Skip to main content
. 2021 Aug 24;10:e68240. doi: 10.7554/eLife.68240

Figure 2. Stimulus-induced ERF and gamma-band response in visual cortex.

(a) Each violet dot shows the selected dipole with the strongest visually induced gamma of one subject. Black-to-white shading indicates areas V1, V2, V3, V3A, and V4. All selected dipoles were located in areas V1 or V2. All analyses referring to activity in V1/V2 used the MEG data projected into these dipoles. (b) Average V1/V2 magnetic dipole moment in response to stimulus onset. (c) Average stimulus-induced power change in V1/V2, calculated as per-trial power from 0.3 to 1.3 s post-stimulus divided by average power during the 1 s baseline. Error bars in (b, c) show 95% confidence intervals based on a bootstrap across subjects. (d) Average stimulus-induced power change in V1/V2 as a function of time and frequency. In (c, d), power values from 1 to 20 Hz (below the gray bar) were computed using Hann tapering, power values of higher frequencies were computed using multi-tapering and line noise was removed using DFT filters. (e) Average stimulus-induced gamma-power change (individual gamma peak ±10 Hz), source projected to all cortical dipoles. Values are significance-masked using a tmax-corrected permutation test. Black-to-white shading indicates areas V1, V2, V3, V3A, and V4.

Figure 2.

Figure 2—figure supplement 1. Stimulus-induced power changes.

Figure 2—figure supplement 1.

(a) Average stimulus-induced alpha-power change (at individual alpha frequency), source-localized to all cortical dipoles. Values are significance-masked using a tmax-corrected paired permutation test. Black-to-white shading indicates areas V1, V2, V3, V3A, and V4, as in Figure 2. Note that alpha-power changes are absent in those areas. (b) Same as (a), but for power changes at the individual beta frequency. (c) Average stimulus-induced gamma-power change on the sensor level. (d) Gamma-power changes (color code) as a function of cortical retinotopic representation (x- and y-axis). Gamma-power changes were first projected into source dipoles. For each dipole in area V1, a group-average retinotopic atlas aligned to the HCP-MMP 1.0 template brain (Benson et al., 2018) was used to find the corresponding retinotopic position. Subsequently, gamma-power changes were projected from source space into retinotopic space. Gamma-power changes were strongest at the representation of the parafoveal eccentricities.