Study reports BOLD signals from white matter in the spinal cord
Researchers have reported reproducible signals from white matter in the spinal cord, which could lead to targeted delivery of treatments for spinal cord injuries.
In a recent study, a team of researchers from Vanderbilt University Institute of Imaging Science (VUIIS; TN, USA), has used functional magnetic resonance imaging (fMRI) to detect of blood oxygenated-level dependent (BOLD) signals in white matter of the spinal cord for the first time. This provides evidence that white matter yields similar hemodynamic responses to grey matter in the spinal cord.
Insights into gray matter, responsible for processing sensation and controlling voluntary movement, and white matter, responsible for sending and receiving signals to the rest of the body, can provide further understanding and development of treatments for the conditions that impact the central nervous system such as spinal cord injury. A key goal in this area of research is establishing how to stimulate nerve regrowth and healing.
The function of white matter, compared to the extensively researched gray matter, remains less understood and underexplored, potentially leaving critical aspects of neural communication and brain health insufficiently addressed. To address this gap in our understanding of the central nervous system, the VUIIS team has been exploring the function and characteristics of white matter for the past few years using fMRI to monitor BOLD signals for activity in the nervous system.
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In a previous study, the team utilized fMRI to scan the brains of individuals performing a task to analyze their brain activity. Interestingly, they observed that BOLD signals increased in the white matter throughout the brain in a similar fashion to grey matter but did not know what the meaning behind it was. They knew that in gray matter, BOLD signals signify an increase in blood flow in response to an increase in nerve cell activity but what did the detected BOLD activity reflect in white matter? Determined, they continued their research to explore the reasons for the changes in white matter signals.
A year later on, the team has now reported their findings having observed BOLD signals at rest and after vibrotactile stimuli on the fingers of squirrel monkeys. Upon observation, they found that when the monkeys responded to the stimulation, the white matter activity was higher in the tracts of ascending fibers that carry the signal from the spine to the brain.
Anirban Sengupta, the corresponding author of the paper, commented on the detection of the BOLD signals from the white matter in the spinal cord stating that, “[it] may be due to the larger volume of white matter in the spinal cord compared to the brain.” He also suggested that the detection of these BOLD signals from white matter may emphasize the crucial role that white matter plays in supporting gray matter.
This finding is significant as it demonstrates that the signals from white matter in the spinal cord can be detected as effectively as those from gray matter. Although there is little knowledge of white matter’s function in the spinal cord, the team’s ability to report these findings may shift the narrative on the study of white matter and its effect on neurodegenerative diseases, such as multiple sclerosis, which involves damage to white matter.
“We will be able to see how activity in the white matter changes in different stages of the disease,” said Sengupta.
The scientists’ findings, could pave a way for researchers to assess the effectiveness of therapeutic modalities, such as electromagnetic stimuli or drugs, in encouraging spinal cord injury recovery.
