An imbalance in neural excitation/inhibition (E/I) has been hypothesized to underlie at least some forms of autism1. Binocular rivalry is a basic visual phenomenon in which different images presented to each eye vie for awareness. This alternating perception is thought to rely, in part, on the balance of excitation and inhibition in the visual cortex. Thus, binocular rivalry may potentially serve as a noninvasive biomarker of E/I balance.
Caroline Robertson’s laboratory has previously shown that individuals with autism exhibit a slower rate of binocular rivalry compared with neurotypical individuals2,3,4, reflecting reductions in the strength of perceptual suppression and GABAergic inhibition5.
In the current project, her group aims to test how binocular rivalry is affected in two genetically distinct autism subpopulations: (1) fragile X syndrome, the most common cause of inherited autism, and (2) 16p11.2 deletion syndrome. Copy number variants in the 16p11.2 locus are among the most frequently observed in individuals with autism. Synaptic dysfunction, leading to an alteration in E/I balance, is evident in mouse models of both disorders.
A demonstration of reduced perceptual suppression in individuals with these conditions will provide compelling evidence that binocular rivalry can serve as a robust, objective behavioral marker of altered neural dynamics in at least some genetic subtypes of autism. Furthermore, it may be a useful tool to deconstruct currently imprecise diagnostic groups and to stratify individuals based on therapies they might be likely to respond to.