Pathways in the emergence of developmental neuroethology: antecedents to current views of neurobehavioral ontogeny

The forgotten militant and his enduring mission: Zing-Yang Kuo and his extraordinary years in behavioral neuroembryology (1929-1939)

Zing-Yang Kuo (1898-1970), hailed as China's behaviorist psychologist, earned "Out-Watsons Mr. Watson" in the international anti-instinct movement. His contributions to the field on behavioral neuroembryology (1929-1939) are often overlooked in comparison to his achievements in psychology. We retrieved the titles of all of Kuo's publications from 1929 to 1939 and examined those related to his research on the origins and development of embryonic behavioral ontogeny and the neural basis of embryonic behavior. Remarkably, Kuo concurrently focused on embryos during the same period as North American neuroembryologists. He maintained an independent stance in the debate over the sequence of behavioral ontogeny, represented by the embryonic neuroscientists Coghill and Windle, and critically pointed out limitations in research on both sides of the debate. Drawing from his experiments with chicken embryos, Kuo proposed the theory of behavioral epigenesis, which attempted to end the nature-nurture dichotomy and promote the transformation of the research path of behavioral embryology from elementary physiological anatomy toward a deep "comprehensive science." Kuo's achievements directly laid the foundation for the interdisciplinary field of developmental psychobiology, constructing a new conceptual framework for the systematic analysis of behavioral development and promoting the establishment and development of a new approach to epiphenotype epigenetics.

Taking advantage of behavioral changes during development and training to assess sensory coding mechanisms

The relationship between behavioral and neural performance has been explored in adult animals, but rarely during the developmental period when perceptual abilities emerge. We used these naturally occurring changes in auditory perception to evaluate underlying encoding mechanisms. Performance of juvenile and adult gerbils on an amplitude modulation (AM) detection task was compared with response properties from auditory cortex of age-matched animals. When tested with an identical behavioral procedure, juveniles display poorer AM detection thresholds than adults. Two neurometric analyses indicate that the most sensitive juvenile and adult neurons have equivalent AM thresholds. However, a pooling neurometric revealed that adult cortex encodes smaller AM depths. By each measure, neural sensitivity was superior to psychometric thresholds. However, juvenile training improved adult behavioral thresholds, such that they verged on the best sensitivity of adult neurons. Thus, periods of training may allow an animal to use the encoded information already present in cortex.

Developing a framework for development: A discussion

A multitude of scientific disciplines study the development of behavior. Their use of different methodological and conceptual approaches makes integration of findings difficult. In a symposium at the 38th Annual Meeting of the International Society for Developmental Psychobiology in Washington DC, the question was discussed if a general theory of development could unify the field. The three participants explain their views and discuss the possibility of a theoretical framework for development.

Development of neuronal circuits and behaviors in the medicinal leech

We are studying the neuronal mechanisms responsible for establishing circuitry underlying the local bending response in the medicinal leech. Local bending replaces an embryonic behavior, circumferential indentation, during the time of initial chemical synaptogenesis in leech embryos. We found that the electrical connections among the motor neurons are established first, about 5% of embryonic time (almost 2 full days) before chemical connections form. The inhibitory connections from muscle inhibitors to muscle excitors are, we hypothesize, responsible for the emergence of local bending. We have also found that the central processes of the excitors--but not the inhibitors--have much longer central processes when their peripheral processes are kept from contacting their target muscles. This system should allow us to test ideas about how individual neurons find their appropriate targets to form functional neuronal circuits.

The irrelevance of infant observations for psychoanalysis

The current consensus among psychoanalysts holds that direct infant observations are one means for testing the developmental propositions of psychoanalytic theory; that the observations have already falsified some of the theory's basic propositions; and that they hold the key to a qualitatively different developmental theory of psychoanalysis. The consensus, although not universal, has motivated a wide range of research programs on early infancy, whose findings are commonly interpreted as disclosing psychoanalytic metapsychology and clinical theory in an entirely new light. This essay examines some of the assumptions that have motivated such investigations, as well as the research strategies by which the new versions of theory are promulgated. On the basis of these explorations it is concluded that psychoanalytically informed infant observations may be the source for new theories of social-emotional development, but that they are essentially irrelevant for psychoanalysis as a psychology of meanings, unconscious ideas, and hidden motives.