Fig. 1.

Experimental setup and paradigm. A: diagram of stereoscopic stimulation. Monkeys were positioned behind a set of calibrated cold mirrors such that each eye received stimulation from independent halves of a CRT monitor (see materials and methods for details). B: grayscale to depict each individual presentation (P₁–P₅) of the stimulation sequence. C: temporal organization of events in each trial. Each trial consisted of 5 stimuli (STIM) randomly presented to one or both eyes (stimulus parameters detailed in materials and methods) while the monkeys maintained fixation (FIX). Whenever the monkeys successfully maintained fixation throughout, they received a juice reward (RWD) at the end of the trial. D: stimulus sizes (dva, degrees of visual angle) and locations for each recording session (n = 61). Colors encode the animal (E48, I34) and recorded V1 hemisphere (L, left; R, right). E–G: laminar profiles of stimulus-evoked local field potential (LFP) responses. Ordinate represents cortical depth from the cortical surface toward the white matter, with 0 marking the L4/L5 boundary (dashed line). E: average current source density (CSD) profile across both animals and all sessions. Abscissa represents time from stimulus onset (0 ms). F: average power spectral density of the V1 LFP across both animals and all sessions (t = 0 to 200 ms). Abscissa represents frequency (f). Power was normalized (norm.) such that at each frequency, the response maximum was set to 1 and the response minimum was set to 0. G: average LFP cross-correlations (R) between all electrode-pair combinations following visual stimulation. Abscissa represents cortical depth from the top of cortex (left) toward the white matter (right). H: representative receptive fields (RF) from a single session based on thresholded multiunit activity for each electrode channel. Each color denotes a different channel of the same linear array. Black line indicates the mean RF across all channels. I: 7T MRI of neocortex showing the location of an electrode penetration perpendicular to the cortical surface of V1. Red outline highlights the susceptibility artifact caused by cerebrospinal fluid in a tissue track where the electrode was located. L, lateral; P, posterior.