Imagine waking up in the hospital to learn you’ve been paralyzed in an accident. Panic and fear wash over you as the realization sinks in that you may never walk, never hug your children, require assistance to get in and out of bed, to bathe, to toilet.
What must it be like to receive the diagnosis you have Lou Gehrig’s Disease—Amyotrophic Lateral Sclerosis (ALS). That one’s a death sentence, though a slow one entailing a progressive loss of muscle control and dignity, until the day you succumb to respiratory complications. When you can no longer breathe.
According to the
Miami Project, 294,000 people within the United States are living with some degree of paralysis due to spinal cord injury. The
ALS Society reports an additional 16,000 Americans are diagnosed with this dread neurodegenerative disease annually. Overall, 240,000 people have some form of neuromuscular disease in the US.
The common denominator for all these people is the loss or impairment of the connection between the motor cortex of the brain and the muscles, affecting movement and speech. But recent technological advances offer hope. For years, researchers have pursued a means to bridge the lost link between brain and body. The result is a device known as a Brian-Computer Interface (BMI).
Like an Electro Encephalogram (EEG), BMIs detect the electrical impulses generated by neuronal activity. EEG sensors are placed on the surface of the head and read cerebral activity diffused by distance and the skull. BMI electrodes, on the other hand, are set directly on or within the cerebral cortex, and can detect the signals of neuronal ensembles. These assemblages of neurons consistently signal together to affect a specific muscle or group of muscles for any given action, whether grasping an object, walking or speech.
Neuronal assemblages will continue to fire even after the connection between brain and muscles is lost. In other words, BMIs can detect intent, and communicate that to restore lost or impaired motor function, or to an external computer to generate text or speech, or to a prosthesis or a device like a motorized wheelchair.
The components of these remarkable devices are micrometer-scale wire sensors laid across or embedded within the motor cortex, a Complementary Metal Oxide Silicon chip (CMOS) that gathers and processes those signals, a battery to power the system, and a means to transmit the ensuing data stream to the outside.
The chip and electrodes must be surgically implanted. This exposes the recipient to the inherent risks associated with general anesthesia and infection. Earlier iterations were hard wired, offering a conduit for pathogens past the skin and skull. Modern designs utilize Bluetooth technology, diminishing long-term infection risk. Though tiny, the wires are rigid compared to the neurons they contact. Bodily motion causes the surfaces to rub against each other, often resulting in inflammation and scar tissue, which can diminish and eventually block the sensor’s ability to read signals. The accuracy and speed of any BCI is proportional to the chip’s number of sensors.
Researchers and commercial enterprises have developed alternative designs to mitigate the above risks and boost performance. Elon Musk’s company Neuralink employs an implantable Bluetooth device, the Link, with 1,024 micron-scale sensors. Its battery is induction rechargeable. Neuralink is developing a robotic surgical system to safely and accurately place the electrodes. Time saved over conventional implant surgery could possibly result in an outpatient procedure, eliminating the need for general anesthesia altogether. At present, Neuralink is pursuing FDA approval for experimental human trials.
Synchron is approaching the risk of inflammation and scarring by inserting the BCI sensors into the cerebral cortex via blood vessels. The sensor array is integrated into a stent. When expanded, it becomes integral with the vessel’s epithelial cells, reducing the danger of rejection and scarring. In July ,2022, Synchron announced its Stentrode device had been installed in its first patient as part of an FDA trial. The minimally invasive procedure took about two hours.
BrainGate’s BCI has been enrolled in clinical trials since 2004. In 2021, they reported FDA approval for their wireless Bluetooth version. Just this month (January 2023) BrainGate released study results that demonstrated their brain chip implants showed a safety profile comparable to other brain implants long used to manage neurodegenerative disorders.
In 2021, the Korea Advanced Institute of Science and Technology (KAIST) announced they developed a soft implant. They utilized an open polymer chain electrode, instead of a metal wire, allowing unhindered molecular exchange between neurons and the cerebral environment. It also enabled the sensor to flex with the adjacent cells, avoiding inflammation and scarring.
BCI technology stands at the threshold of commercialization. Ever-increasing sensor numbers coupled with advances in CMOS technology are leading to smaller size BCI designs with lower power requirements, and higher signal acquisition fidelity. Use of flexible organic materials will lead to longer lasting implants, reducing the need and risk of follow-up surgeries.
Fifteen years from now, mind-controlled prostheses, artificial neuromotor control, artificial speech and mind controlled access devices will be commonplace(assuming insurance coverage). Neurodegenerative diseases like ALS may become manageable chronic conditions, allowing a degree of independence and dignity denied to victims today.
For further Reading
https://en.wikipedia.org/wiki/Brain%E2%80%93computer_interface#:~:text=A%20brain%E2%80%93computer%20interface%20(BCI,a%20computer%20or%20robotic%20limb.
https://neuralink.com/https://www.fiercebiotech.com/medtech/synchron-implants-brain-computer-interface-first-us-patient-paralysis-trialhttps://neurosciencenews.com/implanted-bci-neurotech-22258/https://www.scientificamerican.com/article/new-brain-implant-transmits-full-words-from-neural-signals/https://www.massdevice.com/brain-computer-interface-bci-companies/
