Santa Fe Institute Collaboration Platform

COMPLEX TIME: Adaptation, Aging, & Arrow of Time

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What is Sleep?/Why are brain oscillations important to the function of sleep?

From Complex Time

November 18, 2019
10:30 am - 11:30 am

Presenter

Sara Aton (Univ. Michigan)Kimberley Whitehead (Univ. College London)

Abstract

Sara Aton – The essential role of network oscillations for sleep-dependent memory consolidation

Our laboratory is addressing how sleep contributes to memory consolidation and associated synaptic plasticity in the mouse brain. We hypothesize that some forms of brain plasticity occur preferentially during sleep due to its unique patterns of network activity. Here, I'll discuss our use of optogenetic tools to silence or rhythmically activate subsets of neurons involved in generating sleep-associated thalamocortical network oscillations. We are studying how these manipulations affect both neural and behavioral plasticity. In thalamocortical circuits following novel sensory experiences, we find increases in the coherence of network oscillations during sleep that predict subsequent plasticity. Disruption of these oscillations leads to a loss of plasticity and a failure in long-term memory formation. We have also found that selective reactivation of sensory neurons engaged during prior learning is essential for sleep-dependent consolidation of sensory-cued memories. We hypothesize that sleep-associated network oscillations promote stable reactivation of neuronal ensembles, which in turn drives synaptic plasticity and long-term memory storage across brain circuits.

Kimberley Whitehead - Why are brain oscillations important to the function of sleep in early life?

Sleep dominates early life, during which rapid eye movement (REM) sleep occupies a far greater proportion of sleep time than later in development. Thalamo-cortical oscillations are spatially and temporally organised by sleep-wake state in neonatal mammals, including humans. For example, somatosensory cortical oscillations occur preferentially following REM sleep-associated twitches, and subserve the refinement of neural body maps. Therefore sleep-related brain oscillations in early life may index sensorimotor functional development.

In adults, the intensity of slow wave oscillations during non-REM sleep has been used to model the pressure to sleep, and its restorative functions, but in neonates slow wave oscillations are prevalent during each sleep state, and even wakefulness. I will discuss the challenges of modelling sleep-wake organisation in pre-term human infants, in whom classical brain oscillations such as the alpha rhythm of wakefulness and the slow waves and sleep spindles of non-REM sleep are absent.

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