Efferent connections of the prelimbic (area 32) and the infralimbic (area 25) cortices: An anterograde tracing study in the cat

Abstract

The projections from the caudal part of the medial frontal cortex, encompassing the prelimbic area (PL) and the infralimbic area (IL) (Brodmann's areas 32 and 25, respectively), were studied in the cat with the anterograde autoradiographic tracing technique. The results indicate that the projection fields of IL, in contrast to those of PL, are restricted almost exclusively to limbic structures. Whereas the major thalamic projections from PL reach the mediodorsal, anteromedial, and ventromedial nuclei, the medial part of the lateral posterior nucleus, and the parataenial and reticular nuclei, and weak projections from this area are directed to the nucleus reuniens and other midline nuclei, the nucleus reuniens is the major thalamic termination field of fibers arising from IL. Cortical areas that are reached by fibers originating in PL and, to a lesser degree, also in IL, include more rostral prefrontal areas (areas 8, 6, and 12), the agranular insular, and the rostral perirhinal cortices. In contrast, cortical areas that are more strongly related to IL include the cingulate, retrosplenial, caudal entorhinal, and perirhinal cortices and the subiculum of the hippocampal formation. Another prominent output of PL concerns projections to an extensive medial part of the caudate nucleus and the ventral striatum, whereas fibers from IL only distribute most ventrally in the striatum. In the amygdaloid complex, fibers from PL were found to reach the basolateral, basomedial, and central nuclei, and fibers from IL to distribute to the medial and central nuclei. PL furthermore projects to the claustrum and the endopiriform nucleus. Other structures in the basal forebrain, including the medial septum, the nuclei of the diagonal band, the preoptic area, and the lateral and dorsal hypothalamus are densely innervated by IL and only sparsely by PL. With respect to more caudal parts of the brainstem, projections from PL and IL appeared to be essentially similar. They reach the ventral tegmental area, the periaqueductal gray, the parabrachial nucleus, and in cases of PL injections were followed as far caudally as the pons.

The Role of Ventromedial Prefrontal Cortex in the Recovery of Extinguished Fear

“…Whereas the mPFC projects to both the basolateral and central nuclei of the amygdala (McDonald, 1998), projections to the central nucleus (Ce) arise exclusively from IL (Hurley et al, 1991;Takagishi and Chiba, 1991;Buchanan et al, 1994). In fact, IL projections to Ce are strongest from its caudal part (Room et al, 1985;McDonald et al, 1996). The central nucleus of the amygdala mediates conditioned freezing, autonomic changes, and potentiated startle via its projections to periaqueductal gray (PAG), lateral hypothalamus, and caudal pontine reticular formation, respectively (Davis, 1994;Fendt and Fanselow, 1999;LeDoux, 2000).…”

Assessing cortico-hippocampal functional connectivity under anesthesia and kainic acid using generalized partial directed coherence

“…The present recordings were made in the dorsal hippocampus and functional intrinsic connectivity within the hippocampus requires addressing in the future. This CA1-mPFC projection is primarily unidirectional, given that no direct return projections have been identified (GoldmanRakic et al 1984;Room et al 1985;Sesack et al 1989;Hurley et al 1991;Takagishi and Chiba 1991;Buchanan et al 1994). The monosynaptic hippocampal-to-mPFC pathway innervates both pyramidal cells and interneurons in the rat (Ferino et al 1987;Laroche et al 1990;Jay et al 1995;Tierney et al 2004), and has been implicated in memory acquisition and consolidation, specifically for working spatial memory (reviewed in Goldman-Rakic 1995) (Fig.…”

Pathways for emotion: interactions of prefrontal and anterior temporal pathways in the amygdala of the rhesus monkey

“…Morys et al, 1999). If con¢rmed to be excitatory through physiologic study, then medial prefrontal projections to the amygdala may amplify the output of the BLpc to the hypothalamus, a pathway that may be recruited in concert with a robust direct projection from medial prefrontal cortices to hypothalamic autonomic centers (Leichnetz and Astruc, 1976;Room et al, 1985;Rempel-Clower and Barbas, 1998;Ongur et al, 1998;Freedman et al, 2000). In addition, we noted that medial prefrontal axons terminated in the Co and Me nuclei, engaged in the expressive capacity of the amygdala in gustatory, olfactory, and reproductive functions (for review see De Olmos, 1990).…”