Abstract
In principle, the brain should be best able to associate distinct behavioral responses to two sensory stimuli when these stimuli evoke sensory population response vectors that are close to orthogonal. To investigate whether task training orthogonalizes the population code in primary visual cortex (V1), we measured the orientation tuning of 4,000-neuron populations in mouse V1 before and after training on a visuomotor association task. In the task, two orientations were associated with opposite behavioral responses, while a third was a distractor. The effect of task training on population activity could be captured by a simple mathematical transformation of firing rates, which suppressed responses to the motor-associated stimuli specifically in cells responding to them at intermediate levels. This orthogonalized the representations of the task orientations by sparsening the population responses to these stimuli. The degree of response transformation varied from trial to trial, suggesting a dynamic circuit mechanism rather than static synaptic plasticity. These results indicate a simple process by which visuomotor associations orthogonalize population codes as early as in primary visual cortex.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Addition of analyses on the fidelity of motor-associated stimulus representations before and after task training. Addition of analyses on the relationship between behavioral state and the convexity of trial responses.
