| New research shows how brain works when we're sedated |
| Thursday, 18 October 2007 | ||||
Page 1 of 2 Understanding of the brain’s ability to process information while under sedation has been furthered by research conducted at the MRC Cognition and Brain Sciences Unit (CBSU) in Cambridge, helping to allay the common fear of waking up from sedation during surgery.
Researchers at the MRC CBSU used functional magnetic resonance imaging (fMRI) to map the speech-related brain activity of 12 volunteers during varying degrees of sedation, to ascertain just how much information the brain is able to process under anaesthetic.The team, led by Dr Matt Davis, a cognitive neuroscientist at the Unit, aimed to show how the brain’s response to speech changes as people become more sedated and whether understanding of speech might continue, even while consciousness and memory is impaired. “Everyone knows that if you have a conversation with someone as they are falling asleep they might not answer or have any memory of what you said,” said Davis. “However, it’s hard to know whether this is because drowsy people don’t understand speech or just aren’t awake enough to respond or remember. It’s a similar situation when people are sedated or unconscious. We asked the question: do people have some hidden understanding of speech when they are at a low level of awareness?” The research was aimed to better our understanding of how much information the brain can deal with during sedation, which has implications for fine tuning the amount of anaesthetic to administer to a patient undergoing surgery, but also gives an insight into the brain activity of brain-injured patients in a coma or vegetative state. The 12 volunteers who took part in the study, all anaesthetists, were sedated with a common anaesthetic and scanned before and during sedation. Researchers also gauged responses to sentences and non-speech noises at three levels of awareness – fully awake, lightly sedated and heavily sedated. The heaviest state of sedation didn’t reach the level of a general anaesthetic and all volunteers showed some response to the sound of speech, for instance, waking up when their name was called. As one might expect, the team found that the more sedated the volunteers became, the less active their brains were in response to speech. |
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