Deep brain stimulation promotes excitation and inhibition in subthalamic nucleus in Parkinson's disease

Subthalamic nucleus single-unit recordings were undertaken before and during peripeduncular nucleus-stimulation at clinically relevant frequency (25 Hz) in six patients with Parkinson's disease. Peripeduncular nucleus stimulation changed the firing activity of almost every subthalamic nucleus cell (44/48) by decreasing the ongoing discharge in bursting subthalamic nucleus neurons (-62.1%) and exciting irregular (+ 63.2%) and tonic/regular discharges(+ 20.1%). These conflicting data challenge the definition of peripeduncular nucleus as a new target area for Parkinson's disease. If the modulation of subthalamic nucleus bursting units may corroborate the peripeduncular nucleus therapeutic role, the simultaneous excitatory influence during nonbursty patterns might interfere with a favorable outcome on motor signs. As a result, the implantation of peripeduncular nucleus alone may be hazardous while the association of subthalamic nucleus plus peripeduncular nucleus seems to be reasonable.