The relationship between monkey dentate cerebellar nucleus activity and kinematic parameters of wrist movement.

Extracellular single-unit recordings were made from cerebellar dentate neurones in two conscious monkeys trained to perform wrist flexion and extension movement tasks that produced a range of static joint positions and dynamic velocities. The experiment was designed to establish whether there is a relationship between the discharge of dentate neurones and movement kinematics. The discharge patterns of 58 "wrist-related" neurones were correlated with joint position, duration of unidirectional movement (referred to as duration of velocity) and amplitude of velocity (peak velocity). Significant (P<0.05) correlations were found between the level of tonic discharge and static joint position in 21 of 58 (36%) neurones. Correlations between phasic discharge and at least one of the velocity variables were found in 17 of 43 (40%) neurones [7 of 43 (16%) showed a correlation between the duration of phasic excitation associated with movement and duration of velocity, 5 of 43 (12%) between the peak rate of phasic excitation and peak velocity and 10 of 43 (23%) between the number of discharges in the period of phasic excitation and peak velocity]. We conclude (for reasons outlined in the Discussion) that there is not a strong relationship between neuronal discharge and kinematic parameters of wrist movement in the dentate nucleus.