Cortico-Subthalamic Projections In The Rat

Abstract

The subthalamic nucleus (STN) is a key structure in the basal ganglia and plays a major role in the pathogenesis of Parkinson’s disease. The STN is a popular target for deep brain stimulation (DBS). DBS of the STN improves motor symptoms. Unfortunately, also negative stimulation induced side-effects on behavior and cognition can occur. These side-effects are thought to be caused by direct stimulation of the associative and limbic pathways that run through the STN. In the primate, three functionally segregated parts are clearly described within the STN: a dorsolateral motor part, a medial limbic part and a ventrolateral associative part. In the rodent however, these subdivisions are not well defined. In this review we describe all anterograde cortico-subthalamic tracer studies to map the rodent STN. As a result, a crude functional subdivision in the rodent STN can be made. The lateral two thirds of the STN receive input from the motor and pre-motor cortex, sparing the medial tip. The medial third receives input from the anterior cingulated, the prelimbic and the agranular insular cortices. There is little evidence for a ventrolateral-dorsomedial subdivision of the medial STN. We conclude that, even though the functional subdivisions are not as clear cut as in the primate STN, a partial anatomical subdivision is present in the rodent STN