Figure 2—figure supplement 1. Laminar alignment and receptive field mapping.

(A) Representative receptive fields (RFs) measured with gamma power across recording sites of a single array penetration. RFs across recording sites (z axis) are well aligned, indicating perpendicular penetration. Electrode positioned at left for reference. (B) Current source density (CSD) profile for the same session as (C). The initial sink following visual stimulation was used as a functional marker to determine the layer 4/5 boundary. Current sinks are indicated in red and sources in blue. The black horizontal line indicates the bottom of the granular input sink. Data are smoothed along depth and across time for visualization purposes. (C) Mean CSD profile following alignment of the 30 sessions (monkey Ca 21; He 9). Formatting identical to (B). (D) Columns’ RF locations across sessions and monkeys (cyan, monkey Ca; magenta, He). RF centers determined online, and diameters estimated from previous reports (see V4 RF mapping and electrode orthogonality for details). Concentric circles indicate eccentricities in degrees of visual angle (dva). Radial lines indicate angular positions relative to central fixation (black dot at top center). (E) Additional RF alignments using the magnitude of local field potential (LFP) response along depth, rather than gamma power as in (A), for electrodes found to be in cortex. Leftmost six are examples from monkey Ca (indicated with cyan bar at bottom) and rightmost two are from monkey He (indicated with magenta bar at bottom). Magnitude of LFP response was found for each recording site and normalized from smallest to largest response across visual space leading to the 0–1 normalization. Contours show the location of the largest LFP response along depth. Red vertical line through three-dimensional plot, and red point shown at the top of each plot, indicates the RF measured along depth with black vertical line indicating central fixation. Note the angle for monkey Ca indicates RF’s between 270 degrees (lower visual field vertical meridian) and 0 degrees (right-hand visual field horizontal meridian) and for monkey He indicates RF’s between 180 degrees (left-hand visual field horizontal meridian) and 270 degrees – both consistent with the contralateral positioning of recording chambers for each monkey (monkey Ca left V4, He right V4).