Objective: To evaluate the tremor network in Essential Tremor(ET) patients in rest conditions with respect to Healthy Controls(HC).

Background: Pathophysiology of ET is poorly understood. Neuroimaging, neurophysiological evidences suggested the involvement of cerebello-thalamo-cortical network.

Methods: 23 possible/probable ET patients and 23 matched HC underwent a 3T-MRI with acquisition of a resting state sequence. Connectivity was investigated using a seed-based regression analyses approach. Regions of interest were identified from a between-group activation map obtained in a previous task-related fMRI study. They were located in left primary motor cortex(M1), supplementary motor area(SMA), somatosensory cortex, thalamus and right cerebellum hemisphere. Statistical correlation maps obtained for each seed and each subject were registered to MNI. Between group differences were evaluated using FSL Fixed Effect with correction for multiple comparisons.

Results: ET patients showed compared to HC: reduced connectivity of left M1 both with premotor cortex, SMA and somatosensory areas and with cerebellum; decreased connectivity between cerebellar hemispheres each other; increased connectivity between somatosensory cortex and parietal areas as well as primary motor, premotor cortex, supplementary motor area and also increased connectivity between right cerebellar lobule VI and thalamus and left putamen. In ET SMA were more connected to premotor cortex whereas it was hypoconnected with parietal regions, precentral cortex and left putamen and globus pallidus(GP); thalamus revealed higher connectivity with cerebellum and left caudate and less connectivity with right GP.

Conclusions: The altered connectivity within the cortical sensory-motor network in ET could be due to alterations in cortical integrative processing. The decreased connectivity of cerebral cortex with cerebellum as well as the decreased connectivity within the cerebellum in ET patients is consistent with recent findings showing altered connection of motor network between cerebellum and cerebral cortex. The increased connectivity between cerebellum and thalamus and the complex alteration of connectivity between BG and thalamus are congruent with the crucial role of both cerebellum and thalamus in tremor generation. Thus the oscillatory activity in ET might be due to a dynamic entrainment of several mutually linked cortico-subcortical drivers.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-connectivity-within-the-cerebello-thalamo-cortical-network-in-essential-tremor-a-resting-state-fmri-study/