The blood oxygenation level-dependent (BOLD) functional MRI response to suppressive neural activity has not been tested on a fine spatial scale. Using Gabor patches placed in the near periphery, we precisely localized individual regions of interest in primary visual cortex and measured the response at a range of contrasts in two different contexts: with parallel and with orthogonal flanking Gabor patches. Psychophysical measurements confirmed strong suppression of the target Gabor response when flanked by parallel Gabors. However, the BOLD response to the target with parallel flankers decreased as the target contrast increased, which contradicts psychophysical estimates of local neural activity.
Bibliographical noteFunding Information:
We thank S. Engel, J. Hegdé, D. Kersten, L. Holm, S. Thompson and two anonymous reviewers for their useful comments. Also thanks to Ari Holloway-Nahum for assistance with preliminary versions of the main experiment. The following funding sources supported this research: NIH-NPCS Graduate Student Training Fellowship, MIND Foundation, BTRR P41 RR008079, P30 NS057091 and NIH R01 EY015261.
- Primary visual cortex (V1)
- Surround suppression