Comparing segmentation by time and by motion in visual search: an FMRI investigation.
Brain activity was recorded while participants engaged in a difficult visual search task for a target defined by the spatial configuration of its component elements. The search displays were segmented by time (a preview then a search display), by motion, or were unsegmented. A preparatory network showed activity to the preview display, in the time but not in the motion segmentation condition. A region of the precuneus showed (i) higher activation when displays were segmented by time or by motion, and (ii) correlated activity with larger segmentation benefits behaviorally, regardless of the cue. Additionally, the results revealed that success in temporal segmentation was correlated with reduced activation in early visual areas, including V1. The results depict partially overlapping brain networks for segmentation in search by time and motion, with both cue-independent and cue-specific mechanisms.
Dent
Kevin
K
Behavioural Brain Sciences Centre, School of Psychology, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. e-mail: k.dent@bham.ac.uk
Allen
Harriet
H
Humphreys
Glyn W
GW
D002540:Cerebral Cortex / Q000502:physiology*; D003463:Cues; D006179:Gyrus Cinguli / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008606:Mental Processes / Q000502:physiology; D009039:Motion Perception / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D013028:Space Perception / Q000502:physiology*; D013998:Time Perception / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology