Cortical visual field representation and data integration following optic neuritis

Optic neuritis (ON) is an inflammatory, demyelinating optic neuropathy commonly associated with multiple sclerosis. Its clinical presentation typically includes monocular vision loss, with most visual functions recovering within several weeks. In addition to spontaneous remyelination, brain adaptation has been suggested to play a role in the recovery process. To further investigate this hypothesis, we examined cortical visual field representation and data integration during the first year following a first-ever ON episode. Eight ON participants and ten controls underwent fMRI scans under three viewing conditions: two monocular conditions (affected/fellow eye for ON; dominant/non-dominant eye for controls) and one binocular condition (both eyes open). For each condition, population receptive field (pRF) and connective field (CF) modeling were applied to assess spatial properties and sampling extent across the early visual cortical hierarchy (V1-V3). Consistent with previous studies, controls demonstrated an increase in average pRF and CF sizes along the visual hierarchy, with no significant differences between viewing conditions. In contrast, the ON group exhibited unique patterns. In the fellow eye condition, the typical pRF size increase along the visual hierarchy was absent, primarily due to reduced pRF sizes in V3. Additionally, in the affected eye, CF sizes were significantly larger than in the fellow eye. These modulations may reflect enhanced resolution for the unaffected eye and an increased extent of data processing when visual input is impaired (originating from the affected nerve). Therefore, we suggest that these cortical changes may be part of a spatial adaptation mechanism.