title: Does visual flicker phase at gamma frequency modulate neural signal propagation and stimulus selection?
abstract: Oscillatory synchronization of neuronal populations has been proposed to play a role in perceptual integration and attentional processing. However, some conflicting evidence has been found with respect to its causal relevance for sensory processing, particularly when using flickering visual stimuli with the aim of driving oscillations. We tested psychophysically whether the relative phase of gamma frequency flicker (60 Hz) between stimuli modulates well-known facilitatory lateral interactions between collinear Gabor patches (Experiment 1) or crowding of a peripheral target by irrelevant distractors (Experiment 2). Experiment 1 assessed the impact of suprathreshold Gabor flankers on detection of a near-threshold central Gabor target ("Lateral interactions paradigm"). The flanking stimuli could flicker either in phase or in anti-phase with each other. The typical facilitation of target detection was found with collinear flankers, but this was unaffected by flicker phase. Experiment 2 employed a "crowding" paradigm, where orientation discrimination of a peripheral target Gabor patch is disrupted when surrounded by irrelevant distractors. We found the usual crowding effect, which declined with spatial separation, but this was unaffected by relative flicker phase between target and distractors at all separations. These results imply that externally driven manipulations of gamma frequency phase cannot modulate perceptual integration in vision.
authors.affiliation: UCL Institute of Cognitive Neuroscience, Wellcome Trust Centre for Neuroimaging, University College London, London, UK. Markus.bauer@gmail.com
authors.forename: Markus
authors.initials: M
authors.lastname: Bauer
authors.forename: Thomas
authors.initials: T
authors.lastname: Akam
authors.forename: Sabine
authors.initials: S
authors.lastname: Joseph
authors.forename: Elliot
authors.initials: E
authors.lastname: Freeman
authors.forename: Jon
authors.initials: J
authors.lastname: Driver
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology; D003441:Crowding; D005425:Flicker Fusion / Q000502:physiology*; D006801:Humans; D010507:Periodicity; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*