Objective: Determine the effects of globus pallidus interna (GPi) deep brain stimulation (DBS) on ventral oralis posterior nucleus of the thalamic (Vop) neuronal activity.
Methods: Microelectrode recordings in Vop during high frequency DBS GPi in a patient with dystonia.
Results: Twelve (48%) of 25 neurons in five locations neurons decreased their average discharge frequency, 2 (8%) increased and 11(44%) demonstrated no overall change. The patterns of responses were complex with periods of increase and decreased activity. All neurons were inhibited for the time period 3.5-5ms following the DBS pulse. Eighty-eight percent of neurons showed brief but highly consistent increases in the first 1ms following stimulation, 52% showed increased activities from 1.5 to 3ms. Twenty-four percent of neurons increased activity following inhibition.
Conclusions: These findings are consistent with DBS activation of GPi axons to Vop and probable antidromic activation of Vop axons.
Significance: The physiological effects of DBS are far more complicated and will escape any theory that does not address the mechanisms of DBS as stimulation of a complex network of interactions. Further, the findings of post-inhibitory rebound increased raises questions about the role in inhibition in the current concepts of basal ganglia physiology.