Motor-Cortical Interaction in Gilles de la Tourette Syndrome

Stephanie Franzkowiak,Melanie Jonas,Bettina Pollok,Götz Thomalla,Alexander Münchau,Katja Biermann-Ruben,Alfons Schnitzler,Jennifer Paszek,Michael Orth,Martin Südmeyer,Paul L Gribble

doi:10.1371/journal.pone.0027850

Abstract

BackgroundIn 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 Findings10 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/SignificanceThe 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.

Highlights

Gilles de la Tourette syndrome (GTS) is a common childhood onset neuropsychiatric disorder
Our analyses focused on coherence between the thalamus and premotor and primary motor areas
The results suggest increased functional coupling between supplementary motor area (SMA) and contralateral M1 at beta-frequency

Summary

Introduction

Gilles de la Tourette syndrome (GTS) is a common childhood onset neuropsychiatric disorder. Mink [6] postulated that a focal population of striatal neurons becomes abnormally active in GTS-patients leading to inhibition of globus pallidus pars interna and substantia nigra pars reticulata neurons increasing the excitability of motor-cortical areas Along this line, alterations of the primary sensorimotor cortex and the SMA are assumed to play an important role in the pathophysiology of GTS [5,7,8,9]. As basal ganglia dysfunctions are assumed to play an important role in GTS the data described above imply that SMA and M1 might be abnormally driven by striatal neurons [6] It is less well understood how the basal ganglia affect cortical activation patterns but, it is likely that functional interactions within a striato-thalamo-premotor-motor network are crucial for the observed excitability changes of the motor cortex of GTS patients. The present study aimed at investigating, whether this activation pattern is due to altered functional interaction between motor cortical areas

Methods

Results

Conclusion