ABSTRACT
Neurotoxicity is defined as a structural change or a functionally adverse response of the nervous system to a chemical. biological, or physical agent. Characterization of toxicity in the nervous system encompasses multiple levels of organization and complexity, including structural, biochemical, physiological, and behavioral. This is due to the complexity of the nervous system and its activities necessary to maintain the balance of all of the various organ systems of the body. The smooth coordination of body motion and functioning as well as the integration of complex cognitive functions such as speech, emotion, learning, and memory are dependent upon the normal functioning of the nervous system. Interaction with the external environment is dictated by the nervous system and dependent upon the normal complex arrangement and network of anatomical structures and biochemical and physiological integrative functioning. The temporal and spatial organization of nervous system development is a precise and complex process, with the basic framework of the nervous system laid down in a stepwise fashion in which each step is dependent upon the proper completion of the previous one. Thus, a relatively minor disturbance resulting in a perturbation of the developmental interactions between selective cells for a limited time period may result in a major deleterious outcome. This chapter will present information on critical processes in the normal development of the nervous system and evidence that alterations in the environment of the system can result in long-term damage.
