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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Activation-synthesis hypothesis | 3/3 | https://en.wikipedia.org/wiki/Activation-synthesis_hypothesis | reference | science, encyclopedia | 2026-05-05T11:04:09.469790+00:00 | kb-cron |
==== Activation (A) ==== Large parts of the brain that are activated and sending signals during waking are inactive during NREM sleep and become reactivated during REM sleep. It is based on the fact that the brain and its neural circuitry is plastic and self-regulating, especially in its own activation and inactivation. This was observed by two experiments: development of sleepiness after dopamine neuron destruction in substantia nigra in the midbrain, and discovery of the reticular activating system, which are visual cues received through our eyes and to our brain that begin the waking process, that waking consciousness depends sleep. Following these studies, it became clear that activity levels and quality of consciousness were functions of brain activation and deactivation.
==== Input-output gating (I) ==== It has been shown that the internal activation of the brain is associated with the inhibition of both external sensory input and motor output. This implies that the brain is actively kept offline during REM, and the brainstem guarantees the coordination of factors I and A via the input-output gate control within the brainstem. PGO waves play a part in the ability of the brain to remain asleep while constituting the building blocks for perception and fine motor control via their phasic coordination. It has therefore been proposed that PGO signals are used in the construction of visual imagery of dreams.
==== Modulation (M) ==== The neuromodulator release of aminergic neurons have a broad chemical influence on the brain; they instruct other neurons to keep or discard a record of information they've processed. The mechanics of modulation are not known at this time, and modulation has yet to be quantitatively identified. Qualitatively, aminergic modulation has been shown to be strong during waking but lower during sleep, but more studies need to be conducted. Numerous studies have emerged from the discipline of computational neuroscience that support to the AIM model. The theory of Metalearning in particular describes how these neuromodulators facilitate dynamic learning, though a series of interpretive models all consistent with the AIM model.
== Implications == The three-dimensional AIM model shows that during the cycle of brain states waking-NREM-REM, the brain is dynamically changing constantly, and that this state space described by the AIM has an infinite number of subregions other than the main three. It proposes that via a protoconsciousness brain activation during sleep is necessary for the development and maintenance of waking consciousness and other higher-order brain functions such as problem solving. It suggests the possibility that the state of waking consciousness is only present in humans due to the evolution of extensive cortical structures within the brain. Dreaming is a state of the brain that is similar to yet different from the waking consciousness, and interaction and correlation between the two is necessary for optimal performance from both. One study conducted measuring brain activity via EEG used Hobson's AIM model to show that quantitatively dream consciousness is remarkably similar to waking consciousness.
== References ==