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Spontaneous α Brain Dynamics Track the Episodic "When"
Leila Azizi1, Ignacio Polti2,3, Virginie van Wassenhove4
1Cognitive Neuroimaging Unit, NeuroSpin, Commissariat à l'énergie atomique et aux énergies alternatives, Institut National de la Santé et de la Recherche Médicale, Université Paris-Saclay, Gif/Yvette 91191, France.
Summary
Alpha brain bursts track retrospective time perception in humans. This neural activity predicts how long minutes feel when not actively timing, suggesting a role in conscious time awareness.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychology
Background:
- Neural mechanisms underlying the sense of time passing remain largely unknown.
- Brain activity is known to be nonstationary, with rhythmic bursts, particularly in the alpha frequency range (7-14 Hz).
- Previous hypotheses suggested alpha rhythms might function as an internal clock, but their bursty nature posed challenges to this idea.
Purpose of the Study:
- To investigate whether neural signatures of time-tracking, specifically alpha burst activity, exist in humans.
- To determine if alpha burst characteristics predict retrospective and prospective time estimations.
- To explore the role of alpha bursts in conscious awareness of time passage.
Main Methods:
- Magnetoencephalography (MEG) was used to record brain activity in participants resting quietly.
- Participants were assessed on retrospective time judgments (unaware of timing) and prospective time estimations (instructed to time).
- The duration, power, and amplitude of alpha bursts were analyzed in relation to time perception tasks.
Main Results:
- The relative duration of alpha bursts significantly predicted retrospective time estimates in participants not attending to time.
- Alpha burst duration was a more effective predictor than alpha power or amplitude.
- This predictive relationship vanished during prospective timing, and alpha burst counts differed between prospective and retrospective conditions.
- The association between alpha bursts and retrospective time persisted even during a concurrent visual counting task.
Conclusions:
- Spontaneous alpha bursts, particularly their relative duration, serve as a neural marker for conscious retrospective time perception at the scale of minutes.
- Alpha bursts may represent discrete states of awareness that constitute episodic timing when attention is not directed towards time.
- These findings support the hypothesis that alpha brain activity plays a crucial role in tracking subjective time, especially in the absence of explicit time monitoring.
