Rats with lateral hypothalamic cannulae were injected with norepinephrine and tested when both hungry and satiated on appetitive tasks of varying difficulty. On a simple consummatory test norepinephrine produced more eating than saline at both 0 and 24 hr of deprivation, and performance at 24 hr was more potentiated than that at 0 hr. On a continuously reinforced lever-pressing task, norepinephrine potentiated pressing only at 0-hr deprivation. When pressing was reinforced on a 30-sec variable interval schedule, norepinephrine potentiated pressing at 0 hr of deprivation, but after 24 hr of deprivation norepinephrine-injected rats pressed significantly less than saline-injected controls. These data suggest that norepinephrine produced a motivational depression in a rat's willingness to work for food which is similar to that seen following ventromedial lesions of the hypothalamus.
- Chemical stimulation
- Feeding behavior
ASJC Scopus subject areas
- Experimental and Cognitive Psychology
- Behavioral Neuroscience