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Query: UNIPROT:Q16637 (SMA)
 8,107 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neural activity during the delay period of spatial delayed response (DR) and delayed matching (DM) tasks was investigated by positron emission tomography. A distributed cortical system was activated in each condition. The bilateral dorsolateral prefrontal cortex (DLPFC) was activated in the delay period of both tasks; activation was of higher significance on the right in the DR task and the left in the DM task, and extended to the anterolateral prefrontal cortex in the DM condition. Active representation of spatial location in the DR task was associated with co-activation of the medial and lateral parietal cortex and the extrastriate visual cortex. Active representation of shape in the DM task was associated with co-activation of medial and lateral parietal cortex and the inferior temporal cortex. Response-related activity was observed in both tasks. Activation of anterior cingulate, inferior frontal, lateral promotor and rostral inferior parietal cortex was observed in the DR condition, a task characterized by preparation of a movement to a predetermined location. In contrast, preparation to move to an undetermined location in the DM task was associated with activation predominantly in rostral SMA.
Cereb Cortex
PMID:Active representation of shape and spatial location in man. 867 Jun 86

Repetitive passive movements are part of most rehabilitation procedures, especially in patients with stroke and motor deficit. However, little is known about the consequences of repeated proprioceptive stimulations on the intracerebral sensorimotor network in humans. Twelve healthy subjects were enrolled, and all underwent two functional magnetic resonance imaging (fMRI) sessions separated by a 1-month interval. Passive daily movement training was performed in six subjects during the time between the two fMRI sessions. The other six subjects had no training and were considered as the control group. The task used during fMRI was calibrated repetitive passive flexion-extension of the wrist similar to those performed during training. The control task was rest. The data were analyzed with SPM96 software. Images were realigned, smoothed, and put into Talairach's neuroanatomical space. The time effect from the repetition of the task was assessed in the control group by comparing activation versus rest in the second session with activation versus rest in the first session. This time effect then was used as null hypothesis to assess the training effect alone in our trained group. Passive movements compared with rest showed activation of most of the cortical areas involved in motor control (i.e., contralateral primary sensorimotor cortex, supplementary motor area [SMA], cingulum, Brodmann area 40, ipsilateral cerebellum). Time effect comparison showed a decreased activity of the primary sensorimotor cortex and SMA and an increased activity of ipsilateral cerebellar hemisphere, compatible with a habituation effect. Training brought about an increased activity of contralateral primary sensorimotor cortex and SMA. A redistribution of SMA activity was observed. The authors demonstrated that passive training with repeated proprioceptive stimulation induces a reorganization of sensorimotor representation in healthy subjects. These changes take place in cortical areas involved in motor preparation and motor execution and represent the neural basis of proprioceptive training, which might benefit patients undergoing rehabilitative procedures.
J Cereb Blood Flow Metab 2000 Mar
PMID:Neural substrate for the effects of passive training on sensorimotor cortical representation: a study with functional magnetic resonance imaging in healthy subjects. 1072 12

Lesion and imaging studies have suggested that the premotor cortex (PMC) is a crucial component in the neural network underlying the processing of sequential information. However, whether different aspects of sequential information like interval and ordinal properties are supported by different anatomical regions, and whether the representation of sequential information within the PMC is necessarily related to motor requirements, remain open questions. Brain activations were investigated during a sequence encoding paradigm in 12 healthy subjects using functional magnetic resonance imaging. Subjects had to attend either to the interval or to the ordinal information of a sequence of visually presented stimuli and had to encode the relevant information either before motor reproduction or before perceptual monitoring. Although interval and ordinal information led to activations within the same neural network, direct comparisons revealed significant differences. The pre-supplementary motor area (preSMA), the lateral PMC, the frontal opercular cortex as well as basal ganglia and the left lateral cerebellar cortex (CE) were activated significantly more strongly by interval information, whereas the SMA, the frontal eye field, the primary motor cortex (MI), the primary somatosensory cortex, the cuneus as well as the medial CE and the thalamus were activated more strongly by ordinal information. In addition, serial encoding before reproduction led to higher activations than serial encoding before monitoring in the preSMA, SMA, MI and medial CE. Our findings suggest overlapping but different kinds of sequential representation, depending on both the ordinal and interval aspects as well as motor requirements.
Cereb Cortex 2001 Mar
PMID:Interval and ordinal properties of sequences are associated with distinct premotor areas. 1123 93

