Cerebral and clinical effects of short-term hand immobilisation

In this work, functional changes in the sensorimotor cortex following unilateral hand immobilisation were investigated in 11 healthy volunteers. Sensory and motor function of both hands was also assessed. Cortical activation was monitored with functional magnetic resonance imaging at 3 T. All examinations were performed prior to and directly after 72 h of immobilisation of the dominant hand and wrist. Following unilateral immobilisation, cortical activation increased substantially during tactile stimulation of the non-immobilised hand. This was particularly evident in the ipsilateral somatosensory cortex. Additionally, a redistribution of hemispheric dominance towards zero lateralisation was seen. A bilateral cortical activation increase was also seen during performance of a finger-tapping task by the non-immobilised hand, although this increase was less prominent than during tactile stimulation. In contrast, performance of the finger-tapping task with the immobilised hand resulted in an activation decrease, predominantly in the ipsilateral sensorimotor cortex. This site was anatomically close to the regional activation increase of the non-immobilised hand. These functional changes were associated with reduced grip strength, dexterity and tactile discrimination of the immobilised hand, and simultaneously improved tactile discrimination of the non-immobilised hand. This suggests that brain adaptation following hand immobilisation includes inter-hemispheric dynamics. In summary, the improved sensory function of the non-immobilised hand following unilateral immobilisation is associated with cortical expansion, predominantly contralateral to the immobilised hand, and a redistribution of hemispheric dominance. Both cortical and clinical effects of immobilisation were identified after 72 h, suggesting rapid inter-hemispheric plasticity using existing neural substrates.     

Reorganisation of the sensorimotor cortex after early focal brain lesion: a functional MRI study in monozygotic twins

Sensorimotor cortical reorganization after early brain lesions was studied by means of fMRI in two pairs of monozygotic twins, in each of which one member had a focal brain injury. This offered a unique opportunity to reduce the wide intersubject variability of the controls often found in similar studies. Activation images were acquired during a motor task (sequential opposition finger movements) and a sensory task (passive brushing of palm and fingers). During the tasks with the recovered hand, constant findings in the lesioned subjects were the activation of the undamaged areas adjacent to lesion site and the activation of the ipsilateral sensorimotor cortex. Bilateral activation of the primary sensorimotor cortex was never observed in the healthy co-twin controls.     

Neural substrate for the effects of passive training on sensorimotor cortical representation: a study with functional magnetic resonance imaging in healthy subjects.

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.     

BOLD fMRI signal increases with age in selected brain regions in children

To determine whether the BOLD signal used in fMRI is age dependent in childhood, 332 healthy children (age 4.9-18.9 years) performed tasks in a periodic block design during 3 T fMRI: (1) a verb generation task interleaved with a finger tapping task; (2) a word-picture matching task interleaved with an image discrimination task. Significant correlations between percent signal change in BOLD effect and age occurred in left Broca's, middle frontal, Wernicke's, and inferior parietal regions, and anterior cingulate during the verb generation task; in precentral, postcentral, middle frontal, supplementary motor, and precuneus regions during the finger tapping task; and in bilateral lingula gyri during the word-picture matching task. Thus, BOLD effect increases with age in children during sensorimotor and language tasks.     

