# Exploring the correlation and causation between alpha oscillations and one-second time perception through EEG and tACS

## TL;DR

This study explores how brain alpha waves relate to time perception, using EEG and tACS to investigate their influence on judging a one-second interval.

## Contribution

The study provides new insights into how alpha oscillation frequency and power correlate with time perception accuracy and precision.

## Key findings

- Higher alpha power correlates with better time perception accuracy in the sham condition.
- Alpha frequency correlates with time perception precision in the sham condition.
- Real tACS stimulation weakens these correlations, especially at higher frequencies.

## Abstract

Alpha oscillations have been implicated in time perception, yet a consensus on their precise role remains elusive. This study directly investigates this relationship by examining the impact of alpha oscillations on time perception. Resting-state EEG recordings were used to extract peak alpha frequency (PAF) and peak alpha power (PAP) characteristics. Participants then performed a time generalization task under transcranial alternating current stimulation (tACS) at frequencies of PAF−2, PAF, and PAF+2, as well as a sham condition. Results revealed a significant correlation between PAP and accuracy, and between PAF and precision of one-second time perception in the sham condition. This suggests that alpha oscillations may influence one-second time perception by modulating their frequency and power. Interestingly, these correlations weakened with real tACS stimulations, particularly at higher frequencies. A second analysis aimed to establish a causal relationship between alpha peak modulation by tACS and time perception using repeated measures ANOVAs, but no significant effect was observed. Results were interpreted according to the state-dependent networks and internal clock model.