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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Activation-synthesis hypothesis | 2/3 | https://en.wikipedia.org/wiki/Activation-synthesis_hypothesis | reference | science, encyclopedia | 2026-05-05T11:04:09.469790+00:00 | kb-cron |
=== REM === REM sleep may be a more evolutionarily recent sleep state, and is prominent in most birds and mammals, although may exist in reptiles and other vertebrates to varying degrees. REM stands for rapid eye movement. It is generally a later sleep state following non-REM (NREM) sleep. It is regulated in part by the pontine brainstem. Infants spend most of their time in REM sleep, and rather than enter stage 1 sleep they may go directly to REM sleep. Most REM sleep occurs just above stage I of sleep, and experiences different mental abilities than during NREM sleep. The thought process is sometimes non-logical or even bizarre, sensation and perception is vivid but created internally by the brain, and the body's movements are inhibited. Most REM stages last 10–15 minutes, and the average human will go through 4–6 of these stages during sleep each night. Subsequent REM stages increase in duration, so the last REM stage before awakening is the longest and thus may have the most vivid dream imagery. It has been proposed that REM sleep is necessary for preparation of many integrative functions, of which one is consciousness. It supports the idea that sleep, and dreaming, is necessary or at least optimal preparation for the next day's processes. The scientific tracking of REM sleep stages can be measured by neuronal signals within the pontine brainstem. The interactions of aminergic inhibitory neurons and cholinergic excitatory neurons can be measured, and REM sleep occurs when aminergic cells are at their least active and cholinergic cells are at their most active.
==== Evolution of REM ==== It has been stated that REM sleep is a recent evolutionary behavior in homeothermic animals. In both, there is increased REM sleep in the early stages of life. In humans, REM sleep peaks during the third trimester of gestation, and quickly falls after birth as primary consciousness declines and secondary consciousness grows with the development of the brain. The developing control over stages of sleep and waking suggests that sleep and REM has developed as a way to self-activate in order to anticipate awake-state circumstances.
=== Neuronic modeling === Within the pons, the modeling and tracking of these aminergic inhibitory neurons and cholinergic excitatory neurons occurs via the study of PGO waves. These are phasic waves that occur in cycles, and originate from the pontine brainstem (P), lateral geniculate of thalamus (G), and occipital cortex (O). Aminergic monoamines serotonin, noradrenaline, histamine, and dopamine are balanced between acetylcholine cholinergic signals, and play a part in the regulation of cognition. Aminergic cell signal strength is lowest during REM sleep, increases during NREM, and is highest at waking. Cholinergic cell signal strength is highest during REM, declines during NREM, and is lowest at waking. Changes in sleep state and phase occur when two activity paths cross.
== Theory == The development of consciousness is a gradual, time-consuming and lifelong process that builds upon and uses a more primitive virtual reality generator that is more definable in our dreams. As such, the development of secondary consciousness during the lifetime requires a blank consciousness that during REM sleep creates an imaginary self that has movements and experiences emotions. This is an experimental state not associated with awareness, and this state, or protoconscious, is able to be reached during childhood. This protoconsciousness is a protoself created early in life by the brain as a building block for consciousness to develop, and provides intrinsic predictions of external inputs created by dreaming.
=== Original activation-synthesis hypothesis model === Hobson and McCarley originally proposed in the 1970s that the differences in the waking-NREM-REM sleep cycle was the result of interactions between aminergic REM-off cells and cholinergic REM-on cells. This was perceived as the activation-synthesis model, stating that brain activation during REM sleep results in synthesis of dream creation. Hobson's five cardinal characteristics include: intense emotions, illogical content, apparent sensory impressions, uncritical acceptance of dream events, and difficulty in being remembered.
=== Current model – AIM === Thanks to the development of technology since the original proposal, new experimental data has been collected and additional mechanistic details of neuronal control have been developed. It has been determined that consciousness states can be described with three values, and the AIM model is a model that uses these values for representing the similarities and differences between waking and dreaming. It is a three-dimensional state-space model that describes different states of the brain and their variance throughout the day and night. It is composed of three different values: A – activation, I – input-output gating, and M – modulation. The model is limited however, in that it cannot yet explain the regional differences in brain activity that distinguish REM sleep from waking. Other limitations include the inability to quantifiably identify and measure M in humans. During waking and activation of primary and secondary consciousnesses, high values of A, I, and M have been observed, but during REM sleep high values of A but low I and M have been observed.
==== Protoconsciousness ==== The protoconsciousness is template of consciousness that occurs during sleep, and on which can be constructed other mental conscious processes. Early in childhood, it has been said that this protoconsciousness is where secondary aspects of consciousness are originally developed and tested by the primary consciousness, and the person can slowly develop increased secondary consciousness throughout their life as their protoconscious template is further expanded, developed, and creates more vivid ideas and representations of secondary consciousness.