Neural substrates of tactile object recognition: an fMRI study

A functional magnetic resonance imaging (fMRI) study was conducted during which seven subjects carried out naturalistic tactile object recognition (TOR) of real objects. Activation maps, conjunctions across subjects, were compared between tasks involving TOR of common real objects, palpation of "nonsense" objects, and rest. The tactile tasks involved similar motor and sensory stimulation, allowing higher tactile recognition processes to be isolated. Compared to nonsense object palpation, the most prominent activation evoked by TOR was in secondary somatosensory areas in the parietal operculum (SII) and insula, confirming a modality-specific path for TOR. Prominent activation was also present in medial and lateral secondary motor cortices, but not in primary motor areas, supporting the high level of sensory and motor integration characteristic of object recognition in the tactile modality. Activation in a lateral occipitotemporal area associated previously with visual object recognition may support cross-modal collateral activation. Finally, activation in medial temporal and prefrontal areas may reflect a common final pathway of modality-independent object recognition. This study suggests that TOR involves a complex network including parietal and insular somatosensory association cortices, as well as occipitotemporal visual areas, prefrontal, and medial temporal supramodal areas, and medial and lateral secondary motor cortices. It confirms the involvement of somatosensory association areas in the recognition component of TOR, and the existence of a ventrolateral somatosensory pathway for TOR in intact subjects. It challenges the results of previous studies that emphasize the role of visual cortex rather than somatosensory association cortices in higher-level somatosensory cognition.     

Effects of visual information regarding tactile stimulation on the somatosensory cortical activation:a functional MRI study

Many studies have investigated the evidence for tactile and visual interactive responses to activation of various brain regions. However, few studies have reported on the effects of visuo-tactile multisensory inte-gration on the amount of brain activation on the somatosensory cortical regions. The aim of this study was to examine whether coincidental information obtained by tactile stimulation can affect the somatosensory cortical activation using functional MRI. Ten right-handed healthy subjects were recruited for this study. Two tasks (tactile stimulation and visuotactile stimulation) were performed using a block paradigm during fMRI scanning. In the tactile stimulation task, in subjects with eyes closed, tactile stimulation was applied on the dorsum of the right hand, corresponding to the proximal to distal directions, using a rubber brush. In the visuotactile stimulation task, tactile stimulation was applied to observe the attached mirror in the MRI chamber reflecting their hands being touched with the brush. In the result of SPM group analysis, we found brain activation on the somatosensory cortical area. Tactile stimulation task induced brain acti-vations in the left primary sensory-motor cortex (SM1) and secondary somatosensory cortex (S2). In the visuo-tactile stimulation task, brain activations were observed in the both SM1, both S2, and right posterior parietal cortex. In all tasks, the peak activation was detected in the contralateral SM1. We examined the ef-fects of visuo-tactile multisensory integration on the SM1 and found that visual information during tactile stimulation could enhance activations on SM1 compared to the tactile unisensory stimulation.     

Functional MRI cerebral activation and deactivation during finger movement

OBJECTIVE: To examine interhemispheric interactions of motor processes by using functional MRI (fMRI). BACKGROUND: Despite evidence of interhemispheric inhibition from animal, clinical, and transcranial magnetic stimulation (TMS) studies, fMRI has not been used to explore activation and deactivation during unilateral motor tasks. fMRI changes associated with motor activity have traditionally been described by comparing cerebral activation during motor tasks relative to a "resting state." In addition to this standard comparison, we examined fMRI changes in the resting state relative to a motor task. METHODS: Thirteen healthy volunteers performed self-paced sequential finger/thumb tapping for each hand. During fMRI data acquisition, four epochs were obtained; each comprised of 30 seconds of rest, 30 seconds of right hand activity, and 30 seconds of left hand activity. Resultant echoplanar images were spatially normalized and spatially and temporally smoothed. RESULTS: As expected, hand movements produced activation in the contralateral sensorimotor cortex and adjacent subcortical regions and, when present, the ipsilateral cerebellum. However, hand movement also produced a significant deactivation (i.e., decreased blood flow) in the ipsilateral sensorimotor cortex and subcortical regions, and when present, the contralateral cerebellum. Conjunction analysis demonstrated regions that are activated by one hand and deactivated by the contralateral hand. CONCLUSION: Unilateral hand movements are associated with contralateral cerebral activation and ipsilateral cerebral deactivation, which we hypothesize result from transcallosal inhibition.     

