古典的条件付けにおけるドーパミン放出に寄与する側坐核シェル領域の機能解明

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Rewards induce a transient increase in dopamine neuron firing rate. This reward induced dopamine response is diminished when the reward is predictable. The reduction in the dopamine response evoked by predicted rewards is necessary for the Kamin Blocking Effect (KBE).KB refers to the blocking of the formation of an association between a cue (blocked cue) and a temporally contiguous reward if, during the conditioning procedure, the cue is presented simultaneously with another cue (blocking cue) which has previously been conditioned using the same reward.Research conducted in the previous fiscal year found that output of the nucleus accumbens (NAc) and inhibitory inputs to the dopamine neurons during the compound cue conditioning phase played an important role in KBE. This suggested that the output of the accumbens may exert control over the inhibitory input to the dopamine neurons to produce the reduction in dopamine response to the predicted reward. However, such control would need to be learnt during the conditioning of the blocking cue. In this fiscal year, the output of the nucleus accumbens was inhibited during the conditioning of the blocking cue. This manipulation abolished the KBE, supporting the inference drawn from the previously conducted experiments. It was also found that only sign trackers, and not goal trackers, exhibit the KBE.Ongoing: i) Writing of a thesis towards the completion of my PhD degree; and ii) Writing of papers encompassing the foregoing results.