Figure 2.

Proposed circuitry involved in conveying maternal-derived sensory input to CRH-expressing neurons in the PVN. The PVN receives excitatory and inhibitory projections, including projections from the amygdala, paraventricular thalamic nucleus (PVT), and bed nucleus of the stria terminalis (BNST). These regions are also interconnected by excitatory projections (solid black lines). (A) The amygdala and BNST are both activated after a single day of handling-evoked augmented maternal care, and in turn stimulate the PVN (29). (B) The PVT is not activated after a single day of augmented maternally derived sensory input, but is recruited by recurrent daily barrages. This is thought to activate regions of the BNST that inhibit CRH-expressing neurons in the PVN (31). It is not fully known how this series of events promotes reduced numbers of excitatory synapses on CRH-expressing neurons.