Abstract
Visual deficits by ocular disease or visual system trauma cause lasting damage. To better understand the involvement of cortical plasticity in vision restoration, we aim to evaluate the cortical and visual networks following a deficit over time. A partial optic nerve crush (pONC) serves as an induced visual deficit, allowing for residual vision from surviving cells and cortical plasticity. Thy1-GCaMP6s mice underwent in vivo calcium imaging prior to a bilateral pONC, then 1, 3, 5, 7, 14, 23, and 30 days after. Neuronal responses to monocular light flashes were measured in various cortical visual areas, and correlations between responses were performed. Independently, visual acuity was measured in mice using the optokinetic reflex test in response to moving gratings prior to a bilateral pONC, then 1, 3, 7, 14, 21, and 28 days after. Surviving retinal cells were counted. Following the pONC, the cortical response to the stimulus decreased in V1 and secondary visual areas. Some activity was regained at 3-5 days following the pONC. A loss of correlation between cortical visual areas was also observed, but a recorrelation began around day 5. However, this reorganization was not associated with proportional restoration of visual acuity. There was a drop in the number of surviving ganglion cells following the pONC. Using a lighter pONC intensity showed a partial recovery between days 3-7, and a greater cell survival compared to a strong pONC. There is evidence of cortical reorganization between visual areas following the pONC, indicating that plasticity can occur at the cortical level. The optokinetic reflex test showed a significant visual loss following the pONC, but no recovery. However, a behavioural recovery could be obtained with a lighter crush, suggesting that residual cells may be needed for recovery. This indicates that visual loss and plasticity can be observed behaviourally.
Meeting abstract presented at VSS 2018