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COMPLEX TIME: Adaptation, Aging, & Arrow of Time

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What is Sleep?/KimberleyWhitehead

From Complex Time

Notes by user Kimberley Whitehead (Univ. College London) for What is Sleep?

Post-meeting Reflection

1+ paragraphs on any combination of the following:

  • Presentation highlights
  • Open questions that came up
  • How your perspective changed
  • Impact on your own work
  • e.g. the discussion on [A] that we are having reminds me of [B] conference/[C] initiative/[D] funding call-for-proposal/[E] research group

Common principles of sleep-related oscillations that subserve some form of 'learning', e.g. bursting on a background of neural quiescence - this definition would encompass the unusual features of sleep in early development. Very interested by a) Susan's reference to the Aston-Jones 1981 paper that shows attenuation immediately prior to firing as if to 'boost' the effect of the firing, b) that oscillations can occur but the ones that have many frequency bands coupled together are the most important for memory consolidation, c) Susan's quote 'synchronous activity during sleep provides a substrate for []' (the square brackets could be replaced by nearly all functions!)

Remembering: we need augmented oscillatory power for a stimulus to be learned (Sara's talk) and this can be artifically provided (Ognjanovski et al. 2018), how might this relate to augmented sleep EEG power post brain injury - is it possibly not just a biomarker of damage but a marker of the synchronised activity necessary to 're-learn' new circuits? If a neuron which has learnt something continues to stay more active, for how long? How does that link to the renormalisation mentioned in final slide?

Forgetting: Is it REM sleep or forgetting or dreaming specifically for forgetting? Very interested by Gina's reference to Crick 1983 Nature paper - how could that relate to infants who have MORE REM sleep but probably don't yet dream like we conceive dreaming

Sleep oscillations as a spatial filter: because some neuronal ensembles can't keep up with the speed of oscillations, creates a spatial filter

Cortical region specific projections from Locus Coeruleus (Chander et al. 2019 ref from Gina's talk): a way that sleep-wake states could differentially modulate sensorimotor areas in the developing brain, to help them to differentiate?

Durations of sleep: Bob's conceptual theory that 100ms of sleep would be sufficient to encode a memory e.g. a microsleep. Could that be reversed to think about some adaptive function of the extra-short WAKE durations pre-term infants have e.g. 2 minutes?

Body weight vs. age predicting sleep-wake bout durations: Following up on Geoffrey's question, I will go back to the literature to check those references that biological age is more predictive than body weight. But thinking about his question, my forthcoming project on intra-uterine growth restriction would be an ideal opportunity to look at this in more detail.

Other ways I intend to improve my practice following this meeting: report ambient temperature

Evocative metaphors!: 'Mountain of wakefulness'. Bob's 'Memory evolution', more dynamic than just consolidation which doesn't fully capture sleep's functions. 'Ground truth' - the challenges of establishing this in many aspects of sleep research

Reference material notes

Some examples:

  • Here is [A] database on [B] that I pull data from to do [C] analysis that might be of interest to this group (insert link).
  • Here is a free tool for calculating [ABC] (insert link)
  • This painting/sculpture/forms of artwork is emblematic to our discussion on [X]!
  • Schwartz et al. 2017 offers a review on [ABC] migration as relate to climatic factors (add the reference as well).

Parkes 1992 "Fetal behavioural states: Sleep and wakefulness?" offers a review of the human and sheep fetal literature which casts doubt on whether this is any clear wakefulness in utero. (I was unable to add the reference to the 'reference' section).

Workman et al. 2013 (uploaded) is a nice approach to rigorously comparing development in species - which helps with thinking about ontogeny and phylogeny.

I thought of Baud et al. 2018 (uploaded) after talking to Alex about his research: I wonder if the seizures in this cohort unmasked a multi-day cycle which we all follow?

None of us mentioned the EEG 'cyclic alternating pattern' of sleep until I briefly raised on final day, but I like it as a framework which can encompass various specific graphoelements, e.g. K complexes, ripples, I have attached a paper by Halasz which interprets K complexes with reference to the cyclic alternating pattern.

Reference Materials

Title Author name Source name Year Citation count From Scopus. Refreshed every 5 days. Page views Related file
Modeling transformations of neurodevelopmental sequences across mammalian species Alan D. Workman, Christine J. Charvet, Barbara Clancy, Richard B. Darlington, Barbara L. Finlay Journal of Neuroscience 2013 0 1
Multi-day rhythms modulate seizure risk in epilepsy Maxime O. Baud, Jonathan K. Kleen, Emily A. Mirro, Jason C. Andrechak, David King-Stephens, Edward F. Chang, Vikram R. Rao Nature Communications 2018 0 0
K-complex, a reactive EEG graphoelement of NREM sleep: An old chap in a new garment Péter Halász Sleep Medicine Reviews 2005 0 0
Human cortical excitability increases with time awake Reto Huber, Hanna Mäki, Mario Rosanova, Silvia Casarotto, Paola Canali, Adenauer G. Casali, Giulio Tononi, Marcello Massimini Cerebral Cortex 2013 0 3