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Andrew Yong-Yi Tan

Publications and source records attributed to Andrew Yong-Yi Tan.

2 recordsLinked to original sources

One-shot learning of paired association navigation with biologically plausible schemas

After learning a multiple paired-association (MPA) navigation task, rodents can rapidly learn new cue-location associations after a single exposure, a phenomenon proposed to be facilitated by cognitive schemas. However, it remains unclear what schemas support this behavior and how they could be implemented in biological neural circuits. Here, we identify a set of schemas sufficient for gradual then one-shot paired-association navigation, and implement them in a fully neural agent using biologically plausible plasticity rules. The agent gradually acquires a low-dimensional spatial metric representation using a path-integration based temporal-difference error, enabling self-localization across different environments. It also contains a memory network that forms one-shot associations between sensory cues and goal locations, implemented using reward-modulated exploratory Hebbian (EH) plasticity. A third network performs vector subtraction between the agent's current and goal location to compute goal-directed actions. Supplementing these schemas with an actor-critic enables one-shot navigation past obstacles. Lastly, learning a working-memory gating mechanism using the temporal-difference error enables one-shot learning even with brief cue and distractor presentation. The model reproduces key behavioral features of rodent learning in the MPA task and generates testable predictions about the neural mechanisms underlying schema-based one-shot learning.

cs.NE↗

A nonlinear hidden layer enables actor-critic agents to learn multiple paired association navigation

Navigation to multiple cued reward locations has been increasingly used to study rodent learning. Though deep reinforcement learning agents have been shown to be able to learn the task, they are not biologically plausible. Biologically plausible classic actor-critic agents have been shown to learn to navigate to single reward locations, but which biologically plausible agents are able to learn multiple cue-reward location tasks has remained unclear. In this computational study, we show versions of classic agents that learn to navigate to a single reward location, and adapt to reward location displacement, but are not able to learn multiple paired association navigation. The limitation is overcome by an agent in which place cell and cue information are first processed by a feedforward nonlinear hidden layer with synapses to the actor and critic subject to temporal difference error-modulated plasticity. Faster learning is obtained when the feedforward layer is replaced by a recurrent reservoir network.

cs.NE↗