When the Heart Stops: EEG, Gamma Activity, and Transitional States

Series: Breathing, Body, Consciousness, and the Shifting of the Tensional Selves (Eus Tensionais)

Introduction — Brain Bee (first-person consciousness)

Imagining the heart stopping often brings silence to the mind.
But, curiously, the body does not enter silence immediately.

Even when the pulse disappears, something still happens.
I don’t know if it is feeling, memory, or only lingering electrical activity.
I only know the body does not shut down all at once.

Between beating and not beating, there is an interval—
and that is where science begins to observe.

Cardiac arrest is not an instant “off switch”

Physiologically, cardiac arrest:

• interrupts cerebral perfusion,

• rapidly reduces oxygen delivery,

• alters pressure and metabolism.

But that does not equal an immediate brain shutdown.
EEG studies show that:

• cortical activity can persist for seconds or minutes,

• there are distinct phases of transition,

• the brain enters unstable states—not simply a null state.

What EEG actually measures in these moments

EEG measures synchronized cortical electrical activity, not consciousness directly.
During:

• cardiac arrest,

• cardiopulmonary resuscitation (CPR),

• near-death states,
  EEG can show:

• a global reduction in power,

• abrupt frequency shifts,

• transient bursts of fast activity,

• periods of silence interleaved with reorganization.

These signals do not guarantee conscious experience.
They indicate residual or reorganizational neural activity.

The debate about gamma oscillations

Some recent studies have observed:

• a transient increase in gamma activity,

• especially in frontal and temporal regions,

• close to circulatory arrest or during CPR.

This has generated diverse interpretations—some excessive.

What can be stated rigorously:

• gamma can emerge in states of extreme excitation,

• it may reflect a final attempt at integration,

• it can arise from cortical disinhibition.

What cannot be stated:

• that this is “heightened consciousness,”

• that it represents organized subjective experience,

• that it is universal or reliably replicable in all cases.

Transitional states, not “special” states

The most important point is that these moments are:
physiological transition states, not mystical states.

The brain:

• loses afferent input,

• undergoes progressive hypoxia,

• enters unstable reorganization.

This can generate:

• unusual electrical patterns,

• transient synchronizations,

• paradoxical activity.

But all of it unfolds within known biology—
even if at its limits.

Heart, rhythm, and the loss of the temporal marker

In earlier texts, we saw that:
the R-peak of the QRS acts as a temporal marker,
and the heart provides rhythm to the brain.

When the heart stops:

• that marker disappears,

• the brain loses a central rhythmic reference,

• temporal organization fragments.

Some of the cortical activity that emerges here is, in part,
activity without a metronome.

Tensional Selves under rhythmic collapse

In extreme situations:

• tensional Selves no longer organize as they do in daily life,

• defensive patterns may collapse,

• autonomic states enter progressive failure.

What remains is not a “higher Self,”
but neural activity without full bodily support.

That is why extrapolating universal subjective experiences is scientifically imprudent.

What science still does not know

With honesty, it is essential to say:

• we do not know exactly what the brain “experiences,”

• we cannot reliably separate residual activity from subjective experience,

• we do not know the precise role of gamma activity in these contexts.

What we have are electrical correlates, not verifiable reports.
Scientific rigor requires accepting this limit.

Why this matters for the series

These extreme states reveal something fundamental:
everyday consciousness depends on rhythm,
depends on perfusion,
depends on cardiorespiratory variability.

When these pillars fall,
what emerges is not full freedom—
but disorganized transition.

This reinforces the central idea of the series:
consciousness is the body functioning rhythmically, not an abstraction.

Recognizing limits without denying the phenomenon

Denying the data is a mistake.
Mythologizing it is also a mistake.

A healthy path is to:
observe,
measure,
compare,
repeat,
and accept what we still do not know.

This is the same principle that applies to everyday living physiology.

Closing

When the heart stops, the brain does not become silent immediately.
But it also does not reveal final truths.

What appears are transitional states—
unstable, brief, and deeply embodied.

Understanding this pulls us away from fantasy
and closer to what matters:

conscious life depends on rhythm, variability, and a present body.

This text is part of the series Breathing, Body, Consciousness, and the Shifting of the Tensional Selves (Eus Tensionais), where different aspects of the same living system are approached from complementary angles.

References (post-2020)

Borjigin, J., et al. (2020). Surge of Neurophysiological Coherence and Connectivity in the Dying Brain. PNAS.
→ Reports a transient increase in gamma activity in animal models during circulatory arrest.

Vicente, R., et al. (2022). Enhanced Interplay of Neuronal Oscillations during Human Near-Death States. Frontiers in Aging Neuroscience.
→ Analyzes EEG patterns in humans near death, with interpretive caution.

Chawla, L. S., et al. (2021). Electroencephalography in Cardiac Arrest and Resuscitation. Critical Care Medicine.
→ Clinical review of EEG during cardiac arrest and CPR.

Norton, L., et al. (2020). Cerebral Electrical Activity after Cardiac Arrest. Resuscitation.
→ Discusses persistence and progressive collapse of cortical activity after cardiac arrest.

Pattinson, K. T. S., et al. (2021). Brain Activity in Hypoxia and Anoxia. Journal of Physiology.
→ Explores neural responses to oxygen deprivation without subjective extrapolations.

Sandroni, C., et al. (2020). EEG Monitoring after Cardiac Arrest. Intensive Care Medicine.
→ Defines clinical and interpretive limits of EEG in these contexts.

Mashour, G. A., & Hudetz, A. G. (2021). Neural Correlates of (Un)Consciousness under Extreme Conditions. Trends in Cognitive Sciences.
→ Discusses correlates of consciousness under extreme conditions, including hypoxia.

Seth, A. K., & Bayne, T. (2022). Theories of Consciousness under Physiological Collapse. Nature Reviews Neuroscience.
→ Critically analyzes interpretations of neural activity in extreme physiological states.