Prefrontal system in the rat visualized by means of labeled deoxyglucose--further evidence for functional heterogeneity of the neostriatum.

Abstract

An epileptic focus was formed in the anteromedial part of the prefrontal cortex in rats by means of intracortical injection of penicillin, and radioactively labeled deoxyglucose was immediately injected intravenously. Auto-radiograms revealed that, in addition to the injected cortical area, a number of formations increased their consumption of deoxyglucose. The labeled formations were the posterior medial and perirhinal cortical areas, the anteromedial part of the neostriatum, the anterior and intermediodorsal part of globus pallidus, the entopeduncular nucleus, the reticular portion of the substantia nigra, the claustrum, and the basolateral nucleus of amygdala. In addition, several thalamic nuclei were activated, including the entire parataenial, paraventricular, anteromedial, and axial nuclei, as well as distinct parts of the mediodorsal and lateral nuclei and, in the instances of spread of cortical activity to the dorsal surface, of the ventral nucleus. In some animals, activation of the ventral tegmental area of Tsai was also found. All these formations have previously been shown by neuro anatomical techniques to be directly connected with the anteromedial cortex of the neostriatum. Some of them were included in the "prefrontal system." The present findings, in agreement with earlier neurobehavioral studies, indicate that, in the rat, the anteromedial part of the neostriatum, but not other neostriatal regions, is functionally related to the anteromedial part of the prefrontal cortex. The present and earlier similar studies suggest that the mammalian forebrain contains a number of "systems," each of which consists of a neocortical area and a set of associated subcortical sites.