The Journal of comparative neurology
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The present study was undertaken to establish the precise anatomical relationship of the subthalamic nucleus (STh) with limbic lobe-afferented parts of the basal ganglia in the rat. The anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L), injected in the STh, the globus pallidus, the ventral pallidum, the ventral striatum, and the parafascicular thalamic nucleus, and the retrograde tracers Fluoro-Gold (FG) and cholera toxin B (CTb), injected in the globus pallidus, the ventral pallidum, the ventral striatum, and the ventral mesencephalon, were used for this purpose. The results of these tracing experiments confirm the general notion of reciprocal connections between the STh and pallidal areas. ⋯ The lateral part of the parafascicular thalamic nucleus projects to the lateral part of the STh, whereas parafascicular neurons medial to the fasciculus retroflexus project to the dorsomedial portion of the STh. The medial part of the STh and the adjacent lateral hypothalamus are intimately connected with limbic parts of the basal ganglia in a way similar and parallel to the connections of the lateral STh with motor-related parts of the basal ganglia. These findings suggest a role for the STh in nonmotor functions of the basal ganglia.