Measuring consciousness

Andrea Luppi is co-first author of a new study which aims to get closer to understanding how the unconscious brain functions.

I cannot think of a more fascinating thing to study than how the mind arises out of matter.

Andrea Luppi

How can we measure consciousness? And what role does understanding how the unconscious brain functions play in improving surgery and treating disorders of consciousness?

A new study, on which Gates Cambridge Scholar Andrea Luppi and Thomas Varley are co-first authors, looks at how experts measure brain complexity, a key factor in addressing these questions.

Previous research has long debated whether complexity of the brain could be used to explain differences between the conscious and unconscious brain. 

Complexity relates to two main dimensions: complexity in structure – the different regions of the brain perform different roles –  and time – how brain activity evolves dynamically. Different fields of study
measure this complexity in different ways.

The new study, published in Scientific Reports, looks at whether there is something that unifies all these different approaches which can drive forward research into consciousness.

He and his team looked at seven different ways to measure brain complexity using propofol, one of the most common anaesthesia drugs, and MRI scans. A common way to understand consciousness is through anaesthesia as, unlike sleep, it can be controlled and, unlike consciousness disorders, it is reversible.

The researchers worked on two different datasets to ensure their findings were robust. They found that the seven measures were differently able to discriminate between levels of sedation, with those that focused on the temporal dimension showing higher sensitivity. The study also showed that all the measures were strongly related to a single underlying construct which explained most of the variance, which they say can measure “overall complexity” and could be used to predict the level of consciousness of a patient undergoing anaesthesia.

“We see a relationship between consciousness and complexity,” says Andrea [2019] who is doing a PhD in Clinical Neurosciences. “We think that anaesthesia induces loss of consciousness by reducing the complexity of the brain. It remains to be determined how this is happening, but we hope that our research might eventually help doctors measure a person’s level of consciousness better in surgery and better predict outcomes of disorders of consciousness.”

The new paper complements a previous one published late last year on similarities between disorders of consciousness and anaesthesia.

Andrea has been fascinated by consciousness since secondary school where he developed an interest in understanding the phenomena of dreams. He studied philosophy and psychology at undergraduate level and was increasingly drawn to neuroscience and the light it could shed on how the brain works and on unconsciousness. At Cambridge his laboratory studies consciousness from a range of different angles, which he believes is vital to bringing us closer to understanding how the brain works. He states: “I cannot think of a more fascinating thing to study than how the mind arises out of matter.”

*Picture credit of brain scan: Martin420. Courtesy of Wikimedia Commons.