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This chapter begins with a brief introduction to the neurobiology of serotonin, including common methods of investigation and sources of serotonin-associated genetic variation. It briefly addresses comparative conceptualizations of aggressive behavior in nonhuman primates and people, including the role of antagonistic interaction in primate social dominance and human psychopathology. It summarizes the substantial literature on CNS serotonergic activity as a correlate of aggressive disposition, as seen in studies employing neurochemical indices of serotonergic function, neuropharmacologic challenges, functional neuroimaging, and neurogenetic methodologies. Finally, the chapter attempts to integrate observations derived from studies on monkeys and humans, identify implications of these findings for models of serotonergic influences on aggression, and speculate briefly regarding possible evolutionary origins of these associations.

The importance in science of mentors or role models can hardly be exaggerated. For Hubel and Wiesel, Steve Kuffler played a crucial role in terms of day-to-day importance, and this role was sustained over thirty years. The Hopkins group was broad. Hubel, Wiesel, and Kuffler represented central nervous physiology. Ed Furshpan, David Potter, and Kuffler represented synaptic physiology, and Ed Kravitz represented neurochemistry. Johns Hopkins was informal and friendly, contrasting strongly with the rather pompous prevailing atmosphere at Harvard. This may have been because the medical school and hospital were close to each other, geographically and spiritually, at Hopkins.

In the past few years, the predominant focus of basic science and clinical investigations of serotonergic neurotransmission has been the many serotonin (5-hydroxytryptamine, 5-HT) receptors and their signal transduction mechanisms. In the past decade, the predominant focus of basic science and clinical investigations of serotonergic neurotransmission has been the many serotonin (5-hydroxytryptamine, 5-HT) receptors and their signal transduction mechanisms. Some recent and other older, but still valuable, monographs and reviews should be consulted for coverage in depth of these and related issues.

Nociceptive information, that is, information about potentially damaging stimuli, from the skin of the limbs and the trunk, is carried to the spinal cord by several types of nociceptive dorsal root ganglion (DRG) neurones. This chapter examines neurochemical markers of neuronal subpopulations and excludes those common to all sensory neurones. It therefore reviews data on neurochemical expression in DRG neurones in order to identify molecules expressed in neurones with cell sizes that are appropriate for nociceptive neurones. This type of approach examines circumstantial evidence only and can therefore provide only a guide as to which molecules may be more or less rewarding to study in future ‘pain’ research. It then examines the evidence that certain of these molecules are expressed in cutaneous afferent neurones. Finally, it examines the limited direct evidence on molecular expression in identified nociceptive cutaneous afferent neurones.

This chapter discusses the neurochemistry of performance monitoring and presents an overview of the knowledge gathered in humans using pharmacological challenges and imaging genetics. It describes neuromodulators, such as dopamine, serotonin, and norepinephrine and their roles in performance monitoring and resulting adaptations.

Throughout Greg Egan's career, some of his strongest stories have focused on the theme of identity. This chapter first looks at stories that highlight how malleable our brains are in terms of our neurochemistry. Next, it highlights stories where our consciousness is digitized, eventually becoming immortal. It uses information theory as a lens to examine some of the future consciousnesses proposed in Egan's stories and to consider what it means to divorce consciousness from physical embodiment so strictly. When Egan's fiction takes up the question of identity it generally looks under the skin at the neural system of the brain. There are many questions about neurons and consciousness that science is only now beginning to answer—and the answers provided so far diverge wildly from our day-to-day perceptions of being.

Language has played an essential role in recent human cognitive and cultural evolution, so why possess music as another communication system? Did the immediate ancestors of Homo sapiens possess a common precursor (musilanguage) that somehow partitioned into two interrelated yet distinct language and music streams? Many animals have evolved complex patterns of vocalization and conspecific communication, but only humans synchronize and coordinate their actions both rhythmically and harmonically. Music is arousing and motivating, it elicits activity in brain reward centers and modulates a number of neuroactive chemicals known to influence affective responses. Hypotheses put forward to explain the evolution and universality of music include mate attraction, a need for preverbal mother–infant communication, and a vehicle that promotes prosocial behavior as well as cultural cohesion.

This chapter introduces a new perspective on the role of love in human evolution and human development. The bonds of love, whether between parent and child, lovers, or close friends, may all have a common biological root, activating neurochemicals that make us feel good. Like other human capacities, such as consciousness, learning, and creativity, love has a long and fascinating evolutionary history. Indeed, the evolution of love appears to be integral to the development of our human brain and hence to much that distinguishes us from other species. Moreover, love plays a vital, though still largely unrecognized, role in human development, with evidence accumulating about the negative effects of love deprivation as well as the benefits of love. But whether or not our needs for meaning and love are met, and whether or not our capacities for creativity and love are expressed, are largely determined by the interaction of biology and culture—specifically, the degree to which a culture or subculture orients to the partnership or domination end of the continuum.