Study in Rats Provides Clues to Nerve Cell Connectivity and Body Movement Control

A study in rats has provided new clues as to how the brain works to control body movements, which may have implications for disorders such as Rett syndrome.

The study, “Strong neuron-to-body coupling implies weak neuron-to-neuron coupling in motor cortex,” was published in the journal Nature Communications.

The brain controls every movement and function of the human body, but to do so, it has to coordinate the interactions between large networks of nerve cells. Until now, it was unclear if these interactions resulted from a coordinated collective work or if it resulted from asynchronous dynamics.

To further explore the brain-body connection, University of Arkansas researchers implanted sensors in the brains of rats to record nerve cell activity while at the same time using highly-sensitive recording cameras to measure movement.

The team identified patterns of neuronal activity that could be specifically connected with body movement control.

They found that nerve cells could be classified as being “externally focused” or “internally focused” based on their ability to communicate with and control different parts of the body, or just communicate with each other.

Using different chemical agents that could modulate nerve cell communication, the team found that inhibiting all nerve cells (systemically) would lead to a reduction of rats’ voluntary movements. In contrast, specifically inhibiting nerve cells in the motor cortex of the brain led to an increased activity of internally focused signals.

“Alterations in inhibitory signaling are implicated in numerous brain disorders,” Woodrow Shew, associate professor of physics and senior author of the study, said in a press release. “When we increased inhibition in the motor cortex, those neurons responsible for controlling the body become more internally oriented. This means that the signals that are sent to the muscles from the motor cortex might be corrupted by the ‘messy’ internal signals that are normally not present.”

Understanding how the signals that are sent to the muscles from the motor cortex can be corrupted and result in abnormal motor function could be key to better identify what occurs in numerous human neurological diseases.

Researchers are now planning to further explore how this particular division of labor of nerve cells plays a role in Rett syndrome.