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Ayelet Arazi, Nitzan Censor, Ilan Dinstein; Perceptual thresholds are better in individuals with lower trial-by-trial neural variability. Journal of Vision 2016;16(12):428. doi: 10.1167/16.12.428.
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Introduction The mammalian brain is a remarkably unstable system where neural responses to repeated presentations of an identical stimulus exhibit considerable trial-by-trial variability. Previous electrophysiological studies have shown that the presentation of a stimulus reduces trial-by-trial neural variability in comparison to ongoing neural variability present before stimulus onset. While the post-stimulus reduction in variance has been reported as a general property of neural responses, its potential impact on perception remains unknown. Here, we examined the relationship between the intensity of trial-by-trial neural variability in individual subjects and their contrast discrimination thresholds. Methods Twenty-two subjects performed a two alternative forced choice contrast discrimination task while their brain activity was recorded with EEG. We estimated the contrast discrimination threshold and the slope of the psychometric function for each subject. Trial by trial variability of the EEG recording was quantified before and after stimulus presentation to estimate the relative change in neural variability of each subject. Results Our results revealed that trial by trial variability is reduced ("quenched") by approximately 40% after stimulus onset in comparison to the ongoing variability present in the pre stimulus interval. We found negative correlations between individual levels of quenching and individual discrimination thresholds as well as positive correlations between individual levels of quenching and psychometric function slopes. Participants with larger reductions in neural variability exhibited lower discrimination thresholds and higher psychometric function slopes. Conclusions In agreement with the general principles of signal detection theory, these results suggest that individuals with sensory systems that quench trial-by-trial neural variability to a larger extent are likely to have better and more stable perceptual performance.
Meeting abstract presented at VSS 2016
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