Sit, T. P. H.; Bimbard, C.; Lebedeva, A.; Carandini, M.; Coen, P.; Harris, K. D.

The cortex contains multiple types of excitatory neuron, differentiated primarily by their layer of residence. We recorded from neuronal populations in the mouse visual cortex using 2-photon calcium imaging or Neuropixels probes, and found that excita-tory neurons in layer 2/3 (L2/3) and layer 5 (L5) differ in their encoding of visual vs. nonvisual signals, with L2/3 more strongly modulated by visual stimuli and L5 more strongly modulated by movement. Movement has opposite effects on population synchrony in the two layers, desynchronizing L2/3 by abolishing spontaneous population oscillations, and synchronizing L5, where excitatory cells are less entrained by oscillation and more strongly correlated with movement itself. Spontaneous activity is lower-dimensional in L2/3 than L5, with L2/3 population activity dominated by a single dimension of overlap between spontaneous and stimulus-evoked subspaces. We conclude that the population code of in different layers of the visual cortex differentially balances visual and non-visual signals.