Muscimol induces retrograde amnesia for changes in reward magnitude.
These experiments examined the effect of the GABAA agonist, muscimol (MUS), on memory for changes in reward magnitude. In Experiment 1 rats were trained to run a straight alley for either a large or small food reward. After reaching asymptotic performance rats in the high reward group were shifted to the small food reward. Half the animals received 1.0 or 3.0 mg/kg (ip) of MUS or the equivalent volume of saline immediately after training. Shifted training continued for 3 more days and no further injections were given. Shifted saline animals displayed an increase in response latencies compared to unshifted controls with a sharp peak on the day after the shift. Shifted MUS receiving 1.0 mg/kg performed comparably to shifted saline animals. In contrast, Shifted MUS animals receiving 3.0 mg/kg displayed performance comparable to shifted saline animals on the day of the shift but displayed a sharp increase in response latencies on the second day after the shift. These findings indicate that post-training systemic MUS injections delay the peak increase in response latencies and suggest that MUS induces retrograde amnesia for reward reduction. Experiment 2 examined the effect of MUS on the memory of a reward increase. Rats were first trained as in Experiment 1 and rats under the high reward condition were then shifted to the small reward. On the next training session, the large food reward was reinstated.(ABSTRACT TRUNCATED AT 250 WORDS)
Salinas
J A
JA
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717-3800, USA.
McGaugh
J L
JL
D000648:Amnesia, Retrograde / Q000139:chemically induced*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D007858:Learning / Q000187:drug effects; D008297:Male; D009118:Muscimol / Q000009:adverse effects* / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D013647:Task Performance and Analysis
D009118:Muscimol