Lateral hypothalamic lesions impair flavour-nutrient and flavour-toxin trace learning in rats.
Food-restricted rats with ibotenic acid lesions of the lateral hypothalamus (LHx) learned to prefer a flavour paired with concurrent intragastric (i.g.) infusions of maltodextrin, although their preference was weaker than that displayed by sham controls. Unlike controls, the LHx rats failed to acquire a flavour preference when the i.g. maltodextrin infusion was delayed by 15 min. The same rats learned to avoid flavours paired with i.g. lactose or lithium chloride over short delays (15-30 min), but were impaired, relative to controls, at a long conditioned-unconditioned stimuli delay (2 h). These data indicate that the LH is critical for the formation of flavour-postingestive consequence learning over a delay, particularly with nutrient reinforcement. Lateral hypothalamus lesions might specifically impair the processing of nutrient-generated unconditioned stimuli and, more generally, could interfere with the maintenance of flavour memories.
Touzani
Khalid
K
Department of Psychology, Brooklyn College and the Graduate School, The City University of New York, Brooklyn, NY 11210, USA.
Sclafani
Anthony
A
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D005421:Flavoring Agents; D007026:Hypothalamic Area, Lateral / Q000502:physiology*; D007051:Ibotenic Acid / Q000494:pharmacology; D007785:Lactose; D018021:Lithium Chloride; D008297:Male; D008568:Memory / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D011134:Polysaccharides; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D013649:Taste / Q000502:physiology*; D014118:Toxins, Biological
D005421:Flavoring Agents; D009498:Neurotoxins; D011134:Polysaccharides; D014118:Toxins, Biological; D007051:Ibotenic Acid; C008315:maltodextrin; D018021:Lithium Chloride; D007785:Lactose