First evidence of quantifiable behavioral changes in visual snow syndrome
Behavioral signature of VSS
Visual snow causes being revealed
By JULIA VEITCH 10 September 2020
A/Prof Jo Fielding explains the research. See video
Neuroscientists have recently characterised how visual processing is disrupted in the condition known as Visual Snow Syndrome (VSS).
Senior author A/Prof Fielding said, “The ocular motor network and its processing of visual information is complex, involving a number of distinct steps that allow us to make sense of how we see the world.”
She said that the network includes areas of the brain involved in sending visual information from the eyes to the brain. It then puts together this visual information using cognitive processes to make a cohesive image, resulting in an eye movement.
“Our study provides the first evidence of objective and quantifiable behavioural changes in patients with visual snow syndrome.”
The team discovered that patients with VSS moved their eyes faster than healthy patients towards a suddenly appearing stimulus. In addition, when asked instead to stop that action and move their eyes in the opposite direction, VSS patients were more likely to erroneously move their eyes towards the stimuli.
Interestingly, when the difficulty of each of these tasks increased, therefore requiring increased demands on an individual’s higher order visual processing in the brain, the results were no different. The patients with VSS still responded with faster eye movements and the proportion of erroneous eye movements did not change.
A/Prof Fielding said, “These results suggest that in people with VSS the visual processing changes are not a consequence of disruption to decision-making centres of the brain. Rather, patients with VSS appear to be processing visual stimuli faster than healthy people, leading to hyper-accelerated eye movements.
“This analysis has provided an essential first step into defining a behavioural signature of VSS, and identifying the brain areas and processes affected.
“Once we know what’s causing the issue, that information can be used to develop targeted treatment and better management of this debilitating syndrome.”
Reference: Emma J Solly, Meaghan Clough, Allison M McKendrick, Paige Foletta, Owen B White, Joanne Fielding. Ocular motor measures of visual processing changes in visual snow syndrome. Neurology. First published July 16, 2020, DOI: https://doi.org/10.1212/WNL.0000000000010372