, reduced the sIPSC frequency during PTP. It was concluded that L-type channels provide a means for differential control of spontaneous and impulse-evoked GABA release and that this differential control is prominent during short-term synaptic plasticity. Functional coupling of the presynaptic L-type channels to K(Ca) channels explains the observed effects on eIPSCs.

  • 202.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Differential control of spontaneous and evoked GABA release by presynaptic L-type Ca2+ channels in the rat medial preoptic nucleusManuskript (Annet vitenskapelig)
    Abstract [en]

    To clarify the role of presynaptic L-type Ca2+ channels in GABA-mediated transmission in the medial preoptic nucleus (MPN), spontaneous as well as impulse-evoked inhibitory postsynaptic currents (sIPSCs and eIPSCs, respectively) were recorded from MPN neurons in a slice preparation from rat brain. The effects of different stimulus protocols and pharmacological tools to detect contributions of L-type Ca2+ channels and of Ca2+-activated K+ (KCa) channels were analysed. Block of L-type channels did not affect the sIPSCs properties (frequency, amplitude, decay time course) in the absence of external stimulation, but unexpectedly potentiated the eIPSCs evoked at low stimulus frequency (0.1 – 2.0 Hz). This effect was similar to and overlapping with the effect of KCa-channel blockers. High-frequency stimulation (50 Hz for 10 s) induced a substantial post-tetanic potentiation (PTP) of the eIPSC amplitude as well as of the sIPSC frequency. Block of L-type channels still potentiated the eIPSC during PTP, but in contrast reduced the sIPSC frequency during PTP. It was concluded that L-type channels provide a means for differential control of spontaneous and impulse-evoked GABA release and that this differential control is prominent during short-term synaptic plasticity. Functional coupling of the presynaptic L-type channels to KCa channels explains the observed effects on eIPSCs.

  • 203.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Fast neurotransmission in the rat medial preoptic nucleus.2005Inngår i: Brain Research, ISSN 0006-8993, Vol. 1040, nr 1-2, s. 157-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The functional properties of neurotransmission in the medial preoptic nucleus (MPN) were studied in a brain slice preparation from young male rats. The aims were to evaluate the thin slice preparation for studying evoked synaptic responses in MPN neurons, to characterize the fast responses triggered by activation of presynaptic nerve fibers in the MPN, and to identify the involved receptor types. Presynaptic stimulation within the MPN evoked postsynaptic voltage and current responses that were blocked by 200 microM Cd2+ or by 2.0 microM tetrodotoxin and were attributed to action potential-evoked transmitter release. The relation to stimulus strength and comparison with spontaneous synaptic currents suggested that in many cases only one presynaptic nerve fiber was excited by the stimulus. Furthermore, the transmission was probabilistic in nature, with frequent failures. Thus, response probability, most likely reflecting transmitter release probability, could be evaluated in the thin slice preparation. Evoked excitatory postsynaptic currents recorded under voltage-clamp conditions were, due to kinetics, I-V relation, and pharmacological properties, attributed to AMPA/kainate receptors and NMDA receptors, whereas inhibitory currents were attributed to GABAA receptors. No responses that could be attributed to glycine or other types of primary transmitters were detected. Although serotonin (5-HT) did not appear to function as a primary transmitter, glutamate- as well as GABA-mediated transmission was suppressed by 500 microM 5-HT, with a clear reduction in response probability observed. 5-HT also reduced the frequency, but not the amplitude, of spontaneous postsynaptic currents and was therefore ascribed a presynaptic site of action.

  • 204.
    Malinina, Evgenya
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Druzin, Michael
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Johansson, Staffan
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Short-term plasticity in excitatory synapses of the rat medial preoptic nucleus.2006Inngår i: Brain Research, ISSN 0006-8993, Vol. 1110, nr 1, s. 128-35Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The medial preoptic nucleus (MPN) regulates sexual behavior which is subject to experience-dependent modifications. Such modifications must depend on functional plasticity in the controlling neural circuits. Thus, MPN synapses are likely candidates for the site of alterations. The present work is a first systematic study of functional synaptic plasticity at glutamatergic synapses in the MPN. Short-term activity-dependent plasticity was investigated using a slice preparation from young male rats. The average efficacy of AMPA/kainate-receptor-mediated synaptic transmission was activity-dependent, showing a peak at a steady stimulation rate of 2 Hz. The variation in efficacy was attributed to mainly presynaptic factors since the average response amplitude was roughly paralleled by the response probability. Upon paired-pulse stimulation, paired-pulse facilitation as well as paired-pulse depression was observed. In some cases, paired-pulse facilitation as well as paired-pulse depression was recorded from an individual neuron depending on the interval between the paired stimuli. On average, paired-pulse facilitation was observed at intervals <500 ms, and paired-pulse depression at intervals in the range 1-4 s. The findings thus reveal complex activity-dependent short-term plasticity of the functional synaptic properties in the medial preoptic nucleus.

  • 205.
    Malmberg Gavelin, Hanna
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Stigsdotter Neely, Anna
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Department of Social and Psychological Studies, Karlstad University, Karlstad, Sweden.
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Eskilsson, Therese
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Fysioterapi.
    Slunga Järvholm, Lisbeth
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Boraxbekk, Carl-Johan
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Samhällsvetenskapliga fakulteten, Enheten för demografi och åldrandeforskning (CEDAR). Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Denmark.
    Neural activation in stress-related exhaustion: cross-sectional observations and interventional effects2017Inngår i: Psychiatry Research: Neuroimaging, ISSN 0925-4927, E-ISSN 1872-7506, Vol. 269, s. 17-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The primary purpose of this study was to investigate the association between burnout and neural activation during working memory processing in patients with stress-related exhaustion. Additionally, we investigated the neural effects of cognitive training as part of stress rehabilitation. Fifty-five patients with clinical diagnosis of exhaustion disorder were administered the n-back task during fMRI scanning at baseline. Ten patients completed a 12-week cognitive training intervention, as an addition to stress rehabilitation. Eleven patients served as a treatment-as-usual control group. At baseline, burnout level was positively associated with neural activation in the rostral prefrontal cortex, the posterior parietal cortex and the striatum, primarily in the 2-back condition. Following stress rehabilitation, the striatal activity decreased as a function of improved levels of burnout. No significant association between burnout level and working memory performance was found, however, our findings indicate that frontostriatal neural responses related to working memory were modulated by burnout severity. We suggest that patients with high levels of burnout need to recruit additional cognitive resources to uphold task performance. Following cognitive training, increased neural activation was observed during 3-back in working memory-related regions, including the striatum, however, low sample size limits any firm conclusions.

