# The last signal did not arrive as silence.

A rare 900-second EEG recording around cardiac arrest changed its mix before it faded. Slower rhythms weakened. For a short window, gamma occupied a larger share of what the electrodes still recorded.

One patient. One clinical case. Electrical activity is not a report of consciousness.

## What the paper found

- Broad-band gamma rose from 0.93% of relative power in the interictal window to 8.43% during bilateral suppression.
- Delta, theta, and alpha coherence fell in the post-arrest window.
- Phase-amplitude coupling continued across the four analysis windows and was strongest for alpha phase modulating broad-band gamma during left-sided suppression.

## The four windows

The authors analysed four 30-second slices of a 900-second recording: interictal interval, left suppression, bilateral suppression, and post-cardiac arrest.

Relative power is a share of the analysed signal. It is not a measure of total brain activity.

## The boundary

The patient was an 87-year-old man with traumatic subdural hematoma, seizures, medication, and severe brain injury. The study had no healthy comparison and no uninterrupted pre-event baseline. It does not show that the patient was conscious, replaying memories, or having a near-death experience.

Source: [Vicente et al. (2022)](https://doi.org/10.3389/fnagi.2022.813531), *Frontiers in Aging Neuroscience* 14:813531. Open access under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/).