Maternal care, hippocampal synaptogenesis and cognitive development in rats.

We report that variations in maternal care in the rat promote hippocampal synaptogenesis and spatial learning and memory through systems known to mediate experience-dependent neural development. Thus, the offspring of mothers that show high levels of pup licking and grooming and arched-back nursing showed increased expression of NMDA receptor subunit and brain-derived neurotrophic factor (BDNF) mRNA, increased cholinergic innervation of the hippocampus and enhanced spatial learning and memory. A cross-fostering study provided evidence for a direct relationship between maternal behavior and hippocampal development, although not all neonates were equally sensitive to variations in maternal care.