Conditioned taste aversions and drugs of abuse: a reinterpretation.
A new hypothesis (and supporting data) provides a solution to the 25-year-old paradox whereby positively reinforcing drugs of abuse also support a conditioned taste aversion (CTA). The results show that unlike LiCl-induced CTAs, morphine- and cocaine-induced suppression of conditioned stimulus (CS) intake depends on the rewarding properties of the gustatory CS. This finding argues against the long-standing CTA interpretation in favor of a new reward comparison account. That is, rats decrease intake of a gustatory CS following taste-drug pairings because the value of the CS is outweighed by that of a highly reinforcing psychoactive drug. Suppression of CS intake, then, is a consequence of the well-documented positive reinforcing, rather than the hypothetical aversive, properties of drugs of abuse.
Grigson
P S
PS
Department of Behavioral Science, College of Medicine, The Pennsylvania State University, Hershey 17033, USA. psg6@psu.edu
D000818:Animals; D001245:Association Learning / Q000187:drug effects; D001362:Avoidance Learning / Q000187:drug effects*; D003042:Cocaine / Q000494:pharmacology*; D003214:Conditioning, Classical / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D013287:Illicit Drugs / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D018021:Lithium Chloride / Q000494:pharmacology; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009042:Motivation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013649:Taste / Q000187:drug effects*
D013287:Illicit Drugs; D009020:Morphine; D018021:Lithium Chloride; D003042:Cocaine