Stability and potential inheritance of infanticidal behavior in prairie voles

Neural basis of aggressive behavior toward newborns in Mice: Advances and future Challenges

Infanticidal or pup-directed aggressive behavior is present in most species, including humans. It occurs in both reproductive and non-reproductive contexts and its incidence and biological basis may vary among species, strains, sex, and individual experiences. This review has two objectives: 1) to describe the most likely neural circuit that mediates aggressive behavior towards pups in mice, including hormonal, neuroendocrine and neurochemical changes that may increase the probability of attacking pups; and 2) to discuss whether aggressive behavior toward pups in mice is rewarding, an impulsive or predatory response, or a form of maltreatment or adaptive behavior. We propose a neural model to explain aggressive behavior towards pups and discuss evidence suggesting that infanticidal and pup-directed aggressive behavior, although hard-wired in the brain, can be blocked or inhibited by changing the experiences of the subject prior to the access to pups.

New theoretical and experimental approaches on maternal motivation in mammals

Maternal behavior is expressed in different modalities, physiological conditions, and contexts. It is the result of a highly motivated brain, that allows the female to flexibily adapt her caring activities to different situations and social demands. To understand how mothers coordinate maternal and other motivated behaviors we discuss the limitations of current theoretical approaches to study maternal motivation (e.g. distinction between appetitive and consummatory behaviors), and propose a different approach (i.e. motorically active vs. passive motivations) and a distinction between maternal motivated state and maternal motivated behaviors. We review the evidence supporting dopamine mediation of maternal motivation and describe how different phases of the dopaminergic response - basal, tonic, and phasic release in the nucleus accumbens - relate to increased salience, invigorating behavior, and behavioral switching. The existing and new experimental paradigms to investigate maternal motivation, and its coexpression and coordination with other social or non-social motivations are also analyzed. An example of how specificity of motivational systems (e.g. maternal and sexual behavior at postpartum estrus) could be processed at the neural level is also provided. This revision offers new theoretical and experimental approaches to address the fundamental question of how mothers flexibly adapt and coordinate the different components of maternal behavior with other motivated behaviors, also critical for the survival of the species.