A Visual Perceptual Task Provides Evidence for an Excitatory:Inhibitory Imbalance in Adults with Autism. Jamie Horder, Mendez MA, Spain D, Faulkner J, De La Harpe Golden D, Murphy DGM Department of Forensic and Neurodevelopmental Sciences Institute of Psychiatry, King’s College London
Jamie Horder, Mendez MA, Spain D, Faulkner J, De La Harpe Golden D, Murphy DGM
Department of Forensic and Neurodevelopmental Sciences
Institute of Psychiatry, King’s College London
“Abnormalities in Subcortical Glutamate/Glutamine, but Not GABA, in Adults with an ASD: A [1H]MRS Study”
Saturday 10:42 AM
Marquis A Room
In the visual cortex, contrast-coding neurons inhibit motion-coding cells via lateral GABA firing.
With large stimuli, it is harder to see motion in higher-contrast images compared to low contrast ones. GABA drives this.
‘Paradoxical’: large, high-contrast stimuli are usually easier to see!
If there is a GABA deficit, the paradoxical effect should be lower in ASD i.e. high contrast performance should be better.
It has been used as a probe of GABA in healthy volunteers (Glasser et al 2010) and in depression (Golomb et al 2009) etc.
In the ASD group, the degree of the paradoxical effect was reduced (p=0.022) implying reduced GABA signalling within the visual cortex.
As expected, a paradoxical effect was observed over all participants taken as a whole (higher sensory threshold for large, bright stimuli, compared to small bright)