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This chapter describes maternal behavior of the laboratory rat and outlines various methods of observing and quantifying this behavior. Although in some rodent biparental species males also show parental behavior, this is not the case for most rodents, including R. norvegicus. However, under certain experimental conditions, males also show many of the components of behavior normally shown by the mother rat. The general and specific methods for the testing of maternal behavior are described. Several environmental and situational factors that affect the expression of maternal behavior are considered.

This chapter discusses the factors that affect a new mother's initial responses to her offspring and how she is changed by those responses, taking into account the mechanisms underlying maternal behaviour, with the focus on physiological mechanisms and the different behavioural systems they activate. The factors controlling the expression of maternal behaviour are examined, comparing those in altricial and precocial species with those in humans. For both humans and animals, findings show that mechanisms in both the new mother and the offspring stimulate a kind of bond that meets the needs of the offspring and the social organization to which they belong. Maternal behaviour is seen to require prior changes in other behavioural systems, particularly in the affective, perceptual, and learning systems of the animal, and the emotionality of both animals and humans. Without these changes, the mother expresses inadequate, abnormal, or no maternal behaviour.

This chapter provides an overview of the long-term effects of early stress on the subsequent development of both physical and mental disorder. It then discusses the role of maternal care during pre- and postnatal periods as an early source of these effects, using research conducted in the laboratory with the rat. The chapter then reviews potential mediators of the effects of maternal behavior on gene expression. The chapter concludes with the questions that remain regarding the effects of early stress on pathology.

Chapter 3 describes the hormones that promote the immediate onset of maternal behavior at parturition, drawing on research from rats, rabbits, sheep, mice, and nonhuman primates. The critical hormones include rising levels of estradiol, prolactin, and placental lactogens that occur near the end of pregnancy on a background of progesterone withdrawal. In contrast to the onset of maternal behavior, due to maternal experience, its maintenance does not require hormones. Laboratory strains of female mice, produced by inbreeding and selective breeding, are anomalous in that they do not require pregnancy hormones to show prompt maternal behavior when presented with conspecific infants under low-stress conditions. However, the physiological events of late pregnancy boost maternal motivation in these mice to allow for effective maternal behavior in challenging environments. The same processes operate in species that exhibit naturally occurring alloparental behavior, such as marmosets, where such behavior has evolved by natural selection.

Chapter 9 examines the development of the parental brain in animals, emphasizing that the way a mother treats her offspring affects their brain development and their subsequent maternal behavior, leading to an intergenerational continuity of maternal phenotypes. Two proposals are evaluated. First, maternal treatment influences the development of maternal motivation circuits in offspring. In support, the development of medial preoptic area projections to the mesolimbic dopamine system is affected. Second, maternal treatment influences the development of neural systems that regulate anxiety and stress reactivity in offspring. In support, the development of medial prefrontal cortex regulation of amygdala reactivity to stressful situations is affected. Deficient development of maternal motivation circuits may contribute to neglectful maternal behavior; deficient development of emotion regulation circuits may contribute to abusive maternal behavior. Epigenetics, particularly DNA methylation, and gene by environment interactions are involved in these processes.

Chapter 2 describes the types of parental behavior that can occur in vertebrates: maternal, paternal, and alloparental behavior. The dominant form of parental behavior in mammals is a uniparental maternal care system, where the mother raises her offspring by herself. A mother can form either a nonselective or selective bond with her infants, depending on the maturity of her infants at birth. A biparental care system, in which both maternal and paternal behavior occur, is present in about 5% of mammalian species. Approximately 3% of mammalian species exhibit a cooperative breeding system, where some offspring remain in their social group and help their parents raise subsequent offspring. The parental behavior of these helpers is referred to as alloparental behavior. The occurrence of paternal and alloparental behavior shows that alternative mechanisms, not requiring pregnancy and parturition, can evolve which allow for these forms of parental behavior.

This essay describes neurobiological and neuroendocrine mechanisms that are implicated in human caregiving. Anatomical and biochemical systems that first appeared in the evolutionary transition from reptiles to mammals allowed the emergence of mammalian sociality. Human behaviors are characterized by symbiotic and reciprocal interactions, which are necessary for successful caregiving. The autonomic nervous system, and especially the mammalian changes in the parasympathetic system, provides an essential neural platform for social behavior. Especially critical to coordinating the features of positive sociality are neuropeptides including oxytocin and vasopressin. These neuropeptides modulate the mammalian autonomic nervous system to foster the expression of social behaviors and, when adaptive, defensive behaviors. Oxytocin, the same peptide that regulates various aspects of mammalian reproduction including birth, lactation and maternal behavior, is also involved in the beneficial and reciprocal effects of caregiving on physiology, behavior and health.

