A Signature of Consciousness

I listened to a programme on BBC Radio 4 before Christmas entitled ‘Playing Tennis in a Coma’ which I ended up listening to again and again and got me reading around the subject of consciousness.

I’ve always been fascinated by how our brains work, memory and consciousness and this programme ticked so many boxes in that respect but also opened up a plethora of questions.

As recently as 2006, the only way scientists could measure consciousness was by asking people to respond to verbal commands or by getting them to speak or move in some way. As a result anyone in a vegetative state was considered to be unconscious because they could not respond by speaking or moving. This led scientists to question ‘how do you define consciousness?’ How could you measure it in a person in a vegetative state? Maybe someone can’t move their hand or blink or make a sound, but maybe they could move something in their brain that could be pinpointed and measured. If, through suggestion, a patient could imagine playing tennis, would this activate their motor cortex enough to show that they were conscious and aware?

In June 2006, coinciding with Wimbledon, a study undertaken by nueroscientist Adrian Owen hit the headlines. Owen had taken fMRI scans of the brain of a 23-year-old woman in a vegetative state while asking her to imagine playing tennis and walking through the rooms of her house. Why? Well, to see if it was possible for someone who had been unresponsive for five months after a traffic accident to show signs of consciousness. An fMRI scan can show which regions of the brain are activated during certain thoughts or actions.

When a healthy, conscious adult imagines playing tennis, they consistently show activation in a specific region of the brain that deals with ‘motor imagery’. In contrast, when asked to imagine navigating through the rooms of a house, individuals generate activity in a completely different part of the brain. By using these two distinct forms of visualisation Owen discovered he could ask healthy volunteers yes/no questions and get the correct response, in a word – think ‘tennis’ for yes and ‘home’ for no.

Through the use of the fMRI scanner, he discovered that the woman, who had been unresponsive for five months, had strikingly similar brain activation patterns to the healthy volunteers who were imagining the same activities, proving, in Owen’s mind, that she was conscious. If a vegetative person’s brain did indeed respond to what was going on around them, the method would open up the exciting prospect of allowing patients to communicate with the outside world.

There are tens of thousands of people in a vegetative state around the world and Owen reckons that up to 20% of them are capable of communicating; they just don’t have a way to do so. The term ‘locked-in syndrome’ springs to mind. Getting these patients into the fMRI scanner for testing would be a logistical nightmare. So over the past ten years progress has been made to make the process more portable/accessible and take the scanner to the patient rather than the other way around. Now, through the use of Electroencephalography (EEG) patient brain activity can be monitored and electric brain activity recorded by placing a cap of 128 electrodes on the scalp.

A new study focuses on detecting activity generated by the brain continuously while a patient is resting, through the use of EEG, to assess the quality and robustness of their brain networks. Patients are tested/monitored regularly and this process of assessment continues for several years to note any changes in behaviour. Reading around the subject I discovered that scientists have found that some patients in a vegetative state are aware and have rich robust networks in their brains that could support consciousness. Researchers believe that a combination of the EEG test and the ‘tennis test’ could help improve accuracy in the prognosis for a patient and help identify the patients who could benefit from certain treatments, as well as enabling a few patients to tell their doctors whether they need pain relief.

However Owen’s findings could raise more difficult dilemmas and ethical issues. For example, it is lawful to allow patients in a permanent vegetative state to die by withdrawing all treatment. So could test results like these influence a family’s or clinician’s decision to end a life? If a patient showed that they had awareness and could respond to questions it would no longer be lawful to allow them to die, even if they made it clear that was what they wanted.

One thing is for sure though, this new study gives hope and better understanding to the families who have loved ones trapped in this limbo type vegitative state. It also provides us with and will continue to develop a better understanding of the working of the brain and most importantly consciousness.

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