THE CRITICAL IMPACT OF EARLY CELLULAR ENVIRONMENT ON NEURONAL DEVELOPMENT

Normal brain development requires the precise interactions of environm ental signals with genes that drive cellular differentiation and circu it formation. Experimental studies in animal models reveal that early environmental influences in utero can modulate cell fate choice and ne uronal growth. Modification of the determinants can have long-lasting consequences. Studies using transplant and cell culture methods have e xamined the development of the limbic system, regions of the brain tha t mediate cognition, emotion, memory, and learning. The results show t hat growth factors in the environment of progenitor cells control long -term gene expression that characterizes neurons in limbic brain regio ns. Other studies in which the cellular environment is altered by pren atal cocaine exposure result in modified fetal neurotransmitter functi on and specific pharmacological and structural alterations in the cere bral cortex that lead to abnormal behavior. The cellular milieu of the developing central nervous system prenatally thus serves functions as critical as environmental stimuli postnatally that promote synaptic d evelopment and refinement. (C) 1998 American Health Foundation and Aca demic Press.