c-Fos Expression in Rat’s brain Following Acquisition and Expression of Recent or Remote Memory in an Inhibitory Avoidance Task
Date Issued
2011
Date
2011
Author(s)
Yang, You-Ping
Abstract
The inhibitory avoidance (IA) task is a widely adopted task to assess emotional memory. Accumulating data from pharmacological and other research have shown that acquisition and expression of such memory involved multiple brain regions as well as complicated interaction among them. However, findings from manipulative or electrophysiological recording studies fall short of tracing the full distribution of relevant sites for such learning. To investigate the neural substrates participating in IA learning and potential dynamic reorganization of brain regions involved in recent and remote memories, we tracked down the expression of protein c-Fos, the product of immediate-early gene c-fos, following acquisition, 1 day recall, and 30 day recall of IA memory in multiple brain regions implicated in the IA task. Separate groups of male Wistar rats were trained with context-exposure (C), shock-exposure (S) or context-shock association (IA) in the IA task and tested for memory 50 minutes, 1 day, or 30 days later. One hour after completion of training or testing, rats were perfused transcardially. Brain slices were prepared for c-Fos immunohistochemistry and c-Fos expression was measured in several brain regions implicated in memory formation and retrieval. Compared with the control group only exposed to context or shock, trained rats had increased c-Fos immunoreactivity in the basolateral amygdala and dorsal hippocampus following acquisition, recent or remote recall. In the insular cortex, increased c-Fos expression was observed after acquisition and remote recall. In the medial prefrontal cortex, increased c-Fos was found in prelimbic and cingulate cortex following either recent or remote recall. In contrast, in the medial septal area and nucleus accumbens, c-Fos was increased only following remote recall. No significance difference in c-Fos expression were found between trained rats and controls in the central amygdala and primary motor cortex. An additional correlative analysis further revealed significant high correlation in the CA1 and DG in the acquisition of IA memory. In recent memory recall, significant correlation was found in the BLA, CA1, DG, PrL, M1, and MSA. In remote memory recall, high correlation between the retention performance and c-Fos expression was found in extensive brain regions, including the BLA, CA1, CA3, DG, PrL, Cg1, M1, IC, MSA, and NAcc. These findings suggest a dynamic change of activated brain regions subserving the IA memory over the period from shortly after acquisition to remote retention.
Subjects
emotional memory
inhibitory avoidance
memory formation
recent memory
remote memory
Type
thesis
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