Sleep is a naturally recurring state, which still is a mystery since its function and purpose is not fully understood. In this project we explore the neural networks of the human brain that are involved in the regulation of sleep and wakefulness. For this quest, patients with sleep disorders provide keys to the understanding of why we sleep and why we wake up.

Maria Engström at the MR
It’s about understanding the brain

The aim of this project is to investigate brain function and structure in sleep disorders to explain the link between neurobiology, pathology, and the patients’ symptoms.

To understand the sleep disorders is of equal importance as understanding how normal sleep works. Ultimately it’s about understanding the brain. When trying to understand the normal function it can be very helpful to start with investigating something that is wrong.

Sleep Disorders

In the early 20th century von Economo detected brain areas involved in the regulation of sleep and wakefulness by investigating patients with excessive sleepiness due to brain inflammation. Almost a century later, scientists discovered the important sleep-regulating substance, orexin, which is produced in a certain area of the brain: the hypothalamus. Loss of orexin causes the sleep disorder narcolepsy, which is characterized by involuntary daytime sleep attacks and poor nighttime sleep.

Kleine-Levin syndrome is another sleep disorder where the patients can sleep for extremely long periods, up to several weeks. Unlike narcolepsy, the cause of Kleine-Levin syndrome is still unknown. The relations between disease mechanisms and the symptoms in Kleine-Levin syndrome as well as in narcolepsy are still unresolved.

The Blood Reveals Brain Activity
Brain activity measured with fMRI

Brain function and structure is investigated by magnetic resonance imaging (MRI) and simultaneous electroencephalography (EEG). Brain activity can be monitored with a method called functional magnetic resonance imaging (fMRI). The method is based on the fact that the blood flow is increased in activated areas of the brain to supply energy and oxygen. It is the blood oxygenation differences between active state and rest that is measured with fMRI.

To further understand what the method measures and how the brain works the research group uses mathematical modeling and system biology. What is biologically causing the increased blood flow? The theoretical models of the process are tested against the data collected from patients.

Working Memory, Attention and Rest

The brain function is investigated in relation to working memory and attention, as well as during rest. We also measure neurotransmitter GABA and glutamate concentrations by magnetic resonance spectroscopy (MRS) and tissue properties by quantitative MRI.

The results show that compared to healthy individuals, patients with the Klein-Levin syndrome have cognitive difficulties and a reduced working memory. Narcolepsy patients on the other hand have an intact working memory and the attention problems come from lack of sleep. Patients with narcolepsy have alterations in EEG micro states related to function in the brain’s attentional network during rest and during working memory performance.

Finding out more about the pathology behind sleep disorders is important for finding better treatments and better methods to monitor the effect of the treatment. CMIV offers the arena where professionals from different disciplines can meet that wouldn´t otherwise not naturally meet. To work with patients requires an environment that prioritizes the research and at the same time takes care of the individual patient.

I have a genuine interest in fining out how things work. It is what pushes me forward in my research

Maria Engström, Professor

Project Manager
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Project Members
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Maria Engström, Thomas Karlsson, Anne-Marie Landtblom (2014)

Sleep , Vol.37 , s.379-386 Continue to DOI

Maria Engström, Anne-Marie Landtblom, Thomas Karlsson (2013)

Frontiers in Human Neuroscience , Vol.7 , s.1-17 Continue to DOI

Maria Engström, Patrick Vigren, Thomas Karlsson, Anne-Marie Landtblom (2009)

SLEEP , Vol.32 , s.681-688 Continue to DOI

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