AMPHISLEEP : Integrated and multimodal study of sleep states in amphibian
by Paul-Antoine Libourel
Sleep is a complex system by nature. It is generated by multiple neuronal networks, under the pressure of the hormonal, circadian and metabolic systems. Sleep is also under the pressure of theenvironment (temperature, predation....) and the time devoted to sleep, is in competition with the time to reproduce, forage, feed or give parental care. In addition, the natural selection favored the presence of two sleep states in the “warm blooded” mammals and birds: slow wave sleep and paradoxical or REM sleep, mostly associated with dream in humans.
Why does the evolution favor these two states? One way to answer to that question is to developed a multidisciplinary and integrated approach, by conducting multiparametric and comparative studies. Recently, we demonstrated that lizards, “cold blooded” species, which share a common ancestor with mammals and birds, also show two sleep states. This pushes the probable origin of two sleep states back to 300MYA before present and suggests that these two states originated early-on in the evolution of vertebrates independently of the homeothermia of the warm blooded species.
However, whether amphibians, first terrestrial vertebrates, also show two sleep states remains unknown and if present this could push back the origin of the two states to the emergence. As sleep is associated with variations from the brain (neuronal activity) to the body (hear rate, body temperature,muscle tone ...), we propose here to study the behavior, the physiology and the electroencephalography related to vigilance state changes in a frog species using novel methods. We will use micro device developed by our team to record sleep. Our approach is to study sleep states thanks to the recording of most of the parameters that covary with sleep states in mammals. This study will provide important insights into the origin of our sleep states and even more, will support the development of a unique and integrated approach to understand sleep in a broader context.
