Fig. 3: Laminar recordings in area V4.

a Experimental protocol: Paired Gabor stimuli with varying contrasts (see “Methods”); one stimulus was presented inside the receptive fields (RFs) of the recorded neurons and the other at an equally eccentric location across the vertical meridian. Attention was cued either to the neurons’ RFs (IN) or to the location in the contralateral visual hemifield (AWAY). The orientation of one of the two stimuli changed at a random time. The monkey was rewarded for detecting the change by making a saccade to the corresponding location. Task difficulty was controlled by the magnitude of orientation change. b Left, Recording approach: Laminar recordings in visual area V4. Middle, Stacked contour plot showing spatial receptive fields (RFs) along the laminar probe from an example session. Alignment of RFs indicates perpendicular penetration down a cortical column. Zero depth represents the center of the input layer as estimated with current source density (CSD) analysis. Right, CSD is displayed as a colored map. The x-axis represents time from stimulus onset; the y-axis represents cortical depth. The CSD map has been spatially smoothed for visualization. c An example trial showing single-unit activity across the cortical depth in the attend-in condition. The time axis is referenced to the appearance of the fixation spot. Spikes (vertical ticks) in each recording channel come from either single units (blue, orange) or multi-units (black). Spike waveforms for an example narrow-spiking (blue) and a broad-spiking (orange) single unit are shown. The bars at the bottom depict stimulus presentation epochs, with height indicating relative stimulus contrast. The brain schematic in (b) is adapted from Nandy, A.S., Nassi, J.J., Jadi, M.P., Reynolds, J.H. (2019) Optogenetically induced low-frequency correlations impair perception eLife 8:e35123. https://doi.org/10.7554/eLife.35123 and is under a CC BY license: https://creativecommons.org/licenses/by/4.0/.