  • 206.
    Mansson, Kristoffer N.
    et al.
    Linköping, Sweden.
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Stockholm, Sweden.
    Frick, Andreas
    Uppsala, Sweden.
    Carlbring, Per
    Stockholm, Sweden.
    Furmark, Tomas
    Uppsala, Sweden.
    Olsson, Carl-Johan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CBS). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Gerhard
    Linköping, Sweden; Stockholm, Sweden.
    Interrelated Functional and Structural Amygdala Plasticity Following Internet-delivered Cognitive Behavior Therapy for Social Anxiety Disorder2015Inngår i: Biological Psychiatry, ISSN 0006-3223, E-ISSN 1873-2402, Vol. 77, nr 9 Suppl., s. 51S-51SArtikkel i tidsskrift (Annet vitenskapelig)
  • 207. Marklund, P
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Intersecting the divide between working and episodic memory2007Inngår i: The Conitive Neruoscience of Working Memory, Oxford: Oxford University Press , 2007, s. 305-331Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 208.
    Marklund, Petter
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Fransson, P.
    Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institute, Sweden.
    Cabeza, R.
    Center for Cognitive Neuroscience, Duke University, USA.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Ingvar, M.
    Cognitive Neurophysiology Research Group, Department of Clinical Neuroscience, Karolinska Institute, Sweden.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Unity and diversity of tonic and phasic executive control in episodic and working memory2007Inngår i: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 36, nr 4, s. 1361-1373Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The present study aimed to delineate the extent to which unitary executive functions might be shared across the separate domains of episodic and working memory. A mixed blocked/event-related functional magnetic resonance imaging (fMRI) design was employed to assess sustained (tonic control) and transient (phasic control) brain responses arising from incrementing executive demand (source versus item episodic memory - vis-à-vis - two-back versus one-back working memory) using load-dependent activation overlaps as indices of common components. Although an extensive portion of the regional load effects constituted differential control modulations in both sustained and transient responses, commonalities were also found implicating a subset of executive core mechanisms consistent with unitary or domain general control. 'Unitary' control modulations were temporally dissociated into (1) shared tonic components involving medial and lateral prefrontal cortex, striatum, cerebellum and superior parietal cortex, assumed to govern enhanced top-down context processing, monitoring and sustained attention throughout task periods and (2) stimulus-synchronous phasic components encompassing posterior intraparietal sulcus, hypothesized to support dynamic shifting of the 'focus of attention' among internal representations. Taken together, these results converge with theoretical models advocating both unity and diversity among executive control processes.

  • 209.
    Marklund, Petter
    et al.
    Umeå universitet, Samhällsvetenskaplig fakultet, Psykologi.
    Fransson, Per
    Umeå universitet, Samhällsvetenskaplig fakultet, Psykologi.
    Cabeza, Roberto
    Petersson, Karl M
    Ingvar, Martin
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Sustained and transient neural modulations in prefrontal cortex related to declarative long-term memory, working memory, and attention.2007Inngår i: Cortex, ISSN 0010-9452, Vol. 43, nr 1, s. 22-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Common activations in prefrontal cortex (PFC) during episodic and semantic long-term memory (LTM) tasks have been hypothesized to reflect functional overlap in terms of working memory (WM) and cognitive control. To evaluate a WM account of LTM-general activations, the present study took into consideration that cognitive task performance depends on the dynamic operation of multiple component processes, some of which are stimulus-synchronous and transient in nature; and some that are engaged throughout a task in a sustained fashion. PFC and WM may be implicated in both of these temporally independent components. To elucidate these possibilities we employed mixed blocked/event-related functional magnetic resonance imaging (fMRI) procedures to assess the extent to which sustained or transient activation patterns overlapped across tasks indexing episodic and semantic LTM, attention (ATT), and WM. Within PFC, ventrolateral and medial areas exhibited sustained activity across all tasks, whereas more anterior regions including right frontopolar cortex were commonly engaged in sustained processing during the three memory tasks. These findings do not support a WM account of sustained frontal responses during LTM tasks, but instead suggest that the pattern that was common to all tasks reflects general attentional set/vigilance, and that the shared WM-LTM pattern mediates control processes related to upholding task set. Transient responses during the three memory tasks were assessed relative to ATT to isolate item-specific mnemonic processes and were found to be largely distinct from sustained effects. Task-specific effects were observed for each memory task. In addition, a common item response for all memory tasks involved left dorsolateral PFC (DLPFC). The latter response might be seen as reflecting WM processes during LTM retrieval. Thus, our findings suggest that a WM account of shared PFC recruitment in LTM tasks holds for common transient item-related responses rather than sustained state-related responses that are better seen as reflecting more general attentional/control processes.

  • 210. Marklund, Petter
    et al.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Elgh, Eva
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Linder, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Riklund Åhlström, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Forsgren, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Temporal dynamics of basal ganglia under-recruitment in Parkinson's disease: transient caudate abnormalities during updating of working memory.2009Inngår i: Brain, ISSN 0006-8950, E-ISSN 1460-2156, Vol. 132, nr Pt 2, s. 336-346Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using hybrid-blocked/event-related fMRI and the 2-back task we aimed to decompose tonic and phasic temporal dynamics of basal ganglia response abnormalities in working memory associated with early untreated Parkinson's disease. In view of the tonic/phasic dopamine hypothesis, which posits a functional division between phasic D(2)-dependent striatal updating processes and tonic D(1)-dependent prefrontal context-maintenance processes, we predicted that newly diagnosed, drug-naïve Parkinson's disease patients, with selective striatal dopamine deprivation, would demonstrate transient rather than sustained activation changes in the basal ganglia during 2-back performance. Task-related activation patterns within discrete basal ganglia structures were directly compared between patients and healthy elderly controls. The obtained results yielded uniquely transient underactivation foci in caudate nuclei, putamen and globus pallidus in Parkinson's disease patients, which indicates suboptimal phasic implementation of striatal D(2)-dependent gating mechanisms during updating. Sustained underactivation was only seen in the anterior putamen, which may reflect initial signs of tonic control impairment. No significant changes were exhibited in prefrontal cortex. The present findings resonate well with the tonic/phasic dopamine account and suggest that basal ganglia under-recruitment associated with executive dysfunction in early Parkinson's disease might predominantly stem from deficiencies in phasic executive components subserved by striatum.

