Abstract
Spatial frequency (SF) selectivity serves as a fundamental building block within the visual system, determining what we can and cannot see. Attention is theorized to augment the visibility of items in our environment by changing how we process SFs. However, the specific neural mechanisms underlying this effect remain unclear, particularly in humans. Here, we used functional magnetic resonance imaging (fMRI) to measure voxel-wise population SF tuning (pSFT), which allowed us to examine how attention alters the SF response profiles of neural populations in early visual cortex (V1–V3). In the scanner, participants (5 female, 3 male) were cued to covertly attend to one of two spatially competing letter streams, each defined by low or high SF content. This task promoted feature-based attention directed to a particular SF, as well as the suppression of the irrelevant stream’s SF. Concurrently, we measured pSFT in a task-irrelevant hemifield to examine how the known spatial spread of feature-based attention influenced the SF tuning properties of neurons sampled within a voxel. We discovered that attention elicited attractive shifts in SF preference, towards the attended SF. This suggests that attention can profoundly influence populations of SF preference across the visual field, depending on task goals and native neural preferences.
Significance Statement The spatial frequency (SF) preference of neural populations in early visual cortex governs the coarse and fine details we can see. However, the brain is limited in what it can process, requiring selective attention to prioritize relevant over irrelevant details. Although SF is fundamental to visual processing, it remains unclear how selective attention to SF alters population-level responses to SF. Using fMRI, we measured SF preferences in V1–V3 while participants deployed feature-based attention to one of two competing stimuli solely defined by their SF. We found that attention produced attractive shifts in preferences across the visual field, towards the attended SF, demonstrating that voluntary attention can flexibly reshape SF preferences in early visual cortex.
Footnotes
The authors declare no competing financial interests.
We thank Emily Wiecek, Jasmine Pan, Minsun Park, David Somers, and Taosheng Liu for thoughtful discussion. We also thank the editors and reviewers for their feedback. This research was funded by National Institutes of Health Grant EY028163 to S. Ling and supported by F99NS124144 to L.D. Ramirez. L.D. Ramirez’s current affiliation is with the Department of Psychology at University of California San Diego. This research was carried out at the Boston University Cognitive Neuroimaging Center. This work involved the use of instrumentation supported by the NSF Major Research Instrumentation grant BCS-1625552. We acknowledge the University of Minnesota Center for Magnetic Resonance Research for use of the multiband-EPI pulse sequences. Data was analyzed on a high-performance computing cluster supported by the ONR grant N00014-17-1-2304.
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
