[Specificity of nuclear elements of the motor region of the cortex in organizing a precise motor response].

After elaboration and consolidation of precise instrumental avoidance reflexes in dogs (lifting of a fore-leg to a 4-centimeters wide "safety zone"), a part of motor cortex in the area of moving leg was ablated. After the operation the search for "safety zone" i. e. the precision of estimating the position of the leg was irreversibly impaired, but the animal was still able to hold its extremity at the same level for a long period of time. Artifically elaborated motor coordination--antagonistic to the innate one--also showed irreversible impairment. However, in case of an extremely "drilled" reaction (5.000 pairings) the elaborated coordination persisted. Minimal amplitude of correction movements increased too (i. e. subtlety of movements decreased), but during retraining this parameter of the movement became compensated. The data obtained suggest that the specificity of central cellular elements of the cortical motor area consists in estimation of extremity position which is necessary for finding a given point in space.