Mapping the pathways of information processing from sensation to action in four distinct sensorimotor tasks

Two sensorimotor tasks that share neither sensory nor motor modality can interfere with one another when they are performed simultaneously. A possible cause for this interference is the recruitment of common brain regions by these two tasks, thereby creating a bottleneck of information processing. This hypothesis predicts that such “bottleneck” regions would be activated by each task even when they are performed separately. To test this prediction, we sought to identify, with fMRI, brain regions commonly activated by sensorimotor tasks that share neither sensory input nor motor output. One group of subjects was scanned while they performed in separate runs an auditory‐vocal (AVo) task and a visuo‐manual (ViM) task, while a second group of subjects performed the reversed sensorimotor mapping tasks (AM and ViVo). The results revealed strong activation preferences in specific sensory and motor cortical areas for each sensory and motor modality. By contrast, the posterior portion of the lateral prefrontal cortex (pLPFC), anterior insula, and, less consistently, the anterior cingulate, presupplementary and supplementary motor areas, and subcortical areas were commonly activated across all four sensorimotor tasks. These results were observed in both blocked and event‐related fMRI designs, in both 3D‐group averaged and 2D‐individual subject analyses, and were replicated within individuals across scanning sessions. These findings not only suggest that these brain regions serve a common amodal function in sensorimotor tasks, they also point to these regions—particularly, the pLPFC and anterior insula—as candidate neural substrates underlying a central hub of information processing in the human brain. Hum Brain Mapp, 2009. © 2009 Wiley‐Liss, Inc.     

How does brain activation differ in children with unilateral cerebral palsy compared to typically developing children, during active and passive movements, and tactile stimulation? An fMRI study

The aim of the functional magnetic resonance imaging (fMRI) study was to investigate brain activation associated with active and passive movements, and tactile stimulation in 17 children with right-sided unilateral cerebral palsy (CP), compared to 19 typically developing children (TD). The active movements consisted of repetitive opening and closing of the hand. For passive movements, an MRI-compatible robot moved the finger up and down. Tactile stimulation was provided by manually stroking the dorsal surface of the hand with a sponge cotton cloth. In both groups, contralateral primary sensorimotor cortex activation (SM1) was seen for all tasks, as well as additional contralateral primary somatosensory cortex (S1) activation for passive movements. Ipsilateral cerebellar activity was observed in TD children during all tasks, but only during active movements in CP children. Of interest was additional ipsilateral SM1 recruitment in CP during active movements as well as ipsilateral S1 activation during passive movements and tactile stimulation. Another interesting new finding was the contralateral cerebellum activation in both groups during different tasks, also in cerebellar areas not primarily linked to the sensorimotor network. Active movements elicited significantly more brain activation in CP compared to TD children. In both groups, active movements displayed significantly more brain activation compared to passive movements and tactile stimulation.     

Non-effective increase of fMRI-activation for motor performance in elder individuals

Motor performance declines with increasing age and it has been proposed that elder people might compensate for these deficits with increased cerebral activation. However, it is not known, whether increased activation - especially in motor areas of the contralateral and the ipsilateral cerebral hemisphere - might effectively contribute to motor performance or whether it is an ineffective way to counteract age related deficits in the motor system. We tested this question by mapping brain activation during performance of differentially demanding motor tasks in 18 young (mean 25.39 years) and 17 elderly (mean 66.65 years) healthy individuals. We tested a wide range of hand motor tasks from passive wrist movements, fist clenching at different frequencies, to a somatosensory-guided finger pinch task. In the elderly group functional activation was generally increased for all tasks with comparable motor performance for ipsilateral primary and secondary motor areas. The young group showed increased contralateral primary motor cortex activation for the more difficult somatosensory guided precision grip task. We correlated motor performance of the task with high difficulty and comparable performance with fMRI-activation. Elder participants showed a negative correlation for the ipsilateral supplementary motor area (SMA) and for the ipsilateral sensorimotor cortex (SM1). Young participants showed a positive correlation for contralateral SMA and SM1. Our data suggest an increased cerebral recruitment reflects an inefficient response to an age-related higher difficulty of task and is not an effective way to counteract age-related deficits in the motor system.     