  • 211. Marusiak, Jaroslaw
    et al.
    Jarocka, Ewa
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Jaskolska, Anna
    Jaskolski, Artur
    Influence of number of records on reliability of myotonometric measurements of muscle stiffness at rest and contraction2018Inngår i: ACTA OF BIOENGINEERING AND BIOMECHANICS, ISSN 1509-409X, Vol. 20, nr 3, s. 123-131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: The aim of this study was to determine an effect of myotonometric records' number on stiffness measurements' reliability in muscles at rest and contraction. Methods: Muscle stiffness was measured using Myoton-3 device. Twenty records were taken for: (i) biceps (BB) and triceps brachii (TB) at rest and for BB at 10% of maximal voluntary contraction (MVC) in healthy elderlies (HE) and in Parkinson's disease patients (PD); and (ii) brachioradialis (BR) at rest and at 25, 50 and 80% MVC in healthy young (HY) subjects. Also, in HY group, the 3-records mode was used for BR's measurements at maximal contraction. Each measurement taken with 20-records was classed into five records groups: the whole 20- and the first 15-, 10-, 5- and 3-records. Test-retest reliability for these records groups was analyzed. Results: In HE and PD group measurements' reliability was excellent for all groups of records (20-3 records). In HY group, for the five groups of records taken at rest and submaximal levels of contraction (25, 50 and 80% MVC) the measurements reliability: (i) was mostly excellent or rarely average; and (ii) only in one per three 50% MVC conditions was unacceptable, i.e., for the 3-records group. The reliability of 3-records mode measurements at maximal contraction were unacceptable. Conclusions: Reliable myotonometric stiffness measurements in muscles at rest and during submaximal contractions can be achieved with less than 20 records (15, 10, 5 records) and even for the most of measurements with 3 records in HY and HE as well as in the PD patients. Myotonometric stiffness measurements with 3-records mode during maximal contraction were not reliable.

  • 212.
    Mata, Rui
    et al.
    University of Basel.
    von Helversen, Bettina
    University of Basel.
    Karlsson, Linnea
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Cuepper, Lutz
    RWTH Aachen University.
    Adult age differences in categorization and multiple-cue judgment2012Inngår i: Developmental Psychology, ISSN 0012-1649, E-ISSN 1939-0599, Vol. 48, nr 4, s. 1188-1201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We often need to infer unknown properties of objects from observable ones, just like detectives must infer guilt from observable clues and behavior. But how do inferential processes change with age? We examined young and older adults' reliance on rule-based and similarity-based processes in an inference task that can be considered either a categorization or a multiple-cue judgment task, depending on the nature of the criterion (binary vs. continuous). Both older and young adults relied on rule-based processes in the multiple-cue judgment task. In the categorization task, however, the majority of older adults relied on rule-based processes while young adults preferred similarity-based processes. Moreover, older adults who relied on rule-based processes performed poorly compared with young adults who relied on the same process, suggesting that aging is associated with deficits in applying rule-based processes.

  • 213.
    McGlone, Francis
    et al.
    University of Wales, Bangor.
    Kelly, Edward F
    University of North Carolina.
    Trulsson, Mats
    Karolinska Institute.
    Francis, Susan T
    University of Nottingham.
    Westling, Göran
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bowtell, Richard
    University of Nottingham.
    Functional neuroimaging studies of human somatosensory cortex2002Inngår i: Behavioural Brain Research, ISSN 0166-4328, E-ISSN 1872-7549, Vol. 135, nr 1-2, s. 147-158, PII S0166-4328(02)00144-4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two studies were carried out to assess the applicability of echoplanar fMRI at 3.0 T to the analysis of somatosensory mechanisms in humans. Vibrotactile stimulation of the tips of digits two and five reliably generated significant clusters of activation in primary (SI) and secondary (SII) somatosensory cortex, area 43, the pre-central gyrus, posterior insula, posterior parietal cortex and posterior cingulate. Separation of these responses by digit in SI was possible in all subjects and the activation sites reflected the known lateral position of the representation of digit 2 relative to that of digit 5. A second study employed microneurographic techniques in which individual median-nerve mechanoreceptive afferents were isolated, physiologically characterized, and microstimulated in conjunction with fMRI. Hemodynamic responses, observed in every case, were robust, focal, and physiologically orderly. These techniques will enable more detailed studies of the representation of the body surface in human somatosensory cortex, the relationship of that organization to short-term plasticity in responses to natural tactile stimuli, and effects of stimulus patterning and unimodal/cross-modal attentional manipulations. They also present unique opportunities to investigate the basic physiology of the BOLD effect, and to optimize the operating characteristics of two important human functional neuroimaging modalities-high-field fMRI and high-resolution EEG-in an unusually specific and well-characterized neurophysiological setting.

  • 214.
    Nagel, Irene E
    et al.
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Preuschhof, Claudia
    Max Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Li, Shu-Chen
    Max Planck Institute for Human Development, Berlin.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bäckman, Lars
    Max Planck Institute for Human Development, Berlin, Karolinska Institute.
    Lindenberger, Ulman
    Max Planck Institute for Human Development, Berlin.
    Heekeren, Hauke R
    x Planck Institute for Human Development, Berlin, Freie Universität Berlin.
    Load Modulation of BOLD Response and Connectivity Predicts Working Memory Performance in Younger and Older Adults.2011Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 23, nr 8, s. 2030-2045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Individual differences in working memory (WM) performance have rarely been related to individual differences in the functional responsivity of the WM brain network. By neglecting person-to-person variation, comparisons of network activity between younger and older adults using functional imaging techniques often confound differences in activity with age trends in WM performance. Using functional magnetic resonance imaging, we investigated the relations among WM performance, neural activity in the WM network, and adult age using a parametric letter n-back task in 30 younger adults (21-31 years) and 30 older adults (60-71 years). Individual differences in the WM network's responsivity to increasing task difficulty were related to WM performance, with a more responsive BOLD signal predicting greater WM proficiency. Furthermore, individuals with higher WM performance showed greater change in connectivity between left dorsolateral prefrontal cortex and left premotor cortex across load. We conclude that a more responsive WM network contributes to higher WM performance, regardless of adult age. Our results support the notion that individual differences in WM performance are important to consider when studying the WM network, particularly in age-comparative studies.

  • 215. Nagel, Irene E
    et al.
    Preuschhof, Claudia
    Li, Shu-Chen
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Bäckman, Lars
    Lindenberger, Ulman
    Heekeren, Hauke R
    Performance level modulates adult age differences in brain activation during spatial working memory.2009Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 106, nr 52, s. 22552-22557Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an event-related fMRI study. Thirty younger (20-30 years) and 30 older (60-70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more "youth-like" load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.

