Amygdalostriatal projections in the rat. Topographical organization and fiber morphology shown using the lectin PHA-L as an anterograde tracer

Amygdalostriatal projections in the rat were studied with the anterograde tracer phaseolus vulgaris leucoagglutinin (PHA-L), which allows direct visualization of axon morphology. The appearance of fibers in the striatum which were labeled from injections into the amygdaloid complex suggests that they form 'en passant' synapses. A topographic organization was found in the projection from the basolateral amygdaloid nucleus: the most caudal part of this nucleus projects to the anteromedial edge of the striatum, including the medial nucleus accumbens, while progressively more rostral parts of the nucleus project to more lateral and caudal portions of the striatum. No amygdaloid fibers were found in the most rostro-dorsolateral part of the caudatoputamen.