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Lei Ai, Tony Ro; Alpha oscillations and desynchronizations facilitate visual-tactile multisensory integration. Journal of Vision 2016;16(12):1189. doi: 10.1167/16.12.1189.
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© 2017 Association for Research in Vision and Ophthalmology.
Recent studies have shown that neural oscillations in the alpha band (approximately 7-13 Hz) are involved in visual as well as touch perception, but the role of alpha oscillatory activity in visual-tactile multisensory integration is not very well understood. In this study, we recorded scalp electroencephalographic (EEG) activity to assess how alpha oscillations may affect the temporal dynamics of visual-tactile integration. Near-threshold tactile stimuli and suprathreshold visual stimuli (i.e., LED flashes) were delivered on the left middle finger at stimulus onset asynchronies (SOAs) that ranged from -200 ms (vision first) to 200 ms (touch first) in steps of 50 ms. Compared to the touch-only condition, tactile detection rates were significantly higher if the visual stimulus occurred between -150 ms and 100 ms of the tactile stimulus. In correspondence with these psychophysical data, changes in alpha power were measured across vision first SOAs, with a negative correlation between pre-touch alpha power and touch detection rate. Furthermore, inter-trial phase coherence spiked shortly after the visual stimulus, indicating that the phase of alpha oscillations was also reset by vision. Bootstrap analyses confirmed these phase resets by showing inversions of phase angle polarity that followed an alpha cycle. Unlike previous results showing an alpha phase-dependent effect on detection, however, detection rates were increased at all alpha phases, likely due to the desynchronization/decrease in alpha power. Similarly, when a tactile stimulus was delivered within 100 ms prior to a visual stimulus, detection rates and the P300 event-related potential to the tactile stimulus were also enhanced, likely from alpha power decreases that were induced by the subsequent visual stimulus. These findings suggest that alpha amplitude and phase modulations induced from a visual stimulus may enhance the processing of a tactile stimulus when it is delivered in close temporal proximity.
Meeting abstract presented at VSS 2016
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