How does brain activation differ in children with unilateral cerebral palsy compared to typically developing children,during active and passive movements,and tactile stimulation? An fMRI study

The aim of the functional magnetic resonance imaging (fMRI) study was to investigate brain activation associated with active and passive movements, and tactile stimulation in 17 children with right-sided unilateral cerebral palsy (CP), compared to 19 typically developing children (TD). The active movements consisted of repetitive opening and closing of the hand. For passive movements, an MRI-compatible robot moved the finger up and down. Tactile stimulation was provided by manually stroking the dorsal surface of the hand with a sponge cotton cloth. In both groups, contralateral primary sensorimotor cortex activation (SM1) was seen for all tasks, as well as additional contralateral primary somatosensory cortex (S1) activation for passive movements. Ipsilateral cerebellar activity was observed in TD children during all tasks, but only during active movements in CP children. Of interest was additional ipsilateral SM1 recruitment in CP during active movements as well as ipsilateral S1 activation during passive movements and tactile stimulation. Another interesting new finding was the contralateral cerebellum activation in both groups during different tasks, also in cerebellar areas not primarily linked to the sensorimotor network. Active movements elicited significantly more brain activation in CP compared to TD children. In both groups, active movements displayed significantly more brain activation compared to passive movements and tactile stimulation.     

A PET Study of Somatosensory Discrimination in Man. Microgeometry Versus Macrogeometry

The regional cerebral blood flow (rCBF) was measured with ¹⁵O-butanol and positron emission tomography (PET) in 10 healthy subjects in order to compare cerebral activation involved in the somatosensory discrimination of microgeometric features with cerebral activation associated with the discrimination of macrogeometric features. Subjects performed two-alternative forced choice (2-AFC) discriminations of pairs of stimuli from a series of quantified standardized stimuli that differed in roughness (microgeometry), and a separate 2-AFC task of smooth tactile stimuli that differed in length (macrogeometry). Results are presented from three conditions: (1) a roughness discrimination task; (2) a length discrimination task; and (3) a control trial in which subjects were required to reproduce similar exploratory finger movements only, but without a specific stimulus to feel. Mean subtraction images were computed using the computerized adjustable brain atlas of Greitz et al. (1991, J. Comput. Assisted Tomogr., 15, 26–38) and areas of significant blood flow change were identified. Both the roughness and the length discrimination tasks activated overlapping cortical fields contralaterally in the anterior and posterior lip of the postcentral sulcus. However, in the length discrimination, activation of the posterior lip of the postcentral sulcus extended deeper into the sulcus and there was also a separate additional area of activation in the anterior part of the precentral gyrus. Furthermore, the length discrimination task activated fields in the overt part of the supramarginal gyrus bilaterally as well as fields in the angular gyrus bilaterally. Thus roughness discrimination uses only a subset of the cortical regions that are needed for the recovery of length information, which requires more extensive somatosensory processing. This finding may be partly explained in that length perception needs both edge detection of the stimuli used, as well as integrated information of surface length and velocity, which is not necessary for roughness perception. Specific differences in the acquisition of necessary tactile information between the two discrimination tasks was reflected in different sampling strategies.     

Altered sensorimotor activation patterns in idiopathic dystonia—an activation likelihood estimation meta‐analysis of functional brain imaging studies

