Presentation for CSB445 Seminar in Sleep Neuroscience

1. Alteration in Cortical mEPSCs
Depending on Sleep/ Wake
Evidence for Synaptic Remodeling in Sleep
CSB445: Kathleen Harrison

2. The problem
Evidence to support wake being
associated to synaptic potentiation
and sleep with depression.
Great interest in this hypothesis:
however, there are still areas of
support lacking direct proof for
changes in synaptic alteration.
>1600 Papers
>1000 Citations
600 Citations
On sleep and the
synapse after 2003
On Tononi & Cirelli’
s 2003 paper
45 Papers
On sleep and the
synapse before
2003
On Tononi & Cirelli’
s 2006 paper

3. Remember:
(Wong, Y. 2015)
“(1) Wakefulness is associated with
synaptic potentiation in cortical
circuits;
(2) Synaptic potentiation is tied to the
homeostatic regulation of NREM
sleep EEG slow wave activity;
(3) Slow wave activity is associated
with synaptic downscaling;
(4) Synaptic downscaling is tied to the
beneficial effects of sleep on neural
function and, indirectly, on
performance’’
(Tononi & Cirelli, 2003)

4. Why?
>25% Calories used
in the brain
But only ~2% of mass
4.7 x 109
ATP/ neuron/ second

5. Support for the Model
Neuronal
(Vyazovskiy et al., 2008)
Structural Electrical Synaptic
40% AMPAr post wake/ sleep
Molecular
(Bushey, Tononi, Cirelli. 2011)
# & density post wake/ sleep firing rates post wake/ sleepevoked AP post wake/ sleep
(Vyazovskiy et al., 2008) (Vyazovskiy et al., 2009)

6. Hypothesis:
● Miniature EPSCs (mEPSCs) from frontal
cortex slices of mice and rats
● Awake or asleep should show changes in
frequency and amplitude of mEPSCs
● Increased after waking and decreased after
sleep, independent of time of day
● Sleep Deprivation and recovery sleep should
increase, and decrease mEPSCs respectively

7. Looking for
Change: Pre/Post Synapse
Vesical (Quanta) Release Frequency
AMPAr Trafficking & Scaffold remodeling

8. Experiments
Sleep VS Wake
Cortex harvested when awake,
or asleep - mSPSCs
Sleep Deprived
Cortex harvested at same time,
but one group awake,
Sleep Recovery
Cortex harvested at same time,
but one group given recovery
Sleep in Other Models
Cortex harvested from mice
after sleep deprivation

9. The
Technology Patch Clamp

10. How it works
Step 1
Isolate
Cortex => Neuron
Step 2
Voltage Clamp
Whole cell clamp
Step 3
Record & Analyze
mESPCs: Hz & pA

11. Experiments
Sleep VS Wake
Cortex harvested when awake,
or asleep - mSPSCs
Sleep Deprived
Cortex harvested at same time,
but one group awake,
Sleep Recovery
Cortex harvested at same time,
but one group given recovery
Sleep in Other Models
Cortex harvested from mice
after sleep deprivation

12. Experiments
Sleep VS Wake
Cortex harvested when awake,
or asleep - mSPSCs
Result:
Presynaptic - Higher frequency of NT release
Postsynaptic - Increase in amplitude
(Liu et al. 2010)

13. Experiments
Result:
Presynaptic - Higher frequency of NT release
Postsynaptic - Increase in amplitude
Sleep Deprived
Cortex harvested at same time,
but one group awake,
(Liu et al. 2010)

14. Experiments
Result:
Presynaptic - Decreased frequency of NT release
Postsynaptic - Decrease in amplitude
Sleep Recovery
Cortex harvested at same time,
but one group given recovery
(Liu et al. 2010)

15. Experiments
Result:
Presynaptic - Increased frequency of NT release
Postsynaptic - Increase in amplitude
Sleep in Other Models
Cortex harvested from mice
after sleep deprivation
(Liu et al. 2010)

16. Conclusion:
● Found that Hz and pA of mEPSCs increased after waking, decreased after sleep
● Independent of time of day
● Recovery sleep decreased mEPSCs Hz and pA
● Suggest sleep facilitates synaptic depotentiation
“Stronger synapses require more energy, space, and supplies: generalized
renormalization of synapses may be an important function of sleep.”
(Liu et al. 2010)

17. Pros
● Contradictory results when scaled?
● Importance of checking data!
Cons
● Good Evidence for SHY
● Good area of investigation
● Strengths of hypothesis
Variation in mEPSP post SD
mEPSP post SD same as wake/ control?

18. References:
Bushey, Tononi, Cirelli. (2011) Sleep and Synaptic Homeostasis: Structural Evidence in Drosophila
Liu ZW, Faraguna U, Cirelli C, Tononi G, Gao XB. (2010) Direct Evidence for Wake-Related Increases
and Sleep-Related Decreases in Synaptic Strength in Rodent Cortex
VyazovskiyVV, CirelliC,Pfister-GenskowM,FaragunaU,TononiG (2008) Molecular and
electrophysiological evidence for net synaptic potentiation in wake and depression in sleep.
Vyazovskiy VV, Olcese U, Lazimy YM, Faraguna U, Esser SK, Williams JC, Cirelli C, Tononi G (2009)
Cortical firing and sleep homeostasis.

19. Questions?