- Hormones and Behaviour: A Psychological Approach
In Hormones and Behaviour:A Psychological Approach, Nick Neave introduces the reader to the fascinating concept of how hormones effect behavior and thus cause an effect in the central nervous system. From an endocrinological point of view, hormones have been extensively studied, however it is only recently that scientists such as Neave have begun to appreciate the impact such hormones can have on behavior. The term hormone was introduced by Bayliss and Starling in 1902 to describe a chemical substance that travels around the body influencing physiology and behavior. Although the concept of a hormone had been understood for many years, this scientific definition was long overdue. It was not until 1921, however, that neurohormones were first identified by Otto Loewi, who won the Nobel Prize for the discovery of what he termed "vagusstuff," or what we now call "acetylcholine." Neurohormones are those hormones produced by the neurosecretory cells, usually located in the brain, that have effects on cells distant from the source of the hormone and that underlie many of the behaviors discussed in this book. Importantly, Neave recognizes that there is a reciprocal relationship between hormones and behavior, in that hormones have an effect [End Page 152] on behavior and vice versa. Neave expertly guides the reader through the various types of behavior that hormones play an important role in, such as sexual, emotional, and cognitive behaviors. This book will make engaging reading for individuals interested either in biological psychology or in understanding what controls our behaviors.
Neave begins the book with the necessary introductory chapters on the organization of both the nervous and the endocrine systems. In Chapter 2,"Hormones and the Endocrine System," he provides a good overview of the different types of hormones and their mechanisms of actions. In particular, he describes the two main ways in which hormones can exert their actions on their target cells, either by interacting with cell-surface receptors (to generate a secondary messenger) or by entering cells and binding to intracellular receptors in order to form a "hormone-receptor complex," which is then able to penetrate the cell nucleus and exert its effects.
Over the past 50 years, the field of behavioral endocrinology has emerged as the study of how hormones alter behaviors and how behavioral interactions regulate endocrine physiology. Following a review of the principles of hormone action and basic neuroscience, Chapter 3, "Behavioural Endocrinology," provides a solid, scientific view of some of the important issues in this field of study, such as whether women's intellectual abilities are affected by their menstrual cycle and whether people are "born with" a homosexual orientation. After providing a useful discussion of what is actually meant by "behavior," Neave goes on to explain the two principal ways in which hormones exert their actions on behavior: organizational and activational. The distinction between organizational and activational effects of hormones has been used extensively to discuss the hormones and behavior, but Neave explains why we need to reevaluate this simplistic distinction, which he argues cannot always account for the wide variety of effects produced by hormones.
In Chapter 4, "Neurological Effects of Hormones," Neave provides a useful comparison between neural and endocrine signaling. He goes on to detail how the development and use of autoradiography has allowed us to examine the expression and distribution of hormone receptors throughout the central nervous system. For example, although the molecular structure of estrogen was first isolated and determined in 1929, it wasn't until the late 1950s and the development of autoradiography that the first estrogen receptor was identified. As Neave demonstrates, however, the process of identifying hormone receptors is not always straightforward, as multiple hormones can bind to the same receptor; for example, androgen receptors have the highest affinity for testosterone (and dihydrotestosterone) but also bind with other androgens and progesterone.
Chapters 5 and 6 detail the hormonal effects on sexual determination and differentiation. In particular,Chapter 5 focuses on the fact that although "sex" may refer to the biological qualities that distinguish males...