Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bearded dragons show REM and slow wave sleep

29.04.2016

Brain sleep appeared early in vertebrate evolution

Behavioral sleep is ubiquitous among animals, from insects to man. In humans, sleep is also characterized by brain activity: periods of slow-wave activity are each followed by short phases of Rapid-Eye-Movement sleep (REM sleep).


Sleeping bearded dragon (Pogona vitticeps)

© MPI f. Brain Research/ S. Junek


Sleep constitutes an uninterrupted epoch of regular oscillations between two spectral profiles.

© MPI f. Brain Research/ M. Shein-Idelson, J. Ondracek, H.-P. Liaw, S. Reiter and G. Laurent

These electrical features of brain sleep, whose functions are not well understood, have so far been described only in mammals and birds, but not in reptiles, amphibians or fish. Yet, birds are reptiles—they are the feathered descendants of the now extinct dinosaurs.

How then did brain sleep evolve? Gilles Laurent and members of his laboratory at the Max Planck Institute for Brain Research in Frankfurt, Germany, describe for the first time REM and slow-wave sleep in a reptile, the Australian dragon Pogona vitticeps.

This suggests that brain sleep dates back at least to the evolution of the amniotes, that is, to the beginning of the colonization of terrestrial landmass by vertebrate animals. They reported their findings in the upcoming issue of Science.

Birds, reptiles and mammals are all amniotes, a clade of tetrapod vertebrates, whose eggs could survive outside water, hence enabling land colonization. Amniotes appeared ~320 million years ago, and quickly bifurcated into a group that led to the mammals (including us humans), and another that led to the reptiles and the birds.

Bearded dragons are a type of lizard that branched out of the common reptilian trunk some 250 millions ago, much earlier than the branch that would lead to the dinosaurs and the birds. A phenomenon observed in a lizard, a bird and a mammal would thus most likely have existed in their common ancestor.

Gilles Laurent and his group study the reptilian brain because of its simpler, ancestral design, to understand cortical function, dynamics and computation. In the midst of one of these studies, they observed that brain activity recorded from resting lizards during the night oscillated regularly between two states. The present work derives from this initial observation. They asked: are we seeing REM and slow-wave sleep?

Answering this question requires classifying neuronal activity patterns recorded from the brain, based on a number of statistical, dynamical and anatomical features and correlating them with observable behaviors, such as the presence or absence of rapid eye movements.

In their report, Laurent and his colleagues describe the existence of REM and slow-wave sleep in the Australian dragon, with many common features with mammalian sleep: a phase characterized by low frequency/high amplitude average brain activity and rare and bursty neuronal firing (slow-wave sleep); another characterized by awake-like brain activity and rapid eye movements. Another common feature with mammalian sleep was the coordinated activity of cortex with another area during slow-wave sleep: in dragons this other area is the so-called dorsal ventricular ridge. In mammals it is the hippocampus.

They also report interesting differences: for example, lizard sleep rhythm is extremely regular and fast: the lizard’s sleep cycle is about 80 seconds long at 27oC, vs. 30 minutes in cat or 60-90 minutes in humans. Also, while in lizards slow-wave and REM-sleep have roughly equal durations during each cycle, REM is much shorter then slow-wave sleep in mammals, and both short and irregular in birds. Overall, lizard sleep seems a lot simpler and may thus be closer to the ancestral mode of brain sleep.

How does one know that such evidence points to a common origin, rather than separate but convergent evolution of sleep in reptiles, birds and mammals? “Positing convergent evolution (two or three times in amniote evolution) of a complex phenomenon such as sleep brain dynamics is a lot less plausible than imagining a common origin.

Given the early branching out of the reptiles, additional evidence from several of reptilian branches such as turtles, lizards, or crocodiles will only increase the probability that we are looking at a common origin. The evidence, thus far, points to an origin of REM and slow-wave sleep at least as far back as the common ancestor of reptiles, birds and mammals, which lived about 320 million years ago”, explains Laurent. At that time the earth’s continents formed a single landmass.

The scientists will continue to explore brain activity during sleep and awake states, as a means to understand the common and essential features of vertebrate brain function.

Publication: Shein-Idelson, M., Ondracek, J., Liaw, H.-P., Reiter, S. and Laurent, G. (2016). Slow waves, sharp-waves, ripples and REM in sleeping dragons. Science (in press).

Weitere Informationen:

http://brain.mpg.de/news-events/news.html

Dr. Arjan Vink | Max-Planck-Institut für Hirnforschung
Further information:
http://www.brain.mpg.de/

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>