Objective: Here we directly tested this hypothesis and we investigated the specific functional connectivity patterns of thalamic motor seeds in 24 GTS patients and 24 healthy controls, by means of a seed-based resting state fMRI approach.

Background: Gilles de la Tourette Syndrome (GTS) is a neuropsychiatric disorder characterized by tics, which are recurring and unwanted movements or vocalizations. The disease is an example of dysfunctional motor control, with interferences in planning, selection and programming of voluntary actions. Pharmacological and imaging studies suggest that GTS is characterized by perturbed connectivity within cortico-sub-cortical motor networks.

Method: We used a 3-steps methodology. We first identified the stereotactic coordinates of motoric thalamic seeds by selecting, with a univariate analysis, the most significant peaks of activation in the right and left thalamus recorded during the execution of voluntary finger opposition movements, in both healthy controls and GTS patients. Then, the functional connectivity maps of these regions of interest were calculated for each subject/patient by using a seed-to-voxel whole brain approach. Finally, the individual maps were entered in a full factorial analysis with Group (Patients/Healthy Controls) and Seed (Left Thalamus/Right Thalamus) included as factors.

Results: The results showed significant differences between the two groups in the form of abnormally augmented functional connectivity in GTS patients between the right thalamic seed and the cortical motor areas (premotor and primary motor cortex). This abnormal connectivity was positively related to the severity of the syndrome: the greater the abnormal connectivity, the more severe the disease in terms of tics manifestation. In turn, the strength of such connectivity was compensated for by neuroleptics whereby the larger the dosage of neuroleptics the smaller the value of such connectivity.

Conclusion: Our findings confirm the presence of an altered subcortical-cortical functional network in Gilles de la Tourette syndrome, highlighting the important role of the connections between the motor thalamus and premotor/primary motor cortex.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/abnormal-thalamo-cortical-functional-connectivity-patterns-in-gilles-de-la-tourette-syndrome-a-seed-based-resting-state-fmri-study/