title: Phantoms on the hands: Influence of the body on brief synchiric visual percepts.
abstract: Recent studies have found preferential responses for brief, transient visual stimuli near the hands, suggesting a link between magnocellular visual processing and peripersonal representations. We report an individual with a right hemisphere lesion whose illusory phantom percepts may be attributable to an impairment in the peripersonal system specific to transient visual stimuli. When presented with a single, brief (250 ms) visual stimulus to her ipsilesional side, she reported visual percepts on both sides - synchiria. These contralesional phantoms were significantly more frequent when visual stimuli were presented on the hands versus off the hands. We next manipulated stimulus duration to examine the relationship between these phantom percepts and transient visual processing. We found a significant position by duration interaction, with substantially more phantom synchiric percepts on the hands for brief compared to sustained stimuli. This deficit provides novel evidence both for preferential processing of transient visual stimuli near the hands, and for mechanisms that, when damaged, result in phantom percepts.
authors.affiliation: Department of Psychology, University of Delaware, United States; Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania, United States. Electronic address: jmedina@psych.udel.edu.
authors.forename: Jared
authors.initials: J
authors.lastname: Medina
authors.affiliation: Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania, United States.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Drebing
authors.affiliation: Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania, United States.
authors.forename: Roy H
authors.initials: RH
authors.lastname: Hamilton
authors.affiliation: Department of Neurology, Center for Cognitive Neuroscience, University of Pennsylvania, United States.
authors.forename: H Branch
authors.initials: HB
authors.lastname: Coslett
mesh_terms: D001828:Body Image; D005260:Female; D007839:Functional Laterality; D006225:Hand; D006801:Humans; D008875:Middle Aged; D010468:Perceptual Disorders / Q000473:pathology / Q000503:physiopathology*; D010775:Photic Stimulation; D010812:Physical Stimulation; D055698:Touch Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
keywords: Body schema; Magnocellular; Peripersonal space; Synchiria; Transient visual system