This week, the little one and I were back at Birkbeck Baby Lab to take part in some more experiments. I’ve volunteered us to be part of the control group for the Studying Autism and ADHD Risk in Siblings project, which aims to track the early development of baby brothers and sisters of children with autism spectrum disorders, attention deficit disorders and typical development.
Because it’s a really ambitious, long-term project investigating loads of different factors to do with communication, behaviour and emotion, the researchers have drawn together a whole range of ways to try to get an insight into babies’ brains. Before the visit, I was asked to complete a bunch of questionnaires about my son’s behaviour, preferences and sleep patterns then on the day he was kitted up with some movement and heart rate monitors and recorded playing with various toys and watching short animation sequences (who says television isn’t educational?). During one of these animation sessions, my infant scientist was kitted up with a near infra-red spectroscopy (NIRS) cap.
This was cool for three reasons. Firstly, it makes my baby look like a cute alien. Secondly, the first ever infant study using this technique was pioneered by researchers at Birkbeck, so it’s kind of like eating a pizza in Italy. Thirdly, and most importantly, it’s a very clever piece of kit that gives us new insights into what’s happening inside an infant’s brain when they’re engaging with a task – in this case processing emotional and neutral sounds and images.
There are of course lots of other, more well-known ways to measure brain activity. One approach is to measure neuronal signals directly using electroencephalography (EEG). Unfortunately EEG sensors are great at telling us when a signal occurs, but decidedly vague about where. Alternatively, since we know that when a neuron is active it uses up more oxygen and glucose, we can use positron emission tomography (PET) to track where oxygen and/or glucose is being absorbed, and deduce from that the areas that are hardest at work. Unfortunately, PET relies on the use of radioisotopes and overprotective parents like me aren’t so keen on their precious offspring being injected with radioactive substances when not strictly necessary. Alternatively, blood flow can be monitored non-invasively with functional magnetic resonance imaging (fMRI), as long as the participant is completely still whilst completing the relevant task…not something babies are so good at. This leaves us with NIRS.
Anyone who has ever shone a torch against their skin knows that flesh and blood is fairly transparent to light. It turns out that the quality of this light (i.e. the proportions of different wavelengths) varies according to the levels of oxygenation of the blood – so if we record the changes in the light signal at different points around the head, we can deduce which areas are most active. The light will only penetrate the outer layer of the brain, the cortex, but it just so happens that the cortex is involved in all kinds of different activities. So far NIRS-based techniques have been used to identify the specific areas of the infant cortex involved in observing and producing motion, language processing and emotion recognition .
The technology isn’t perfect yet – for instance researchers are still grappling with how to deal with hair, which not only reduces the grip of the headgear but can affect the way light penetrates the scull, leading to unreliable measurements. Nevertheless, if it means we can build up an image of what’s going on inside babies’ brains without immobilizing or irradiating them, then a bias towards bald baby scientists like mine may be a compromise worth making.