Music is a powerful force and a universal language. Whether it’s classical Mozart or hip-hop, when people hear music we often have an instinctual urge to move our bodies.
"The connection between [the] brain and music has been known for a long time. And even a baby, if you play some music, they will respond with movement. So we know there is a music movement connection," explains Dr. Kajana Satkunendrarajah, associate professor of neurosurgery and a member of the Medical College of Wisconsin's Neuroscience Research Center. "But what we haven't known for a long time is how is this music transformed to movement? That's really the focus of the research in our lab."
Satkunendrarajah recently discovered that certain neurons in the primary sensory cortex of our brain, which play a crucial role in initiating movement, also respond to music. This monumental finding led to a national grant to examine how music can help these neurons “dance," which could potentially help play a role in helping patients recover and restore basic body movements after spinal cord injury.
"What we discovered in 2020 and published was that the sensory cortex, contrary to what's taught in the textbooks, that this region has all the information about our auditory, visual, and our somatosensory information, can actually affect movement — that is cause movement," says Satkunendrarajah. These discoveries were cemented through the team's study of mice.
The team's rodent experiments permit the creatures to move about naturally with no external interference or motivation. The mice move about, eat, walk and groom themselves freely while their neurons are closely observed by the team.
"And that's how we discovered that there are neurons that fire just prior to [when] the animal decides to move and then continue to fire. So, they're not just preparing for movement, but they're also part of the execution as they're continuing to be active even after the movement," Satkunendrarajah explains. "And these same neurons will be completely quiet when the animal is doing something else. So, we know that it's specifically involved in initiating movement."
Finding these "dance neurons" demonstrated that this area of the brain can integrate auditory, visual and sensory information to impact our ability to walk. "Which is an important finding for human beings, as we know that many neurological conditions can negatively impact our ability to walk," Satkunendrarajah adds.
What this suggests is that as long as the neurological pathways from the sensory cortex of the brain to the spine are still intact, medical professionals would have the opportunity to restore partial or even full walking movement to a patient following a spinal cord injury by harnessing music in therapies. For Satkunendrarajah, it's all part of a rewarding endeavor.
"I think discovery is really important because we can't just test treatments, we need to further understand these pathways and see how we can manipulate [them]," she says.
Satkunendrarajah's initial discovery demonstrated that the cellular and circuit level response to music is present in both humans and animals. As her research progresses, the team will continue recording from patients who are undergoing other surgeries to see if this similar pathway related to movement exists and if stimulating this pathway can initiate movement as it did in the rodents.
"I feel really excited [about the] prospects of translating this to restore walking in spinal cord injury patients," says Satkunendrarajah. "I'm really fortunate to be part of a neurosurgical department at the Medical College, which means that I'm in contact with other physicians and surgeons... So I'm motivated to get them involved, to be able to really understand my research so that we can form these partnerships where we're taking basic science to bedside by translating some of these findings in clinical research and then, ultimately, to treatments."
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