Behavioral Embryology

Studies on the Development of Behavior and the Nervous System

Gilbert Gottlieb

• Publisher: Academic Press
• Year: 2013
• Print ISBN: 9780126093018
• eBook ISBN: 9781483266411
• Topic: Biological Sciences
• Subtopic: Zoology
• Index: Biological Sciences

Behavioral Embryology deals with the theoretical, philosophical, and empirical problems of behavioral embryology. The book is composed of studies on prenatal neural and behavioral development. The text discussed various topics on behavioral embryology such as the genetic aspects of neuro-embryology; prenatal ""organizing"" effect of gonadal hormones on the brain and later behavior; sensory, motor, or central neural function; overt embryonic or fetal sensitivity; and overt motility and actual behavior. Embryologists, anatomists, cell biologists, physiologists, physicians, and medical researchers will find the book invaluable.

Behavioral Embryology

Outline

Introduction to Behavioral Embryology

Introduction to Behavioral Embryology

Gilbert Gottlieb, Psychology Laboratory, Division of Research, North Carolina Department of Mental Health, Raleigh, North Carolina

Publisher Summary

This chapter presents an introduction to behavioral embryology. The overriding background theme in behavioral involves the role of functional factors—sensory stimulation, the use or exercise of sensory and motor organs, and the spontaneous functional activity of neural or behavioral systems—in the neural maturation process and behavioral development. A conception of development holds that the development of behavior can be explained entirely in terms of neurosensory and neuromotor maturation without the participation of any of the functional factors. There is very little clear evidence for or against this latter point of view because very few experiments have been designed in such a way that it could be tested. At the behavioral level, it is possible to study the relationships between early function and later function in a very fruitful way, without necessarily studying the neuroanatomical or neurophysiological correlates of the activity in question, although such studies always gain in significance when the latter are included. There are likewise no strictures on the neuroanatomical and neurophysiological levels of analysis, except that such analyses do tend to hold promise when overt organismic motility, behavior, or sensitivity is kept in view.

I Aims

II Tradition

III Procedures

A Descriptive-Correlational Stage

B Deductive-Manipulative Stage

IV Conceptions of Development

A Epigenesis

B Predetermined Epigenesis

C Probabilistic Epigenesis

V Theoretical Issues

A Motor Primacy: Autogenous Motility

B Patterned Movement

C Nerve Fiber Growth and Synapse Formation

D Sensory and Perceptual Processes: Physiology and Anatomy

E Perceptual Processes: Behavior

VI Summary and Conclusions

References

I Aims

Behavioral embryology, which incorporates neurogenesis and developmental neurobiology, involves the study of the very early development of the nervous system and behavior with a viewtoward understanding how the formative periods of neural and behavioral development affect later stages of neurobehavioral ontogeny. The guiding philosophy is that neural and behavioral development at any given point in time can only be comprehended fully in light of the immediate and remote developmental history of the organism. For atruly comprehensive picture, the “forwardreference” of development must also be considered. A most important and pervasive aspect of embryonic behavior is its “anticipatory” or “preparatory” nature—crucial adaptive functions always develop well in advance of their necessity for the survival of the newborn, and several writers have emphasized that aspect of development in particular (e.g., Anokhin, 1964; Carmichael, 1970; Coghill, 1929).

A subsidiary aim of behavioral embryology involves the establishment of detailed and intimate relationships between neuroanatomy, neurophysiology, neurochemistry, and behavior. It is felt that these relationships can be established most readily and most meaningfully during the formative stagesof embryonic development, at which time the investigator is in a position to actually observe the increasingly complex changes in organization manifest themselves. A “naturalistic” theme pervades behavioral embryology in that most studies involve living specimens in their ordinary surroundings and, as far as is possible, there is an attempt to relate the results of in vitro studies to the in vivo and in situ conditions.

To paraphrase the words of Pearl (1904), the study of the ontogenetic history of an organismis regarded of prime importance in elucidating the adult condition. This method of study can gain thecomplete explanation of many structures and functions which are inexplicable when only the adult condition is considered. Thus, in many quarters, embryological study has come to be regarded as a necessary part of almost any anatomical, physiological, or behavioral investigation which aims at completeness, including human psychology. [See, for example, the recent review of behavioral embryology by Trevarthen (1973) for The Handbook of Perception. Carmichael’s classical review of the older literature has been a standard feature of handbooks of child psychology for many years (Carmichael, 1933, 1970).]

