Precise instrumental conditioned reflexes and the role of different sensory modalities in their execution in dogs.

Elaboration of an instrumental reaction involving conditioned rearrangement of innate motor coordination takes a long time to attain in dogs. Particular difficulties are encountered in the execution of conditioned movement when painful stimulation evokes an inborn response opposite to the conditioned one. Exclusion of visual control of performance selectively impairs the phase of searching for the "safety zone" by the animal, whereas the ability to maintain the limb in a constant position for a long time and to carry out its correct readjustments was not affected. Exclusion of afferents from the joint led to profound and irreversible motor disturbances: along with considerable impairment of the ability to maintain the limb at a given height. Also affected were searching for the "safety zone" and the ability to carry out prompt and correct adjustments upon exposure to painful stimuli. As a result, motor reactions were accompanied by a large number of shocks when the "safety zone" was wide and could not be carried out at all when it was narrow. Forcing the animals into the unusual posture strongly disrupted the elaborated reactions: the animals were no longer able to find the "safety zone" either during the isolated action of the signal or during painful stimulation. The observed disturbances tended to progress and gradually led to the derangement of the motor habit, up to complete dropping out of the conditioned reflex component.