  • 216.
    Naghavi, Hamid Reza
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Cortical regions underlying successful encoding of semantically congruent and incongruent associations between common auditory and visual objects.2011Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 505, nr 2, s. 191-195Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent studies implicate regions in the frontal, temporal and occipital cortices of the brain in audio-visual (AV) integration of familiar objects. It remains unclear, however, which brain regions contribute to the creation of object-related AV memories, and whether activation of these regions is affected by crossmodal congruency. Here we used event-related functional MRI in a subsequent memory paradigm to investigate the neural substrates of successful encoding of semantically congruent and incongruent AV memories. Creation of both types of memories activated a region in the left inferior frontal gyrus (IFG). In addition, successful encoding of semantically related and unrelated AV pairs was correlated with increased activity in regions within the right lateral occipital cortex and bilateral lateral temporal cortex, respectively. These results may highlight a common role of IFG in retrieval of semantic information during encoding and suggest that the occipital and temporal cortices differentially process perceptual versus conceptual associations of AV memories.

  • 217.
    Naghavi, Hamid Reza
    et al.
    Tehran University of Medical Sciences, Institute for Cognitive Science Studies, Tehran, Iran.
    Eriksson, Johan
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    The claustrum/insula region integrates conceptually related sounds and pictures2007Inngår i: Neuroscience Letters, ISSN 0304-3940, E-ISSN 1872-7972, Vol. 422, nr 1, s. 77-80Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The brain is able to create coherent percepts from multisensory input. This phenomenon, known as multisensory integration (MSI), is a ubiquitous feature of everyday life and has been found to be essential for a reliable interaction with the environment. Recent functional neuroimaging studies suggest that several different networks are engaged in various forms of MSI depending on the nature of information being integrated. However, little is known about the neural basis of a fundamental form of MSI in natural conditions; integration of common auditory and visual objects which are conceptually related, such as when we look at a cat and hear a meowing sound. Here we used event-related fMRI to compare the brain response to conceptually related and unrelated pairs of audio-visual stimuli denoting common objects. Our protocol was designed to preclude contamination of the results by cognitive processes additional to those needed for MSI. The results indicate that higher-order temporal and occipital areas respond to coincident sounds and pictures regardless of their semantic relationship; whereas, the right claustrum/insula region is differentially activated in association with multisensory integration of conceptually related common objects. This observation has important implications for understanding how multimodal information about common objects is represented in the brain.

  • 218.
    Naghavi, Hamid Reza
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Lind, Johanna
    Department of Psychology, University of Oslo, Oslo, Norway.
    Nilsson, Lars-Göran
    Department of Psychology, Stockholm University, Stockholm, Sweden.
    Adolfsson, Rolf
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk vetenskap, Psykiatri.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Personality traits predict response to novel and familiar stimuli in the hippocampal region2009Inngår i: Psychiatry Research, ISSN 0165-1781, E-ISSN 1872-7123, Vol. 173, nr 2, s. 94-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Current evidence from genetic, neurochemical, and clinical research supports the notion that a combination of high novelty seeking and low harm avoidance traits (NS-ha) is reliably dissociable from the opposite personality profile (i.e., low novelty seeking and high harm avoidance, ns-HA). Little is known, however, about how the differences between these two types of personality are regulated by brain function. Here we used functional magnetic resonance imaging (fMRI) and recruited two groups of individuals, one group with the NS-ha profile and the other group with the ns-HA profile, to examine whether there is a difference between the two groups in their brain response to novel versus familiar word stimuli. Results revealed a differential pattern of response in an area in the hippocampal region, with the NS-ha group showing a greater sensitivity to novel stimuli and the ns-HA group demonstrating a greater response to familiar stimuli. We conclude that the response pattern to novel and familiar stimuli in the hippocampal region has a role in mediating differences between the NS-ha and ns-HA temperamental profiles.

  • 219. Naghavi, Hamid Reza
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Common fronto-parietal activity in attention, memory, and consciousness: shared demands on integration?2005Inngår i: Consciousness and Cognition, ISSN 1053-8100, E-ISSN 1090-2376, Vol. 14, nr 2, s. 390-425Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Fronto-parietal activity has been frequently observed in fMRI and PET studies of attention, working memory, and episodic memory retrieval. Several recent fMRI studies have also reported fronto-parietal activity during conscious visual perception. A major goal of this review was to assess the degree of anatomical overlap among activation patterns associated with these four functions. A second goal was to shed light on the possible cognitive relationship of processes that relate to common brain activity across functions. For all reviewed functions we observed a consistent and overlapping pattern of brain activity. The overlap was most pronounced for the bilateral parietal cortex (BA 7 and BA 40; close to the intraparietal sulcus), and dorsolateral prefrontal cortex (right BA 9 and left BA 6). The common fronto-parietal activity will be discussed in terms of processes related to integration of distributed representations in the brain.

  • 220. Naghavi, HR
    et al.
    Nyberg, Lars
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Common fronto-parietal activity in attention, memory, and consciousness: Shared demands on integration?2005Inngår i: CONSCIOUSNESS AND COGNITION, ISSN 1053-8100, Vol. 14, nr 2, s. 390-425Artikkel, forskningsoversikt (Annet (populærvitenskap, debatt, mm))
  • 221. Naghavi, HR
    et al.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Integrative action in the front-parietal network: A cure for a scattered mind2007Inngår i: Behavioral and Brain Sciences, ISSN 0140-525X, E-ISSN 1469-1825, Vol. 30, nr 2, s. 161-162Artikkel i tidsskrift (Fagfellevurdert)
  • 222.
    Nevalainen, Nina
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Axelsson, Jan
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Ögren, Mattias
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Lövdén, M
    Aging Research Center, Karolinska Institutet & Stockholm University, Stockholm.
    Lindenberger, U
    Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
    Bäckman, L
    Aging Research Center, Karolinska Institutet & Stockholm University, Stockholm.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.2015Inngår i: Brain Research, ISSN 0006-8993, E-ISSN 1872-6240, Vol. 1612, s. 83-103Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cognitive decline is a characteristic feature of normal human aging. Previous work has demonstrated marked interindividual variability in onset and rate of decline. Such variability has been linked to factors such as maintenance of functional and structural brain integrity, genetics, and lifestyle. Still, few, if any, studies have combined a longitudinal design with repeated multimodal imaging and a comprehensive assessment of cognition as well as genetic and lifestyle factors. The present paper introduces the Cognition, Brain, and Aging (COBRA) study, in which cognitive performance and brain structure and function are measured in a cohort of 181 older adults aged 64 to 68 years at baseline. Participants will be followed longitudinally over a 10-year period, resulting in a total of three equally spaced measurement occasions. The measurement protocol at each occasion comprises a comprehensive set of behavioral and imaging measures. Cognitive performance is evaluated via computerized testing of working memory, episodic memory, perceptual speed, motor speed, implicit sequence learning, and vocabulary. Brain imaging is performed using positron emission tomography with [(11)C]-raclopride to assess dopamine D2/D3 receptor availability. Structural magnetic resonance imaging (MRI) is used for assessment of white and gray-matter integrity and cerebrovascular perfusion, and functional MRI maps brain activation during rest and active task conditions. Lifestyle descriptives are collected, and blood samples are obtained and stored for future evaluation. Here, we present selected results from the baseline assessment along with a discussion of sample characteristics and methodological considerations that determined the design of the study.

