Fig. 1.

Experimental setup and distribution of noise correlations. A: 4 types of stimuli, with illustrative single frames. B: Utah array and the position of its sites in an orientation preference map of cat V1. On each electrode, spike waveforms were clustered in principal component analysis space. Two clusters correspond to single units (orange and purple) and one to multiunit noise [multiunit activity (MUA), black]. C: histogram of spike widths shows 2 clear distinct peaks, corresponding to narrow-spiking and broad-spiking cells. D: waveforms of a narrow-spiking cell (orange) and a broad-spiking cell (purple). They correspond to the colored clusters in B. E: distribution of pairwise noise correlations at a timescale of Δ = 100 ms obtained across all cats (n = 7) and all stimulus conditions. F, Same as in E, but computed at 3 timescales (Δ = 20, 100, and 500 ms). G: same as in E but split into each stimulus condition. H: average noise correlations as a function of timescale for each stimulus condition. Error bars are included for only 2 conditions for ease of visualization but are comparable across conditions.