"It has been suggested that dopamine (DA) represents reward-prediction-error (RPE) defined in reinforcement learning and therefore DA responds to unpredicted but not predicted reward. However, recent studies have found DA response sustained towards predictable reward in tasks involving self-paced behavior, and suggested that this response represents a motivational signal. We have previously shown that RPE can sustain if there is decay/forgetting of learned-values, which can be implemented as decay of synaptic strengths storing learned-values. This account, however, did not explain the suggested link between tonic/sustained DA and motivation. In the present work, we explored the motivational effects of the value-decay in self-paced approach behavior, modeled as a series of ‘Go’ or ‘No-Go’ selections towards a goal. Through simulations, we found that the value-decay can enhance motivation, specifically, facilitate fast goal-reaching, albeit counterintuitively. ..."
Model Concept(s): Reinforcement Learning
Simulation Environment: MATLAB
Implementer(s): Kato, Ayaka ; Morita, Kenji [morita at p.u-tokyo.ac.jp]
References:
Kato A, Morita K. (2016). Forgetting in Reinforcement Learning Links Sustained Dopamine Signals to Motivation. PLoS computational biology. 12 [PubMed]