Children in the Lab

A roar fills the spaceship. Landscapes and places pass before Neo’s eyes. The voice of the ground station sounds intermittently through the speakers.

This isn’t a scene from a science fiction movie. The action takes place right here on Earth at the Max Planck Institute for Human Development in Berlin. Neo is a participant in a neuroscientific study on Memory – and he’s only six years old. The experiment is tailored to young volunteers like him and is therefore packaged as a story: The children are astronauts, the MRI scanner is a spaceship, and the lab is the ground station.

Whether researchers want to study brain development in basic research or the effects of treatments in clinical trials, children and babies are highly sought-after participants in neuroscience (see info box). But brain research involving minors is anything but child’s play. Even though children’s games are exactly what researchers often offer their young subjects to keep them entertained during the experiments.

An hour and a half beforehand: Researchers at the Max Planck Institute in Berlin are carefully preparing Neo for the scans in the Magnetic resonance imaging (MRI) machine. Among other things, functional measurements are to be taken. Even small movements of the head or neck can compromise the quality of the fMRI images. Using the stuffed animal Oskar, a research assistant explains to Neo why it’s so important to stay still. “It’s like taking a regular photo of you,” she says. “Here, he moved.” Oskar appears blurry in an image on the computer monitor.

Lying still in a scanner is no easy task for the young participants; after all, depending on the examination, the scans can take up to an hour. The fact that MRI is so sensitive to movement is also why brain scans of babies and toddlers are rarely performed in basic research. There are only two options: sedating the little ones, which is ethically questionable – or hoping that the sandman comes on his own. Psychologist Alice Graham and her colleagues at the University of Oregon did the latter in a study published in 2013. They found that even babies’ brains register the emotional tone of voices – even when the little ones are blissfully slumbering in the scanner, as in the study.

Of course, many things cannot be studied this way, such as how the brain reacts to visual stimuli. That is why researchers rely on other methods, especially when working with babies and toddlers. With electroencephalography (EEG) using electrodes on the scalp, a child can sit comfortably on their mother’s lap and view stimuli presented on a screen. However, this method offers poor spatial resolution and measures only processes on the brain’s surface.

Consequently, neuroscientists are increasingly using near-infrared spectroscopy (NIRS) to send long-wavelength infrared light through a child’s skull. The reflected light allows them to estimate neural activity. Compared to EEG, NIRS allows for a deeper look into the brain, and the young subjects can move freely during the measurements without interfering with the signal. But even NIRS cannot penetrate deeper regions of the brain such as the Hippocampus and the Amygdala. That is reserved for MRI.

In Berlin, researchers are now familiarizing Neo with the MRI scanner. Some participants find it distressing to be confined in the narrow tube; some even have claustrophobia or experience a panic attack. Others are bothered by the noise – the loud knocking sounds of the scanner. At the Max Planck Institute, staff therefore ask parents in advance whether their child shows signs of agoraphobia or claustrophobia. If so, the children cannot participate in the study. To psychologically prepare the children for the scanner, the researchers use an MRI simulator that looks strikingly similar to the real device. “And just in case, there’s also an emergency button,” says Attila Keresztes, a cognitive neuroscientist and one of the researchers involved in the study. “The children can press this button if they feel uncomfortable. Then the test is paused.”

In the scientific literature, it has so far been debated whether MRI scans are more stressful for children than for adults. For this reason, researchers led by psychologist Charlotte Jaite from Charité in Berlin have just conducted a corresponding study. The scientists examined whether and to what extent MRI examinations trigger negative Emotions in children and adolescents. According to Section 41, Paragraph 2 of the German Medicines Act, which regulates, among other things, the testing of drugs, research must not impose more than “minimal stress” on minors. Jaite’s team therefore compared the effects of MRI scans with those of EEG examinations. After all, the latter are currently considered “minimal burden.” “Based on our observations to date during data collection, pediatric and adolescent patients do not appear to exhibit higher anxiety levels before and during an MRI scan than children and adolescents undergoing EEG examinations.” The researchers wrote this in 2013 in a summary of their study design.

After Neo has spent some time getting used to the simulator, it’s now time for the real scanner. “Hello Captain Neo, this is ground control,” comes the voice from the speaker. “Are we launching your rocket now?” “Yes,” replies the brave astronaut. In keeping with the astronaut story, he is supposed to press a button every time he spots an alien in the images showing him various landscapes and locations. Sometimes the scenes repeat themselves; other times, they are only very similar. “The study focuses on how so-called pattern separation in the brain develops over the course of a lifetime,” explains Attila Keresztes. “This function of Memory allows us to store two very similar experiences differently.” The Berlin researchers suspect that a subregion of the seahorse-shaped Hippocampus plays an important role in such interwoven memories.

To draw out the secrets from Neo’s head, he is now surrounded by a strong magnetic field and radio waves inside the scanner. Unlike computed tomography, for example, MRI does not produce ionizing X-rays. “Physically speaking, the MRI scan has no harmful effects,” says Attila Keresztes. Studies confirm this. Three decades of MRI use in humans have shown no acute effects or long-term biological consequences. This was reported by researchers led by biostatistician Mekibib Altaye of the University of Cincinnati College of Medicine in a study from 2014. Most regulatory bodies therefore classify MRI scans as posing a minimal risk. In their own long-term study, the researchers also found no statistically significant evidence that the mental or physical development of child participants had suffered over a ten-year period due to annual MRI scans. However, this was only a small study with few participants, and the researchers used only weight, height, and body mass index as physical markers.

Either way, ethical concerns remain. “Studies involving minors present a tricky moral problem,” says philosopher Bert Heinrichs of the Institute for Science and Ethics at the University of Bonn. “Clinical trials are primarily about scientific findings and, at most, secondarily about benefits for the participants.” This applies all the more to basic research. “With adults, this is generally not a problem; they can give their consent and they know what they’re getting into.” But depending on their age, children are either not capable of giving consent at all or only to a limited extent. “On the other hand, without any research on minors, we wouldn’t have medications tailored for children,” says Heinrichs.

In Germany, there is no specific law regulating research on humans. There are only the Medicines Act and the Medical Devices Act, each of which regulates specific aspects. “Otherwise, we have general laws such as the Civil Code,” adds Heinrichs. This stipulates that parents are obligated to act in the best interests of the child when making decisions that affect the child. “In my view, therefore, both the risk and the burden must not exceed a minimal level.” Yet the problem remains: which examinations meet these criteria?

Neo seems to have survived his long wait in his spaceship unscathed. “Good,” he replies somewhat shyly when asked how it went. And then he breaks into a broad smile, a typical child’s smile.

Further reading

• Holland, S.K. et al.: Data on the safety of repeated MRI in healthy children. Neuroimage Clin. 2014 Feb 9;4:526–3, (abstract).

Originally published on March 18, 2016
Last updated on March 18, 2026