The Defensive Activation Theory: REM Sleep as a Mechanism to Prevent Takeover of the Visual Cortex

Eagleman, David M.; Vaughn, Don A.

doi:10.3389/fnins.2021.632853

Cited by 12 publications

(24 citation statements)

References 55 publications

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“…If this indeed was the case, this, in turn, would then enable for a typical spatio-temporal organization of early visual areas by eccentricity 49 to develop even in the life-long absence of vision. 32 Moreover, such notion would arguably also explain striking ability of congenitally and totally blind subjects to draw symbolic representations of various visual images 38 in eerie likeness to those drawn by normally sighted subjects. Somewhat analogous hypotheses have been in past advanced to explain the protracted language acquisition in the autistic individuals by comparison to those with neurotypical development, and are in line with notion of Hebbian correlation learning in neuroanatomically structured networks which yield distributed circuits binding action and perception information 50 .…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, sleep itself, and more speci cally, rapid eye movement (REM) sleep 26 , appear fundamental for the full development of the visual cortex 27,28 , and therefore of mental imagery [28][29][30][31] . Notably, Eagleman and Vaughn have recently proposed that the circuitry underlying REM sleep serves to selectively amplify the visual system's activity periodically throughout the night, allowing it to defend its territory against takeover from other sensory inputs 32 . It has been also argued that, during the distinct microstates of REM 33 , phasic brain-state co-ordination leads to transient differential coherence with hippocampal and other wider thalamo-(visuo)cortical regions 34 .…”

Section: Introductionmentioning

confidence: 99%

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Homoiōma in Dreams of Congenitally Blind

Kang

Bertani

Raheel

et al. 2022

Preprint

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It is unclear to what extent the absence of vision affects the sensory sensitivity for oneiric construction. Similarly, the presence of visual imagery in the mentation of dreams of congenitally blind people has been largely disputed. We investigate the presence and nature of oneiric visuo-spatial impressions by analysing the dreams of the congenitally blind people identified from the online database DreamBank. A higher presence of auditory, haptic, olfactory and gustatory sensation in dreams of congenitally blind was demonstrated, by comparison to normally sighted individuals. Nonetheless, oneiric visual imagery in reports of congenitally blind subjects was also noted, in opposition to some previous studies and raising the questions about the possible underlying neuromechanisms.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Homoiōma in Dreams of Congenitally Blind

Kang

Bertani

Raheel

et al. 2022

Preprint

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“…Specifically, the LC is relevant to the DAT because of its involvement in the sleep-waking cycle (Aston-Jones and Bloom, 1981;Takahashi et al, 2010), REM-phase control (Hobson et al, 1975;Aston-Jones and Bloom, 1981;Khanday et al, 2016), and brain plasticity (Bear and Singer, 1986;Hu et al, 2007;Edeline et al, 2011;Martins and Froemke, 2015). All of these mechanisms are central to the DAT, or the arguments used by Eagleman and Vaughn (2021) to support the DAT. Therefore, it is natural to ask if the literature on the LC can add anything to the debate on the DAT.…”

Section: The Locus Coeruleus and Its Relation To The Datmentioning

confidence: 99%

“…An intriguing idea presented by Eagleman and Vaughn (2021) proposes that dreams are primarily visual because REM sleep dreaming serves as a protective activation as otherwise long periods of sleep might cause an inactive visual cortex to be repurposed for other brain functions. Since our senses of touch, hearing, and smell are not shut off during sleep, the DAT would state that dreams need no or few auditory, olfactory, or tactile components as the cortical areas involved in these senses are not deprived of input during sleep.…”

Section: Introductionmentioning

confidence: 99%

“…They coin their hypothesis the Defensive Activation Theory (DAT). As basis for their suggestion, Eagleman and Vaughn (2021) refer to studies demonstrating such a degree of cortical plasticity that input-deprived regions are taken over for other purposes after less than an hour of inactivity. This illustrates not only how plastic the cortex is but also that the brain uses this plasticity to provide on its surface a continually updated representation of the world based on the strength of sensory input to the cortex.…”

Section: Introductionmentioning

confidence: 99%

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Locus coeruleus and the defensive activation theory of rapid eye movement sleep: A mechanistic perspective

Knopper

Hansen²

2023

Front. Neurosci.

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The defensive activation theory (DAT) was recently proposed to explain the biological function of dreaming. Briefly, DAT states that dreams are primarily visual to prevent plastic take-over of an otherwise inactive visual cortex during sleep. Evidence to support the DAT revolve around the interplay between dream activity (REM%) and cortical plasticity found in evolutionary history, primate studies, and coinciding decline in human cortical plasticity and REM% with age. As the DAT may prove difficult to test experimentally, we investigate whether further support for the DAT can be found in the literature. Plasticity and REM sleep are closely linked to functions of the Locus Coeruleus (LC). We therefore review existing knowledge about the LC covering LC stability with age, and the role of the LC in the plasticity of the visual cortex. Recent studies show the LC to be more stable than previously believed and therefore, the LC likely supports the REM% and plasticity in the same manner throughout life. Based on this finding, we review the effect of aging on REM% and visual cortex plasticity. Here, we find that recent, weighty studies are not in complete agreement with the data originally provided as support for DAT. Results from these studies, however, are not in themselves irreconcilable with the DAT. Our findings therefore do not disprove the DAT. Importantly, we show that the LC is involved in all mechanisms central to the DAT. The LC may therefore provide an experimental window to further explore and test the DAT.

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A new perspective on positive symptoms: expression of damage or self-defence mechanism of the brain?

Antonioni,

Raho,

Sensi

et al. 2024

Neurol Sci

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Usually, positive neurological symptoms are considered as the consequence of a mere, afinalistic and abnormal increase in function of specific brain areas. However, according to the Theory of Active Inference, which argues that action and perception constitute a loop that updates expectations according to a Bayesian model, the brain is rather an explorer that formulates hypotheses and tests them to assess the correspondence between internal models and reality. Moreover, the cerebral cortex is characterised by a continuous “conflict” between different brain areas, which constantly attempt to expand in order to acquire more of the limited available computational resources, by means of their dopamine-induced neuroplasticity. Thus, it has recently been suggested that dreams, during rapid eye movement sleep (REMS), protect visual brain areas (deprived of their stimuli during rest) from being conquered by other normally stimulated ones. It is therefore conceivable that positive symptoms also have a functional importance for the brain. We evaluate supporting literature data of a ‘defensive’ role of positive symptoms and the relevance of dopamine-induced neuroplasticity in the context of neurodegenerative and psychiatric diseases. Furthermore, the possible functional significance of idiopathic REMS-related behavioural disorder as well as phantom limb syndrome is examined. We suggest that positive neurological symptoms are not merely a passive expression of a damage, but active efforts, related to dopamine-induced plasticity, to maintain a correct relationship between the external world and its brain representation, thus preventing healthy cortical areas from ousting injured ones.

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The Defensive Activation Theory: REM Sleep as a Mechanism to Prevent Takeover of the Visual Cortex

Cited by 12 publications

References 55 publications

Homoiōma in Dreams of Congenitally Blind

Homoiōma in Dreams of Congenitally Blind

Locus coeruleus and the defensive activation theory of rapid eye movement sleep: A mechanistic perspective

A new perspective on positive symptoms: expression of damage or self-defence mechanism of the brain?

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