Recent evidence indicates that classical 'motor' areas may also have cognitive functions. We performed three neuroimaging experiments to investigate the functional neuroanatomy underlying three types of nonmotor mental-operation tasks: numerical, verbal, and spatial. (i) Positron emission tomography showed that parts of the posterior frontal cortex, which are consistent with the pre-supplementary motor area (pre-SMA) and the rostral part of the dorsolateral premotor cortex (PMdr), were active during all three tasks. We also observed activity in the posterior parietal cortex and cerebellar hemispheres during all three tasks. Electrophysiological monitoring confirmed that there were no skeletomotor, oculomotor or articulatory movements during task performance. (ii) Functional magnetic resonance imaging (fMRI) showed that PMdr activity during the mental-operation tasks was localized in the depths of the superior precentral sulcus, which substantially overlapped the region active during complex finger movements and was located dorsomedial to the presumptive frontal eye fields. (iii) Single-trial fMRI showed a transient increase in activity time-locked to the performance of mental operations in the pre-SMA and PMdr. The results of the present study suggest that the PMdr is important in the rule-based association of symbolic cues and responses in both motor and nonmotor behaviors.
Cereb Cortex 2002 Nov
PMID:The role of rostral Brodmann area 6 in mental-operation tasks: an integrative neuroimaging approach. 1237 4

We used positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) in human subjects to investigate whether the ventral and dorsal visual stream cooperate when active judgements about color have to be made. Color was used as the attribute, because it is processed primarily in the ventral stream. The centrally positioned stimuli were equiluminant shades of brown. The successive color discrimination task was contrasted to a dimming detection task, in which retinal input was identical but with double the number of motor responses. The stimulus presentation rate was parametrically varied and a constant performance level was obtained for all conditions. The visual activation sites were identified by retinotopic mapping and cortical flattening. In addition, one psychophysical and two fMRI experiments were performed to control for differences in visuospatial attention and motor output. Successive color discrimination involved early visual areas, including V1 and VP and the ventral color-responsive region, as well as anterior and middle dorsal intraparietal sulcus, dorsal premotor cortex and pre-SMA. Cortical regions involved in dimming detection and motor output included area V3A, hMT/V5+, lateral occipital sulcus, posterior dorsal intraparietal sulcus, primary motor cortex and SMA. These experiments demonstrated that even with color as the attribute, successive discrimination, in which a decision process has to link visual signals to motor responses, involves both ventral and dorsal visual stream areas.
Cereb Cortex 2004 Jul
PMID:Color discrimination involves ventral and dorsal stream visual areas. 1505 55

Three previous studies using the GO/NOGO task were examined to characterize the pattern of functional activation seen during error-related processing. The large sample size (n = 44) also allowed investigation of the influence of individual differences in age, sex, self-reported absentmindedness and reaction speed on the level of activation. Errors were seen to activate a network of regions including the anterior cingulate cortex (ACC), pre-supplementary motor area (pre-SMA), bilateral insula, thalamus and right inferior parietal lobule. Split-half comparisons performed for each of the individual difference variables indicated greater ACC and pre-SMA activation for older subjects while slower responders showed greater activation in the parietal, lateral PFC, insula and ACC regions. Whereas males and females demonstrated equivalent levels of activation in both the ACC and insula, self-reported absentmindedness related to reduced activation in these regions. Our review of the current imaging literature on error-related activation indicates that, despite the use of a variety of other cognitive paradigms, the network of regions identified here is consistent with these previous studies, suggesting that these regions are critical to a 'general' error-related response. Furthermore, this response is, in part, influenced by individual differences in both demographic characteristics and behavioural performance.
Cereb Cortex 2004 Sep
PMID:Individual differences in error processing: a review and reanalysis of three event-related fMRI studies using the GO/NOGO task. 1511 34

