Defining what consciousness is not, to help those with severe brain injury

Consciousness is everything we experience and is inextricably linked to our very essence, to the understanding of ourselves as human beings. The origin and nature of these experiences has been a mystery that has preoccupied philosophers and scientists from the earliest days of antiquity right up to the present.

While our personal experiences may be different, consciousness is a fundamental feature of human experience, common to all of us.  Yet, understanding how the brain produces consciousness remains one of the biggest unsolved puzzles of modern science.

We don’t question whether others around us are conscious. This is not so, however, for patients who after severe brain injury completely lose their ability to communicate their thoughts and feelings through language or behaviour, and, on this basis, are often mistakenly diagnosed to be in a vegetative state, or to lack consciousness.

To understand how the brain produces consciousness and how it can be preserved after devastating brain injury, in a new international collaboration study published in the journal Nature Communications, researchers at three universities started by defining what consciousness is not.

Dr Lorina Naci, from the School of Psychology, Trinity College and Trinity College Institute of Neuroscience, and one of the three senior collaborators on the study said:

 “We studied healthy individuals who became fully unconscious under general anesthesia, with a routine anesthetic drug like propofol, and patients who became unconscious following severe brain injury.” 

“We knew that, when an individual loses consciousness, connections among brain regions are disrupted – information cannot travel back and forth freely. What we did not know up to now is whether all of these connections matter equally for consciousness.”

Commenting on the exciting findings, she said:

“We found remarkably similar brain signatures of consciousness loss in vastly different scenarios. Whether due to deep anaesthesia or due to severe brain-injury, loss of consciousness was accompanied by reduced functional diversity and integrative capacity in the default mode network of the brain. These insights have implications for improved diagnosis and prognosis of patients, presumed to be vegetative, who are in fact conscious and aware of everything going on around them.”

The study, first authored by Andrea Luppi at the University of Cambridge, is a fantastic example of the power of teams to push science forward. It is the result of an international collaboration between three research groups, each led by Professor Lorina Naci at Trinity College Dublin, Professor Emmanuel A Stamatakis at the University of Cambridge (UK), and Professor Adrian M Owen at the University of Western Ontario (Canada), respectively.

You can read the full article in Nature Communications here: https://www.nature.com/articles/s41467-019-12658-9

You can find out more about the research work of Dr Lorina Naci here