Dystonia is characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements or postures. Functional neuroimaging studies have yielded abnormal task‐related sensorimotor activation in dystonia, but the results appear to be rather variable across studies. Further, study size was usually small including different types of dystonia. Here we performed an activation likelihood estimation (ALE) meta‐analysis of functional neuroimaging studies in patients with primary dystonia to test for convergence of dystonia‐related alterations in task‐related activity across studies. Activation likelihood estimates were based on previously reported regional maxima of task‐related increases or decreases in dystonia patients compared to healthy controls. The meta‐analyses encompassed data from 179 patients with dystonia reported in 18 functional neuroimaging studies using a range of sensorimotor tasks. Patients with dystonia showed bilateral increases in task‐related activation in the parietal operculum and ventral postcentral gyrus as well as right middle temporal gyrus. Decreases in task‐related activation converged in left supplementary motor area and left postcentral gyrus, right superior temporal gyrus and dorsal midbrain. Apart from the midbrain cluster, all between‐group differences in task‐related activity were retrieved in a sub‐analysis including only the 14 studies on patients with focal dystonia. For focal dystonia, an additional cluster of increased sensorimotor activation emerged in the caudal cingulate motor zone. The results show that dystonia is consistently associated with abnormal somatosensory processing in the primary and secondary somatosensory cortex along with abnormal sensorimotor activation of mesial premotor and right lateral temporal cortex. Hum Brain Mapp 37:547–557, 2016. © 2015 Wiley Periodicals, Inc.     

Modulatory effects of 5Hz rTMS over the primary somatosensory cortex in focal dystonia—An fMRI‐TMS study

Dystonia is associated with impaired somatosensory ability. The electrophysiological method of repetitive transcranial magnetic stimulation (rTMS) can be used for noninvasive stimulation of the human cortex and can alter cortical excitability and associated behavior. Among others, rTMS can alter/improve somatosensory discrimation abilities, as shown in healthy controls. We applied 5Hz‐rTMS over the left primary somatosensory cortex (S1) in 5 patients with right‐sided writer's dystonia and 5 controls. We studied rTMS effects on tactile discrimination accuracy and concomitant rTMS‐induced changes in hemodynamic activity measured by functional magnetic resonance imaging (fMRI). Before rTMS, patients performed worse on the discrimination task than controls even though fMRI showed greater task‐related activation bilaterally in the basal ganglia (BG). In controls, rTMS led to improved discrimination; fMRI revealed this was associated with increased activity of the stimulated S1, bilateral premotor cortex and BG. In dystonia patients, rTMS had no effect on discrimination; fMRI showed similar cortical effects to controls except for no effects in BG. Improved discrimination after rTMS in controls is linked to enhanced activation of S1 and BG. Failure of rTMS to increase BG activation in dystonia may be associated with the lack of effect on sensory discrimination in this group and may reflect impaired processing in BG‐S1 connections. Alternatively, the increased BG activation seen in the baseline state without rTMS may reflect a compensatory strategy that saturates a BG contribution to this task. © 2010 Movement Disorder Society     

Within-session and between-session reproducibility of cerebral sensorimotor activation: a test--retest effect evidenced with functional magnetic resonance imaging.

The aim of the current study was to assess the reproducibility of functional magnetic resonance imaging (fMRI) brain activation signals in a sensorimotor task in healthy subjects. Because random or systematic changes are likely to happen when movements are repeated over time, the authors searched for time-dependent changes in the fMRI signal intensity and the extent of activation within and between sessions. Reproducibility was studied on a sensorimotor task called "the active task" that includes a motor output and a sensory feedback, and also on a sensory stimulation called "the passive task" that assessed the sensory input alone. The active task consisted of flexion and extension of the right hand. The subjects had performed it several times before fMRI scanning so that it was well learned. The passive task consisted of a calibrated passive flexion and extension of the right wrist. Tasks were 1 Hz-paced. The control state was rest. Subjects na?ve to the MRI environment and non--MRI-na?ve subjects were studied. Twelve MRI-na?ve subjects underwent 3 fMRI sessions separated by 5 hours and 49 days, respectively. During MRI scanning, they performed the active task. Six MRI-na?ve subjects underwent 2 fMRI sessions with the passive task 1 month apart. Three non--MRI-na?ve subjects performed twice an active 2-Hz self-paced task. The data were analyzed with SPM96 software. For within-session comparison, for active or passive tasks, good reproducibility of fMRI signal activation was found within a session (intra-and interrun reproducibility) whether it was the first, second, or third session. Therefore, no within-session habituation was found with a passive or a well-learned active task. For between-session comparison, for MRI-na?ve or non--MRI-na?ve subjects, and with the active or the passive task, activation was increased in the contralateral premotor cortex and in ispsilateral anterior cerebellar cortex but was decreased in the primary sensorimotor cortex, parietal cortex, and posterior supplementary motor area at the second session. The lower cortical signal was characterized by reduced activated areas with no change in maximum peak intensity in most cases. Changes were partially reversed at the third session. Part of the test-retest effect may come from habituation of the MRI experiment context. Less attention and stress at the second and third sessions may be components of the inhibition of cortical activity. Because the changes became reversed, the authors suggest that, beyond the habituation process, a learning process occurred that had nothing to do with procedural learning, because the tasks were well learned or passive. A long-term memory representation of the sensorimotor task, not only with its characteristics (for example, amplitude, frequency) but also with its context (fMRI), can become integrated into the motor system along the sessions. Furthermore, the pattern observed in the fMRI signal changes might evoke a consolidation process.     

