The brain is organized into distinct, flexible networks. Within these networks, cognitive variables such as attention can modulate sensory representations in accordance with moment-to-moment behavioral requirements. These modulations can be studied by varying task demands; however, the tasks employed are often incongruent with the postulated functions of a sensory system, limiting the characterization of the system in relation to natural behaviors. Here we combine domain-specific task manipulations and ultra-high field fMRI to study the nature of top-down modulations. We exploited faces, a visual category underpinned by a complex cortical network, and instructed participants to perform either a stimulus-relevant/domain-specific or a stimulus-irrelevant task in the scanner. We found that 1. perceptual ambiguity (i.e. difficulty of achieving a stable percept) is encoded in top-down modulations from higher-level cortices; 2. the right inferior-temporal lobe is active under challenging conditions and uniquely encodes trial-by-trial variability in face perception.
Bibliographical noteFunding Information:
Funding for this study was provided by National Institutes of Health Grants RF1 MH117015 (Ghose), RF1 MH116978 (Yacoub), P41 EB027061 (Ugurbil) and P30 NS076408 (Ugurbil). The authors would also like to thank Dr. Kendrick Kay for conceptual discussions regarding stimulus ambiguity and feedback.
- Cognitive Neuroscience
- Cortical Network
- Task modulations
- Ultra High Field
PubMed: MeSH publication types
- Journal Article