Comparison of the role of the first and second cortical somatosensory areas in the conditioned behavior of animals

Conclusions

• 1. Unilateral and bilateral extirpation of area SI in animals previously taught conditioned reflexes to tactile discrimination between rough and smooth surfaces and conditioned reflexes of choice of the side of reinforcement to the ringing of a bell and beating of a metronome, had very little effect on the production and realization of the motor conditioned reflexes named above. Similar injuries in animals without preliminary training led to some difficulty in learning conditioned reflexes to tactile discrimination compared with intact animals.

• 2. Unilateral and bilateral extirpation of area SII in animals previously taught the same conditioned reflex skills led to sharp deterioration of tactile differentiation between the surfaces (35% of correct responses after unilateral and 26% after bilateral extirpation) and to a definite change in the correct choice of the side of reinforcement to the bell and metronome (80% of correct choices after unilateral and 72% after bilateral extirpation). In the previously untrained animals, after bilateral extirpation of SII tactile differentiation could not be formed, and the formation of the reflex of choice of side of reinforcement was considerably impaired and reached a value of 69%.