Single-neuron perturbations reveal feature-specific competition in V1

We developed a method – influence mapping – that uses single-cell perturbations to reveal how local neural populations reshape representations. We used two-photon optogenetics to trigger action potentials in a targeted neuron and calcium imaging to measure the effect on neighbors’ spiking in awake mice viewing visual stimuli. In V1 layer 2/3, excitatory neurons on average suppressed other neurons and had a center-surround influence profile over anatomical space. A neuron’s influence on a neighbor depended on their similarity in activity. Notably, neurons suppressed activity in similarly tuned neurons more than dissimilarly tuned neurons. Also, photostimulation reduced the population response, specifically to the targeted neuron’s preferred stimulus, by ~2%. Therefore, V1 layer 2/3 performed feature competition, in which a like-suppresses-like motif reduces redundancy in population activity and may assist inference of the features underlying sensory input. We anticipate influence mapping can be extended to uncover computations in other neural populations.