EEG alpha power predicts the temporal sensitivity of multisensory perception

Area of Science:

• Neuroscience
• Sensory Perception
• Psychophysics

Background:

• Pre-stimulus electroencephalogram (EEG) alpha oscillations (8-13 Hz) are known to influence multisensory perception, particularly sensitivity to temporal lags.
• Existing research often links alpha power to inhibition and alpha frequency to perceptual cycle duration, primarily using visual detection tasks with sub-threshold stimuli.
• Generalizability of these findings to above-threshold multisensory stimuli remains unclear.

Purpose of the Study:

• To investigate whether pre-stimulus electroencephalogram (EEG) oscillations, specifically alpha power and frequency, predict trial-by-trial temporal discrimination sensitivity in multisensory perception.
• To examine if findings from sub-threshold stimuli generalize to above-threshold auditory and visual stimuli.

Main Methods:

• Recorded electroencephalogram (EEG) from participants performing a temporal-order judgment task with above-threshold auditory and visual stimuli.
• Measured temporal discrimination sensitivity for audiovisual stimuli.
• Applied a jackknife procedure to correlate single-trial pre-stimulus alpha power and instantaneous frequency with psychometric measures of temporal sensitivity.

Main Results:

• A significant association was found between lower alpha power in a posterior brain region and higher temporal discrimination sensitivity for audiovisual stimuli.
• No statistically significant relationship was observed between instantaneous alpha frequency and temporal sensitivity.
• These findings indicate that moment-to-moment fluctuations in alpha power, not frequency, are linked to temporal sensitivity for above-threshold multisensory integration.

Conclusions:

• Temporal sensitivity for above-threshold multisensory stimuli is not constant but fluctuates dynamically.
• Modulations in pre-stimulus alpha power, particularly in posterior brain regions, serve as an index for these moment-to-moment variations in temporal sensitivity.
• The inhibitory role of alpha power may be crucial for precise temporal processing in multisensory perception even with suprathreshold stimuli.