Alzheimer's clue homes in on musical memory
Ever struggled to get an annoyingly catchy tune out of your head? Blame your right anterior temporal lobe – a thumb-shaped region of the brain just behind the right ear. Damage to this brain region in people with some forms of dementia is what leaves them unable to recognise famous melodies, a study suggests. Olivier Piguet and colleagues at Neuroscience Research Australia in Sydney wanted to understand why people with Alzheimer's disease have difficulties with memory, yet can remember information if it is sung to them. One clue comes from a 2006 study which found that the right anterior temporal lobe is responsible for the way we understand words and concepts. To find out more, Piguet asked 27 volunteers with dementia to listen to pairs of tunes. Fourteen volunteers had Alzheimer's and 13 had semantic dementia (SD), a condition in which people can speak fluently but lose the ability to remember the names of objects, people and abstract concepts. Twenty healthy volunteers also participated. Piguet suspected that people with SD would have more trouble than those with Alzheimer's when it came to identifying tunes. If so, he could pinpoint the area of the brain responsible for processing music by comparing which <a href="http://www.guccibags-discount.com/chanel-handbags-2010-black-46037350-p-6944.html"><strong>chanel bags 2.55</strong></a> brain regions were damaged in the two groups. Jingle Bells Participants were asked to listen to 60 melodies. Thirty were well <a href="http://www.nfljerseys-onlinebuy.com/"><strong>nflÂ*jerseys</strong></a> known – for example, Jingle Bells – and each of these was matched with a new, unfamiliar tune in the same key and with the same tempo. The 60 melodies were played to participants in a random order, and after hearing each tune they were asked to say whether or not it was famous. Participants also heard 48 everyday sounds, such as a trumpet tooting, and had to match the sound to the appropriate image – in this case, that of a trumpet – in a set of six that they were presented with for each sound. As expected, people with SD performed worst at the tasks, picking out the famous tunes with a success rate of around 60 per cent. Those with Alzheimer's and healthy participants scored around 85 and 90 per cent, respectively. People with SD matched the everyday sound to the right image around half the time; those with Alzheimer's and the healthy participants were correct most of the time. Severely shrunken MRI scans revealed that the right anterior temporal lobe was severely shrunken in most of the people with SD. On average, people with more damage in this area were worse at identifying famous tunes. "But performance on the everyday sound task was not related to atrophy in this part of the brain," says Piguet. Difficulty in recognising the source of everyday sounds was associated with damage further back in the brain. People with Alzheimer's did not show significant damage to either brain region, which explains why they can recognise music and identify everyday sounds. Piguet suspects that the right anterior temporal lobe is attacked in SD but not in Alzheimer's disease. Deposits of a toxic protein called TDP-43 are present in the brains of people with SD, while different proteins, called tau and beta-amyloid plaques, form in Alzheimer's. "Different nerve cells in these particular brain regions may be more vulnerable to different proteins," he says. Elizabeth Valentine at Royal Holloway University of London, who was not involved in the study, says this "provides good evidence" that the right anterior temporal lobe is involved in the recognition of famous tunes. Journal ref: Brain, in press If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights <a href="http://www.cheapghdstraighteners-sales.com/ghd-mk4-dark-black-hair-straightener-p-29.html"><strong>limited edition ghd</strong></a> to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.
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