Area 25 Of Infralimbic Prefrontal Cortex

The percentages that WGA-HRP retrogradely labelled neurons composed of the projection neurons in individual layers of infralimbic (IL; area 25) prelimbic (PL; area 32), and dorsal anterior cingulate (ACd; area 24b) cortices were calculated.  

The areas studied were the prelimbic (PL, area 32) and infralimbic (IL, area 25) cortices and the dorsal anterior agranular insular (AId) and regions of posterior insular cortex (PI-comprising the agranular, dysgranular and granular fields).  

In separate experiments, pseudorabies virus (PRV) was injected into one of the three different cytoarchitectonic regions that comprise the medial prefrontal cortex: infralimbic (Brodmann area 25), prelimbic (Brodmann area 32), and cingulate (Brodmann area 24) cortical areas.  

Immunocytochemical and ultrastructural evidence is presented indicating that direct inputs from the hippocampal CA1 field to prelimbic (area 32) and infralimbic (area 25) cortices in the rat, innervate not only 'spiny' (presumed pyramidal) neurons but also monosynaptically contact NADPH-diaphorase reactive cells and parvalbumin-containing local circuit neurons-the latter cell type is shown to be GABA immunoreactive.  

To determine the subcortical projections of this region in primates, injections of Phaseolus vulgaris leukoagglutinin, biotinylated dextran amine, or rhodamine-labeled dextran amine were placed in area 25 in three monkeys. In contrast to the efferents from area 25 previously described in the rat, there were no projections to autonomic effector regions, such as the nucleus of the solitary tract, magnocellular neurosecretory cell groups in the hypothalamus, ventrolateral medulla, or intermediolateral column of the spinal cord. These connections support the idea of a role for cortical area 25 in emotional and autonomic responses, albeit less direct than that described in rodents..  

The ventral striatal inputs in the macaque monkey were studied in relation to the connections from the orbitofrontal cortex, focusing on the infralimbic area (IL or area 25), thalamic nuclei and the vagal-solitary nuclear complex (NTS-X).  

The afferent connections of the infralimbic area (area 25) of the medial prefrontal cortex in rats were studied using WGA-HRP as the tracer.  

However, the primary thalamic projections from area 25 were to the intralaminar and midline nuclei. Amygdala projections from areas 32 and 24 were primarily to the lateral, basolateral and basomedial nuclei, but area 25 also projected to the central nucleus. area 25 and the ventral portions of area 32 also showed a bilateral projection to the parabrachial nuclei and dorsal and ventral medulla.  

We investigated the projection from the infralimbic division of the prefrontal cortex (area 25) to histaminergic neurons in the posterior hypothalamic area.  

Those injections confined to the projection cortex of the suprageniculate-magnocellular medial geniculate nuclear complex also led to labeling in contralateral prefrontal regions, particularly in area 25 (infralimbic region).  

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