Role of Basolateral Amygdala in Formation of Anxiety Related Memory

Abstract

Objective: Amygdala plays a critical role in affect, is involved in anxiety disorders and anxiety related environmental fear conditioning. The aim of this study was to investigate the role of basolateral amygdala (BLA) in hereditary anxiety/fear behaviours and learned cognitive and affective anxiety/fear behaviours. Material and Methods: Wistar male rats were used in our study. Subjects were divided into two groups as sham (control) group and BLA lesion group. Rats were allowed to heal for two weeks after surgical procedure and were tested thereafter. Effect of BLA on acquisition, storage and recalling of cognitive and affective fear behaviours was evaluated using learning tests like passive avoidance test and unsigned Pavlov type fear conditioning. Results: In the passive avoidance test, immediately after and 48 hours after the shock, impairment was seen in freeze and avoidance from dark behaviors in rats with BLA lesions compared to control rats. This finding indicates that acquisition and cognitive fear conditioning performance in memory was impaired. When the test in the shock applied environment (unsigned Pavlov type conditioning mechanism) was repeated, BLA lesion impaired conditional freeze; this finding indicates that lesion impairs acquisition and storage processes in affective fear conditioning. Conclusion: We suggest that BLA is involved in the expression of unconditional freeze memory and in establishing a relatinship between environmental clues and sensorial component of unconditional stimulus.