The global aim of the core is to advance understanding of the mechanisms by which environmental toxicants damage the nervous system. This aim is being addressed using contemporary methods in neuroscience, coupled with approaches derived from Center members pursuing other avenues of toxicological research. The Specific Aims are to, a) elucidate the molecular and cellular changes during development, which underlie the age-specific susceptibilities to neurotoxicants; b) characterize the distinct regions of the nervous system, which exhibit differential sensitivity to environmental toxicants; c) examine the degree to which the developmental and regional sensitivity to toxicants might relate to or serve as models for neurodegenerative diseases or behavioral impairments; and d) obtain correlative molecular, biochemical, morphological and behavioral data to better understand mechanisms of neurotoxicity.