SURVEY OF GENETIC NEUROLOGY 



By Paul Weiss 



University of Chicago 



The content and conclusions of the fol- 

 lowing report have been derived from 

 five main sources: (1) the author's personal 

 experience; (2) a symposium arranged by 

 the Committee on Neurobiology (appendix 

 A); (3) a survey through questionnaires 

 (appendix B); (4) a survey of the per- 

 tinent literature resulting in a comprehen- 

 sive bibliography (appendix C); (5) an 

 international conference, held in Chicago 

 March 25-26, 1949, under the auspices of 

 the International Union of Biological 

 Sciences (UNESCO), published as a sep- 

 arate volume GENETIC NEUROLOGY, Univer- 

 sity of Chicago Press, 1950. 



The term "genetic neurology," as used in 

 the following, designates a discipline de- 

 voted to the study of the development 

 ("genesis"), growth, differentiation, ma- 

 turation, maintenance, heredity, aber- 

 rations, regeneration, and adjustments of 

 the nervous system, including the neural 

 basis of behavior; especially, the causal an- 

 alysis of the factors and forces involved. 



In contrast to the well established dis- 

 ciplines of neuroanatomy, neurophysiology, 

 and psychology, dealing with the structure 

 and operation of the mature nervous sys- 

 tem, genetic neurology does not yet con- 

 stitute a systematic field of its own. As 

 indicated in the above definition, genetic 

 neurology has areas in common with anato- 

 my, biochemistry, cytology, embryology, 

 genetics, histology, neurology, pathology, 

 physiology, psychology, and surgery. In 

 the study of the development of the ner- 

 vous system itself, the prevailing ap- 

 proaches have been descriptive and com- 

 parative, while the causal analysis of the 

 described phenomena has not yet been 

 undertaken on a scale commensurate to 

 the importance of the field. 



CONTENT 



The following listing of topics circum- 

 scribes roughly the subject matter and 

 problems of genetic neurology. The list 

 is tentative and incomplete, but adequate 

 for the present purpose. 



A. Emhnjonic determination of the central 

 nervous system. 



1) Induction of neural development; 



regional differences; species dif- 

 ferences; symmetry. 



2) Progressive differentiation of the 



central nervous system (locali- 

 zation of parts; effects of sur- 

 rounding tissues; shifts). 



3) Abnormalities (spina bifida; hy- 



drocephalus; cyclopia; anence- 

 phaly). 



B. Morphogenesis of the central nervous 

 system. 



Factors determining form and archi- 

 tecture of brain, spinal cord, gang- 

 lia, placodes (differential folding; 

 fissures; gyri; segmentation; con- 

 fining action of meninges and 

 skull; origin and morphogenetic 

 role of cerebro-spinal fluid; shape 

 of ventricles; lamination of wall). 



C. Cytodifferentation in the nervous sys- 

 tem. 



1) Speciation of cell types (dichoto- 



my of neuroblasts and spongio- 

 blasts; microscopic, submicro- 

 scopic and chemical criteria of 

 speciation; pathological, phar- 

 macological and immunological 

 criteria ) . 



2) Affinities among different cell 



types ( association between 

 nerve fibers and sheath cells; 

 selective connections with re- 

 ceptor and effector organs; se- 



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