VISUAL CORTICAL ACTIVITY DURING TACTILE SPATIAL DISCRIMINATION IN SIGHTED AND BLIND HUMANS
Poster Presentation

Krish Sathian
Dept. of Neurology, Emory Univ Sch Med

*Randall Stilla
Dept. of Neurology, Emory Univ Sch Med

*Erica Mariola
Dept. of Neurology, Emory Univ Sch Med

     Abstract ID Number: 75
     Full text: Not available
     Last modified: March 18, 2005
     Presentation date: 06/05/2005 11:30 AM in MART Auditorium
     (View Schedule)

Abstract
The blind recruit visual cortical activity in many non-visual tasks. However, the significance of such recruitment for perception remains uncertain, since many previous studies have focussed on linguistic tasks. Further, sighted subjects recruit visual cortical regions during tactile perception, and it is unclear whether the blind differ in this regard. The present study investigated visual cortical activity during tactile spatial discrimination in blind and sighted humans. The stimulus was a linear 3-dot array, with the central dot offset to the right or left, presented to the immobilized index fingerpad using a pneumatic stimulator. In the experimental task, subjects discriminated left from right offsets. In a control task, an array without offset was presented and subjects discriminated stimulus duration. Functional magnetic resonance imaging was performed while subjects performed these tasks in a block design. Relative to the control task, tactile spatial discrimination by sighted subjects evoked activity in parietal somatosensory regions, the frontal eye fields and the lateral occipital complex bilaterally. In the blind, in addition to activity in these areas, there were extensive activations in ventral visual cortical areas. We conclude that the blind recruit larger expanses of visual cortex into tactile spatial perception than the sighted.