  • 223.
    Nilsson, Lars-Göran
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Sternäng, Ola
    Department of Psychology, Stockholm University, Sweden.
    Rönnlund, Michael
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för befolkningsstudier (CPS).
    Challenging the notion of an early-onset of cognitive decline.2009Inngår i: Neurobiology of Aging, ISSN 0197-4580, E-ISSN 1558-1497, Vol. 30, nr 4, s. 521-524; discussion 530Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Salthouse claims that cognitive aging starts around 20 years of age. The basis for this claim is cross-sectional data. He dismisses longitudinal data, which typically show the cognitive decline to start much later, around 60 years of age. He states that longitudinal data cannot be trusted because they are flawed. There is a confounding between the effects of maturation and retest effects. We challenge Salthouse's strong claim on four accounts.

  • 224.
    Nordmark, Per F.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Structural and functional changes in the brain after surgically repaired median nerve injury2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Despite the best available surgical repair, traumatic median nerve injury within the forearm typically causes lifelong impairment in hand function. This stems from an inadequate reinnervation of the nerves supporting sensory functions of the thumb, index and long finger, and of nerves supplying intrinsic hand muscles. This thesis examines whether median nerve injuries can cause structural and functional changes in the brain. Understanding such changes can help the development of new treatments for improved recovery of hand function.

    The first study introduces a novel apparatus and paradigm for examining tactile neural processing with fMRI under well-controlled behavioral conditions. The scientific issue challenged was whether, in healthy adults, different cortical areas could be involved in processing tactile stimuli depending on their temporal frequency content. In a threshold-tracking paradigm, the participants’ task was to detect oscillatory mechanical stimulations of various frequencies delivered to the tip of either left or right middle finger. Regardless of stimulated hand, tactile detection of audible frequencies (20 and 100 Hz) engaged the left auditory cortex while detection of slow object displacements (3 Hz) engaged visual cortex. These results corroborate and advance the metamodal theory of brain function, which posits that brain areas can contribute to sensory processing by performing specific computations – those for which they are specialized – regardless of input modality.

    The second and third studies concern structural and functional changes in the brain of adults with one reinnervated hand after an injury transecting the median nerve in the forearm. Healthy individuals matched for sex, handedness and age served as controls. Irrespective of side of injury (left or right), voxel-based morphometry applied on T1 MR-images revealed reductions of gray matter in the left ventral and right dorsal premotor cortex, and reductions of white matter in related commissural pathways. We interpreted these as activity-dependent structural adaptations to reduced neural processing linked to restrictions in the diversity of the natural manual dexterity repertoire caused by a disturbed innervation of the hand. Conversely, increases in gray matter were observed bilaterally in a motion-processing visual cortical area. We interpreted this as a structural manifestation of increased neural processing linked to greater dependence on vision for controlling manual dexterity due to impaired tactile innervation of the affected hand.

    To reveal functional changes in tactile cortical processing after median nerve reinnervation, we recorded brain activity using fMRI when study participants performed perceptually demanding tactile threshold-tracking and oddball detection tasks with our novel apparatus. The hand representation of the contralesional primary somatosensory cortex (S1) showed greater activity compared to the controls when the reinnervated index finger was engaged in the tasks, but strikingly also when fingers of both hands innervated by uninjured nerves were engaged, i.e., little finger of the reinnervated hand and index and little finger of the other hand. The generally increased activity indicates a general disinhibition of contralateral S1, suggesting that increased functional reorganization is an ongoing process of chronic nerve injury. In addition, prefrontal areas implicated in processes that support decision-making and response selection showed increased activity, suggesting that such processes were more computationally demanding after nerve injury.

    Together, these results indicate that brain areas can undergo significant changes after peripheral nerve injury, even when followed by best available surgical repair and reinnervation conditions. These changes can include activity-dependent structural adaptations consisting of either regional decreases or increases in gray matter concentration, which likely depend on an area's functional specialization and on changes in its processing load due to behavioral constraints imposed by the injury. Moreover, the results also suggest that the affected hand's primary cortical projection area is still in a state of ongoing functional reorganization despite the fact that peripheral reinnervation of the hand should have been completed long ago, which should inspire the development of new therapeutic regimens for what today is considered a chronic impairment.

  • 225.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Kir och Periop, Handkirurgi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB).
    Disinhibition of human primary somatosensory cortex after median nerve transection and reinnervationManuskript (preprint) (Annet vitenskapelig)
  • 226.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Ljungberg, Christina
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Handkirurgi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Structural changes in hand related cortical areas after median nerve injury and repair2018Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikkel-id 4485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transection of the median nerve typically causes lifelong restriction of fine sensory and motor skills of the affected hand despite the best available surgical treatment. Inspired by recent findings on activity-dependent structural plasticity of the adult brain, we used voxel-based morphometry to analyze the brains of 16 right-handed adults who more than two years earlier had suffered injury to the left or right median nerve followed by microsurgical repair. Healthy individuals served as matched controls. Irrespective of side of injury, we observed gray matter reductions in left ventral and right dorsal premotor cortex, and white matter reductions in commissural pathways interconnecting those motor areas. Only left-side injured participants showed gray matter reduction in the hand area of the contralesional primary motor cortex. We interpret these effects as structural manifestations of reduced neural processing linked to restrictions in the diversity of the natural manual dexterity repertoire. Furthermore, irrespective of side of injury, we observed gray matter increases bilaterally in a motion-processing visual area. We interpret this finding as a consequence of increased neural processing linked to greater dependence on vision for control of manual dexterity after median nerve injury because of a compromised somatosensory innervation of the affected hand.

