A high density functional near-infrared spectroscopy system for mapping the neural substrates of mental and cognitive health across the lifespan

Functional Near-Infrared Spectroscopy (fNIRS) is a brain imaging technique that measures changes in the amount of oxygen in the blood supply to the brain. fNIRS works by shining weak rays of light into the head from small sources placed in a head cap. Sensors in the cap then measure the colour of the light reflected back. If the brain is busy responding to something and is using lots of oxygen, the blood will be red.

If the blood has less oxygen, it will be a more blueish colour. So, by measuring these colour changes while a person carries out an activity, watches something on a screen, or rests, we can see which parts of the brain are active.

fNIRS has several advantages over the magnetic resonance imaging (MRI) scanners you can find in hospitals and large research facilities. People taking part in fNIRS research do not have to lie still in a restricted space within a scanner. Instead, they can move around and interact with others while we measure their brain activity.

Therefore, fNIRS is ideal for doing research with participants who are uncomfortable or anxious about enclosed spaces or are not able to lie still or follow instructions. For example, we are starting to learn much about early brain development by using fNIRS with babies. At the other end of the lifespan, fNIRS can help us understand more about how the brain changes when we get older, including what healthy aging looks like in the brain and changes associated with diseases such as stroke and dementia.

fNIRS technology has improved substantially in recent years. In the early days of fNIRS, brain activation from only a single location could be measured. However, a new type of fNIRS device now makes it possible to pick up brain activation across the entire head and to determine, with high precision, which parts of the brain are active when people engage in different activities, use different skills, sleep, or simply rest.

We will use this device, which can be worn comfortably like a cap, to measure changes in the brain that happen when we think, feel and interact with others, and we will study changes in the brain that happen as part of the natural cycle of life (e.g., children growing up, people getting older) and when health problems occur (e.g., the effects on children when they experience a lack of oxygen at birth, the effect of cardiovascular problems on the brain). The use of fNIRS will allow us to understand these changes in many different groups of people (because fNIRS is easy to use and is much less restrictive than an MRI scanner) and in substantially more depth and detail than we have been able to in the past.