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Jumping to delusions - how the brain takes dangerous shortcuts

Why do some people with mental illnesses entertain bizarre and seemingly irrational beliefs that make their lives a misery?

Speaking at the Café Scientifique public forum at the ADC Theatre, Cambridge, on the 24th March, Professor Paul Fletcher of the Department of Psychiatry University of Cambridge explained how scientists study behaviour, image brain oxygen levels, and manipulate humans with pharmacological agents in order to uncover how such delusional beliefs might arise.

According to Professor Fletcher:

"our senses only give us sketchy evidence about our world. In order to make the best of our vague sensory impressions and to avoid information-overload, the brain takes important short cuts, being selective about where it directs its attention and thereby ignoring a great deal of information and filling in the gaps – often seeing what should be there rather than what actually is there".

This means that the brain creates the world around it based upon prior knowledge (predictions) and an assessment of what should be recorded and what should be ignored.

As Paul explained:

" While this approach to processing the world is efficient and rapid, a drawback is that it can make us inflexible and irrational. People are more likely to focus on evidence that confirms their expectations and less likely to change their beliefs in response to evidence that contradicts their expectations

Therefore, given scientific observations on the normal processes of the brain and belief formation, perhaps the delusional beliefs of mental illness can be more easily understood and can be recognised as not so far from rationality as they might first appear."

Paul's lecture was a hugely popular (unfortunately some members of the public were unable to gain entrance as the event was too popular) with plenty of questions from the audience spilling over into the post lecture wine reception.

The evening was recorded by the BBC Radio show Naked Scientists, and will be available to listen to on this site shortly.

Café Scientifique is a friendly informal gathering for everyone interested in chatting about the science that is changing our lives. Each month a different scientist discusses their work and takes question from the floor. The events are free, and last night was held at the Larkum Studio, ADC Theatre, Park Street, Cambridge. For further information on future Cafe Scientifique events please click here.

The series is sponsored by the Medical Research Council and organised as part of the national Café Scientifique forum in association with The Triple Helix Cambridge, a student society that explores interdisciplinary issues surrounding science.

Article written by Dr. Hannah Critchlow, Cambridge Neuroscience Coordinator.

Posted on 24/03/2010

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