MAPPING BRAIN NETWORKS ENGAGED BY, AND CHANGED BY, LEARNING

Citation
Cm. Gall et al., MAPPING BRAIN NETWORKS ENGAGED BY, AND CHANGED BY, LEARNING, Neurobiology of learning and memory (Print), 70(1-2), 1998, pp. 14-36
Citations number
111
Categorie Soggetti
Psychology,"Behavioral Sciences",Neurosciences,Psychology
ISSN journal
10747427
Volume
70
Issue
1-2
Year of publication
1998
Pages
14 - 36
Database
ISI
SICI code
1074-7427(1998)70:1-2<14:MBNEBA>2.0.ZU;2-M
Abstract
Major goals of research into the neurobiology of learning and memory a re to identify (1) brain areas/circuitries that subserve different mne monic functions and (2) chemistries that encode the memory trace. The discovery that activity modulates neuronal gene expression provided te chniques attendant to the first goal and candidates for cellular chang es pertinent to the second. Studies in our laboratories have exploited activity-regulated changes in c-fos gene expression to map regions en gaged in two-odor discrimination learning, with particular interest in neuronal groups in hippocampus and amygdala. The results of these stu dies demonstrate that the subdivisions of hippocampus and amygdala do not act in concert across behaviors but are differentially activated d epending on task demands. In hippocampus, preferential activation of f ield CA3 was uniquely associated with initial learning of an odor pair , whereas predominant activation of CA1 occurred with exploration of a novel field and with overtrained responding to odors. The reappearanc e of precisely the same balance of subfield activation within disparat e behavioral contexts was taken to suggest that the hippocampus has ba sic modes of function that recur in different circumstances and make r ather generalized contributions to behavior. Within the amygdala, the basolateral division was most prominently active during task acquisiti on but not during performance of the well-learned discrimination. Inde ed, the amygdala appeared to play the dominant role relative to hippoc ampus in the early stages of associating positive and negative valence s with discriminative cues. These results demonstrate that the balance of neuronal activity both within and between limbic structures change s across sequential stages of odor learning in a fashion that is likel y to define behavioral output. (C) 1998 Academic Press.