Closing the Sensory-Motor Loop on Dopamine Signalled Reinforcement Learning

Abstract

It has been shown recently that dopamine signalled modulation of spike timing-dependent synaptic plasticity (DA-STDP) can enable reinforcement learning of delayed stimulus-reward associations when both stimulus and reward are delivered at precisely timed intervals. Here, we test whether a similar model can support learning in an embodied context, in which timing of both sensory input and delivery of reward depend on the agent’s behaviour. We show that effective reinforcement learning is indeed possible, but only when stimuli are gated so as to occur as near-synchronous patterns of neural activity and when neuroanatomical constraints are imposed which predispose agents to exploratative behaviours. Extinction of learned responses in this model is subsequently shown to result from agent-environment interactions and not directly from any specific neural mechanism.