  • 227.
    Nordmark, Per F.
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Pruszynski, J. Andrew
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Roland S.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    BOLD Responses to Tactile Stimuli in Visual and Auditory Cortex Depend on the Frequency Content of Stimulation2012Inngår i: Journal of cognitive neuroscience, ISSN 0898-929X, E-ISSN 1530-8898, Vol. 24, nr 10, s. 2120-2134Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although some brain areas preferentially process information from a particular sensory modality, these areas can also respond to other modalities. Here we used fMRI to show that such responsiveness to tactile stimuli depends on the temporal frequency of stimulation. Participants performed a tactile threshold-tracking task where the tip of either their left or right middle finger was stimulated at 3, 20, or 100 Hz. Whole-brain analysis revealed an effect of stimulus frequency in two regions: the auditory cortex and the visual cortex. The BOLD response in the auditory cortex was stronger during stimulation at hearable frequencies (20 and 100 Hz) whereas the response in the visual cortex was suppressed at infrasonic frequencies (3 Hz). Regardless of which hand was stimulated, the frequency-dependent effects were lateralized to the left auditory cortex and the right visual cortex. Furthermore, the frequency-dependent effects in both areas were abolished when the participants performed a visual task while receiving identical tactile stimulation as in the tactile threshold-tracking task. We interpret these findings in the context of the metamodal theory of brain function, which posits that brain areas contribute to sensory processing by performing specific computations regardless of input modality.

  • 228.
    Nordström, Anna
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Rehabiliteringsmedicin. Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin.
    Edin, Benoni B.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Lindström, Sara
    Nordström, Peter
    Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Geriatrik.
    Cognitive function and other risk factors for mild traumatic brain injury in young men: nationwide cohort study2013Inngår i: BMJ. British Medical Journal, E-ISSN 1756-1833, Vol. 346, s. f723-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective To investigate cognitive function and other risk factors for mild traumatic brain injury in young men.

    Design Nationwide prospective cohort study.

    Setting Sweden.

    Participants 305 885 men conscripted for military service from 1989 to 1994.

    Main outcome measure mild traumatic brain injuries in relation to cognitive function and other potential risk factors assessed at conscription and follow-up.

    Results Men with one mild traumatic brain injury within two years before (n=1988) or after cognitive testing (n=2214) had about 5.5% lower overall cognitive function scores than did men with no mild traumatic brain injury during follow up (P<0.001 for both). Moreover, men with at least two mild traumatic brain injuries after cognitive testing (n=795) had 15% lower overall cognitive function scores compared with those with no such injury (P<0.001). Independent strong risk factors (P<1x10(-10)) for at least one mild traumatic brain injury after cognitive testing (n=12 494 events) included low overall cognitive function, a previous mild traumatic brain injury, hospital admission for intoxications, and low education and socioeconomic status. In a sub-cohort of twin pairs in which one twin had a mild traumatic brain injury before cognitive testing (n=63), both twins had lower logical performance and technical performance compared with men in the total cohort with no mild traumatic brain injury (P<0.05 for all).

    Conclusion Low cognitive function, intoxications, and factors related to low socioeconomic status were strong independent risk factors for mild traumatic brain injuries in men. The low cognitive function in twin pairs discordant for mild traumatic brain injury suggests a genetic component to the low cognitive function associated with such injuries. The study included only men, so inferences to women should be made with caution.

  • 229.
    Nyberg, Lars
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi.
    Den anpassningsbara hjärnan2004Inngår i: Stroke - ett slag mot hjärnan: Forskningens dag 2004, Medicinska fakulteten, Umeå , 2004, s. 37-45Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 230.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Functional imaging studies of intentional and incidental reactiviation: Implications for the bidning problem2006Inngår i: Handbook of binding and memory: Perspective from cognitive neuroscience, Oxford: Oxford University Press , 2006, s. 493-515Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 231.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Imaging cognition: Recent developments and a tentative hierarchiacal cognitive model2006Inngår i: Psychological Science around the world, Psychology Press , 2006Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
  • 232.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper.
    Impaired and intact cognitive functions in Alzheimer's disease.2008Inngår i: American Journal of Psychology, nr 49, s. 133-140Artikkel, omtale (Annet (populærvitenskap, debatt, mm))
  • 233.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Intact frontal memory effect in older age and dementia2004Inngår i: Neuron, ISSN 0896-6273, E-ISSN 1097-4199, Vol. 42, nr 5, s. 701-702Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Older adults and demented patients show preserved functioning on certain tests of implicit memory. In this issue of Neuron, Lustig and Buckner demonstrate that both groups show comparable repetition-based effects on response time and prefrontal activity relative to younger adults.

  • 234.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Introduction to the special section on "cognitive control"2009Inngår i: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 50, nr 1, s. 3-Artikkel i tidsskrift (Fagfellevurdert)
  • 235.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Kognitiv neurovetenskap: studier av sambandet mellan hjärnaktivitet och mentala processer2009 (oppl. 2)Bok (Annet vitenskapelig)
  • 236.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Micael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Forsgren, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap, Neurologi.
    Jakobson Mo, Susanna
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Marklund, Petter
    Nilsson, Lars-Göran
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Bäckman, Lars
    Striatal dopamine D2 binding is related to frontal BOLD response during updating of long-term memory representations.2009Inngår i: NeuroImage, ISSN 1053-8119, E-ISSN 1095-9572, Vol. 46, nr 4, s. 1194-1199Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi-modal brain imaging was used to examine the relation between individual differences in resting-state striatal dopamine D2 binding and the magnitude of prefrontal BOLD activation during updating of long-term memory (LTM) representations. Increased activity in the left prefrontal cortex was observed when LTM updating was required, and there was a positive correlation between striatal D2 activity and the magnitude of left prefrontal activity during updating. These findings support predictions from neurocomputational models of a relation of dopaminergic neurotransmission to transient cognitive operations and related brain activity.

  • 237.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bäckman, Lars
    Cognitive aging: A view from brain imaging2004Inngår i: New frontiers in cognitive aging, Oxford University Press, Oxford , 2004, s. 135-159Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The contributions in this volume, and numerous other journal articles and chapters, provide unequivocal evidence that cognitive functions decline across the adult lifespan Importantly, though, some cognitive functions are more affected than others For example, in recent work from the Betula project (Nilsson eta!, 1997), we contrasted episodic and semantic long term memory (Nyberg eta!, 2003) It was found that episodic memory performance deteriorated gradually from middle age through young-old age to old-old age By contrast, semantic memory performance increased from middle-age to young-old age, and the old-old participants performed at a level comparable to the middle aged (Figure 7 la) Furthermore, within the domam of episodic memory, increasing age was associated with a greater reduction of pei form ance on measures of recall compared to measures of recognition (Figure 7 ib) These results provide evidence that episodic long-term memory is more age-sensitive than semantic long-term memory, and that recall is more age-sensitive than recognition.

