Transcranial alternating current stimulation with speech envelopes modulates speech comprehension.

摘要: Abstract Cortical entrainment of the auditory cortex to broadband temporal envelope a speech signal is crucial for comprehension. Entrainment results in phases high and low neural excitability, which structure decode incoming signal. strongest theta frequency range (4–8 Hz), average envelope. If degraded, weaker intelligibility declines. Besides perceptually evoked cortical entrainment, transcranial alternating current stimulation (tACS) entrains oscillations by applying an electric brain. Accordingly, tACS-induced has been shown improve perception. The aim study was modulate externally means tACS such that corresponds presented stream (i.e., envelope-tACS). Participants performed Oldenburg sentence test with sentences noise combination envelope-tACS. Critically, induced at time lags 0–250 ms 50-ms steps relative onset (auditory stimuli were simultaneous or preceded tACS). We single-subject sinusoidal, linear, quadratic fits comprehension performance across lags. could show sinusoidal fit described modulation best. Importantly, 5.12 Hz, corresponding peaks amplitude spectrum stimulated envelopes. This finding supported significant 5-Hz peak power individual series. Altogether, envelope-tACS modulates noise, presumably enhancing disrupting (time lag in- out-of-phase stimulation, respectively) cortex.