Cerebral activation patterns in patients with writer's cramp: a functional magnetic resonance imaging study

Functional MRI (fMRI), visualizing changes in cerebral blood oxygenation, has to date not been performed either in patients with writer's cramp or in healthy subjects during writing. We compared the cerebral and cerebellar activation pattern of 12 patients with writer's cramp during writing with a group of 10 healthy subjects performing the same tasks over 30-s periods of rest or writing. Sixty echo planar imaging multi-slice datasets were analysed using SPM96 software. Data were analysed for each subject individually and groupwise for patients vs. controls. Healthy subjects showed a significant activation of the ipsilateral dentate nucleus, contralateral cerebellar hemisphere, contralateral primary sensorimotor cortex, and contralateral precentral gyrus during writing. Patients with writer's cramp showed significantly greater activation of the ipsilateral cerebellar hemisphere than controls. Also the activation in the primary sensorimotor cortex extended further caudally and anteriorly towards the premotor association area. Activation was observed in the thalamus during writing only among the patients. Our results indicate an increased basal ganglia output via the thalamus to the motor and premotor cortical areas in dystonia patients and support the notion of disinhibition of the motor cortex leading to coconcentrations and dystonic postures. Received: 10 November 1999 / Received in revised form: 4 April 2000 / Accepted: 26 April 2000     

Functional consequences of experience‐dependent plasticity on tactile perception following perceptual learning

Continuous training enhances perceptual discrimination and promotes neural changes in areas encoding the experienced stimuli. This type of experience‐dependent plasticity has been demonstrated in several sensory and motor systems. Particularly, non‐human primates trained to detect consecutive tactile bar indentations across multiple digits showed expanded excitatory receptive fields (RFs) in somatosensory cortex. However, the perceptual implications of these anatomical changes remain undetermined. Here, we trained human participants for 9 days on a tactile task that promoted expansion of multi‐digit RFs. Participants were required to detect consecutive indentations of bar stimuli spanning multiple digits. Throughout the training regime we tracked participants’ discrimination thresholds on spatial (grating orientation) and temporal tasks on the trained and untrained hands in separate sessions. We hypothesized that training on the multi‐digit task would decrease perceptual thresholds on tasks that require stimulus processing across multiple digits, while also increasing thresholds on tasks requiring discrimination on single digits. We observed an increase in orientation thresholds on a single digit. Importantly, this effect was selective for the stimulus orientation and hand used during multi‐digit training. We also found that temporal acuity between digits improved across trained digits, suggesting that discriminating the temporal order of multi‐digit stimuli can transfer to temporal discrimination of other tactile stimuli. These results suggest that experience‐dependent plasticity following perceptual learning improves and interferes with tactile abilities in manners predictive of the task and stimulus features used during training.     

