Involvement of cholinergic mechanisms in impairment of working memory in rats following basolateral amygdaloid lesions.
In order to clarify the role of the amygdala in the working and reference memory of rats in the three-panel runway task, the effects of lesions of subnuclei of the amygdaloid complex on this behavior were studied. Rats that had been trained preoperatively, until they achieved the criterion of learning, were subjected to lesions of the amygdala. In the working memory task, lesions of the basolateral subdivision of the amygdala caused a significant increase in the number of errors (attempts to pass through two incorrect panels of the three panel-gates at four choice points), while lesions of the corticomedial amygdala had no effect on working memory errors. The increase in working errors, observed in basolateral amygdaloid-lesioned rats, declined gradually as retraining sessions were given once each day, reverting to control levels on and after the sixth session. In the reference memory task, the number of errors was not affected by lesions of the basolateral or corticomedial amygdala. The increase in working memory errors, induced by lesions of the basolateral amygdala was significantly reduced by intraperitoneal administration of the inhibitors of cholinesterase, tetrahydroaminoacridine (0.32-1.0 mg/kg) and physostigmine (0.032-0.1 mg/kg), and the muscarinic receptor agonist, oxotremorine (0.1 mg/kg), before the runway test. These findings suggest that the basolateral amygdala is selectively involved in working memory but not in reference memory and that the lowering of central cholinergic function may account for the impairment of working memory, induced by lesions of the basolateral amygdala.
Ohno
M
M
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Yamamoto
T
T
Watanabe
S
S
D000679:Amygdala / Q000033:anatomy & histology / Q000502:physiology*; D000818:Animals; D007858:Learning / Q000187:drug effects; D008297:Male; D008568:Memory / Q000187:drug effects; D008570:Memory, Short-Term / Q000502:physiology*; D010095:Oxotremorine / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013619:Tacrine / Q000494:pharmacology
D013619:Tacrine; D010095:Oxotremorine; D010830:Physostigmine