Any parent who’s tried to coax a squirming, screaming baby into a diaper—or watched their beloved child fidget free from a supposedly secure swaddle—would swear that every move was designed to frustrate them. A battle of wills the baby wins again and again.
But those wriggly infants are just as innocent as they look. It takes babies months to figure out how to control their bodies: most early movements are involuntary or reflexive. And even the ones they mean to make are jerky—often as bewildering to the infant as their parents.
In Sargent’s Development, Experience, and Motor Recovery Lab, neuroscientist Claudio L. Ferre studies how babies—especially those with, or at risk of, cerebral palsy—learn to fine-tune their motor skills.
He recently started a National Institute of Neurological Disorders and Stroke–funded project that uses a portable optical imaging technology to watch what happens in the infant brain as it begins to exert greater control over motion. With functional near-infrared spectroscopy (fNIRS), which beams noninvasive light into the head, Ferre is monitoring which brain areas are working hardest—or not working as expected—as babies try to turn reflexive jiggles into determined grasps.
“The idea is to prospectively track infants at high risk for developing cerebral palsy and see what’s different about their movements, their ability to experience sensation of movement,” says Ferre, an assistant professor of occupational therapy. “One of the unique things about this project is that we want to understand that in terms of brain development.”
Ferre’s goal is to better understand how we learn to govern our bodies—the development of the circuits that connect brain and limbs—and use that information to help improve therapies and outcomes for children with motor disorders.
Mapping Brain Activity
Around one in 345 children in the United States has cerebral palsy, according to the Centers for Disease Control and Prevention. A group of motor disorders often caused by a brain injury before, during, or soon after birth—and more common in preterm babies—cerebral palsy can leave people with stiff muscles, poor coordination, or uncontrollable spasms. There’s no cure, but early interventions have been shown to help.
“Cerebral palsy brain injury happens very early on in development, which means the brain has a lot of time to reorganize,” says Ferre, who recently published a paper in Neurorehabilitation & Neural Repair on how different types of newborn brain injury impact hand function. Cerebral palsy can be congenital or caused by injury, infection, or decreased blood or oxygen flow. “It’s very different from an adult stroke, for example, where usually a very singular focal area is affected. The changes we see in the brain in children with cerebral palsy tend to be more widespread, which also means there’s a lot of variability.”
“There’s actually a lot we don’t know about the integration of motor and sensory development in typically developing infants.” —Claudio L. Ferre
For the latest project, Ferre is using an fNIRS machine to examine brain activity as infants move their hands and arms. The infants in the study wear a small cap covered in optodes—optical sensors—that transmit and receive infrared light, which travels about 5 to 10 millimeters underneath the cranium. By tracking how much of the light gets absorbed and how much bounces back, he can see which parts of the brain are drawing the most oxygen to power activity and which aren’t.
“The light penetrates, just diffuses through the scalp and skull into the brain and is absorbed by hemoglobin,” says David Boas, a BU professor of biomedical engineering and fNIRS pioneer who’s working with Ferre. “When there’s brain activity, it modulates hemoglobin concentration and we can get maps of brain activity.”
Because fNIRS doesn’t require subjects to lie motionless, they can be monitored while performing routine activities; the babies in Ferre’s project lie on a play mat or sit in their caregiver’s lap.
It’s a technology Boas is using with other Sargent researchers, too, charting the brain during stroke recovery and Parkinson’s treatment. He’s also collaborating with Swathi Kiran, associate dean for research, and Terry Ellis, chair of physical therapy and athletic training, to develop new, even more portable fNIRS tech. Existing versions still require subjects to be tethered to a machine—albeit using very long cables—but they’re working on an all-in-one wearable system that Boas says will “enable neuroimaging in the everyday world.”
Matching Movement to Thought
Ferre begins a typical fNIRS session measuring five minutes of spontaneous movements in the infants, some considered at risk for cerebral palsy, some not, and all aged between two and six months.
“They’re not reaching for objects yet, they’re not doing a whole lot with their limbs—it’s not what we would consider skilled motor behavior,” he says. “What they’re doing is kind of fidgeting around and so we’re going to be using some wearable sensors on the wrists and just below the shoulder that essentially track those movements and observing that in relation to brain activity using fNIRS.”
He’s also developed novel devices—including one built in collaboration with a BU College of Engineering student, Manuel Sobol (ENG’22)—to stimulate the infants’ hands and control their twitches and sensations. He says matching actions to brain activity is particularly helpful in infants with a brain injury.
“Usually when there is a neural injury, parts of the brain that would have controlled movement are no longer active or they become less active,” says Ferre, who also has a background in psychology and kinesiology and teaches a class on functional movement. Watching as unaffected brain areas start taking over will help him see how the brain reorganizes after an injury.
After a year, Ferre will reconnect with the at-risk children to confirm any cerebral palsy diagnoses and review their activity again. He hopes the study will not only uncover the relationship between motor and sensory development in children with a disorder, but in the general population too.
“There’s actually a lot we don’t know about the integration of motor and sensory development in typically developing infants,” says Ferre. The current theory is that early uncontrolled squirming and reflexive waving teaches the brain how movement works, providing the foundation for more deliberate and precise limb control. “Early in development, spontaneous movements are generated by subcortical and spinal pathways. But every time these movements occur, they provide an opportunity for the infant to learn about how their limbs move through space.”
Despite the study’s potential, there’s one thing Ferre and Boas won’t be able to help the families in their research with: just how you get a waving, kicking infant into that diaper.