Slow potential changes in cat brain during classical appetitive conditioning of jaw movements using two levels of reward

Abstract

1. 1. Slow potential changes (SPCs) were recorded from epidural motor cortex and several subcortical areas in cat brain, during classical appetitive conditioning of jaw movement using two levels of reward. 2. 2. Before conditioning was started a tone, subsequently used as a conditioned stimulus (CS), elicited SPCs from the lateral hypothalamic area, the medial and the lateral amygdala. Tone-evoked SPCs did not occur in motor cortex, ventro-medial hypothalamus and mesencephalic reticular formation. 3. 3. During conditioning CS-evoked negative SPCs from motor cortex became increasingly larger in a group which received a large reward; this did not occur in a small reward nor pseudo-conditioning group. CS-evoked positive SPCs during conditioning became larger in the lateral hypothalamic area in both large and small rewards groups, and these SPCs were larger than those shown by a pseudo-conditioning group. SPCs evoked by the CS and correlated with conditioning did not develop in the mesencephalic reticular formation, ventro-medial hypothalamus, nor in medial and lateral amygdala. 4. 4. After conditioning, positive SPCs were shown to occur as responses to a large reward, but not a small reward, in motor cortex, lateral hypothalamus and medial amygdala. The mesencephalic reticular formation responded to both reward levels with positive SPCs that did not differ significantly in magnitude. SPCs did not occur as responses to reward in lateral amygdala nor ventro-medial hypothalamus. 5. 5. The results were discussed in terms of neuroanatomical specificity in the generation of subcortical SPCs and the motivating conditions necessary for the occurence of SPCs in both cortical and subcortical areas.