Motor-Cortical Interaction in Gilles de la Tourette Syndrome

BACKGROUND: In Gilles de la Tourette syndrome (GTS) increased activation of the primary motor cortex (M1) before and during movement execution followed by increased inhibition after movement termination was reported. The present study aimed at investigating, whether this activation pattern is due to altered functional interaction between motor cortical areas. METHODOLOGY/PRINCIPAL FINDINGS: 10 GTS-patients and 10 control subjects performed a self-paced finger movement task while neuromagnetic brain activity was recorded using Magnetoencephalography (MEG). Cerebro-cerebral coherence as a measure of functional interaction was calculated. During movement preparation and execution coherence between contralateral M1 and supplementary motor area (SMA) was significantly increased at beta-frequency in GTS-patients. After movement termination no significant differences between groups were evident. CONCLUSIONS/SIGNIFICANCE: The present data suggest that increased M1 activation in GTS-patients might be due to increased functional interaction between SMA and M1 most likely reflecting a pathophysiological marker of GTS. The data extend previous findings of motor-cortical alterations in GTS by showing that local activation changes are associated with alterations of functional networks between premotor and primary motor areas. Interestingly enough, alterations were evident during preparation and execution of voluntary movements, which implies a general theme of increased motor-cortical interaction in GTS

Investigating the human mirror neuron system by means of cortical synchronization during the imitation of biological movements.

The human mirror neuron system (MNS) has recently been a major topic of research in cognitive neuroscience. As a very basic reflection of the MNS, human observers are faster at imitating a biological as compared with a non-biological movement. However, it is unclear, which cortical areas and their interactions (synchronization) are responsible for this behavioural advantage. We investigated the time course of long-range synchronization within cortical networks during an imitation task in 10 healthy participants by means of whole-head magnetoencephalography (MEG). Extending previous work we conclude that left ventrolateral premotor, bilateral temporal and parietal areas mediate the observed behavioural advantage of biological movements in close interaction with the basal ganglia and other motor areas (cerebellum, sensorimotor cortex). Besides left ventrolateral premotor cortex, we identified the right temporal pole and the posterior parietal cortex as important junctions for the integration of information from different sources in imitation tasks that are controlled for movement (biological vs. non-biological) and that involve a certain amount of spatial orienting of attention. Finally, we also found the basal ganglia to participate at an early stage in the processing of biological movement, possibly by selecting suitable motor programs that match the stimulus

Right hemisphere contributions to imitation tasks

Humans respond faster to biological as compared with non-biological movements. The faster response has been attributed to an activation of the human mirror neuron system (MNS), which is thought to match the observation and the execution of actions. However, it is unclear, which cortical areas are responsible for this behavioural advantage and little is known about the timing of activations. Using whole-head magnetoencephalography (MEG) we recorded neuronal responses to single biological finger movements and non-biological dot movements while the subjects were required to perform an imitation task or an observation task, respectively. Previous imaging studies on the human MNS suggested that activation in response to biological movements would be stronger and faster in ventral premotor, parietal and superior temporal regions. In accordance with previous studies, reaction times to biological movements were faster than those to dot movements in all subjects. The analysis of evoked magnetic fields revealed that the reaction time benefit was paralleled by stronger and earlier activation of the left temporo-occipital cortex, and the right superior temporal and ventral premotor area. The activity patterns suggest that the latter areas mediate the observed behavioural advantage of biological movements and indicate the contribution of the right hemisphere to action-observation execution-matching processes

Do simple intransitive finger movements consistently activate frontoparietal mirror neuron areas in humans?

