Just under 50 years later, a macaque monkey played Pong with the power of its mind.
The audacious trial took place at Elon Musk-owned Neuralink to showcase the latest iteration of the company’s Link device, a type of brain-machine or brain-computer interface (BCI).
The N1 Link is a “fully implanted neural recording and data transmission device”, capable of reading brain signals and decoding their intention. A total of 1,024 thread-like electrodes are placed in key parts of the brain, where they monitor the activity of neurons. The device amplifies and digitises the voltages containing those signatures, which are detected and aggregated by onboard algorithms and transmitted over Bluetooth to a computer running custom decoding software.
For the Monkey MindPong demonstration, the Link was implanted in the hand and arm areas of the motor cortex, a part of the brain involved in planning and executing movements. First, the researchers gave the macaque a joystick that moved a dot around a screen to hit target areas. After modelling the relationship between patterns of neural activity and intended movement, they built a model to predict the direction and speed of upcoming movements. These predictions were then used to control the Pong paddles in real time, with the joystick taken away.
The company’s goal is to develop a fully implanted wireless BCI to enable paralysed people to quickly and easily control computers and mobile devices with their minds. It aims to scale up the number of electrodes for robustness and higher information throughput, and to automate the implant surgery to make it as quick and safe as possible. It is developing a surgical robot capable of placing the threads with micron precision, and mapping and tracking the moving brain during surgery.
While the MindPong demonstration needed training with joystick movements, BCIs for people with paralysis can be calibrated using motor cortex neurons that remain ‘directionally tuned’ to movement. This was shown by the BrainGate consortium, another BCI project which had its own breakthrough this year – the consortium, including Brown University in Rhode Island and Stanford University in California, demonstrated the first human use of a wireless transmitter capable of delivering high-bandwidth neural signals.
Previous iterations involved long, cumbersome cables attached to the user’s head, but the latest system transmits signals at single-neuron resolution without physical tethering to a decoding system. The 40g transmitter sits on the user’s head and connects to an electrode array within the motor cortex, using the same port as wired systems.
The recent IEEE Transactions on Biomedical Engineering study involved two trial participants with paralysis using the BrainGate system to point, click and type on a tablet computer. Researchers said the study is an important step towards a fully implantable system that aids in restoring independence for users. The wireless aspect of the technology means it can be monitored for long periods, giving researchers a valuable insight into how neural signals evolve over time.
Ultimately, wireless BCIs could restore mobility for paralysed people by controlling prosthetic limbs, or restoring damaged links between brain signals and nerves to stimulate muscles. BCIs will need to monitor many more of the brain’s billions of neurons. Placing the electrodes in such a complex mass is one thing, while developing software to process the data is another huge challenge.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.