Behavioral Analysis of the Transplantation Phenomenon within a Motor and Sensory System

Abstract

Traditionally, research in neuropsychology has taken the following two directions: (1) removal of a neural structure by surgical means of ablation or electrolytic lesion and study of the concomitant deficit or loss of function, and (2) stimulation of a neural structure to study the immediately following response. These two approaches, being complementary in nature, have provided great insight into the problems of sturcture/function of the brain. In recent years, research on neural transplantation initiated by Das and his associates (Das 1975, Das and Hallas 1978) seems to offer new ways of approaching research in neuropsychology. Potentially, there are at least two different directions of research that may be pursued. First, removal of or chemical change to a neural structure in the host animal to induce functional abnormality or deficit, followed by transplantation of neural tissue to study recovery from the abnormal or deficient function. Second, transplantation of neural tissue with a high growth potential in order to replace a large volume of a specific region of the host brain by the transplant, followed by the study of the behavior of these animals, and this in turn, followed by the ablation of the transplant to study the loss or deficit in the function. The first approach has been used by Bjorklund and Stenevi (1979). But the second approach has been less widely employed other than for work in our laboratories (Wallace and Das 1982). This approach has a potential of exploring problems of “functional compensation” and “functional plasticity” of neural tissues. It can be best investigated if heterotopic conditions of transplantation are employed (e.g., transplantation of embryonic neocortical tissue into the cerebella of host animals). Such transplants are intraparenchymal and are completely integrated with the host brain, and there are no pathological reactions in the transplant or the host brain even after 2 or more years following transplantation.