News & Views: "Sleeping to remember"

08/02/2018

Last month, we were fortunate to welcome Prof Antoine Adamantidis as a speaker at our monthly GIGA conference. Prof Adamantidis is a world-renowned researcher in the field of molecular, cellular, and behavioural neurobiology. He received the R. Broughton Young Investigator Award from the Canadian Sleep Society in 2013 and a Human Frontier Science Program Young Investigator’s Grant in 2012.¹ He is now a professor in the Department of Clinical Research at the University of Bern and the Department of Neurology at Bern University Hospital.² Prof Adamantidis studies the neural circuits that underlie the wake/sleep cycle using ultramodern technologies such as genetic mouse engineering, electrophysiology, and optogenetics³ (a technique in which the researcher can control the activity of genetically defined neurons using pulses of light⁴; see Fig. 1).

 

fig1

 

Figure 1:

1. Using blue or yellow light, optogenetics allows the activation or inhibition of specific types of neurons.
2. Light can be delivered straight into the brain via an optical fibre chronically implanted and affixed to the skull (adapted from Pama et al.5).

 

Recently, Adamantidis and his colleagues used optogenetics to investigate the functional role of rapid-eye movement (REM) sleep by selectively inhibiting GABAergic neurons in the medial septum (MS) (Fig. 2) 6. Sleep is classically divided into two phases – REM sleep (also called paradoxical sleep) and non-REM (NREM) sleep, which can be further divided into different depth stages.

 

fig2

Figure 2: Location of the MS and placement of the injection needed.6

 

The researchers used the novel object place recognition test, in which they presented two different stimuli to mice and let them explore the cage (Fig. 3). After a period of sleep during which REM sleep was disrupted, the mice were again exposed to the same cage, with one stimulus in the same spot as before the sleep period; the other stimulus was in a novel location. Normally, mice preferentially investigate the novel stimulus, so control mice (with normal REM sleep) are driven to the novel stimuli; in contrast, mice that had disrupted REM sleep did not show any preference between the two stimuli. Adamantidis and his colleagues also confirmed the importance of REM sleep in spatial memory consolidation using a fear-conditioning protocol.

 

fig3

Figure 3: The novel object place recognition test, with the familiarisation (1) and object place recognition (2) components (adapted from Boyce et al.6).

 

This type of fundamental research is essential for improving our understanding of how the brain controls sleep and cognition, as well as the relationship between these two processes. Given that approximately 30% of the general population have a sleep disorder7, and given that sleep plays an important role in the pathogenesis of a wide range of conditions, including Alzheimer’s disease, it is easy to appreciate the essential role of this research in global health. Importantly, the work being done by Prof Adamantidis and his team will also likely help researchers develop new ways of treating sleep disorders, thereby helping prevent the negative consequences of these disorders, including impaired cognition.

 

 

References

  1. 1.     Tidis-lab.org. Available at: http://tidis-lab.org/index.php/group-members [Accessed 31 Jan. 2018]
  2. 2.     Ellines.com. Available at: https://www.ellines.com/en/achievements/27851-discovered-a-method-to-wake-up-the-brain/ [Accessed 31 Jan. 2018]
  3. 3.      Douglas Mental Health University Institute. [online] Doulas.qc.ca. Available at: http://www.douglas.qc.ca/researcher/antoine-adamantidis?locale=en [Accessed 31 Jan. 2018]
  4. 4.     Guru, A., Post, R.J., Ho, Y.Y., & Warden, M.R. (2015). Making sense of optogenetics. International Journal of Neuropsychopharmacology18(11):pyv079.
  5. 5.     Pama, E.A., Colzato, L.S., & Hommel, B. (2013). Optogenetics as a neuromodulation tool in cognitive neuroscience. Frontiers in Psychology4:610.
  6. 6.     Boyce, R., Glasgow, S.D., Williams, S., & Adamantidis, A. (2016). Causal evidence for the role of REM sleep theta rhythm in contextual memory consolidation. Science352(6287):812-816.
  7. 7.     LeBlanc, M., Beaulieu-Bonneau, S., Mérette, C., Savard, J., Ivers, H., & Morin, C.M. (2007). Psychological and health-related quality of life factors associated with insomnia in a population-based sample. Journal of Psychosomatic Research63(2):157-166.

 

Authors

Daphne Chylinski, GIGA-CRC In vivo Imaging, Sleep Research Group, PhD student

Pamela Villar González, GIGA-CRC In vivo Imaging, Memory and Ageing Group, PhD student

 

This “News & Views” item is written as a part of the course “Reading and understanding scientific literature and presentations” offered by GIGA Graduate School