No cognitive processing in the unconscious, anesthetic‐like, state of sleep

Abstract

We review evidence challenging the hypothesis that memories are processed or consolidated in sleep. We argue that the brain is in an unconscious state in sleep, akin to general anesthesia (GA), and hence is incapable of meaningful cognitive processingthe sole purview of waking consciousness. At minimum, the encoding of memories in sleep would require that waking events are faithfully transferred to and reproduced in sleep. Remarkably, however, this has never been demonstrated, as waking experiences are never truly replicated in sleep but rather appear in very altered or distorted forms. General anesthetics (GAs) exert their effects through endogenous sleep-wake control systems and accordingly GA and sleep share several common features: sensory blockade, immobility, amnesia and lack of awareness (unconsciousness). The loss of consciousness in non-REM (NREM) sleep or to GAs is characterized by: (a) delta oscillations throughout the cortex; (b) marked reductions in neural activity (from waking) over widespread regions of the cortex, most pronounced in frontal and parietal cortices; and (c) a significant disruption of the functional connectivity of thalamocortical and corticocortical networks, particularly those involved in "higher order" cognitive functions. Several (experimental) reports in animals and humans have shown that disrupting the activity of the cortex, particularly the orbitofrontal cortex, severely impairs higher order cognitive and executive functions. The profound and widespread deactivation of the cortex in the unconscious states of NREM sleep or GA would be expected to produce an equivalent, or undoubtedly a much greater, disruptive effect on mnemonic and cognitive functions. In conclusion, we contend that the unconscious, severely altered state of the brain in NREM sleep would negate any possibility of cognitive processing in NREM sleep.

The Neural Circuits Underlying General Anesthesia and Sleep

“…People awaken from sleep with the sense that time has passed, and sleep plays an important role in memory processing and consolidation. 22,23 On emergence from general anesthesia, patients often describe feeling like no time had passed since induction, even after many hours of surgery. It has been reported that the formation of new memories during emergence does not occur until patients can maintain sustained wakefulness.…”

Диагностические Возможности Анализа Сновидений: Теоретические Предпосылки И Методические Подходы

“…Несмотря на некоторое сходство переживаемых в сновидении событий с реальностью у спящего снижается волевая активность и произвольный контроль над собой и происходящими событиями (Nir & Tononi, 2010). Отсутствие самоконтроля во время сна может быть связано со снижением активности таких областей мозга, как нижняя теменная, орбитофронтальная, дорсолатеральная и префронтальная кора (Van De Poll & van Swinderen, 2021;Vertes & Linley, 2021). Действительно, было показано, что снижение активности в префронтальной области коры во время сенсорного восприятия в бодрствовании сопровождалось снижением самосознания (Yang & Lewis, 2021;Kim et al, 2022).…”