Gamma-frequency entrainment using audiovisual 40 Hz flicker
Gurram Thimmugari, Rahulkrishna
MetadataShow full item record
Neural oscillations, or brain waves, are endogenous rhythms of synchronized electrical activity that are the result of communication between large groups of cortical and/or subcortical neurons. Using entrainment methodologies, neural oscillations can be exogenously modulated in a non-invasive manner. One such methodology is gamma-frequency audiovisual stimulation, referred to here as “flicker”. Building on previous work which has shown that flicker can significantly improve Alzheimer’s Disease pathology, the present work tests the effects of flicker on memory and attention in healthy adults. Using the Rapid Series Visual Presentation (RSVP) behavioral task, we found statistically significant improvements in response time as a result of 40 Hz stimulation, with an effect size (using Cohen’s d) of 0.7026 when compared to No Stimulation and 0.5233 when compared to Random stimulation. We also found that Random stimulation, which delivers the same amount of stimulation as 40 Hz but on the minute timescale (while being asynchronous at the millisecond scale), increases False Alarm Rate (FAR), which is the rate at which subjects answer “Yes” on the RSVP task when the correct answer is “No”. Using the Signal Detection Model, these results were linked to the stimulation conditions affecting either the sensory and/or decision processes through either synchroneity/asynchroneity or through a power effect, i.e., sheer amount of stimulation. However, to support these speculations about the neural processes belying the behavioral results will require neuroimaging data. The key direction to take this study in the future would be to gather neuroimaging data, likely EEG.