In recent years, there have been major advances in brain imaging technologies, permitting neuroscientists to explore and examine our brain in more detail than ever before.
So far, however, these technologies remained in laboratory settings, with controlled experiments designed to study specific functions.
Researchers at Kernel, a US-based neurotech company, hope to change that by taking brain imaging out of the lab and into everyday life.
Kernel Flow is based on the time-domain functional near-infrared spectroscopy (TD-fNIRS) of brain imaging technique.
fNIRS uses light in the near-infrared spectrum to determine the changes in light absorption by haemoglobin in the blood circulating in the brain.
These changes can shed light on brain function as the concentration of haemoglobin changes in the functional areas of the brain because they need oxygen to power this activity.
Although TDfNIRS isn’t a new technique, previous systems suffered from low channel numbers and slow sampling frequency, which limited their usefulness in neuroimaging field.
Kernel researchers designed an adjustable head-set consisting of 52 modules arranged in 4 plates on every side of the head to cover the entire brain surface.
Each module consists of a laser source surrounded by 6 hexagonally arranged photodiode detectors capable of detecting more than a billion photons per second.
Two lasers in the source emit light at various wavelengths (690 and 850 nm) that is directed through the surface of the scalp to the brain.
The scattered and reflected light is then collected by detectors placed 10mm from the laser source.
The arrival times of the detected photons are recorded in histograms with a sampling rate of 200 Hz, with a total system sampling frequency of 7.1 Hz.
The team tested the system with an optical phantom: a tank filled with a mixture of water, ink & emulsion with known optical properties and a small black PVC target placed at different depths to mimic brain activity.
This is a standard tool to characterize the capabilities of a TDfNIRS system. Kernel Flow showed comparable performance to larger desktops, maintaining or improving performance while remaining smaller and light enough to wear.
Ultimately, the team tested Kernel Flow on human volunteers. Two participants took part in a neuroscientific test of the system, using left and right fingers to tap in blocks with rest periods.
The channels on the participants’ motor cortices showed significant haemodynamic changes, during finger-tapping tasks.
Additionally, a channel on the fore-head of one among the participants could detect the oscillation of their heartbeat, a capability unique to this TDfNIRS system and is enable by its high sampling rate.
These promising results have led to some follow-up studies on the application of kernel flow system, which includes one exploring using the system to measure the effects of a psychedelic drug.
However, the researchers recognize the limitations of fNIRS and are evaluating the performance of their system on different hair and skin types, which may affect the effectiveness of optical brain imaging tools.
While Kernel Flow is not (yet) as commercially viable as its smart watch device, its introduction and promise of commercial systems available by 2024 suggests that measurements of brain function will soon be as accessible as those currently used to measure heart rate or tracking your sleep.