The projection of the amygdaloid nuclei to various areas of the limbic cortex in the rat

Abstract

The connections of the amygdaloid body with the areas of the limbic cortex in the rat were studied by means of the method on the axonal retrograde transport of the fluorescent tracer Fluoro-Gold. The tracer was injected into the anterior and posterior limbic cortices (cingulate gyrus, granular- and agranular retrosplenial area, respectively. The localization of the corresponding amygdalar- projection zones was investigated and the semiquantitative analysis of the connections was conducted. The projection zones in the rat amygdaloid body are organized topographically. Administration of the fluorescent tracer to the anterior and posterior part of the limbic cortex in the rat (cingulate gyrus and both retrosplenial areas, respectively) reveals labeling of cells only for injections to the former one. The labeled cells were present only in the major components of the basolateral amygdaloid complex. The main source of this projection was anterior part of basolateral nucleus (BLA). Some labeled neurons were found in the lateral nucleus and few in the ventral part of basolateral nucleus. No labeled cells were found within the basomedial nucleus.