Efferent projections of infralimbic and prelimbic areas of the medial prefrontal cortex in the Japanese monkey, Macaca fuscata

The infralimbic area (IL) and prelimbic area (PL) have been postulated as a n autonomic motor region in the medial prefrontal cortex. The present study was conducted to reveal the projection sites of IL and PL of the monkey. M acaca fuscata, using biotinylated dextran amine as an anterograde tracer. I L and PL projected densely to the ventromedial caudate nucleus, the cure an d shell of the nucleus accumbens (Acb), parvicellular lateral basal and mag nocellular accessory basal nuclei of the amygdala, lateral preoptic area, v entromedial hypothalamic nucleus, tubero-mammillary nucleus (TM), medial pa rt of the magnocellular and dorsal part of the parvicellular (MDpc) dorsome dial thalamic nuclei, reunience and medial part of the medial pulvinar nucl eus, and dorso-lateral part of the periaqueductal gray (PAGdl) in the mesen cephalon. Moderately to weakly projected areas were the intermediate and la teral parts of the agranular insular cortex, orbital part of area 12, agran ular and dysgranular part of the temporal pole cortex (TPa-g), auditory tem poral cortex, lateral and medial (MS) septal nuclei, bed nucleus of the str ia terminalis. diagonal hand of Broca, substantia innominata, and medial pr eoptic area, dorsomedial, lateral, and posterior hypothalamic nuclei, magno cellular lateral basal and lateral amygdaloid nuclei, paratenial, paraventr icular (PV), inter-antero-medial (IAM), reticular, central medial (CeM), pa rafascicular (PF) and limitans nuclei of the thalamus, lateral habenular nu cleus, pedunculo-pontine nucleus. dorsal part of the lateral lemniscal nucl eus, ventral tegmental area (VTA), dorsal raphe, superior central nucleus. medial and lateral parabrachial nuclei (PBI) and nucleus locus coeruleus (L C). A few scattered terminals were observed in the perifornical nucleus of the hypothalamus and substantia nigra pars compacta. PL and area 24 were ch aracterized by projections to the entorhinal (Ent) and piriform (Pir) corte x as well as to the magnocellular part of the ventral anterior thalamic nuc leus (VAmc). The morphology of the terminal arborization in each nuclei was different in appearance, perhaps reflecting the synaptic interaction betwe en the nerve terminals and postsynaptic dendrites. PL projected uniquely to Ent. Pir and VAmc and IL projected uniquely to TPa-g, MS, IAM, CeM, MDpc, PF, PBI and LC. IL projected more strongly than PL to the shell of Acb, amy gdaloid nuclei, PV, TM, VTA and PAGdl. The present results support the hypo thesis that IL is a major cortical autonomic motor area and PL integrates l imbic and autonomic inputs in the primate. (C) 2001 Elsevier Science B.V. A ll rights reserved.