Researchers Want to Restore ‘Good Noise’ to the Old Brain


To eavesdrop a brain, one of the best tools available to neuroscientists is the fMRI scan, which helps map blood flow, and therefore the oxygen spikes that occur when a particular region is used. in the brain. It reveals a noisy world. Blood oxygen levels vary from time to time, but those spikes never completely break down. “Your brain, even at rest, isn’t completely silent,” says Poortata Lalwani, a PhD student in cognitive neuroscience at the University of Michigan. He imagined the brain, even the most peaceful, like a tennis player waiting to return to a service: “He won’t stop. He’ll be pacing a little, preparing to hit the backhand.”

Many fMRI studies filter out that noise to detect specific spikes that researchers want to investigate. But for Lalwani, that noise is the most articulate signal of all. For him, it was a sign of mental flexibility. Young, healthy brains are more likely to have signals that there are many variations in blood oxygen levels from time to time. The elderly are less diverse, at least in some regions of the brain.

About a decade ago, scientists first showed an association between low neural signal variability and the type of cognitive decline that accompanies healthy aging, rather than being specific. dementia. Brain noise is a strong proxy for details that are more abstract, Lalwani says: “How efficient is the transfer of information, how well the neural networks are connected, in general how well the underlying neural network works. “

but Why that change that happens with age is a mystery. So is the question of whether it will return.

on published the results in November at Journal of Neuroscience, Lalwani’s team has shown that small doses of Lorazepam, an anti-anxiety drug, can reverse the decline in signal changes, at least temporarily. The medication dials messages to control the brain but makes it more dynamic, ready to respond and responds quickly. In the study, brain signals in older participants who had previously been poorly performed on cognitive tasks returned to noise levels more similar to those in younger ones.

“Ten years ago, most people thought brain renewal was a bad thing,” said Cheryl Grady, a cognitive neuroscientist at the Rotman Research Institute who studies signal changes in brain but was not included in Lalwani’s study. But now, he feels, many people are realizing the potential of this new scale. “I’m very in favor of this whole approach.”

Around 2008, the researchers began to suspect that the so -called noise of fMRI signals had a deeper meaning. In 2010, Douglas Garrett, a PhD student, demonstrated that variability in blood oxygen fMRI signals predicted a person’s age better than the size of the spikes in the readings. His hypothesis is that standard deviation — a measure of how similar or different the signals are in a raw dataset — can tell stories that are impossible to average spike sizes.



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