Researchers hope to restore “good noise” in the elderly brain

tapping For the brain, one of the best tools neuroscientists have is fMRI scans, which help to map blood flow, so oxygen spikes occur when specific brain areas are used. It reveals a noisy world. Blood oxygen levels change from time to time, but these peaks never level out completely. “Your brain, even if it is resting, is not completely quiet,” said Poortata Lalwani, a PhD student in Cognitive Neuroscience at the University of Michigan. She imagined the brain, even in the calmest time, a bit like a tennis player waiting to serve: “He won’t stand still. He will pace a little, ready to hit the backhand.”

Many fMRI studies filter out these noises to find specific spikes that the researcher wants to examine carefully. But for Lalwani, noise is the most telling signal. For her, this is a sign of cognitive flexibility. Young, healthy brains tend to signal that blood oxygen levels change over time. Older people have less differences, at least in certain areas of the brain.

About ten years ago, scientists showed for the first time the link between low neural signal variability and the cognitive decline that accompanies healthy aging, rather than a specific DementiaThe noise of the brain is a reliable representative of more abstract details, Lalwani said: “How efficient is the information transmission, how well the neural network is connected, and in general, what is the function of the underlying neural network.”

but why The changes that occur with age have always been a mystery. So is the question of whether it is reversible.

exist Results published November at Journal of Neuroscience, Lalwani’s team showed that low-dose lorazepam (an anti-anxiety drug) can at least temporarily reverse the decline in signal variability. This drug will call up the inhibitory information in the brain, but it will make it more vigorous and ready to react and respond quickly. In this study, the brain signals of older participants who had previously poorly performed on cognitive tasks returned to noise levels that looked more like young people.

“About ten years ago, most people thought the variability of the brain was a bad thing,” said Cheryl Grady, a cognitive neuroscientist at the Rotman Institute, who studied the variability of brain signals but was not involved in Lalwani’s research. . But now, she feels that more people are aware of the potential of this new indicator. “I very much approve of the whole method.”

Around 2008, researchers Begin to suspect that the so-called noise in the fMRI signal has a deeper meaning. By 2010, Douglas Garrett, a PhD student at the time, stated that Variability of blood oxygen fMRI signal It is more predictive of a person’s age than the size of the spikes in those readings. His hunch is that the standard deviation-a measure of the similarity or different degrees of signals in the original data set-can tell a story that a simple average spike size cannot do.

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