title: Visual cortical activity reflects faster accumulation of information from cortically blind fields.
abstract: Brain responses (from functional magnetic resonance imaging) and components of information processing were investigated in nine cortically blind observers performing a global direction discrimination task. Three of these subjects had responses in perilesional cortex in response to blind field stimulation, whereas the others did not. We used the EZ-diffusion model of decision making to understand how cortically blind subjects make a perceptual decision on stimuli presented within their blind field. We found that these subjects had slower accumulation of information in their blind fields as compared with their good fields and to intact controls. Within cortically blind subjects, activity in perilesional tissue, V3A and hMT+ was associated with a faster accumulation of information for deciding direction of motion of stimuli presented in the blind field. This result suggests that the rate of information accumulation is a critical factor in the degree of impairment in cortical blindness and varies greatly among affected individuals. Retraining paradigms that seek to restore visual functions might benefit from focusing on increasing the rate of information accumulation.
authors.affiliation: Department of Psychology, Kennesaw State University, Kennesaw, GA 30144, USA. tma2010@yahoo.com
authors.forename: Tim
authors.initials: T
authors.lastname: Martin
authors.forename: Anasuya
authors.initials: A
authors.lastname: Das
authors.forename: Krystel R
authors.initials: KR
authors.lastname: Huxlin
mesh_terms: D000328:Adult; D000368:Aged; D019575:Blindness, Cortical / Q000503:physiopathology* / Q000523:psychology; D016022:Case-Control Studies; D003657:Decision Making / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods / Q000523:psychology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000523:psychology; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009039:Motion Perception / Q000502:physiology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology / Q000523:psychology; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*