Magnetic Resonance Imaging Helps Unravel the Mysteries of Sleep

0
459
Mysteries Sleep

Revealed: The Secrets our Clients Used to Earn $3 Billion

Our state of awareness modifications considerably throughout phases of deep sleep, simply as it carries out in a coma or under basic anesthesia. Scientists have actually long thought — however couldn’t be specific — that brain activity decreases when we sleep. Most research study on sleep is carried out utilizing electroencephalography (EEG), a technique that involves determining brain activity through electrodes put along a client’s scalp. However, Anjali Tarun, a doctoral assistant at EPFL’s Medical Image Processing Laboratory within the School of Engineering, chose to examine brain activity throughout sleep utilizing magnetic resonance imaging, or MRI. According to Dimitri Van De Ville, who heads the laboratory, “MRI scans measure neural activity by detecting the hemodynamic response of structures throughout the brain, thereby providing important information in addition to EEGs.” During these experiments, Tarun trust EEG to recognize when the research study individuals had actually gone to sleep and identify the various phases of sleep. Then she took a look at the MRI images to produce spatial maps of neural activity and identify various brain states.

Difficult information to get

The just catch was that it wasn’t simple to carry out brain MRIs on individuals while they were sleeping. The makers are extremely loud, making it difficult for individuals to reach a state of deep sleep. But dealing with Prof. Sophie Schwartz at the University of Geneva and Prof. Nikolai Axmacher at Ruhr-Universität Bochum, Tarun might utilize synchronised MRI and EEG information from around thirty individuals. The brain-activity information were covered a duration of almost 2 hours while individuals were oversleeping an MRI device. “Two hours is a relatively long time, meaning we were able to obtain a set of rare, reliable data,” states Tarun. “MRIs carried out while a patient is performing a cognitive task usually last around 10-30 minutes.”

Brain activity throughout sleep

After monitoring, examining and comparing all the information, what Tarun discovered was unexpected. “We calculated exactly how many times networks made up of different parts of the brain became active during each stage of sleep,” she states. “We discovered that during light stages of sleep — that is, between when you fall asleep and when you enter a state of deep sleep — overall brain activity decreases. But communication among different parts of the brain becomes much more dynamic. We think that’s due to the instability of brain states during this phase.” Van De Ville includes: “What really surprised us in all this was the resulting paradox. During the transition phase from light to deep sleep, local brain activity increased and mutual interaction decreased. This indicates the inability of brain networks to synchronize.”

The function of default-mode networks and the cerebellum

Consciousness is typically connected with neural networks that might be connected to our self-questioning procedures, episodic memory and spontaneous idea. “We saw that the network between the anterior and posterior regions broke down, and this became increasingly pronounced with increasing sleep depth,” states Van De Ville. “A similar breakdown in neural networks was also observed in the cerebellum, which is typically associated with motor control.” For now, the researchers don’t understand precisely why this takes place. But their findings are a primary step towards a much better understanding of our state of awareness while we sleep. “Our findings show that consciousness is the result of interactions between different brain regions, and not in localized brain activity,” states Tarun. “By studying how our state of consciousness is altered during different stages of sleep, and what that means in terms of brain network activity, we can better understand and account for the wide range of brain functions that characterize us as human beings.”

Reference: “NREM sleep stages specifically alter dynamical integration of large-scale brain networks” by Anjali Tarun, Danyal Wainstein-Andriano, Virginie Sterpenich, Laurence Bayer, Lampros Perogamvros, Mark Solms, Nikolai Axmacher, Sophie Schwartz and Dimitri Van De Ville, 22 January 2021, iScience.
DOI: 10.1016/j.isci.2020.101923