Anesthesiologist Annalotta Scheinin defended her PhD dissertation entitled:
“Probing the (Un)Conscious Brain – Electroencephalogram and Positron Emission Tomography Studies on Healthy Human Subjects Using Propofol, Dexmedetomidine and Natural Sleep”
The question about the biological basis of consciousness has puzzled neuroscientists for decades. Traditional way to study the neural correlates of consciousness have been to compare two distinct states of consciousness; an awake and an anesthetized state. However, previous studies have used several drugs with varying does and might thus fail in unraveling the neural correlates of consciousness, unconsciousness and their different dimensions.
Annalotta Scheinin, together with Adjunct professor Harry Scheinin’s Anesthesia Mechanisms group, aimed to use rigorous experimental protocols to study human consciousness in healthy subjects. They used two anesthetics (propofol and dexmedetomidine) and natural sleep and explored EEG changes in association to different states of consciousness during increasing doses and a steady-state infusion of two anesthetics. In addition, they measured with EEG N400 event related potentials whether or not sematic processing persists during an unresponsive state induced by the two drugs. Lastly, they used positron emission tomography (PET) imaging to reveal brain activity alterations between connected and disconnected states induced by anesthesia and sleep.
The results were somewhat surprising and highlight the multidimensional nature of human consciousness. With PET imaging the group was able to identify a central core brain network that is fundamental for human consciousness and noticed the effects of anesthesia and sleep on brain activity was pretty similar. With EEG recordings the group found that consciousness is not necessarily fully lost during anesthesia and semantic processing was partly preserved during general anesthesia.
Warmest congratulations, Annalotta!
In the picture Annalotta Scheinin (on the left), Custos Professor Teijo Saari from University of Turku and Opponent Adjunct Professor Anne Vakkuri from Helsinki University Hospital.
Image courtesy: Harry Scheinin