Time perception as a human capacity has a major role in almost all cognitive abilities, speech and motion perception, cross-modal interactions, and motor coordination. This capacity helps human beings keep in synchrony with the environment through discrimination and the processing of short- and long-term intervals. The time intervals are learned and processed in the brain, although the underlying mechanisms of this learning process are not yet well understood. An efficient process of temporal scales requires a self-organized brain system exhibiting scale-free behavior. Thus, fractal properties of different rhythmic oscillations in EEG signals are suitable measures to quantify this mechanism. In this study, we aim to show how changes in EEG fractal dimensions (FDs) are associated with learning temporal intervals. In this regard, 12 healthy volunteers underwent training on an auditory time-interval discrimination task over 6 days, while their brain activity was recorded via EEG during the first and last sessions. Our findings indicate that subjects' performance (temporal interval discrimination ability) improves with practice, and the fractal structure of EEG signals, particularly in the central and temporoparietal regions, follows this improvement. These regions are primarily dedicated to auditory sensory processing, and distinct regional and frequency patterns are observed for sub- and supra-second intervals. These results indicate that regional multi-scale self-similar activities are linked to time-discrimination abilities.
Kashefpoor et al. (Tue,) studied this question.