In sum, the developmental method is basic to all disciplines which deal with organisms, whether from the genetic, biochemical, anatomical, physiological, behavioral, or psychological points of view, and behavioral embryology pushes this method of study to its logical extreme. The developmentalmethod is an analytic tool par excellence.

II Tradition

Since its inception in the modern era by W. Preyer (1885), to whose memory this book is dedicated, the field of behavioral embryology has remained broadly comparative in its interests and has aligned itself closely with the study of neurogenesis. These two trends are manifest in the work of the contributors to the first two volumes in this serial publication: the species under study include crustaceans, amphibians, birds, and various placental mammals, and many of the behavioral observations on these forms speak at least indirectly to the neural mechanisms which may underlie them (and vice versa).

While, in a very real sense the study of prenatal behavioral development entails problems (methodological and theoretical) peculiar to itself, and the same can be said of neurogenesis, there isan attempt to try to unite the relevant aspects of these two disciplines in the study of behavioral embryology.

This attempt at unified study has obvious advantages, but it also entails “communication” problems which are attributable to the background of the research workers in the field. To wit, most of the contributors in behavioral embryology have been trained almost exclusively either inbiology or in psychology. The former bring great expertise to the study of neurogenesis, while the latter bring sophistication to the study of behavior. The twain do meet, of course, but when they do the most “natural” and flagrant biases or blind spots frequently surface. This sort of problem, which has important implications for both theory and method, can not be entirely rectified untila new generation appears on the scene, all of whom have a broad-based education in neuroembryology as well as behavior (developmental psychobiology).

III Procedures

Regardless of the particular aims and aspirations of individual researchers in behavioral embryology, work proceeds almost inevitably through two stages, the first of which is necessarily descriptive-correlational and the second of which is causal-analytic or deductive-manipulative.

A Descriptive-Correlational Stage

In this preliminary stage, cross-sectional relationships are established between behavior and age (or stage), or nervous system and age (stage), eventually yielding a fairly complete longitudinal picture (in ideal instances) of behavior-stage-nervous system correlations. The behavior in question can be a highly specific activity (e.g., the manifestation of tactile or other sensitivity, sucking reflex, locomotion) or rather general movements (such as the cyclic motility of avian and other embryos). The investigator usually tries to establish the onset and subsequent course of the activity inquestion and, if he or she is in a position to do so, goes on to designate its neuroanatomical, neurophysiological, and/or neurochemical counterparts. In the not too distant future, it will probably become common to push such correlations to the molecular domain, which will be quiteexciting and most rewarding for those who are competent to do it.

Another approach employed during the descriptive stage of inquiry is peculiar to developmental study and provides an exceedingly fertile basis for the derivation of hypothetical “mechanisms” which can later be put to experimental test. Namely, after a number of cross sections have been compiled into a longitudinal picture of embryonic neural and/or behavioral development, the investigator begins to see possible functional relationships between earlier and later states of the system such that a certain earlier state (or event) comes to be regarded tentatively as the “precursor” to a particular later state. Such precursors come in two varieties: facilitative and determinative. Facilitative precursors exercise a direct and specific quantitative or temporal influence on the later state, such that quantitative or temporal alterations in the earlier state produce quantitative or temporal changes in the later state. That is, these precursors affect the rate of behavioral development or neural maturation, the number or size of neural elements, changes in behavioral or neural threshold, the degree of behavioral or neural differentiation, etc. [Some examples: the rate of “clicking” within and between quail embryos regulates their time of hatching (Vince, this volume); increased postnatal stimulation leads to an increase in the density of dendritic spines in neonatal rats (Schapiro and Vukovich, 1970); reduction of auditory input in duck embryos leads to an elevated behavioral threshold of response to species-specific auditory stimulation after hatching (Gottlieb, 1971a).] Determinative precursors differ from facilitative ones in that they force or channel neurobehavioral development in one direction rather than another, and the particular direction taken is a consequence of the action of the precursor, such that if the particular precursor had not been active, the particular direction would not have been taken. Genes, hormones, and the inductor...

Table of contents

• Cover image
• Title page
• Table of Contents
• Consulting Editors
• Copyright page
• List of Contributors
• Preface
• Dedication to W. Preyer (1841-1897)
• Section 1: Behavioral Embryology
• Section 2: Embryonic Motility and its Neural Correlates
• Section 3: Hatching: Hormonal, Physiological, and Behavioral Aspects
• Section 4: Sensory Processes: Embryonic Behavior in Birds