Phantoms on the hands: Influence of the body on brief synchiric visual percepts. (February 2016)

• Record Type: Journal Article
• Authors: Medina, Jared; Drebing, Daniel E.; Hamilton, Roy H.; Coslett, H. Branch
• Is Part Of: Neuropsychologia. Volume 82(2016)
• Page Start: 104
• Page End: 109
• Publication Date: 2016-02
• Subjects: Synchiria -- Body schema -- Peripersonal space -- Magnocellular -- Transient visual system; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2016.01.016
• Languages: English
• ISSNs: 0028-3932

Abstract

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. Highlights: We report a brain-damaged individual who reports phantom visual percepts. These phantom synchiric percepts occur subsequent to ipsilesional stimulation. Phantoms occur most often for brief visual stimuli (≤250 ms) presented on the body. Provides evidence supporting enhanced processing for brief stimuli near hands. Damage to this system may result in removal of inhibition and phantom percepts.