Dopamine and social cooperation describes how, in humans, dopamine-innervated brain areas or cell body regions are activated during cooperative social interactions, suggesting that social stimuli may be primary incentive stimuli. Lactating female rats lever press for access to their pups, nucleus accumbens dopamine is released during maternal behavior, and accumbens dopamine lesions decrease maternal behavior, implicating incentive learning in maternal care. Adult male Syrian hamsters learn a preference for a place associated with a female scent that increases nucleus accumbens dopamine and a dopamine receptor antagonist blocks the learning implicating dopamine in incentive learning in sexually mature males. In songbirds, striatal dopamine release is associated with directed song used to attract a mate; dopamine may influence the incentive value of the mate. Dopamine is linked to social behavior in reptiles, amphibians, fish, and insects. Dopamine-mediated incentive learning may contribute to the organization of socially cooperative behavior in many species.

This chapter begins with some history of the field of behavioral neuroendocrinology and traces the origins of the classic organizational-activational hypothesis to explain sexual differentiation of the brain and behavior and hormonal influences on sex-typical social behaviors. The classic hypothesis posits that testicular hormones masculinize and defeminize neural circuits during a perinatal sensitive period, programming sex-typical activational responses to gonadal hormones in adulthood. Research since the mid- to late 1980s shows that a second wave of hormone-dependent organization of the brain and behavior occurs during puberty and adolescence and that ovarian hormones are actively involved in feminization of the brain during the adolescent period of organization. Next, a conceptual framework is presented for studying adolescent development of social cognition (the mental processes by which an individual encodes, interprets, and responds to sensory information from an animal of the same species) in the context of social reorientation, when during adolescence the source of social reward shifts from family to peers. The chapter reviews the literature on what social behaviors and aspects of social cognition are organized by pubertal hormones in males, as well as the nonsocial behaviors that are organized by pubertal hormones in males and females.

Contemporary personalized psychiatry faces head-on the tension to be individualized and patient-centered, while also striving to be scientific. We explore this tension by applying two accounts of scientific causal explanation, Woodward’s interventionist account and Silva, Landreth, and Bickle’s metascientific account, to recent research in social neuroscience and environmental epigenetics that bear directly on psychopathology. We’re less concerned in this chapter with which account of causal-mechanistic explanation is right, although we will have some comments about the relative advantages of each. Instead we stress two lessons for personalized psychiatry. First, properly understood, basic scientific research is not necessarily inconsistent with the aims of personalized psychiatry. There are even ways the former can advance the latter. Second, non-epistemic considerations such as clinical utility and therapeutic applicability partly determine which account of scientific causal explanation best fits with reasonable interpretations of personalized psychiatry, including questions about the most appropriate level at which to explain psychiatric disorders.

This chapter sums up the key findings of this study on the treeshrews of Borneo. It explains that the small number of living tupaiid species and the fossil record suggests that the treeshrews' characteristics never provided much potential for evolutionary diversification, but that they can be considered an evolutionary success because they have been able to hold their own amid more populous orders. The chapter argues that the while the absentee maternal-nursing system works, it provides little flexibility in litter size or maternal behavior, and would not seem likely to offer much potential for evolving into other strategies needed for treeshrews to succeed in very cold climates or in places where survival of young was much lower.

Parents, siblings, and others provide young children with a context in which development occurs and supports and promotes early learning. In this chapter, we consider the roles of various individuals and early interventions in social, language, and cognitive development before children enter school. Because most deaf children are born to nonsigning, hearing parents, communication in the home is given special consideration, particularly with regard to the kinds of information and experience that contribute to those domains. We also consider the importance of implicit instruction in relation to fostering educational readiness and the potential effects on long-term academic achievement and personal growth. Parents will encounter both opportunities and challenges in raising a deaf child, and research has demonstrated a variety of ways in which they can optimize their child’s development. Therefore, we devote some space to describing the field on which early development takes place. Most important, we will see the importance of deaf children having early access to language, social interaction, and experiential diversity. Because most cases of deafness are not hereditary, many deaf children will have congenital or early-onset hearing losses that are totally unexpected (and usually unrecognized for some time) by their parents. Some of those children will be considered at risk at birth because of the maternal, fetal, or neonatal medical problems that contributed to their hearing losses. Beyond the consequences of initial medical difficulties, factors related to prenatal or postnatal hearing loss may well influence the quantity or quality of interactions the infant has with others in the environment during the first few months. These earliest influences, and their effects, can have ever-widening consequences for development over the first months and years of life. Even before birth, sounds perceived from within the womb can influence the course of development. Early in the last trimester of pregnancy, a fetus will rotate and adopt a new position with the head against the mother’s pelvis. Most fetuses already have considerable responsiveness to sound at this point and can perceive the mother’s voice and heartbeat through bone conduction (Als et al., 1979).