title: Attention extracts signal in external noise: a BOLD fMRI study.
abstract: On the basis of results from behavioral studies that spatial attention improves the exclusion of external noise in the target region, we predicted that attending to a spatial region would reduce the impact of external noise on the BOLD response in corresponding cortical areas, seen as reduced BOLD responses in conditions with large amounts of external noise but relatively low signal, and increased dynamic range of the BOLD response to variations in signal contrast. We found that, in the presence of external noise, covert attention reduced the trial-by-trial BOLD response by 15.5-18.9% in low signal contrast conditions in V1. It also increased the BOLD dynamic range in V1, V2, V3, V3A/B, and V4 by a factor of at least three. Overall, covert attention reduced the impact of external noise by about 73-85% in these early visual areas. It also increased the contrast gain by a factor of 2.6-3.8.
authors.affiliation: Department of Psychology, University of Southern California, SGM 501, 3620 McClintock Ave., Los Angeles, CA 90089-1061, USA. zhonglin@usc.edu
authors.forename: Zhong-Lin
authors.initials: ZL
authors.lastname: Lu
authors.forename: Xiangrui
authors.initials: X
authors.lastname: Li
authors.forename: Bosco S
authors.initials: BS
authors.lastname: Tjan
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Dosher
authors.forename: Wilson
authors.initials: W
authors.lastname: Chu
mesh_terms: D000328:Adult; D000465:Algorithms; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005364:Field Dependence-Independence; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008959:Models, Neurological; D010100:Oxygen / Q000097:blood; D010470:Perceptual Masking / Q000502:physiology*; D012016:Reference Values; D013028:Space Perception / Q000502:physiology; D014793:Visual Cortex / Q000098:blood supply / Q000378:metabolism / Q000502:physiology*
chemical_list: D010100:Oxygen