Longitudinal effects of an optic nerve injury on visual behaviour
Disease or trauma to the visual system can cause long-term damage and severe visual deficits. However, recent research has turned to neural plasticity as a means to recover functional vision despite anatomical damage. To understand the involvement of neural plasticity and reorganization following a deficit, the present thesis investigated the spontaneous recovery of visual functions over time using behavioural tests in mice. Specifically, a partial optic nerve crush (pONC) was induced with two injury intensities, while still allowing for residual vision from surviving retinal cells. Behavioural assessments of visual functions included the optomotor reflex test, which measured the mouse’s tracking reflex in response to moving sinusoidal gratings, while the visual cliff test evaluated depth avoidance behaviour by simulating a cliff to observe the animal’s perception of depth. The tests were performed once before the injury, then at multiple time points up to 28 days. Retinal ganglion cell survival was subsequently quantified. Results showed that the high-intensity pONC led to a complete loss of visual acuity and depth avoidance, with no improvement in the following 28 days, whereas the low-intensity pONC showed a partial recovery. There were fewer surviving cells after the high-intensity pONC, especially in proximal regions. These results show evidence of spontaneous recovery of visual functions, but only with a certain amount of cell survival.
Visual Recovery Behaviour Visual Deficit