Neuron
Volume 90, Issue 1, 6 April 2016, Pages 177-190
Journal home page for Neuron

Article
Reward-Guided Learning with and without Causal Attribution

https://doi.org/10.1016/j.neuron.2016.02.018Get rights and content
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Highlights

  • Reward-guided learning is driven by several mechanisms operating in parallel

  • These mechanisms either respect or only approximate the causal structure of the world

  • Learning mechanisms respecting causal structure rely on orbitofrontal cortex

  • Other regions mediate learning based on temporal proximity and statistical regularity

Summary

When an organism receives a reward, it is crucial to know which of many candidate actions caused this reward. However, recent work suggests that learning is possible even when this most fundamental assumption is not met. We used novel reward-guided learning paradigms in two fMRI studies to show that humans deploy separable learning mechanisms that operate in parallel. While behavior was dominated by precise contingent learning, it also revealed hallmarks of noncontingent learning strategies. These learning mechanisms were separable behaviorally and neurally. Lateral orbitofrontal cortex supported contingent learning and reflected contingencies between outcomes and their causal choices. Amygdala responses around reward times related to statistical patterns of learning. Time-based heuristic mechanisms were related to activity in sensorimotor corticostriatal circuitry. Our data point to the existence of several learning mechanisms in the human brain, of which only one relies on applying known rules about the causal structure of the task.

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This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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