Human behavior can be influenced by information that is not consciously perceived. Recent behavioral and electrophysiological evidence suggests, however, that the processing of subliminal stimuli is not completely beyond an observer's conscious control. The present study aimed to characterize the cortical network that implements strategic control over interfering subliminal information at multiple stages. Fourteen participants underwent functional magnetic resonance imaging (fMRI) scanning while performing a metacontrast masking paradigm. We systematically varied the amount of conflicting versus non-conflicting trials across experimental blocks, and behavioral performance demonstrated strategic effects whenever a high proportion of subliminal prime stimuli induced response competition. A psychophysiological interaction analysis revealed the pre-supplementary motor area (pre-SMA) to exhibit context-dependent covariation with activation in the lateral occipital complex (LOC) and the putamen. The pre-SMA thereby appears to fulfill a superordinate function in the control of processing subliminal information by simultaneously modulating perceptual analysis and motor selection.
Cereb Cortex 2006 Jun
PMID:Changes in connectivity profiles as a mechanism for strategic control over interfering subliminal information. 1613 79

Event-related functional magnetic resonance imaging was used to investigate brain processing of the signals ascending from peripheral C and Adelta fibers evoked by phasic laser stimuli on the right hand in humans. The stimulation of both C and Adelta nociceptors activated the bilateral thalamus, bilateral secondary somatosensory cortex, right (ipsilateral) middle insula, and bilateral Brodmann's area (BA) 24/32, with the majority of activity found in the posterior portion of the anterior cingulate cortex (ACC). However, magnitude of activity in the right (ipsilateral) BA32/8/6, including dorsal parts in the anterior portion of the ACC (aACC) and pre-supplementary motor area (pre-SMA), and the bilateral anterior insula was significantly stronger following the stimulation of C nociceptors than Adelta nociceptors. It was concluded that the activation of C nociceptors, related to second pain, evokes different brain processing from that of Adelta nociceptors, related to first pain, probably due to the differences in the emotional and motivational aspects of either pain, which are mainly related to the aACC, pre-SMA, and anterior insula.
Cereb Cortex 2006 Sep
PMID:Brain processing of the signals ascending through unmyelinated C fibers in humans: an event-related functional magnetic resonance imaging study. 1628 Apr 63

The inhibition of speech acts is a critical aspect of human executive control over thought and action, but its neural underpinnings are poorly understood. Using functional magnetic resonance imaging and the stop-signal paradigm, we examined the neural correlates of speech control in comparison to manual motor control. Initiation of a verbal response activated left inferior frontal cortex (IFC: Broca's area). Successful inhibition of speech (naming of letters or pseudowords) engaged a region of right IFC (including pars opercularis and anterior insular cortex) as well as presupplementary motor area (pre-SMA); these regions were also activated by successful inhibition of a hand response (i.e., a button press). Moreover, the speed with which subjects inhibited their responses, stop-signal reaction time, was significantly correlated between speech and manual inhibition tasks. These findings suggest a functional dissociation of left and right IFC in initiating versus inhibiting vocal responses, and that manual responses and speech acts share a common inhibitory mechanism localized in the right IFC and pre-SMA.
Cereb Cortex 2008 Aug
PMID:Common neural substrates for inhibition of spoken and manual responses. 1824 44

Fluid intelligence (g(f)) influences performance across many cognitive domains. It is affected by both genetic and environmental factors. Tasks tapping g(f) activate a network of brain regions including the lateral prefrontal cortex (LPFC), the presupplementary motor area/anterior cingulate cortex (pre-SMA/ACC), and the intraparietal sulcus (IPS). In line with the "intermediate phenotype" approach, we assessed effects of a polymorphism (val(158)met) in the catechol-O-methyltransferase (COMT) gene on activity within this network and on actual task performance during spatial and verbal g(f) tasks. COMT regulates catecholaminergic signaling in prefrontal cortex. The val(158) allele is associated with higher COMT activity than the met(158) allele. Twenty-two volunteers genotyped for the COMT val(158)met polymorphism completed high and low g(f) versions of spatial and verbal problem-solving tasks. Our results showed a positive effect of COMT val allele load upon the blood oxygen level-dependent response in LPFC, pre-SMA/ACC, and IPS during high g(f) versus low g(f) task performance in both spatial and verbal domains. These results indicate an influence of the COMT val(158)met polymorphism upon the neural circuitry supporting g(f). The behavioral effects of val allele load differed inside and outside the scanner, consistent with contextual modulation of the relation between COMT val(158)met genotype and g(f) task performance.
Cereb Cortex 2008 Sep
PMID:COMT val158met genotype affects recruitment of neural mechanisms supporting fluid intelligence. 1825 43


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