Jun 10 2004
Scientists have shown how the brain builds up an early warning detection system by working out the odds on potentially harmful experiences.
Previous events which have involved danger or discomfort are logged in key areas of the brain even though we might not be aware of this self-preservation activity.
An experiment conducted by Dr Ben Seymour and colleagues at the Wellcome Department of Imaging Neuroscience, University College London, revealed that volunteers couldn’t recall the details of a specific test which had resulted in them receiving a mild electric shock. But activity in the brain revealed that they had correctly logged the information using a series of complicated computations.
“The brain is a phenomenal biological computer with around 100 billion nerve cells which determine our thoughts and behaviour,” said Dr Seymour.
“Evolution clearly favours animals that are good at looking after themselves. Although we may not always be aware of it, the brain tries to ensure our self-preservation through a complex mathematical strategy. In fact, computer scientists have recently started using the same strategy to help them build artificial brains for robots.
“We have shown how it works out what are potentially dangerous or painful episodes by interpreting chains of events and basically assessing the odds.”
Dr Seymour’s study, which is detailed in this week’s issue of Nature, involved fourteen men and women undergoing a half-hour test while lying in a functional magnetic resonance brain scanner. They were then shown a series of abstract pictures followed by a one-second electric shock – equivalent to a pin-prick.
When the tests were completed many of the volunteers could not recall the sequence of images. But the scanner revealed that two key areas, the ventral striatum and part of the cerebral cortex, were working together to figure out what was coming next.
“If we showed a square followed by a circle followed by the painful shock this part of the brain could soon learn to predict that the circle was bad news,” said Dr Seymour who was funded by the Wellcome Trust biomedical research charity. “However, after a while, it would learn that the square wasn’t that good either, as it was followed by the circle. By recording these chains of events, the brain was able to set early alarm bells ringing in the volunteer
“Imagine you are bitten by your neighbour’s dog. You soon learn not only to avoid the dog, but also things associated with it like its favourite haunts.”
Dr Seymour hopes that further research on the brain’s computational skills could eventually help many people who suffer ongoing pain –which affects about 10 percent of the UK population at some time in their lives.
“Although chronic pain is relatively common, it remains poorly understood and often remarkably difficult to treat,” he added.
The Wellcome Trust is an independent research-funding charity established in 1936 under the will of tropical medicine pioneer Sir Henry Wellcome. The Trust’s mission is to promote research with the aim of improving human and animal health and it currently spends more than £400m p.a