Volume: 130 • Number: 5 • Pages: 1092-1102

Essential tremor (ET) is a neurological disorder characterized by involuntary oscillations of the limbs. Previous studies have hypothesized that ET was a cerebellar disorder and reported impairments in motor adaptation. However, recent advances have highlighted that motor adaptation involved several components linked to anticipation and control, all dependent on cerebellum. We studied the contribution of both components in adaptation to better understand the adaptation impairments observed in ET from a behavioural perspective. To address this question, we investigated behavioural markers of adaptation in ET patients (n=20) and age-matched neurologically intact volunteers (n=20) in saccadic and upper limb adaptation tasks, probing compensation for target jumps and for velocity-dependent force fields, respectively. We found that both groups adapted their movements to the novel contexts, however, ET patients adapted to a lesser extent compared to neurologically intact volunteers. Importantly, components of the movement linked to anticipation were preserved in the ET group, whereas components linked to movement execution appeared responsible for the adaptation deficit in this group. Altogether, our results suggest that execution deficits may be a specific functional consequence of the alteration of neural pathways associated with ET.