Brain re-growth after 19 years unconscious

voss_study_dti_scan.jpgTerry Wallis, a man who was in a coma-like minimally conscious state for 19 years after a car crash, seems to have shown brain re-growth since he recovered consciousness.

A research team led by Henning Voss scanned Wallis’ brain using a technique called diffusion tensor imaging or DTI that can pick out the white matter pathways in the brain.

An image from Wallis’ DTI scan is shown on the left, and shows the connections in the rear section of the brain.

The image is shown as if we’re looking down and from the side into the brain. Note how the structures do not match on either side – often a good indicator of brain injury.

Crucially, the researchers re-scanned Wallis’ brain after 18 months and found that the density of the white matter seemed to increase over time, suggesting that his axons were regenerating. These are the long insulated fibres that connect the brain’s neurons.

When scanned using a PET scanner, the increase in white matter also seemed to match an increase in the use of glucose, suggesting greater levels of brain activity in these areas.

In the last decade it was discovered that adults can grow limited numbers of new neurons, but the regeneration of the brain’s connections is still largely unknown, and especially not in people who have suffered such severe brain injury.

Wallis was the subject of a 2005 Bodyshock documentary called The Man Who Slept For 19 Years.

Contrary to depictions in many films (where people tend to gently open their eyes and return to normality), Wallis is still markedly disabled by his brain injury and is not able to care for himself.

Wallis’ recovery is no less remarkable, however, and highlights shortcomings in the scientific understanding of both coma-like states and the neuroscience of consciousness.

UPDATE: Pure Pedantry has a great article looking at some of the background issues to do with this case, such as the exact definitions of different coma-like states. Well worth checking out.

Link to ‘Rewired brain’ revives patient after 19 years from New Scientist.
Link to write-up from The Age (thanks Kate!)
Link to full-text of scientific study.
Link to previous Mind Hacks story on minimally conscious state.

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