PATHOPHYSIOLOGIC MODELS OF PSYCHIATRIC DISORDERS

Models of the nature of brain dysfunction inmajor psychiat-ric disorders have evolved substantially over the past several decades in parallel with the progression in knowledge result-ing from investigations of the neurobiological mechanisms that contribute to normal cognition, emotion, and behavior. Some models of psychopathology have emphasized, in their simplest forms, the central contribution of excesses or defi-cits in the functional activity of a given neurotransmitter to the disease process of interest. In general, these models have been very useful in motivating investigations of the molecular underpinnings and biochemical functions of the neurotransmitter systems of interest, and in spurring the development of novel psychopharmacologic agents that in-fluence these systems. However, in extreme cases, these models tended to view individual psychiatric disorders a