INSIGHTS into the mechanisms that enable the brain to separate information depending on importance, thus protecting the working memory from interference, have been displayed by researchers from the Universities of Tübingen and Munich, Germany. The findings could help uncover new therapy avenues for memory disorders.
Through experiments on rhesus monkeys, the team observed that low frequency waves (theta waves) of 4–10 cycles per second appear to be used by nerve cells to judge the importance of information. This is particularly vital when people are confronted by a multitude of stimuli. Lead author Dr Simon Jacob, University of Munich, commented: “Our results show that cognitive brain functions require precise interaction of nerve cells. It makes sense to use the mechanisms investigated in the animal model for therapeutic purposes in patients with memory disorders, for example by stimulating co-ordinated communication between the brain regions studied.”
In the study, rhesus monkeys were trained to separate relevant numbers, which they had to remember in a short time, from interfering numbers. Using microelectrodes, the researchers measured the electrical signals of nerve cells in the cerebral cortex of the monkeys; this showed that large-scale fluctuations in electrical brain activity was caused by the simultaneous discharge of thousands of nerve cells.
Importance of Theta Waves
Both the relevant and interfering information was found to be transmitted within theta waves of 4–10 cycles per second. The team then observed that nerve cells responsible for the relevant information always discharged when the theta wave was at its lowest point; conversely, when the theta wave was at its highest, the nerve cells responsible for the disturbing stimulus would always discharge.
“We believe that the brain uses certain frequency channels to transmit information synchronously, but at the same time this wealth of information is also sorted according to whether it is important and unimportant during the transmission between brain areas,” said Prof Andreas Nieder, University of Tübingen.
The team added that further studies are now required to see whether the cognitive information is processed in the same manner across separate regions of the brain.
James Coker, Reporter
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