REINFORCING EFFECT EXERTED BY MESOCEREBRAL LOBE STIMULATION IN THE SNAIL HELIX-LUCORUM

Reinforcing effect of extracellular stimulation of two brain zones on spontaneous opening of pneumostome was investigated in semi-intact preparation of the snail. It was found that mesocerebrum stimulation increased the frequency of the reinforced movement, but decreased the frequency of the same movement if its absence was reinforced. These results suggest positive reinforcing effect for this brain area involved in control of sexual behaviour. Different results were obtained for stimulation of rostral part of parietal ganglia where giant cells controlling avoidance behaviour are located. Stimulation of this area decreased the frequency of the ongoing spontaneous movements. Implications for the control of behaviour are considered.