Cookies on this website
We use cookies to ensure that we give you the best experience on our website. If you click 'Continue' we'll assume that you are happy to receive all cookies and you won't see this message again. Click 'Find out more' for information on how to change your cookie settings.

In a variety of attention and search tasks, single-cell recordings of the primate brain have frequently shown an enhancement of responses in early visual areas to selected target stimuli. This enhancement is observed only at longer latencies, suggesting the possibility that it reflects the action of feedback or return signals from upstream processing areas. However, in typical studies, targets are specified on the basis of elementary visual features; as these are coded at multiple levels of the visual system, it is impossible to determine where enhanced target processing begins. Using human functional magnetic resonance imaging (fMRI), we demonstrate enhancement of activity in early visual areas even when low-level visual information is insufficient for target detection to occur. We found enhanced activity in early visual areas to targets defined purely by semantic category, suggesting that feedback signals returning from at least as far forward as temporal lobe semantic processing can influence visual responses. These findings also suggest feedback signaling as a mechanism by which early and late brain systems coding for different properties of a target object can integrate their activity, allowing for the target object to dominate overall processing.

Original publication

DOI

10.1016/j.neuropsychologia.2009.02.011

Type

Journal article

Journal

Neuropsychologia

Publication Date

06/2009

Volume

47

Pages

1721 - 1727

Keywords

Adolescent, Attention, Brain, Brain Mapping, Feedback, Female, Humans, Image Processing, Computer-Assisted, Magnetic Resonance Imaging, Male, Oxygen, Photic Stimulation, Reaction Time, Semantics, Signal Detection, Psychological, Young Adult