Near-death experiences (NDEs) occur in patients who have been close to death, sometimes during periods of low oxygen. However, the preservation or restoration of brain activity is essential for generating and retaining NDE memories. While the occurrence of complex conscious experiences (such as NDEs) despite severe brain stress has been studied, the underlying brain function during the event has never been completely absent.
However, it has been suggested that during NDEs, the brain's inhibitory functions diminish or fail, leading to heightened perception or exaggerated neural activity. This theory is plausible and supported by scientific research. Studies indicate that, as the brain undergoes oxygen deprivation and energy conservation during the process of dying, it loses normal inhibitory control, particularly in areas such as the visual system. This loss of inhibition, or 'disinhibition', can cause the overactivation of brain circuits, resulting in phenomena such as the perception of bright light or other vivid sensory experiences reported in NDEs.
Disinhibition may also affect memory and emotional areas of the brain, which could explain reports of life review, out-of-body sensations and profound feelings of peace. The neurochemical environment changes dramatically during this process, including surges in neurotransmitters such as serotonin, which can produce experiences resembling hallucinations or mystical visions.
Neurophysiological recordings in animal models reveal increased high-frequency brain oscillations and cortical activity during the dying process, alongside loss of normal inhibitory function. These findings provide a mechanistic basis for how unconscious or near-unconscious brains might generate such experiences.
Therefore, the idea that a failing inhibitory system in the dying brain leads to amplified sensory and cognitive phenomena is well-grounded in current neuroscience and is a plausible explanation for many NDE characteristics.