| Summary: | 碩士 === 慈濟大學 === 神經科學研究所 === 97 === Emotion can have a powerful impact on memory, and can strengthen the
formation of memory. Emotional memory can be affected by many factors. For
example, pre-exposure of context may induced the phenomenon of latent inhibition to
interfere the emotional memory. The amygdala (AMY) involvs in the learning and
memory processes of emotion events and anterior cingulate cortex (ACC) plays an
important role in the latent inhibition. This study examined how the pre-exposure of
context affected the neuronal activities of AMY and ACC in the inhibitory avoidance
task. The micro-wire electrodes were chronically implanted in the AMY and ACC of
Long-Evans rats. The neuronal activities of AMY and ACC in conscious rats were
recorded extracellularly during the pre-exposure of context and inhibitory avoidance
(IA) training. The animals of pre-exposure (PE) group were exposed to the context of
IA for five days before training. The animals of non-pre-exposure (NPE) group were
exposed to the context different from the shuttle box. On the sixth day, the rats was
tested before training and then received the foot-shock (0.4 mA , 1s) in the dark side
of apparatus. The rats were tested on the next day of foot shock training. The retention
latencies of both PE and NPE groups were enhanced after the IA training. However,
shorter retention latency was shown in the PE group than the NPE group. These
results suggested that the rats learned the IA task and pre-exposure of context induced
latent inhibition (LI) effect. Multiple single-unit activities of AMY and ACC in both
groups were recorded simultaneously during the pre-exposure period and IA task.
After training, the unit activities of AMY and ACC were change. The change of AMY
unit activities in the PE group was less then the one in the NPE group. The change of
ACC unit activities in the PE group was more then the one in the NPE group. These
results showed that the process of context pre-exposure induced the latent inhibition
in IA paradigm and the neuronal activities of AMY and ACC were affected in the
phenomenon of latent inhibition. It has been suggested that AMY and ACC might be
involved in the modulation of fear emotion and memory.
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