    These age-related long-term memory changes can be related to patterns of data in working-memory tasks (Gick, Crajic, and Morris, 1988) Working-memory tasks differ with regard to their demand on executive processing and it has been found that age differences are small when the executive demands are low, and substantial wlten such demands are high (see Morris, Gick and Craik, 1988). Many cognitive tasks require working memory functions to a smaller or greater extent, and it has been shown that working memory capacity accounts for a considerable portion of the variance in long-term memory tasks (Hultsch, I-Iertzog, and Dixon, 1990; Park eta!., 1996). Relatedly, the relationship between age and episodic memory has been found to be mediated by proficiency of executive functioning (Troyer, Graves, and Cullum, 1994).

  • 238.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Bäckman, Lars
    Influences of Biological and Self-Initiated Factors on Brain and Cognition in Adulthood and Aging2006Inngår i: Lifespan Development and the Brain: The Perspective of Biocultural Co-Constructivism / [ed] Paul B. Baltes, Patricia A. Reuter-Lorenz, Frank Rösler, Cambridge: Cambridge University Press, 2006, s. 239-254Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Age-related memory deficits are most pronounced on demanding tests of working memory and episodic memory, and are more pronounced in some older individuals than in others. In this chapter, we review individual-difference factors that influence memory functioning in adulthood and aging. A distinction is drawn between two categories of factors. The first includes biological factors that impose constraints by predisposing the aging brain toward cognitive decline. The second category includes a more heterogeneous collection of factors that are self-initiated and may be seen as offering possibilities rather than imposing constraints. We conclude by presenting some intriguing avenues for future research.

  • 239.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Bäckman, Lars
    Memory changes and the aging brain: a multimodal imaging approach2010Inngår i: Handbook of the psychology of aging / [ed] K.W Schaie & S L Willis, Elsevier Press , 2010, 7, s. 121-132Kapittel i bok, del av antologi (Fagfellevurdert)
  • 240.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Dahlin, Erika
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Stigsdotter Neely, Anna
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Bäckman, Lars
    Aging Research Center, Karolinska Institutet, Stockholm.
    Neural correlates of variable working memory load across adult age and skill: dissociative patterns within the fronto-parietal network2009Inngår i: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 50, nr 1, s. 41-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We examined neural changes related to variations in working memory load by using an n-back task with three levels and functional magnetic resonance imaging. Younger adults were divided into high- and low-performing groups (Young-High; Young-Low) and compared with older adults. Relative to Young-High, capacity-constraints in working memory were apparent between load 1-2 for the elderly and between load 2-3 for Young-Low. Capacity-constraints in neural activity followed this pattern by showing a monotonically increasing response in parietal cortex and thalamus for Young-High, whereas activity leveled off at 1-back for the elderly and at 2-back for Young-Low. The response in dorsal frontal cortex followed a similar pattern with the addition that the magnitude of activation differed within capacity limitations (Old > Young at 1-back; Young-Low > Young-High at 2-back). These findings indicate that an important determinant of WM capacity is the ability to keep the frontal cortex adequately engaged in relation to current task demands.

  • 241.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinsk fakultet, Integrativ medicinsk biologi, Fysiologi. Umeå universitet, Medicinsk fakultet, Strålningsvetenskaper, Diagnostisk radiologi.
    Habib, R
    Hemispheric Asymmetry of Memory.2008Inngår i: Encyclopedia of NeuroscienceArtikkel i tidsskrift (Fagfellevurdert)
  • 242.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Birgander, Richard
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Sundström, Torbjörn
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Riklund Åhlström, Katrine
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Comparing 1,5T and 3T BOLD fMRI imaging of finger tapping with familiar and novel sequences.2007Inngår i: Neuroscience Imaging, ISSN 1556-4010, Vol. 2, nr 1, s. 53-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It has been suggested that fMRI at 3T yields stronger and more extensive BOLD activations than fMRI at 1.5T, and that imaging at higher field strengths can reveal unique activations. In the present study we compared, within-subjects, activation patterns during a finger-tapping task at 1.5 and 3T. The data were analyzed with a random-effects model in SPM2. At a strict statistical level (p<0.05, FWE correction for multiple comparisons), ipsilateral cerebellar activation was revealed at 1.5T. At 3T, activation in sensory-motor regions in the contra-lateral cerebrum was identified in addition to the activation in cerebellum. At a less stringent statistical threshold, imaging at 1.5T and 3T revealed overlapping cortical regions with more extensive clusters at 3T. A similar pattern was seen in a comparison of familiar and novel sequences. However, subcortical activations of thalamus and parts of the basal ganglia were uniquely identified at 3T. Analyses at the individual level substantiated the group results by showing that the higher sensitivity of the 3T resulted in images with higher between-individual consistency in activation patterns.

  • 243.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Lövdén, Martin
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Riklund, Katrine
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi.
    Lindenberger, Ulman
    Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany.
    Bäckman, Lars
    Aging Research Center, Karolinska Institutet, Stockholm, Sweden.
    Memory aging and brain maintenance2012Inngår i: Trends in cognitive sciences, ISSN 1364-6613, E-ISSN 1879-307X, Vol. 16, nr 5, s. 292-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Episodic memory and working memory decline with advancing age. Nevertheless, large-scale population-based studies document well-preserved memory functioning in some older individuals. The influential 'reserve' notion holds that individual differences in brain characteristics or in the manner people process tasks allow some individuals to cope better than others with brain pathology and hence show preserved memory performance. Here, we discuss a complementary concept, that of brain maintenance (or relative lack of brain pathology), and argue that it constitutes the primary determinant of successful memory aging. We discuss evidence for brain maintenance at different levels: cellular, neurochemical, gray- and white-matter integrity, and systems-level activation patterns. Various genetic and lifestyle factors support brain maintenance in aging and interventions may be designed to promote maintenance of brain structure and function in late life.

  • 244.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    The APOE epsilon 4 allele in relation to brain white-matter microstructure in adulthood and aging2014Inngår i: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 55, nr 3, s. 263-267Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Apolipoprotein E (ApoE) epsilon 4 allele is a major genetic risk factor for sporadic Alzheimer's disease and has been associated with structural and functional brain alterations across the adult life span. Recent studies have presented evidence that epsilon 4 affects microstructural properties of brain white matter (WM) in non-demented carriers of the epsilon 4 allele, but conflicting evidence has been presented as well. The main purpose of the present study was therefore to examine ApoE effects on WM in a large sample of middle-aged and older adults (N=273). Diffusion tensor imaging (DTI) data was acquired, and tract-based as well as voxel-wise analyses were conducted. The tract-based analyses revealed no significant ApoE effects, and no significant interactions between genotype and age were observed. Taken together, the findings of the present study suggest that ApoE effects on white-matter microstructure are less abundant than has been suggested in some previous studies.

