summary: Historically, scientific research has focused primarily on the brain’s gray matter, with the equally important white matter less well studied. However, a recent groundbreaking study used fMRI to detect significant brain activity in the white matter.
As subjects performed the task, the researchers observed an increase in BOLD signal throughout the white matter.
The findings challenge conventional ideas about brain activity and highlight the potential importance of white matter in understanding a variety of brain disorders.
Important facts:
- A Vanderbilt University team led by Dr. John Gore used fMRI to identify BOLD signals that indicate brain activity in white matter, a previously little-studied area.
- As subjects performed the task during the study, BOLD signal significantly increased in white matter throughout the brain.
- Although these white matter signals are currently not fully understood, they offer valuable insight, especially since many brain diseases, including epilepsy and multiple sclerosis, disrupt the brain’s “connectivity.” is believed to contain.
sauce: Vanderbilt University
The human brain is made up of two types of substances. Nerve cell bodies (gray matter) that process sensation, control voluntary movements, and enable speech, learning, and cognition, and axons (white matter) that connect each cell. Project onto others and the rest of the body.
Historically, scientists have ignored the white matter, which makes up half of the brain, and focused on the gray matter of the cortex, which they believe is the site of activity. Researchers at Vanderbilt University are working to change that.
For several years, Dr. John Gore, director of the Imaging Sciences Institute at Vanderbilt University, and his colleagues have been using functional magnetic resonance imaging (fMRI) to detect blood oxygenation level-dependent (BOLD) signals, or We have detected blood oxygenation level dependent (BOLD) signals. Brain activity in white matter.
In the latest paper published on October 12th, Proceedings of the National Academy of Sciencesresearchers report that when people whose brains are being scanned with fMRI perform tasks such as wiggling their fingers, BOLD signals increase in white matter throughout the brain.
“We don’t know what this means,” said Dr. Curt Schilling, lead author of the paper and research assistant professor of radiology and radiological sciences at VUMC. “All we know is that something is happening. There are really strong signals in the white matter.”
Schilling said this was important to pursue because various diseases such as epilepsy and multiple sclerosis disrupt the brain’s “connectivity.” This suggests that something is happening in the white matter.
To find out, researchers plan to continue studying changes in white matter signals previously detected in schizophrenia, Alzheimer’s disease, and other brain diseases. They also hope to elucidate the biological basis of these changes through animal studies and tissue analysis.
In gray matter, the BOLD signal reflects an increase in blood flow (and oxygen) in response to increased neuronal activity.
Presumably, axons, or the glial cells that maintain the protective myelin sheath around them, also use more oxygen when the brain is “working.” Or maybe these signals are somehow related to what’s happening in the gray matter.
But even if nothing biological is happening in the white matter, “there’s still something going on here,” Schilling says. “The signal is changing. It’s changing differently in different white matter pathways, and it’s a unique finding that it’s present in all white matter pathways.”
One reason why white matter signals have not been well studied is that they have lower energy than gray matter signals, making them difficult to distinguish from the brain’s background “noise.”
VUMC researchers have established trends by repeating visual, language, or motor tasks over and over again in people whose brains are being scanned, and by averaging the signals across many different white matter fiber pathways, they have determined the signal-to-noise ratio. increased the ratio.
“For 25 or 30 years, we’ve been ignoring the other half of our brain,” Schilling says. Some researchers have not only ignored white matter signals, but have also removed them from their reports of brain function.
Vanderbilt’s findings suggest that many fMRI studies “not only may be underestimating the true extent of brain activation…but may also be missing important information from the MRI signal. ”, the researchers concluded.
About this neuroscience research news
author: bill snyder
sauce: Vanderbilt University
contact: Bill Snyder – Vanderbilt University
image: Image credited to Neuroscience News
Original research: Closed access.
“Time-locked functional signal changes in the whole brain, gray matter, and white matter using simple tasks and model-free analysisWritten by Kurt G. Schilling et al. PNAS
abstract
Time-locked functional signal changes in the whole brain, gray matter, and white matter using simple tasks and model-free analysis
Recent studies have revealed that time-locked blood oxygenation level-dependent (BOLD) functional MRI (fMRI) signals are generated throughout the brain in response to a task, leading to the presence of sparse and localized brain function. This raises questions and highlights the potential prevalence of false negatives. fMRI findings.
“Whole brain” actually refers to the gray matter, which is the only tissue traditionally studied with fMRI. However, several reports have demonstrated reliable detection of her BOLD signal in white matter, which has so far been largely ignored.
Using a simple task and analysis, we demonstrate bold signal changes across the brain in both white and gray matter in a manner similar to previous reports of whole-brain studies.
We investigated whether white matter displays time-locked BOLD signals across multiple structural pathways in response to stimulation, in a manner similar to cortex. We show that both white and gray matter show time-locked activation throughout the brain, and that the majority of both tissue types show statistically significant signal changes in response to all task stimuli investigated. I discovered that
We observed a wide range of signal responses to the task, showing different bold signal changes in different regions for the same task. Furthermore, we found that each region can have a different bold response to different stimuli.
Overall, we found that essentially all white matter in the brain, as well as all gray matter, exhibits time-locked BOLD signal changes in response to multiple stimuli, consistent with the idea of sparse functional localization. , present convincing evidence that challenges the conventional wisdom that treats white matter as BOLD. I need to remove the signal as an artifact.
