Exercise alone impacts short-term adult visual neuroplasticity in a monocular deprivation paradigm

Abstract

Adult homeostatic visual plasticity can be induced by short-term patching, heralded by a shift in ocular dominance in favor of the deprived eye after monocular occlusion. The potential to boost visual neuroplasticity with environmental enrichment such as exercise has also been explored; however, the results are inconsistent, with some studies finding no additive effect of exercise. Studies to date have only considered the effect of patching alone or in combination with exercise. Whether exercise alone affects typical outcome measures of experimental estimates of short-term visual neuroplasticity is unknown. We therefore measured binocular rivalry in 20 healthy young adults (20-34 years old) at baseline and after three 2-hour interventions: patching (of the dominant eye) only, patching with exercise, and exercise only. Consistent with previous work, the patching interventions produced a shift in ocular dominance toward the deprived (dominant) eye. Mild-to moderate-intensity exercise in the absence of patching had several effects on binocular rivalry metrics, including a reduction in the dominant eye percept. The proportion of mixed percept and the time to first switch (onset rivalry) did not change from baseline across all interventions. Thus, we demonstrate that exercise alone can impact binocular rivalry outcomes measures. We did not observe a synergistic effect between patching and exercise in our data.

Aerobic Exercise and Human Visual Cortex Neuroplasticity: A Narrative Review

“…The ability of exercise to enhance visual cortex neuroplasticity is evident in animal models; however, these effects have yet to be unequivocally demonstrated in human adults, while there is some evidence to support the notion that exercise can augment visual cortex neuroplasticity in healthy young adults [ 17 , 18 , 21 , 62 , 63 ], other studies report no effect of exercise [ 16 , 64 – 67 ] and possibly a counterproductive effect depending on the timing of exercise [ 68 ] (see Table 1 ). Nonetheless, structural and neurochemical changes within the human brain have been associated with exercise [ 69 , 70 ].…”

“…Recently, Virathone et al [ 21 ] observed that mild-to-moderate cycling completed in 10-minute intervals distributed across 2 hours reduced binocular rivalry eye dominance in young healthy adults. This finding demonstrates that exercise alone without monocular deprivation, visual learning paradigms, or other interventions may impact binocular rivalry outcomes, perhaps by reducing cortical inhibition.…”

“…The authors found no significant effect of physical exercise on ocular dominance plasticity [ 16 ]. In a subsequent study, the group was also unable to replicate Lunghi and Sale's [ 17 ] results despite using an identical visual task [ 21 , 67 ]. An absence of exercise effects has also been reported in studies using EEG [ 65 ], psychophysical surround suppression [ 64 , 65 ], and perceptual learning [ 68 ] to assess visual cortex neuroplasticity.…”

“…Whether this effect of exercise intensity holds for the visual cortex is unknown. For instance, no enhancement of visual cortex neuroplasticity following high intensity exercise has been shown across multiple studies [ 16 , 64 , 66 , 67 ], while others found evidence of neuroplasticity enhancement [ 17 , 18 , 21 , 63 ]. On the other hand, moderate exercise seems to have no effect on visual cortex neuroplasticity [ 16 , 65 , 68 ].…”

“…Of these various neuroplasticity enhancers, aerobic exercise is perhaps the most attractive because of its general health benefits. There is strong evidence that physical exercise can enhance neuroplasticity in cortical networks ([ 19 ]; see [ 20 ] for a recent review; [ 21 ]). In particular, enhanced cognitive and motor performance has been positively associated with exercise and physical activity [ 22 , 23 ].…”