Serial functional imaging poststroke reveals visual cortex reorganization.
OBJECTIVE
Visual cortical reorganization following injury remains poorly understood. The authors performed serial functional magnetic resonance imaging (fMRI) on patients with visual cortex infarction to evaluate early and late striate, ventral, and dorsal extrastriate cortical activation.


METHODS
Patients were studied with fMRI within 10 days and at 6 months. The authors used a high-level visual activation task designed to activate the ventral extrastriate cortex. These data were compared to those of age-appropriate healthy control participants.


RESULTS
The results from 24 healthy control individuals (mean age 65.7 +/- SE 3.6 years, range 32-89) were compared to those from 5 stroke patients (mean age 73.8 +/- SE 7 years, range 49-86). Patients had infarcts involving the striate and ventral extrastriate cortex. Patient activation patterns were markedly different to controls. Bilateral striate and ventral extrastriate activation was reduced at both sessions, but dorsal extrastriate activated voxel counts remained comparable to controls. Conversely, mean percent magnetic resonance signal change increased in dorsal sites.


CONCLUSIONS
These data provide strong evidence of bilateral poststroke functional depression of striate and ventral extrastriate cortices. Possible utilization or surrogacy of the dorsal visual system was demonstrated following stroke. This activity could provide a target for novel visual rehabilitation therapies.
Brodtmann
Amy
A
National Stroke Research Institute, Austin Health, University of Melbourne, Heidelberg, Melbourne, Australia. amyb@alphalink.com.au
Puce
Aina
A
Darby
David
D
Donnan
Geoffrey
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping; D004185:Disability Evaluation; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology*; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000473:pathology / Q000503:physiopathology*; D014786:Vision Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D014793:Visual Cortex / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D014795:Visual Pathways / Q000473:pathology / Q000503:physiopathology