title: Neural activities in v1 create a bottom-up saliency map.
abstract: The bottom-up contribution to the allocation of exogenous attention is a saliency map, whose neural substrate is hard to identify because of possible contamination by top-down signals. We obviated this possibility using stimuli that observers could not perceive, but that nevertheless, through orientation contrast between foreground and background regions, attracted attention to improve a localized visual discrimination. When orientation contrast increased, so did the degree of attraction, and two physiological measures: the amplitude of the earliest (C1) component of the ERP, which is associated with primary visual cortex, and fMRI BOLD signals in areas V1-V4 (but not the intraparietal sulcus). Significantly, across observers, the degree of attraction correlated with the C1 amplitude and just the V1 BOLD signal. These findings strongly support the proposal that a bottom-up saliency map is created in V1, challenging the dominant view that the saliency map is generated in the parietal cortex.
authors.affiliation: Department of Psychology and Key Laboratory of Machine Perception (Ministry of Education), Peking University, Beijing 100871, China.
authors.forename: Xilin
authors.initials: X
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Zhaoping
authors.forename: Tiangang
authors.initials: T
authors.lastname: Zhou
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D001931:Brain Mapping; D015350:Contrast Sensitivity / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008954:Models, Biological; D009949:Orientation; D010100:Oxygen / Q000097:blood; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D011930:Reaction Time; D014793:Visual Cortex / Q000098:blood supply / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen