title: On-line attentional selection from competing stimuli in opposite visual fields: effects on human visual cortex and control processes.
abstract: We used fMRI to investigate competition and on-line attentional selection between targets and distractors in opposite visual hemifields. Displays comprised a high-contrast square-wave grating, defined as target by its orientation, presented alone (unilateral) or with a similar distractor of orthogonal orientation in the opposite hemifield (bilateral displays). The target appeared unpredictably on the left or right, precluding anticipatory attention to one side. We found greater activation in target-contralateral superior occipital gyrus for unilateral than for bilateral displays, indicating suppression of the target's visual representation by distractor presence despite the competing distractor projecting to a different occipital hemisphere. Several frontal and parietal regions showed greater activation for bilateral than unilateral trials, suggesting involvement in on-line attentional selection. This was particularly pronounced for regions in bilateral intraparietal sulcus (IPS), which also showed greater functional coupling with occipital cortex specifically on bilateral trials that required selection plus some repetition-suppression effects when target side was repeated, but again only on bilateral trials requiring selection. Our results indicate that competition between visual stimuli in opposite hemifields can influence occipital cortex, and implicate IPS in resolution of this competition by selection.
authors.affiliation: UCL Institute of Cognitive Neuroscience, University College London, London, United Kingdom. jgeng@ucdavis.edu
authors.forename: Joy J
authors.initials: JJ
authors.lastname: Geng
authors.forename: Evelyn
authors.initials: E
authors.lastname: Eger
authors.forename: Christian C
authors.initials: CC
authors.lastname: Ruff
authors.forename: Arni
authors.initials: A
authors.lastname: Kristjánsson
authors.forename: Pia
authors.initials: P
authors.lastname: Rotshtein
authors.forename: Jon
authors.initials: J
authors.lastname: Driver
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D003627:Data Interpretation, Statistical; D005133:Eye Movements / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009862:Online Systems; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000502:physiology; D010775:Photic Stimulation; D017397:Prefrontal Cortex / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*
chemical_list: D010100:Oxygen