How brain cells communicate with each other remains largely a mystery, but a probe that records neuronal signals with unprecedented clarity and precision may help, according to a study by researchers at Massachusetts General Hospital (MGH) to unlock these secrets
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The findings, published in the journal Nature Neuroscience, could lay the foundation for a better understanding of how the brain works, the origins of neurological diseases and more
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In 2017, a Belgian digital technology company called IMEC partnered with the Howard Hughes Medical Institute (including the Janelia Research Campus) to launch the Neuropixel Probe, a tool for recording the activity of brain cells or neurons
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"Neuropixel devices have revolutionized the field of neuroscience," said neuroscientist and electrophysiologist Angelique Paulk, PhD, a researcher at MGH's Center for Neurotechnology and Neural Recovery and lead author of the study
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Early techniques for recording neuronal activity often relied on relatively large electrodes inserted into the brain
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"They can pick up the activity of thousands of brain cells at once, but that creates a blurry view," Paulk said
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She used an acoustic analogy to describe the recording quality of older equipment: Imagine you're standing in the middle of an overcrowded football field, listening to the cheers of the crowd
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In contrast, Neuropixels probes are much smaller but have a much higher resolution
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"Instead, it's like you're able to record hundreds of separate sounds, each with its own microphone
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However, the original neuropixel probe was designed as a research tool for use in small laboratory animals such as rodents
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Neuroscientists were immediately interested in a tool that could be used to study the human brain, one that required some modifications
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For example, the original neuropixel detector was too fragile to be used in a large human brain, so it had to be made thicker
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However, Paulk said, the probe is only three hairs wide
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The goal of this report in Nature Neuroscience is to develop a technique that uses modified neuropixel probes to record brain activity in human patients undergoing neurosurgery in the operating room
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Nine patients already scheduled to undergo neurosurgery for several different diseases agreed to allow MGH neurosurgeons to record their brain activity during the procedure
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The team, which includes epilepsy specialist Sydney Cash, MD, and neurosurgeon Ziv Williams, MD, both members of the MGH, encountered challenges using the Neuropixels probe in humans after six unsuccessful attempts to record brain activity
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However, they managed to record brain activity in three patients, one of whom was being treated for epilepsy and two who received implants that provide deep brain stimulation to treat movement disorders
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In one of the patients, the team recorded the activity of 202 individual neurons
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Why is recording the behavior of individual neurons important? "Thanks to new high-resolution tools, we found that different types of cells are doing very interesting things," Paulk said
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For example, excitatory neurons produce signals, while inhibitory neurons slow or stop the signal
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Small probes can already record the activity of one or two neurons, "but that means you're not really capturing the diversity of cell types, being able to sample 200 cells at once and tell us how those cells communicate with each other
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It's this particular interaction that keeps our brain circuits working
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Decoding the communication between neurons with neuropixel detectors and other tools could lead to new discoveries about neurological diseases such as epilepsy and how tumor cells invade neighboring cells in the brain, Paulk said, as well as helping to develop tools for people with disabilities to use Their brains operate computers and robotic devices, allowing them to live more independently
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Ultimately, this new technology could provide valuable insights into the nature of cognition, such as how we form thoughts and perceive the world around us
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article title
Large-scale neural recordings with single neuron resolution using Neuropixels probes in human cortex
