The neurobiology of parenting: A neural circuit perspective

Abstract

Social interactions are essential for animals to reproduce, defend their territory, and raise their young. The conserved nature of social behaviors across animal species suggests that the neural pathways underlying the motivation for, and the execution of, specific social responses are also maintained. Modern tools of neuroscience have offered new opportunities for dissecting the molecular and neural mechanisms controlling specific social responses. We will review here recent insights into the neural circuits underlying a particularly fascinating and important form of social interaction, that of parental care. We will discuss how these findings open new avenues to deconstruct infant-directed behavioral control in males and females, and to help understand the neural basis of parenting in a variety of animal species, including humans. Please also see the video abstract here.

Keywords: MPOA; hormones; hypothalamus; infanticide; infants; neural circuits; neuropeptides; parenting; social behavior.

Figure 1

Representative parenting styles in mammalian species. (Upper left) Koalas, as well as the vast majority of marsupials, show female uniparental behavior (photo reproduced with permission from Creative Commons©). (Upper right) In titi monkeys (pictured here: Callicebus oenanthe), male fathers are partially uniparental, performing all aspects of parenting with the exception of nursing (photo reproduced with permission from Anneke DeLuycker©). (Lower left) California mice share parental duties equally between the father and mother (photo courtesy of Andrés Bendesky). (Lower right) African wild dogs live in packs and cooperate in parental care (photo reproduced with permission from the African Wildlife Conservation Fund©).

Figure 2

Circuit diagram for regulation of parental behavior. Parallel pro-parental and pro-infanticidal circuits integrate sensory stimuli and – depending on the animal’s internal state – instruct parental behavior or infant-directed aggression. Abbreviations: AOB, accessory olfactory bulb; AVPe, anteroventral periventricular nucleus; BNST, bed nucleus of the stria terminalis; lHb, lateral habenula; MeA, medial amygdala; MOE, main olfactory epithelium; MPOA, medial preoptic area; NAc, nucleus accumbens; PAG, periaqueductal grey; PVN, paraventricular nucleus of the hypothalamus; RRF, retrorubral field; VMH, ventromedial hypothalamus; VNO, vomeronasal organ; VTA, ventral tegmental area.

Figure 3

Hormone levels during and after human pregnancy. Estrogen, progesterone and prolactin steadily increase throughout pregnancy. Childbirth is characterized by a rapid drop in estrogen and progesterone and a surge in oxytocin levels that initiates uterine contractions. During breastfeeding in the postpartum period, pulses of prolactin levels stimulate milk production between feedings, alternating with oxytocin pulses, which lead to milk ejection during breastfeeding in response to the infant’s suckling (let-down reflex).

Figure 4

Brain areas activated by parenting versus infanticide. Whole brain imaging of the immediate early gene c-fos after behavior reveals that while parental female mice have a high level of activation in the MPOA (top panel), infanticidal males show more neuronal activation in the posterior hypothalamus, as well as MeA and cortex (lower panel). Horizontal brain sections are shown (adapted from Renier et al. [82]).

Figure 5

Psychiatric hospitalizations increase after childbirth. Psychiatric hospitalizations for women dramatically increase in the early postpartum period. Admissions are shown for the city of Edinburgh catchment area (population 470,000 at the time of the study) within a 12-year period (adapted from Kendell et al. [120]).