  • 245.
    Nyberg, Lars
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Salami, Alireza
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Andersson, Mikael
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Eriksson, Johan
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Kalpouzos, Grégoria
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB). Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Kauppi, Karolina
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Lind, Johanna
    Center for Study of Human Cognition, Department of Psychology, University of Oslo, Norway.
    Pudas, Sara
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Persson, Jonas
    Department of Psychology and Stockholm Brain Institute, Stockholm University, 106 91 Stockholm, Sweden .
    Nilsson, Lars-Göran
    Department of Psychology and Stockholm Brain Institute, Stockholm University, 106 91 Stockholm, Sweden .
    Longitudinal evidence for diminished frontal cortex function in aging2010Inngår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, nr 52, s. 22682-22686Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cross-sectional estimates of age-related changes in brain structure and function were compared with 6-y longitudinal estimates. The results indicated increased sensitivity of the longitudinal approach as well as qualitative differences. Critically, the cross-sectional analyses were suggestive of age-related frontal overrecruitment, whereas the longitudinal analyses revealed frontal underrecruitment with advancing age. The cross-sectional observation of overrecruitment reflected a select elderly sample. However, when followed over time, this sample showed reduced frontal recruitment. These findings dispute inferences of true age changes on the basis of age differences, hence challenging some contemporary models of neurocognitive aging, and demonstrate age-related decline in frontal brain volume as well as functional response.

  • 246.
    Ohki, Yukari
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Edin, Benoni B
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Johansson, Roland S
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Predictions specify reactive control of individual digits in manipulation.2002Inngår i: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 22, nr 2, s. 600-10Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When humans proactively manipulate objects, the applied fingertip forces primarily depend on feedforward, predictive neural control mechanisms that depend on internal representations of the physical properties of the objects. Here we investigate whether predictions of object properties also control fingertip forces that subjects generate reactively. We analyzed fingertip forces reactively supporting grasp stability in a restraining task that engaged two fingers. Each finger contacted a plate mounted on a separate torque motor, and, at unpredictable times, both plates were loaded simultaneously with forces tangential to the plates or just one of the plates was loaded. Thus, the apparatus acted as though the plates were mechanically linked or as though they were two independent objects. In different test series, each with a predominant behavior of the apparatus and with interspersed catch trials, we showed that the reactive responses clearly reflected the predominant behavior of the apparatus. Whether subject performed the task with one hand or bimanually, appropriate reactive fingertip forces developed when predominantly both contact plates were loaded or just one of the plates was loaded. When a finger was unexpectedly loaded during a catch trial, a weak initial reactive response was triggered, but the effective force development was delayed by approximately 100 msec. We conclude that the predicted physical properties of an object not only control fingertip forces during proactive but also in reactive manipulative tasks. Specifically, the automatic reactive responses reflect predictions at the level of individual digits as to the mechanical linkage of items contacted by the fingertips in manipulation.

  • 247.
    Olsson, Carl-Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Jonsson, Bert
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för psykologi.
    Larsson, Anne
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Motor representations and practice affect brain systems underlying imagery: an FMRI study of internal imagery in novices and active high jumpers2008Inngår i: The Open Neuroimaging Journal, ISSN 1874-4400, E-ISSN 1874-4400, Vol. 2, s. 5-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study used functional magnetic resonance imaging (fMRI) to investigate differences in brain activity between one group of active high jumpers and one group of high jumping novices (controls) when performing motor imagery of a high jump. It was also investigated how internal imagery training affects neural activity. The results showed that active high jumpers primarily activated motor areas, e.g. pre-motor cortex and cerebellum. Novices activated visual areas, e.g. superior occipital cortex. Imagery training resulted in a reduction of activity in parietal cortex. These results indicate that in order to use an internal perspective during motor imagery of a complex skill, one must have well established motor representations of the skill which then translates into a motor/internal pattern of brain activity. If not, an external perspective will be used and the corresponding brain activation will be a visual/external pattern. Moreover, the findings imply that imagery training reduces the activity in parietal cortex suggesting that imagery is performed more automatic and results in a more efficient motor representation more easily accessed during motor performance.

  • 248.
    Olsson, Carl-Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för kirurgisk och perioperativ vetenskap, Idrottsmedicin. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Brain simulation of action may be grounded in physical experience2011Inngår i: Neurocase, ISSN 1355-4794, E-ISSN 1465-3656, Vol. 17, nr 6, s. 501-505Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An intriguing quality of our brain is that when actions are imagined, corresponding brain regions are recruited as when the actions are actually performed. It has been hypothesized that the similarity between real and simulated actions depends on the nature of motor representations. Here we tested this hypothesis by examining S.D., who never used her legs but is an elite wheel chair athlete. Controls recruited motor brain regions during imagery of stair walking and frontal regions during imagery of wheel chair slalom. S.D. showed the opposite pattern. Thus, brain simulation of actions may be grounded in specific physical experiences.

  • 249.
    Olsson, Carl-Johan
    et al.
    Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI). Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Nyberg, Lars
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi. Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Diagnostisk radiologi. Umeå universitet, Medicinska fakulteten, Umeå centrum för funktionell hjärnavbildning (UFBI).
    Motor imagery: if you can't do it, you won't think it2010Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 20, nr 5, s. 711-715Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Since long, motor imagery has been recognized as a method for studying motor representations. In the last few years, important advances regarding the use of motor imagery have been made. In particular, issues concerning the functional equivalence between imagery and action have been addressed, and how equivalence affects the use of imagery to study motor representations. In this paper, we review recent findings in order to highlight the current state of knowledge about motor imagery and its relation to motor action. Three topics are discussed: (i) the imagery perspective, (ii) task complexity, and (iii) the importance of physical experience. It is shown how theses factors are closely related and how previous studies may have underestimated to what extent these factors affect the interpretation of results. Practical implications for imagery interventions are considered. It is concluded that if you cannot perform an action physically, you cannot imagine it in a way that is necessary for a high degree of functional equivalence.

  • 250.
    Olsson, Kurt Å.
    Umeå universitet, Medicinska fakulteten, Institutionen för integrativ medicinsk biologi (IMB), Fysiologi.
    Hypothalamic and cortical control of jaw reflexes1979Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed.

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