Combined Activation and Deactivation of Visual Cortex During Tactile Sensory Processing

• Published in: Journal of neurophysiology 2007-02, Vol.97 (2), p.1633-1641
• Main Authors: Merabet, Lotfi B, Swisher, Jascha D, McMains, Stephanie A, Halko, Mark A, Amedi, Amir, Pascual-Leone, Alvaro, Somers, David C
• Format: Article
• Language: English
• Subjects: Adult; Brain Mapping; Data Interpretation, Statistical; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Occipital Lobe - physiology; Oxygen - blood; Psychomotor Performance - physiology; Sensation - physiology; Touch - physiology; Vision, Ocular - physiology; Visual Cortex - physiology; Visual Pathways - cytology; Visual Pathways - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00806.2006

1 Perceptual Neuroimaging Laboratory, Department of Psychology and Program in Neuroscience, Boston University, Boston; 2 Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown; and 3 Center for Non-Invasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts Submitted 3 August 2006; accepted in final form 20 November 2006 The involvement of occipital cortex in sensory processing is not restricted solely to the visual modality. Tactile processing has been shown to modulate higher-order visual and multisensory integration areas in sighted as well as visually deprived subjects; however, the extent of involvement of early visual cortical areas remains unclear. To investigate this issue, we employed functional magnetic resonance imaging in normally sighted, briefly blindfolded subjects with well-defined visuotopic borders as they tactually explored and rated raised-dot patterns. Tactile task performance resulted in significant activation in primary visual cortex (V1) and deactivation of extrastriate cortical regions V2, V3, V3A, and hV4 with greater deactivation in dorsal subregions and higher visual areas. These results suggest that tactile processing affects occipital cortex via two distinct pathways: a suppressive top-down pathway descending through the visual cortical hierarchy and an excitatory pathway arising from outside the visual cortical hierarchy that drives area V1 directly. Address for reprint requests and other correspondence: L. B. Merabet, Dept. of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Ave., KS 430, Boston, MA 02215 (E-mail: lmerabet{at}bidmc.harvard.edu )