Poster Session A, Saturday, March 23, 1:30 pm - 3:30 pm, Pacific Concourse
Visual cortex activity during non-visual tasks is “cross-modal” in late but not congenital blindness.
Rita Loiotile1, Marina Bedny1; 1Johns Hopkins University
Studies of blindness provide a window into the timecourse of plasticity. In congenitally blind individuals, “visual” cortices are highly active during auditory and tactile tasks (Wanet-Defalque et al., 1988; Sadato et al., 1996). Some “cross-modal” activity is observed even in late blind and blindfolded sighted adults (Merabet et al., 2008, Burton et al., 2002). Do visual cortices support similar cognitive functions in these populations, albeit to different degrees? Alternatively, does cortex have distinctive cognitive potential early in life? Sighted (N=21), congenitally (N=21) and late blind (N=9; age of vision loss >= 17y) participants performed an auditory go-no/go task, while undergoing fMRI. Participants made fast button presses (within 900ms) in response to two “go” sounds (75% of all trials, frequent-go 50%, infrequent go 25%) and withheld responses to infrequent “no-go” sounds (25% of all trials). Resting state data were also collected. We observed a right-lateralized response-inhibition effect (no-go > infreq-go > freq-go) in the “visual” cortices of congenitally but not late blind or sighted groups and in the inferior frontal cortices of all groups. Crucially, “visual” cortices of sighted and late but not congenitally blind groups responded like sensorimotor cortices: all go i.e. with button press > no-go trials. We hypothesize that visual cortices are more functionally tethered to non-visual sensory-motor systems in sighted and adult-onset blind than in congenitally blind individuals. “Visual” cortices assume higher-cognitive functions in congenital blindness, but show “cross-modal” responses in late blindness.
Topic Area: EXECUTIVE PROCESSES: Development & aging