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Maximilien Chaumon, Niko Busch; Effects of ongoing brain oscillations on psychometric functions. Journal of Vision 2012;12(9):381. doi: 10.1167/12.9.381.
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Ongoing brain oscillations in the alpha frequency range (8-12 Hz) strongly affect perception and neuronal responses to incoming visual stimuli. However, the nature of their effect on perception remains largely unknown. Mechanisms of cognitive processes that affect perception and neuronal responses – such as attention or perceptual learning – have been studied extensively by examining threshold and gain of psychometric functions. Estimation of these functions requires presenting target stimuli at different stimulus intensities. Until now, alpha oscillations have been typically studied by comparing alpha power between hits and misses in detection tasks using only a single peri-threshold stimulus intensity. Therefore, it remains elusive whether alpha oscillations modulate the threshold or rather the gain of the psychometric function. In this study, we examined the effect of pre-stimulus oscillations on psychometric functions. We tested participants’ detection performance across a wide range of stimulus intensities and examined the effect of pre-stimulus brain oscillations on the slope and threshold of the psychometric function. We found that the power of pre-stimulus alpha oscillations at occipital electrodes mostly affected performance for low-intensity stimuli, making subthreshold stimuli more likely to be detected. Furthermore, alpha oscillations had stronger effects on the slope of psychometric functions than on thresholds. These results specify the role of pre-stimulus alpha oscillations and suggest that an optimal tuning of ongoing oscillations promotes sensory processing.
Meeting abstract presented at VSS 2012
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