Mechanisms of cross-modal plasticity in early-blind subjects.
A variety of studies have demonstrated enhanced blood oxygenation level dependent responses to auditory and tactile stimuli within occipital cortex as a result of early blindness. However, little is known about the organizational principles that drive this cross-modal plasticity. We compared BOLD responses to a wide variety of auditory and tactile tasks (vs. rest) in early-blind and sighted subjects. As expected, cross-modal responses were larger in blind than in sighted subjects in occipital cortex for all tasks (cross-modal plasticity). Within both blind and sighted subject groups, we found patterns of cross-modal activity that were remarkably similar across tasks: a large proportion of cross-modal responses within occipital cortex are neither task nor stimulus specific. We next examined the mechanisms underlying enhanced BOLD responses within early-blind subjects. We found that the enhancement of cross-modal responses due to early blindness was best described as an additive shift, suggesting that cross-modal plasticity within blind subjects does not originate from either a scaling or unmasking of cross-modal responsivities found in sighted subjects.
Lewis
Lindsay B
LB
Department of Ophthalmology, McGill Vision Research, McGill University, Montreal, Quebec, Canada.
Saenz
Melissa
M
Fine
Ione
I
D000161:Acoustic Stimulation; D000328:Adult; D001301:Audiometry, Pure-Tone; D001306:Auditory Pathways / Q000503:physiopathology; D001766:Blindness / Q000151:congenital / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology*; D009778:Occipital Lobe / Q000098:blood supply / Q000503:physiopathology*; D010898:Pitch Perception / Q000502:physiology*; D013017:Sound Localization / Q000502:physiology*
D006454:Hemoglobins; C100003:deoxyhemoglobin