Remapping in Human Visual Cortex

• Published in: Journal of neurophysiology 2007-02, Vol.97 (2), p.1738-1755
• Main Authors: Merriam, Elisha P, Genovese, Christopher R, Colby, Carol L
• Format: Article
• Language: English
• Subjects: Acoustic Stimulation; Adult; Algorithms; Bayes Theorem; Brain Mapping; Cerebrovascular Circulation - physiology; Eye Movements - physiology; Female; Fixation, Ocular - physiology; Functional Laterality - physiology; Humans; Magnetic Resonance Imaging; Male; Memory - physiology; Models, Neurological; Models, Statistical; Photic Stimulation; Psychomotor Performance - physiology; Retina - physiology; Saccades - physiology; Visual Cortex - physiology; Visual Fields - physiology; Visual Perception - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00189.2006

1 Department of Neuroscience, University of Pittsburgh; 2 Department of Statistics, Carnegie Mellon University; and 3 Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania Submitted 21 February 2006; accepted in final form 1 November 2006 With each eye movement, stationary objects in the world change position on the retina, yet we perceive the world as stable. Spatial updating, or remapping , is one neural mechanism by which the brain compensates for shifts in the retinal image caused by voluntary eye movements. Remapping of a visual representation is believed to arise from a widespread neural circuit including parietal and frontal cortex. The current experiment tests the hypothesis that extrastriate visual areas in human cortex have access to remapped spatial information. We tested this hypothesis using functional magnetic resonance imaging (fMRI). We first identified the borders of several occipital lobe visual areas using standard retinotopic techniques. We then tested subjects while they performed a single-step saccade task analogous to the task used in neurophysiological studies in monkeys, and two conditions that control for visual and motor effects. We analyzed the fMRI time series data with a nonlinear, fully Bayesian hierarchical statistical model. We identified remapping as activity in the single-step task that could not be attributed to purely visual or oculomotor effects. The strength of remapping was roughly monotonic with position in the visual hierarchy: remapped responses were largest in areas V3A and hV4 and smallest in V1 and V2. These results demonstrate that updated visual representations are present in cortical areas that are directly linked to visual perception. Address for reprint requests and other correspondence: E. P. Merriam, Center for Neural Science, 6 Washington Place, Rm 962, New York, NY 10003 (E-mail: eli{at}cns.nyu.edu )