Brain research is often conducted in whitewashed clinical laboratory spaces, where human and animal brain activity is measured via sensors and wired connections. Yao-Hong Liu, imec scientific director at the Holst Center, is working with his Intranet of Neurons project on an efficient wireless method for researching the brain in a more natural environment and thus disease detection. “We ultimately want to help stroke patients regain control of their limbs.”
In a laboratory environment, animals’ brain activity can be accurately measured via neural sensors and wired connections. However, the brain-implanted interfaces are connected to the computer with wires, which is inconvenient, moreover, it is unpleasant for humans and animals. After all, freedom of movement is severely restricted. This is while there is a great need in neuroscience to measure the brain activity of humans and animals in normal situations on an objective scale, for scientific purposes, to detect diseases in the brain and even eventually to stimulate brain regions to treat disorders.
Yao-Hong Liu of imec at the Holst Center received €2 million from the European Research Council (ERC) in 2020 for his Intraneuronal Network (IoN). The goal of the project is to advance neuroscience by enabling efficient wireless transmission of neurosensory information at a high data rate. The device can be compared to a cochlear implant: a hearing prosthesis implanted in the inner ear. “It’s a very small device that is placed in the brain and can send signals,” says Liu. “We are busy developing the prototype.”
From hundreds to thousands
One of the great advantages of the Liu device is the large number of neurons that can be measured, which allows for more extensive research into the brain. Since the 1960s, neuroscientists have worked hard on techniques for measuring brain activity. Since then, the number of neurons we can record with a wired connection has doubled every six years. Up to one million neurons can be measured in this way. However, currently available wireless brain-computer interfaces can only record fewer than a hundred neurons. To make it widely applicable, and eventually even to restore movements and thus help paralyzed patients, a solution is needed that can record more than ten thousand neurons simultaneously.
“With the new device, it is possible to capture data on more than 100 times the number of neurons compared to current technologies. In addition, we can collect information from neurons spread across multiple regions of the human brain. This gives us a better picture of how patients are doing,” says Liu. .
Measuring brain activity via the new connection has more advantages. Currently available wireless interfaces are large units implemented, with a risk of accidents and surgical complications. “With the wireless implant, only a small hole needs to be made in the skull, rather than having to open it completely. This greatly reduces the risk of infection.”
Before wireless device can be applied to people, there are still hurdles to overcome. One of the biggest challenges with the project, Liu says, is working together in multidisciplinary teams. “I am focusing on the wireless communication of the instrument, but another team at imec is working on the encapsulation, and another team is working on decoding the data. It is an interesting challenge coordinating the collaboration between all these groups of experts.”
There is also room for improvement in technology. How do we make sure that the machine does not cause problems in the brain? It is ultimately the intention that we will be able to take measurements for a long period of months, even years. Therefore the implant must be well packed and made resistant to bodily fluids and the like. In the coming years, we will continue to improve the tool in this area.”
Currently, brain activity can only be measured using the prototype. Liu predicts that in ten or twenty years it will already be possible to stimulate the brain via wireless communication. “In the future, for example, we can help patients who have had a stroke or other disease by giving them control of their limbs again.”
Simply being able to wirelessly record neural activity in different brain regions is already a big step for science. There is currently no objective assessment tool for detecting a brain disorder. With this tool, I hope we can tell patients a lot about the course of the disease at an early stage.”