Adaptive cortical plasticity in higher visual areas after acute optic neuritis

The ability to distinguish adaptive cortical reorganization may help to target future therapeutic strategies after neurological insult. We investigated cortical plasticity by prospectively applying visual functional magnetic resonance imaging (fMRI) and optic nerve MRI to 20 patients with acute optic neuritis at baseline, 1, 3, 6, and 12 months. We performed three types of correlation analyses to investigate the relationships between fMRI activity, clinical function, and optic nerve structure. The first analysis directly correlated the fMRI response to clinical function or optic nerve structure and found dynamic relations especially within the first 3 months. The second analysis used a novel technique that modeled the fMRI response and optic nerve structure together with clinical function, to determine the contribution fMRI made to clinical function after accounting for structural factors. Significant effects were found at baseline only, within the right peristriate cortex, and bilaterally in the lateral occipital complexes, which are normally involved in higher order visual processing. The third analysis investigated the relation between the modeled visual recovery rate and fMRI response but found no significant effects. The key findings of this study are from the second analysis and suggest a genuine adaptive role for cortical reorganization within extrastriate visual areas early after optic neuritis. Ann Neurol 2005;57:622–633