Epinephrine Modulation of Fear Conditioning under Awake and Anesthetic States
Date Issued
2006
Date
2006
Author(s)
Chao, Shu-Tang
DOI
zh-TW
Abstract
Temporal contiguity has been proved to be one of the most influential factors in associative learning. Stimulus saliency may also contribute significantly to learning. However, learning nonetheless happens without intention or even awareness. Thus, there should be mechanisms subserving the saliency function other than subjective awareness. Evidence indicated that learning under anesthesia occurs more during presentation of noxious stimuli that may release epinephrine. This study aimed to test whether epinephrine also modulates learning and memory processes under an anesthetic state. Conditioned freezing and conditioned potentiation of startle were chosen to assess memory of fear conditioned to a specific stimulus, the training environment or both using shock as unconditioned stimulus. The result showed that post-training epinephrine injections under an awake state did not modulate subsequent freezing behavior induced by the specific conditioned stimulus, the training environment or both of them. In contrast, pre-training epinephrine subcutaneous injection enhanced memory of fear-potentiated startle formed under awake and anesthetic states. In conclusion, epinephrine may be one of the mechanisms representing the stimulus saliency under awake and even anesthetic states.
Subjects
壓力激素
條件化僵直反應
恐懼增益驚跳反應
杏仁核
恐懼記憶
stress hormones
conditioned freezing
fear-potentiated startle
amygdala
Type
other
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