Thalamic Neurostimulation and Effects on Movement Consolidation in Essential Tremor

Area of Science:

• Neuroscience
• Motor Control
• Neurological Disorders

Background:

• Essential tremor (ET) significantly impacts motor function.
• Deep brain stimulation (DBS) of the ventralis intermedius nucleus of the thalamus (VIM DBS) is a primary treatment for ET.
• The effect of VIM DBS on motor learning, particularly consolidation, remains under-investigated.

Purpose of the Study:

• To investigate the influence of VIM DBS on motor learning consolidation in individuals with ET.
• To compare motor learning performance between ET patients with DBS ON versus DBS OFF and healthy controls (HC).

Main Methods:

• 16 individuals with ET undergoing VIM DBS and 16 HC participated.
• ET participants performed a goal-directed ankle dorsiflexion task over two days.
• Practice occurred with DBS ON or OFF; retention was tested with the alternate condition. Spatial accuracy, movement smoothness (Jerk), and tibialis anterior (TA) muscle activity were measured.

Main Results:

• No significant differences in practice session spatial error or smoothness were observed.
• On retention, the DBS OFF group exhibited greater spatial error and Jerk magnitude compared to DBS ON and HC groups.
• A positive association was found between practice and retention Jerk magnitude (R² = 0.48).
• 4-to-8-Hz TA muscle oscillations predicted Jerk magnitude during practice (R² = 0.37) and retention (R² = 0.27).

Conclusions:

• Thalamic neurostimulation via VIM DBS appears to enhance motor learning consolidation in ET.
• The findings suggest VIM DBS may positively influence other aspects of motor learning.
• The observed 4-to-8-Hz TA oscillations and their link to movement smoothness warrant further investigation in ET motor learning.