Evidence for a neural law of effect

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Science  02 Mar 2018:
Vol. 359, Issue 6379, pp. 1024-1029
DOI: 10.1126/science.aao6058

How to select and shape neural activity

When we learn a new skill or task, our movements are reinforced and shaped. Learning occurs because the neural activity patterns in the movement control–related brain regions that are rewarded are repeated. But how does this reinforcement work? Athalye et al. developed a closed-loop self-stimulation paradigm in which a target motor cortical activity pattern resulted in the optogenetic stimulation of dopaminergic neurons. With training, mice learned to reenter specific neuronal activity patterns, which triggered self-stimulation and shaped their neural activity to be closer to the target pattern.

Science, this issue p. 1024


Thorndike’s law of effect states that actions that lead to reinforcements tend to be repeated more often. Accordingly, neural activity patterns leading to reinforcement are also reentered more frequently. Reinforcement relies on dopaminergic activity in the ventral tegmental area (VTA), and animals shape their behavior to receive dopaminergic stimulation. Seeking evidence for a neural law of effect, we found that mice learn to reenter more frequently motor cortical activity patterns that trigger optogenetic VTA self-stimulation. Learning was accompanied by gradual shaping of these patterns, with participating neurons progressively increasing and aligning their covariance to that of the target pattern. Motor cortex patterns that lead to phasic dopaminergic VTA activity are progressively reinforced and shaped, suggesting a mechanism by which animals select and shape actions to reliably achieve reinforcement.

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