A recent study may help to explain why older people find difficulty remembering. During sleep the normal replay of brain activity from the day is undertaken by a region of the brain known as the hippocampus. This replay activity is believed to be important for memory consolidation and is something that reduces as people get older.
Dr. Carol Barnes and colleagues from the University of Arizona in Tucson compared how young and old rats ‘replay' their actions during sleep. The research team implanted electrodes into the hippocampus of each rat's brain. All 22 rats, half young and half old, were then given a food reward for completing a maze task. Brain activity was monitored during the maze activity and again during the period of sleep.
In younger rats the normal neural activity of the brain during sleep was seen to closely match the activity seen during the maze task. In older rats the patterns were more disorganized.
In later experiments young rats were able to remember a series of activities whereas the older rats struggled. The only exception was in rats whose night time neural activity came closer to that seen in the day.
According to Barnes this is the first study to suggest that an animal's ability to perform a spatial memory task relates to memory consolidation during sleep.
Not everyone is quite so convinced. Dr John Groeger, from the Sleep Research Institute at the University of Surrey, UK, said the precise role of the hippocampus in the storing and recall of memory was yet to be proven. He said the rat experiment would be extremely difficult to test in humans because of the wide differences in sleep patterns of older and younger people.
However, Barnes and the research team are now actively investigating possible drugs that could correct deficits in memory replay. "If we're able to reverse it, even a little bit, we should have a better sequence reactivation," and this could reduce forgetfulness.
Published On: August 13, 2008