Katharina Rufener | Investigating human auditory temporal resolution using transcranial electrical stimulation (tES)

Neural oscillations in the gamma range are the dominant rhythmic activation pattern, i.e. the resonance frequency (RF), of the human auditory cortex. With regard to speech processing, there is broad consensus that gamma oscillations parse the acoustic stream into linguistically meaningful units at the phonemic scale. An RF of about 40 Hz has been suggested as most functional since the mean duration of phonemes (the smallest linguistically meaningful unit) is in a range of about 25 ms. A significantly increased or decreased RF should thus severely affect the integration of successively incoming features to a meaningful entity. However, to date, there is only limited data available that casually confirm this theoretical framework.

In a series of behavioural and electrophysiological studies we used tES to shed more light on the relationship between neural gamma oscillations and phoneme processing. In addition, we systematically assessed the effect of tES on the auditory system's temporal resolution. I will discuss the findings of these studies with regard to the underlying mechanisms of action and implications for clinical applications.