The posterior inferior frontal gyrus (pIFG) and anterior inferior parietal lobule (aIPL) form the core regions of the human “mirror neuron system” that matches an observed movement onto its internal motor representation. We used event-related functional MRI to examine whether simple intransitive finger movements evoke “mirror activity” in the pIFG and aIPL. In separate sessions, participants either merely observed visuospatial stimuli or responded to them as quickly as possible with a spatially compatible finger movement. A picture of a relaxed hand with static dots on the tip of the index and little finger was continuously presented as high-level baseline. Four types of stimuli were presented in a pseudorandom order: a color change of a dot, a moving finger, a moving dot, or a simultaneous finger-dot movement. Dot movements were spatially and kinematically matched to finger movements. Participants were faster at imitating a finger movement than performing the same movement in response to a moving dot or a color change of a dot. Though imitative responses were facilitated, fMRI revealed no additional “mirror activity” in the pIFG and aIPL during the observation or imitation of finger movements as opposed to observing or responding to a moving dot. Mere observation of a finger movement alone failed to induce significant activation of the pIFG and aIPL. The lack of a signature of “mirror neuron activity” in the inferior frontoparietal cortex is presumably due to specific features of the task which may have favored stimulus–response mapping based on common spatial coding. We propose that the responsiveness of human frontoparietal mirror neuron areas to simple intransitive movements critically depends on the experimental context

Body-part specific interactions of action verb processing with motor behaviour

The interaction of action-related language processing with actual movement is an indicator of the functional role of motor cortical involvement in language understanding. This paper describes two experiments using single action verb stimuli. Motor responses were performed with the hand or the foot. To test the double dissociation of language-motor facilitation effects within subjects, Experiments 1 and 2 used a priming procedure where both hand and foot reactions had to be performed in response to different geometrical shapes, which were preceded by action verbs. In Experiment 1, the semantics of the verbs could be ignored whereas Experiment 2 included semantic decisions. Only Experiment 2 revealed a clear double dissociation in reaction times: reactions were facilitated when preceded by verbs describing actions with the matching effector. In Experiment 1, by contrast, there was an interaction between verb-response congruence and a semantic variable related to motor features of the verbs. Thus, the double dissociation paradigm of semantic motor priming was effective, corroborating the role of the motor system in action-related language processing. Importantly, this effect was body part specific

Endoscopic ultrasound and fine-needle aspiration for the detection of residual nodal disease after neoadjuvant chemoradiotherapy for esophageal cancer

Background â Endoscopic ultrasound (EUS) and fine-needle aspiration (FNA) are potential tools for the detection of residual disease after neoadjuvant chemoradiotherapy (nCRT) for esophageal cancer. This study investigated yield of EUS and FNA for detection of malignant lymph nodes (LNs) after nCRT. Methods â This was a post hoc analysis of the preSANO trial. EUS was performed 10âŠ-âŠ12 weeks after nCRT. 18F-fluorodeoxyglucose positron emission tomographyâŠ-âŠcomputed tomography (18 F-FDG PET-CT) was used to guide targeting of suspicious LNs. Consecutive FNA sampling was performed for suspicious LNs identified on EUS and/or PET-CT. EUS nodal staging was compared with histopathological examination of the resection specimen. The primary outcome was the proportion of correctly identified patients with malignant LNs by radial EUS. Results â 101 consecutive patients were included: 79 patients had no malignant LNs, of whom 62 were classified correctly by EUS (specificity 78âŠ%); 22 patients had malignant LNs, of whom 11 were identified (sensitivity 50âŠ%). Six of these patients had ≥âŠ1 suspicious LN not fulfilling EUS criteria (round, hypoechogenic, >âŠ5âŠmm). Malignant LNs in falsely negative patients were predominantly located at distal LN stations. Specificity and sensitivity of conclusive FNA outcomes were 100âŠ% (7/7) and 75âŠ% (3/4), respectively. FNA outcome was uncertain in eight patients, half of whom appeared to have malignant LNs. Conclusions â EUS only detected 50âŠ% of patients with malignant LNs 10âŠ-âŠ12 weeks after nCRT. To optimize sensitivity and minimize the risk of missing residual disease, FNA of LNs should be performed even in cases of low endosonographic suspicion

Earth system governance: a research framework

Accountability, Adaptiveness, Agency, Allocation and access, Architecture, Global governance, Earth system analysis, Earth system governance,