Ageing brains unable to cope with distracting information

December 8th, 2008 - 5:08 pm ICT by IANS  

Toronto, Dec 8 (IANS) Older adults aren’t able to filter out distracting information as readily as youngsters and this effects their ability to memorise things, according to new research.Scientists at the Rotman Research Institute in Toronto, Canada say that annoying noise is behind their latest discovery of unique brain activity underlying memory encoding failure, which appears to occur only in older brains.

Volunteers for the study had their brains scanned inside a functional magnetic resonance imaging (fMRI) scanner. While the powerful technology can yield remarkable computerised images of the brain working to form a new memory, the high powered magnet has an inconvenient quirk - it’s noisy, especially if you’re inside it.

As part of the study, 12 younger adults (average age 26) and 12 older adults (average age 70) took part in a face recognition task that involved having their brains scanned with fMRI while they were shown pictures of faces and later again when trying to recall whether they’d seen each face before, said a Rotman release.

Researchers found that when younger and older adults had difficulty encoding a new memory (certain face), it was marked by decreased activity in brain regions important for encoding, such as the hippocampus.

The researchers weren’t surprised by this based on an abundance of scientific evidence indicating the importance of hippocampus for making memories.

But the older brains showed additional increased activation in certain regions during memory encoding failure that was not found in younger brains. This was because they were unable to filter unnecessary information since they were distracted by the noise.

“The older brains showed increased activation in certain regions that normally should be quieter or tuned down,” said Dale Stevens, who led the study as a doctoral student at Rotman Research Institute.

It is known from earlier studies that older adults are more easily distracted, but this was the first to look at what is going on in the brain when people try to form a memory and fail, said Stevens.

While older adults performed as well as their younger cohorts in the number of faces correctly recognised, older adults forgot more faces overall than younger adults.

The study was published in the November issue of The Journal of Neuroscience.

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