| 研究実績の概要 |
In Heisei 28 we have made tremendous progress. We examined the contribution of the contribution of the brainstem locus coeruleus/LC-noradrenaline system to fear and extinction learning. In the last year we used viral approaches to manipulate and trace the efferent connectivity of specific LC-noradrenaline cell populations to the amygdala or medial prefrontal cortex (mPFC). In anatomical studies we found that the LC contains distinct cell populations which project to amygdala or mPFC. We then used a retrograde virus approach to optogenetically inhibit either the LC-noradrenaline cells projecting to amygdala or mPFC. We found that inhibition of amygdala projecting LC neurons blocked fear learning. By contrast, inhibiting the mPFC projecting LC-noradrenaline cells reduced fear extinction learning. Interestingly, inhibition of the amygdala projecting cells enhanced extinction learning, suggesting opposing interactions between amygdala and mPFC projecting LC cells during extinction learning. Finally, we used another retrograde viral approach to map the brain-wide efferent connectivity of these amygdala and mPFC projecting LC-noradrenaline cell populations. We found that each innervated amygdala or mPFC and functionally related, neighboring brain regions, but did not project to other brain regions.
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