Objective: To 1) study neuronal activity of medial thalamic nuclei (MD, CM-Pf) and its role in cognitive and motor human activity and 2) evaluate neuronal processes occurring in these structures in cervical dystonia state during motor acts with and without neck muscles tension.

Background: Medial thalamus as a part of high-order nuclei is known to be involved in a variety of cognitive functions including attention, memory processing and organization of goal-directed behavior. The growing evidence and facts of positive effects of medial thalamic nuclei stimulation observed during the Parkinson’s disease and dystonia treatment supports the idea of medial thalamic nuclei participation in movement disorders and motor activity as a whole. But neuronal mechanisms underlying medial thalamic nuclei involvement in cognitive processing and movement realization are still remained unclear and being of particular interest.

Methods: The extracellular activity of medial thalamic nuclei (MD, CM-Pf) was recorded during the micro-electrode guided neurosurgical operations in patients with cervical dystonia under local anesthesia. Spontaneous single unit activity and neuronal reactions in response to cognitive tasks and movement performance with and without neck muscles tension in relation to simultaneously registered electromyographic changes were analyzed.

Results: Spontaneous neuronal activity of medial thalamus was represented by two main subtypes of neuronal activity patterns: irregular single-spike activity (A-type) and low-threshold Ca2+-dependent bursts (B-type), both of them were reactive to execution cognitive and motor tests. Neuronal reactions on different functional tests were much alike: A-type neurons had a tendency to increase their firing rate, while B-type neuron responses were mainly characterized by inhibition or stabilization of low-frequency oscillations at 3-5 Hz range. The most pronounced and prolonged reactions were observed during voluntary movements with neck muscle exertion.

Conclusions: Our data suggest of medial thalamic nuclei participation in both motor and cognitive behavior and an important role of rhythmic processes in its implementation. Neck-related activity may indicate involvement of medial thalamus in cervical dystonia pathology.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/single-unit-activity-of-medial-thalamus-during-goal-directed-motor-and-cognitive-behavior-in-patients-with-cervical-dystonia/