The Role of Amygdala in Reward and Avoidance Learning: Single-Unit Activity Study on Consolidation and Retrieval of Affective Memory
Date Issued
2009
Date
2009
Author(s)
Chi, Chu-Yun
Abstract
The amygdala is well documented to mediate defensive behavior under fear and anxiety, but its role in appetitive behavior may be just as important according to the literature. A question arises whether the amygdala codes positive and negative stimuli in the same or different population of neurons. This study addressed this issue by examining involvement of the amygdala in an inhibitory avoidance task and a reward place preference task. In the first three experiments, we suppressed or lesioned the amygdala by microinfusion of tetrodotoxin or ibotenic acid before or after training on either task and verified that the amygdala was required to learn both tasks adopted. In the fourth experiment, the single unit activity was recorded from amygdala neurons at various phases of the two tasks we designed. It was shown that while some neurons responded with excitation or inhibition immediately after either one of the two tasks, other neurons did not change their firing rate unit a delay period of time. Furthermore, lateralized activation of the amygdala was detected after training. In the retention period, the individual responsive neurons also changed their firing rates either in the reward test or in the avoidance test and few neurons responded to both the reward and the avoidance tasks. Thus positive and negative stimuli were processed by two distinct populations of amygdala neurons. These findings shed lights on how the amygdala neurons represent various kinds of emotional experience.
Subjects
emotion
place preference
single-unit recording
lateralization
rats
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