Motherhood Induces and Maintains Behavioral and Neural Plasticity across the Lifespan in the Rat

Abstract

Maternal behavior is multidimensional, encompassing many facets beyond the direct care of the young. Formerly unfamiliar activities are required of the mother. These include behaviors such as retrieving, grouping, crouching-over, and licking young, and protecting them against predators, together with enhancements in other behaviors, such as nest building, foraging, and aggression (inter/intra-species, predatory, etc.). When caring for young, the mother must strike a seemingly lose-lose bargain: leave the relative safety of the nest and her helpless offspring to forage for food and resources where predators await both mother and her vulnerable young, or remain entrenched and safe, thereby ensuring a slow and inexorable fate. Two predictions thus arise from this maternal cost-benefit ratio: first, there may be enhancements in behaviors on which the female relies, for example, predation and spatial ability, used for acquiring food and resources and for navigating her environment. Second, there may be reductions in the fear and anxiety inherent to the decision to leave the nest and to forage in an unforgiving environment where encounters with predators or reluctant/resistant prey await. There is overwhelming support for both hypotheses, with improvements in learning and memory accompanied by a diminution in stress responses and anxiety. The current review will examine the background for the phenomenon that is the maternal brain, and recent relevant data. In sum, the data indicate a remarkable set of changes that take place in the maternal (and, to a lesser extent, the paternal), brain, arguably, for the natural, simple but singular experience of reproduction.

Plasticity in the olfactory bulb of the maternal mouse is prevented by gestational stress

“…To the best of our knowledge, this is the first time this type of memory is tested in relation to motherhood, and future studies will be needed to analyze the full consequences of this improvement in the context of maternal care. However, enhancement of other types of memory was previously reported in mothers, in particular their increased ability to learn and remember spatial environment, which is fundamental to their capacity to locate their pups, remember food location, and decreasing the probability for harmful encounters while away from the nest40. Altogether, the enhanced memory for odor observed in mothers is thus part of a general improved processing of the surroundings that seems central to successful parenting.…”

The plasticity of human maternal brain: Longitudinal changes in brain anatomy during the early postpartum period.

“…These findings may provide evidence that these changes in parent brain structure require exposure to infant-related stimuli. In rats, a rich amount of olfactory, auditory, somatosensorial, and visual information during physical interactions with pups and suckling stimuli during nursing were associated with the reorganization of the thalamus, parietal lobe, and someosensory cortex in lactating mothers (Kinsley et al, 2008; Lonstein et al, 1998; Xerri et al, 1994). Moreover, these changes in the parietal cortex only occurred when mothers interacted with their pups but not when they were only exposed to the pups’ smells or sounds (Fleming & Korsmit, 1996).…”

Inflammatory insult during pregnancy accelerates age-related behavioral and neurobiochemical changes in CD-1 mice

“…To date, the generally accepted notion is that exposure to stressors (such as inflammation) during early development can accelerate AAMI progression (Hao et al 2010;Sterlemann et al 2010). In addition to early development, however, the greatest change that a woman will undergo is her reproductive experience, including pregnancy and maternal behaviors (Kinsley et al 2008). This exposure to sharply altered hormone levels during pregnancy and the postpartum period can result in obviously reactive changes in the brain, including changes in the increment of cell body size, the extension of dendritic branches, and alteration of neurogenesis in several brain regions, such as the forebrain and hippocampus (Prange-Kiel and Rune 2006;Tomizawa et al 2003).…”