| Research Abstract |
It was attempted to clarify the functional difference in the limbic system in regard to "short-term memory", using several memory tasks.
1)Olfactry bulbctomy(OB lesion)markedly impaired both reference and working memory in a 3-panel runway tasks and delayd matching-to-sample(DMTS)performance in a 3-lever operant tasks. Reversal learning in a 2-lever operant task was also markedly impaired by OB lesion.
2)Dorsal hippocampal(DH)lesion markedly impaired working memory and DMTS performance, but not reference memory. Furthermore, reversal learning was impaired by DH lesion. Cholinesterase inhibitor physostigmine and tetrahydroaminoacridine(THA)improved the impairments of memory produced by DH lesion. While, impaired of working memory, but not reference memory, was produced by microinjection of muscarinic antagonist scopolamine, nicotinic antagonist mecamylamine, BZP/GABA_A agonist muscimol and chlordiazepoxide, 5-HT_<1A>agonist 8-OH-DA, NMDA antagonist CGS19755 and CPP, and NO synthase inhibi
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tor L-NAME into the dorsal hippocampus.
3)Mamillary body(MB)lesion produced impairments of both working and reference memory, but not DMTS performance and reversal learning. While, dorsomedial thalamus(DMT)lesion impaired DMTS performance without affecting both 3-panel runway task and reversal learning. THA failed to improve the impairment of memory in both MB-lesioned rats and DMT-lesioned rats.
4)Basolateral amygdaloid lesion impaired the working memory, but not reference memory. Corticomedial amygdaloid lesions failed to impair both working and reference memory. Microinjection of scopolamine and CPP into the basolateral amygdala produced impairment of working memory, but not reference memory.
5)Basal forebrain lesion markedly impaired both working and reference memory and DMTS performance. Reversal learning was also impaired by the basal forebrain lesion.
In this way, focal brain lesions mentioned above resiults in characteristic dysfunction of memory, depending on lesioned site of brain. These results may provide a useful clue for understanding functional localization of memory. Less
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