| 研究実績の概要 |
In Heisei 27 we made a great deal of progress. we set out to examine how fear memories can be reduced when they are no longer appropriate, a process called extinction learning. We first examined whether dopamine neurons in the ventral tegmental area (VTA), whic are important for reward, detect when fear memories are no longer appropriate to signal extinction learning. In the last year we found that activity in dopamine neurons when aversive outcomes are expected yet don't occur is required to extinguish fear memories. To do this we expressed optogenetic proteins in a genetically modified rat to inhibit dopamine neurons in a temporally and cell type specific manner. We then examine the effects of this manipulation on intracellular signaling in areas that store extinction memories, the amygdala and medial prefrontal cortex. We found that in addition to blocking extinction learning, inhibiting dopamine neurons during unexpected omission of aversive outcomes also blocked the phosphorylation of MAP kinase in amygdala and mPFC.
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| 今後の研究の推進方策 |
Separate populations of VTA dopamine neurons project to the amygdala, mPFC and nucleus accumbens. In the next fiscal year we will examine the contribution of these specific cell VTA-dopamine cell populations to extinction learning. specifically we will use a genetically modified TH-cre rat to express an inhibitory opsin in dopamine neurons and in their nerve terminals in the amygdala, mPfC and accumbens. We will then inhibit nerve terminal release in these regions and examine the effects of these manipulations on extinction learning and memory.
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