Sexual Differentiation of the Brain

Investigating the relative importance of genes, hormones, and environment in the formation of sexual behavior. This book, based on a Work Session of MIT's Neurosciences Research Program, presents a balanced account of a controversial topic -- the relative importance of genes, hormones, and environment in the formation of sexual behavior. Research on rodents, birds, and primates, including humans, is reviewed, and the authors conclude that 'the biological substrate seems important in humans as in other mammals.' The information in this volume will help lay the foundation for an improved understanding of the physical bases of human sexual psychopathology. A major goal of the Work Session was to investigate the sequence of events in the developing brain that gives rise to sexually dimorphic behaviors. In birds and mammals, the organization of such behaviors is shown to occur during a critical period in development and appears to involve permanent changes in brain structure and function. These changes are attributable, for the most part, to the action of gonadal steroids. An introductory chapter defines sexually dimorphic behavior and presents a central hypothesis about its organization. A general review of sex differences in heavior in rodents, birds, and primates is then presented, discussing among other topics the issue of a possible endocrine basis for homosexuality among human males. Two chapters are devoted to an examination of genetic and biochemical aspects of sexual differentiation, and a concluding chapter discusses cellular bases of sexual dimorphisms of brain structure and function. A major bibliographic review of the relevant literature is included.