Infants, also known as tiny humans, have bodies and medical issues that can differ greatly from their fully-grown counterparts. Perhaps most glaringly, infant brains tend to be far more difficult to understand than adult brains, mostly because infants can't communicate as well as adults. We can’t ask babies what they think or feel, so we rely on behavioral clues and scans that show the neurological workings of their brains. Despite these difficulties, we’ve discovered some pretty important things about the brains of our tiniest members of society in the last few years.

Infants Feel Pain “Like Adults”…

It may seem like a ridiculous assumption today, but prior to 1987, many medical professionals believed babies didn’t feel pain. After a groundbreaking experiment that year, clinical practices changed to allow for pain relief drugs to be given to infants (something doctor’s previously didn't do). Still unclear, though, was how infants processed pain.

In 2015, a team led by Dr. Rebeccah Slater, of Oxford University’s Department of Pediatrics, decided to use functional magnetic resonance imaging (fMRI) scans to compare brain activity levels in infants and adults when presented with a pain stimulus. Previous studies had already used fMRI to help researchers understand pain, but this experiment was the first to use the technology on babies.

The brain scans revealed 18 of the 20 pain regions that were active in adult brains were similarly active in the infants. Additionally, the babies’ brains responded to a weak pin prick with the same intensity as adults who experienced a prick four times as strong. This led the team to believe that not only do infants feel pain like adults, but that they also have a lower threshold for pain.

…But A Mother’s Love Can Ease Pain, Impact Brain Development

Though little ones may have a lower pain threshold than adults, it seems a little TLC from mom can soothe this pain. A team of researchers from New York University found that in rat infants, several hundred genes became active when they experienced pain. With their mothers present, though, fewer than 100 genes were similarly expressed.

According to senior study investigator and neurologist Dr. Regina Sullivan, the research is the first to show the short-term effects of maternal care on an infant’s brain while they’re in pain. But the study also demonstrated some long-term consequences of a mother’s nurture.

“Our study shows that a mother comforting her infant in pain does not just elicit a behavioral response, but also the comforting itself modifies — for better or worse — critical neural circuitry during early brain development,” Sullivan said in a statement.

She explained that the more researchers learn about the infant brain and pain, the more equipped we are to deal with related problems.

Arguing In Front Of Baby

Every parent knows raising a child and managing their own life at the same time can be super stressful. It’s important not to let this stress explode in front of a child, however, since research has shown exposure to angry voices may have a significant impact on an infant’s brain development.

It might be tempting to think babies aren’t privy to what we’re talking about, but they are capable of differentiating between vocal tones. Babies’ brains are highly malleable — they can learn about and respond quickly to new environments and situations. This is a good thing in many cases, but exposure to stresses like abuse, mistreatment, and anger can significantly affect their brain development. Using fMRI brain imaging, a team from the University of Oregon exposed 20 infants to nonsense sentences in a range of emotional tones including very angry, slightly upset, neutral, and happy. They discovered that “even during sleep, infants showed distinct patterns of brain activity depending on the emotional tone of voice we presented.

The babies’ parents then filled out questionnaires about the level of conflict in their homes and the researchers compared their answers to brain imaging results from the infants. They found babies from high-conflict homes had stronger reactivity to very angry tones in brain areas like the thalamus, hypothalamus, and cingulate cortex, all of which are associated with stress and emotional regulation.

The researchers said follow-up studies would be necessary to judge the specific long-term impact of high-conflict homes on the development of infant brains.

Newborns Recognize Expressions Earlier Than We Thought

Using a 15-year-old idea, researchers from the Institute of Psychology and the University of Uppsala and Eclipse Optics in Stockholm, Sweden, developed an experiment that yielded some important results about newborn vision. Using previous research about infants’ contrast sensitivity and spatial resolution, the team matched these stats to animations of human faces, and essentially demonstrated what a newborn sees.

Adult participants were then asked to identify the emotional expressions on these faces at different distances. Based on these answers, the researchers concluded newborns can see the difference between emotions, but only from the short distance between a mother’s face and her baby while she nurses. This is possible at merely 2 to 3 days old.

Actually, Their Vision As A Whole Is More Advanced Than We Thought

It’s been a struggle to map how infants’ visual functions mature since there haven’t been any functional imaging tests conducted on very young infants while they’re awake and engaged. A September 2015 study provided the first direct window into infant vision maturation, and revealed that the visual brain of a 7-week-old baby is surprisingly mature.

The study, which utilized fMRI to examine the brains of infants while they were both awake and asleep, provided the first maps of visual cortical function in young infants. These maps demonstrated how neural plasticity works early in life, with associative regions of the cortex (responsible for motion processing) responding similarly in infants and adults. The experiments were designed to overcome previous challenges of recording infant responses to visual stimuli, including their tendency to not cooperate and observe the mandated stimuli.

“To encourage infants to watch the visual stimulus, we made the stimulus very salient for that age, and reassured them by keeping them in the arms of the experimenter during the scan,” explained Maria Concetta Morone, of the IRCCS Stella Maris Foundation and the University of Pisa, in a press release. “They happily looked at the stimuli for long enough to yield reliable data acquisition.”

Overall, the experiments showed that the major areas processing motion in adults are already operative by 7 weeks of age. They also showed infants are able to sense their own body positions. These discoveries could have important clinical implications, like guiding clinicians to “select appropriate rehabilitation strategies in appropriate time windows” when dealing with neurodevelopmental disorders that impair vision.

Babies And Scientists: Not So Different When It Comes To Learning

Surprises may be able to make a baby laugh (think peek-a-boo), but a recent study out of Johns Hopkins suggests surprises could play an important role in brain development and learning experiences in infants. According to the researchers, the element of surprise can help engage babies to learn more efficiently, acting as a trigger for intrigue in the infant’s mind.

The study involved a series of four experiments with both predictable and surprising situations pertaining to an object. For example, one experiment presented infants with a ball rolling down a ramp, only to reroute it with a wall unseen by the infants, which made it appear as if the ball had magically changed direction. The infants exposed to surprising events like this were able to learn more efficiently afterward compared to babies who saw only predictable events.

“Babies are always taking things in, learning, and observing the world,” the study’s lead author Dr. Aimee Stahl told Medical Daily in April 2015. “Once they saw something that surprised them, their engagement with the object peaked and their learning behavior improved significantly. But we’re not overturning their knowledge by showing them unexpected events.”

Infants may still present us with baffling behavior now and then, but the inner workings of their (tiny) heads are coming into focus. technological advancements have eased the study of sometimes uncooperative babies, and future research building on these breakthroughs is sure to shed even more light on the processes, development, and capabilities of babies' brains.