Schematic drawing of a sagittal section through the rat basal forebrain highlighting possible circuitry by which the medial prefrontal cortex (mPFC) may influence stress-related hypothalamic paraventricular nucleus (PVH) effector mechanisms. These studies have also established a contingent of GABAergic neurons in anterior bed nucleus of the stria terminalis (aBST) as the likely source of relays for prelimbic cortex (PL) inhibitory influences over acute stress-induced hypothalamo-pituitary-adrenocortical (HPA) axis output. The dashed line from the infralimbic cortex (IL) indicates that the projection has not been formally established. ac, anterior commissure; Ant. Pit., anterior pituitary; ACd, anterior cingulate cortex, dorsal subdivision; aBST, bed nucleus of the stria terminalis, anterior subdivision; cc, corpus callosum; CRH, corticotropin-releasing hormone; mPFC, medial prefrontal cortex; IL, infralimbic area; ot, optic tract; Pre-Auto, preautonomic subdivisions; PVH, paraventricular nucleus of the hypothalamus; PL, prelimbic area.