Extensive lesions in the gustatory cortex in the rat do not disrupt the retention of a presurgically conditioned taste aversion and do not impair unconditioned concentration-dependent licking of sucrose and quinine.
Although damage to gustatory cortex (GC) in the rat has been reported to severely impair, if not eliminate, retention of a presurgically conditioned taste aversion (CTA), it has equivocal effects on taste preference as measured by intake tests. Because intake tests can be influenced by nongustatory (e.g., postingestive) factors, we employed the brief-access taste test to assess the effects of ibotenic acid-induced lesions targeting the GC on unconditioned licking to a sucrose and then a quinine concentration series in a specialized lickometer. As a functional lesion assessment, a presurgical CTA to 0.1M NaCl was established in thirsty rats by following 15-min intake with intraperitoneal administration of either LiCl (or NaCl for control) on 2 occasions. Both conditioned sham-operated (SHAM) rats and rats with histologically confirmed extensive damage to the GC (GCX) avoided a NaCl concentration series relative to unconditioned controls in a postsurgical brief-access CTA test, with no difference between the surgical groups in their responses to NaCl or similar concentrations of KCl. GCX rats also did not differ from SHAM rats in the EC50 of concentration-response functions for sucrose or quinine. Clearly, the critical cortical area required for the retention of a presurgical CTA falls outside of the extensive area of damage, which was well centered within the conventionally defined gustatory zone of the insular cortex. The absence of an effect on unconditioned responsiveness to sucrose and quinine suggests that the damaged region is also unnecessary for the normal expression of affective licking responses to tastants.
Department of Psychology, Florida State University, 1107 West Call Street, PO Box 3064301, Tallahassee, FL 32306-4301, USA. spector@psy.fsu.edu.
Koji
K
Hashimoto
Alan C
AC
Spector
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal; D002540:Cerebral Cortex / Q000187:drug effects / Q000473:pathology*; D003214:Conditioning, Classical / Q000187:drug effects; D008297:Male; D011803:Quinine / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology*; D013649:Taste; D055697:Taste Perception / Q000187:drug effects
D012965:Sodium Chloride; D013395:Sucrose; D011803:Quinine
hedonics; insular cortex; palatability