NIGRAL AND EXTRANIGRAL PATHOLOGY IN PARKINSONS-DISEASE

This article reviews data on the internal organization, neuronal types , and interconnections of limbic and motor components of the human bra in, and the specific lesions which a few of them undergo during the co urse of Parkinson's disease (neuronal loss associated with the develop ment of Lewy bodies and Lewy neurites). The severe involvement of nigr al neuromelanin-laden projection cells has received particular attenti on during the past decades. This lesion interferes with normal functio n of the striatum and probably contributes to many of the motor dysfun ctions characteristically occurring in Parkinson's disease. The simila rly severe involvement of several areas and nuclei outside of the subs tantia nigra has often escaped notice. However, the pathology of Parki nson's disease cannot be completely described unless changes in these extranigral areas are taken into account. Interpretation of the charac teristic lesional pattern is facilitated by combining schemata of both the limbic and motor systems. This approach reveals a key role by the amygdala and related structures in extranigral pathology. Severe lesi ons occur in the central amygdaloid nucleus, in nuclei projecting to t he cerebral cortex in a non-specific manner, and in nuclei regulating endocrine and autonomic functions. It is suggested that extranigral le sions contribute to the development of behavioral changes and autonomi c dysfunction.