Conveying Temporal Information to the Auditory System via Transcranial Current Stimulation

This review paper investigates whether non-invasive application of electric current to the human scalp can be utilized to convey perceptually relevant temporal information to the auditory system. Recent studies have corroborated this notion by demonstrating that transcranial current stimulation (TCS) with temporally structured (sinusoidal and/or sound envelope-shaped) current biases neural processing and auditory perception toward the temporal pattern of the applied current. However, the perceptual benefits achieved with TCS so far are fairly modest. In sum, the temporally specific modulatory ability of TCS makes it a useful scientific tool for identifying temporal mechanisms for auditory perception. Practical or clinical applications (e.g., to enhance or restore auditory functions in normal or hearing-impaired populations) are currently still premature and require further optimization of stimulation parameters

The Involvement of Endogenous Neural Oscillations in the Processing of Rhythmic Input: More Than a Regular Repetition of Evoked Neural Responses

It is undisputed that presenting a rhythmic stimulus leads to a measurable brain response that follows the rhythmic structure of this stimulus. What is still debated, however, is the question whether this brain response exclusively reflects a regular repetition of evoked responses, or whether it also includes entrained oscillatory activity. Here we systematically present evidence in favour of an involvement of entrained neural oscillations in the processing of rhythmic input while critically pointing out which questions still need to be addressed before this evidence could be considered conclusive. In this context, we also explicitly discuss the potential functional role of such entrained oscillations, suggesting that these stimulus-aligned oscillations reflect, and serve as, predictive processes, an idea often only implicitly assumed in the literature

Speech Entrainment: Rhythmic Predictions Carried by Neural Oscillations

It has been hypothesized that stimulus-aligned brain rhythms reflect predictions about upcoming input. New research shows that these rhythms bias subsequent speech perception, in line with a mechanism of predictio