Researchers want to restore ‘good noise’ in ancient brains


to eavesdrop on Brain, one of the best tools neuroscientists have is an fMRI scan, which helps map blood flow, and thus the spike in oxygen that occurs whenever a specific area of ​​the brain is used. It reveals a noisy world. Oxygen levels in the blood vary from moment to moment, but these spikes never flatten completely. “Your mind, even at rest, will not be completely silent,” said Portata Lalwani, a PhD student in cognitive neuroscience at the University of Michigan. It visualizes the brain, even in its quietest state, like a tennis player waiting for the serve response: “He will not stand still. He will take small steps, preparing to strike the backhand.”

Many fMRI studies filter that noise to find the specific mutations that researchers want to examine. But for Alwani, that noise is the most telling signal of all. For her, it’s a nod to cognitive flexibility. Young, healthy brains tend to get signals with a lot of variation in blood oxygen levels from moment to moment. Older types differ less, at least in certain areas of the brain.

About a decade ago, scientists first demonstrated the link between reduced variance of nerve signals and the type of cognitive decline that accompanies healthy aging, rather than specific dementia. Brain noise is a powerful proxy for more abstract details, says Lalwani: “How efficiently information is transmitted, how well neural networks are connected, and how well the underlying neural network performs in general.”

but Why This change that occurs with age has been a mystery. So is the question of whether it is reversible.

In the results published in November in Neuroscience JournalLalwani’s team showed that a small dose of lorazepam, an anti-anxiety drug, could reverse the reduction in signal variability, at least momentarily. The drug delivers inhibitory messages in the brain but makes it more dynamic, ready to react and respond quickly. In the study, the brain signals of older participants who had previously performed poorly on cognitive tasks returned to noise levels that sounded more like those of younger adults.

“A decade or so ago, most people thought variability in the brain was a bad thing,” says Cheryl Grady, a cognitive neuroscientist at the Rotman Research Institute who has studied brain signal variability but was not involved in the Lalwani study. But she now feels that more people are realizing the potential of this new scale. “I strongly support this whole approach.”

Circa 2008, researchers It is beginning to be suspected that the purported noise in the fMRI signals has a deeper meaning. By 2010, Douglas Jarrett, who was a doctoral student at the time, showed that variation in blood oxygen fMRI signals predicted a person’s age better than the magnitude of the spike in those readings. His hunch was that standard deviation – a measure of how similar or different signals in a raw data set are – could tell stories that average height sizes simply could not tell.



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