Thalamic Neurostimulation and Effects on Movement Consolidation in Essential Tremor

Deep brain stimulation (DBS) of the ventralis intermedius nucleus of the thalamus (VIM DBS) effectively suppresses upper limb tremor in the setting of essential tremor (ET); however, its effect on motor learning remains unclear. This study aimed to evaluate the influence of DBS on movement consolidation, an important feature of motor learning.

A total of 16 individuals with ET undergoing VIM DBS treatment and 16 healthy controls (HC) matched for age and sex participated in this study. Participants with ET performed a goal-directed ankle dorsiflexion task over two consecutive days. On day 1, a group of participants with ET (n = 8) practiced the task with DBS off (DBS OFF), whereas the comparison group (n = 8) practiced with DBS on (DBS ON). Task retention was assessed on day 2 with the alternate condition for each group. Spatial accuracy, movement smoothness (Jerk), and tibialis anterior (TA) muscle activity were recorded during practice (day 1) and retention (day 2) for both groups.

During the practice session, spatial error and movement smoothness were not significantly different among the three groups. However, on retention, spatial error and Jerk magnitude were greater in the DBS OFF group than in the DBS ON group and HC group. A significant positive association was found between practice and retention Jerk magnitude (R² = 0.48). All participants manifested 4-to-8-Hz oscillations in the TA muscle, which predicted Jerk magnitude during both practice (R² = 0.37) and retention (R² = 0.27).

These findings suggest that thalamic neurostimulation improves consolidation and may influence other motor learning processes. The presence of 4-to-8-Hz TA oscillations in all individuals with ET and their association with movement smoothness highlight a potential area of interest for further research.