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Combined activation and deactivation of visual cortex during tactile sensory processing
Lotfi B Merabet1, Jascha D Swisher, Stephanie A McMains
1Department of Neurology, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, KS 430, Boston, MA 02215, USA. lmerabet@bidmc.harvard.edu
Journal of Neurophysiology
|December 1, 2006
Summary
Tactile exploration activates the primary visual cortex (V1) while deactivating other visual areas. This suggests distinct pathways influence occipital cortex during non-visual sensory processing.
Area of Science:
- Neuroscience
- Sensory Processing
- Visual Cortex
Background:
- Occipital cortex is involved in sensory processing beyond vision.
- Tactile processing modulates higher-order visual and multisensory areas.
- The role of early visual cortical areas in tactile processing is unclear.
Purpose of the Study:
- To investigate the involvement of early visual cortical areas in tactile processing.
- To understand how tactile exploration affects the occipital cortex in sighted individuals.
Main Methods:
- Functional magnetic resonance imaging (fMRI) was used.
- Normally sighted subjects were briefly blindfolded.
- Subjects tactually explored and rated raised-dot patterns.
Main Results:
- Tactile task performance activated the primary visual cortex (V1).
- Extrastriate cortical regions (V2, V3, V3A, hV4) were deactivated.
- Greater deactivation occurred in dorsal subregions and higher visual areas.
Conclusions:
- Tactile processing impacts the occipital cortex through distinct pathways.
- A suppressive top-down pathway affects the visual cortical hierarchy.
- An excitatory pathway directly drives area V1 from outside the visual hierarchy.
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