Neuroscientists have utilized a tiny sensor to monitor spinal cord neurons in freely moving mice, a breakthrough that may lead to the advancement of treatments for spinal cord disease and injury.
Implantable technologies have greatly enhanced our ability to study and potentially influence the behavior of neurons in the brain. However, observing neurons in the spinal cord while they are active is more challenging.
“Understanding how spinal cord neurons process sensations and control movement could pave the way for improved treatments for spinal cord diseases and injuries,” expressed Yu Wu, a research scientist from Rice University’s team of neuroengineers addressing this issue.
“We have created a small sensor, called spinalNET, capable of recording the electrical activity of spinal neurons while the subject engages in normal, unrestrained activities,” explained Wu, the lead author of a study about the sensor published in Cell Reports. “Being able to gather this information is an initial but crucial step in finding cures for the millions suffering from spinal cord ailments.”
According to the study, the sensor could notably record neuronal activity in the spinal cord of freely moving mice for extended periods and with high precision, even following the same neuron over multiple days.
“Historically, the spinal cord has been somewhat of a mystery,” noted Lan Luan, an associate professor of electrical and computer engineering and a co-author of the study. “The challenge lies in the fact that the spinal cord moves significantly during regular activities. Every time you move your head or bend over, spinal neurons also move.”
During such movements, rigid sensors implanted in the spinal cord may disrupt or damage the delicate tissue. In contrast, SpinalNET is more than a hundred times smaller than a hair’s width, making it extremely soft and flexible, almost as gentle as neural tissue itself.
“This flexibility provides the necessary stability and biocompatibility to safely record spinal neurons during spinal cord movements,” explained Chong Xie, an associate professor of electrical and computer engineering and bioengineering and a co-author of the study. “With spinalNET, we obtained clear signals from hundreds of neurons.”
The spinal cord plays a crucial role in controlling movement and other essential functions. The ability to record spinal neurons with precise spatial and temporal resolution during unrestricted motion offers insights into the mechanisms that enable this. Using spinalNET, researchers identified that spinal neurons in the central pattern generator, a neuronal circuit capable of generating rhythmic motor patterns like walking without specific timing information, appeared to be associated with much more than just rhythmic movements.
“Some are closely tied to leg movement, while surprisingly, many neurons show no obvious connection to movement,” Wu remarked. “This indicates that the spinal circuit governing rhythmic movements is more complex than initially assumed.”
The researchers aim to delve deeper into this complexity in future studies and address questions such as the distinctions in how spinal neurons process reflex movements, such as being startled, compared to intentional actions.
“Aside from the scientific insights, we believe that as the technology advances, it holds significant potential as a medical device for individuals with spinal cord neurological disorders and injuries,” said Luan.
The study received support from the National Institutes of Health (R01NS102917, U01NS115588, U01NS131086, R01NS109361, R01NS123160, R01NS108034, U19NS112959), Rice University, the Salk Institute, and the Mary K. Chapman Foundation. The authors bear sole responsibility for the content of this press release, which may not necessarily reflect the views of the funding agencies.
