spinalNET sensor records electrical activity of spinal neurons

Detailed in Cell Reports, spinalNET will help expand knowledge of how neurons in the spinal cord process sensation and control movement, an advance that could lead to better treatments for spinal cord disease and injury.

In a statement, Yu Wu, a research scientist who is part of a team of Rice University neuroengineers, said: “Being able to extract such knowledge is a first but important step to develop cures for millions of people suffering from spinal cord diseases.”

According to the study, the sensor was used to record neuronal activity in the spinal cord of freely moving mice for prolonged periods and with great resolution, even tracking the same neuron over multiple days.

“Up until now, the spinal cord has been more or less a black box,” said Lan Luan, an associate professor of electrical and computer engineering and a corresponding author on the study. “The issue is that the spinal cord moves so much during normal activity. Every time you turn your head or bend over, spinal neurons are also moving.”

During such movements, rigid sensors implanted in the spinal cord disturb or even damage tissue. SpinalNET, however, is over a hundred times smaller than the width of a hair, making it extremely soft and flexible.

“This flexibility gives it the stability and biocompatibility we need to safely record spinal neurons during spinal cord movements,” said Chong Xie, an associate professor of electrical and computer engineering and bioengineering and a corresponding author of the study. “With spinalNET, we were able to get low-noise signals from hundreds of neurons.”

The ability to record spinal neurons with fine-grained spatial and temporal resolution during unrestrained motion offers a window into the mechanisms that make this possible. Using spinalNET, researchers were able to determine that the spinal neurons in the central pattern generator - the neuronal circuit that can produce rhythmic motor patterns such as walking in the absence of specific timing information - seem to be involved with a lot more than rhythmic movement.

“Some of them are strongly correlated with leg movement, but surprisingly, a lot of neurons have no obvious correlation with movement,” said Wu, lead author of the paper. “This indicates that the spinal circuit controlling rhythmic movement is more complicated than we thought.”

The researchers said they hope to help unravel some of this complexity in future research, tackling questions such as the difference between how spinal neurons process reflex motion versus volitional action.

“In addition to scientific insight, we believe that as the technology evolves, it has great potential as a medical device for people with spinal cord neurological disorders and injury,” said Luan.