Tactile-visual cross-modal shape matching: a functional MRI study

The process and location of integration of information from different sensory modalities remains controversial. We used functional MRI to investigate the neural representation of cross-modal matching between tactile and visual shape information in eleven normal volunteers. During the scan, patterns of 2D shapes were presented both tactually and visually, simultaneously. Four different matching tasks were performed: tactile-tactile with eyes closed (TT), tactile-tactile with visual input (TTv), visual-visual with tactile input (VVt), and tactile-visual (TV). The TT task activated the contralateral primary sensorimotor area, and the postcentral gyrus, superior parietal lobules, anterior portion of the intraparietal sulcus, secondary somatosensory cortex, thalamus, dorsal premotor area, cerebellum, and supplementary motor area bilaterally, without occipital involvement. Visual matching activated the primary visual cortex and the lingual and fusiform gyri bilaterally. A cross-modal area was identified by subtracting TTv images from TV images, subtracting VVt images from TV images, and then determining common active areas. There was one discrete area that was active bilaterally; the posterior intraparietal sulcus close to the parieto-occipital sulcus. These data suggest that shape information from different sensory modalities may be integrated in the posterior intraparietal sulcus during tactile-visual matching tasks.     

Sensorimotor organization in double cortex syndrome

Subcortical band heterotopia is a diffuse malformation of cortical development related to pharmacologically intractable epilepsy. On magnetic resonance imaging (MRI), patients with "double cortex" syndrome (DCS) present with a band of heterotopic gray matter separated from the overlying cortex by a layer of white matter. The function and connectivity of the subcortical heterotopic band in humans is only partially understood. We studied six DCS patients with bilateral subcortical band heterotopias and six healthy controls using functional MRI (fMRI). In controls, simple motor task elicited contralateral activation of the primary motor cortex (M1) and ipsilateral activation of the cerebellum and left supplementary motor area (SMA). All DCS patients showed task-related contralateral activation of both M1 and the underlying heterotopic band. Ipsilateral motor activation was seen in 4/6 DCS patients. Furthermore, there were additional activations of nonprimary normotopic cortical areas. The sensory stimulus resulted in activation of the contralateral primary sensory cortex (SI) and the thalamus in all healthy subjects. The left sensory task also induced a contralateral activation of the insular cortex. Sensory activation of the contralateral SI was seen in all DCS patients and secondary somatosensory areas in 5/6. The heterotopic band beneath SI became activated in 3/6 DCS patients. Activations were also seen in subcortical structures for both paradigms. In DCS, motor and sensory tasks induce an activation of the subcortical heterotopic band. The recruitment of bilateral primary areas and higher-order association normotopic cortices indicates the need for a widespread network to perform simple tasks.     

A multicentre study of motor functional connectivity changes in patients with multiple sclerosis

In this multicentre study involving eight European centres, we characterized the spatial pattern of functional connectivity (FC) in the sensorimotor network from 61 right-handed patients with multiple sclerosis (MS) and 74 age-matched healthy subjects assessed with the use of functional magnetic resonance imaging (fMRI) and a simple motor task of their right dominant hand. FC was investigated by using: (i) voxel-wise correlations between the left sensorimotor cortex (SMC) and any other area in the brain; and (ii) bivariate correlations between time series extracted from several regions of interest (ROIs) belonging to the sensorimotor network. Both healthy controls and MS patients had significant FC between the left SMC and several areas of the sensorimotor network, including the bilateral postcentral and precentral gyri, supplementary motor area, middle frontal gyri, insulae, secondary somatosensory cortices, thalami, and right cerebellum. Voxel-wise assessment of FC revealed increased connectivity between the left SMC and the right precentral gyrus, right middle frontal gyrus (MFG) and bilateral postcentral gyri in MS patients as compared with controls. ROI analysis also showed a widespread pattern of altered connectivity, characterized by increased FC between the right MFG, the left insula and the right inferior frontal gyrus in comparison with many regions of the sensorimotor network. These results provide further evidence for increased bihemispheric contributions to motor control in patients with MS relative to healthy controls. They further suggest that multicentre fMRI studies of FC changes are possible, and provide a potential imaging biomarker for use in experimental therapeutic studies directed at enhancing adaptive plasticity in the disease.