Neuralink

Neuralink is a company founded by Elon Musk that aims to develop implantable brain-machine interfaces and has given rise to a host of ethical debates. The company's business model centers itself around brain machine interfaces (BMIs), with its first product being called the Link. The Link will be a communication center for the multiple threads that hold the electrodes that will be embedded in the user's brain. The company advertises the LINK as a conduit that will provide a seamless connection between the minds of its patients and electronic devices such as computers, phones, etc. The company's products are currently being market towards the physically disabled, with hopes that the LINK can greatly increase their quality of life. However, the company hopes to expand its products and target the general market so that in the future, BMIs will be the norm rather than the exception. As of now the company has not tested its product in human patients but it has shown a proof of concept device in monkeys, which allowed them to play rudimentary video games such as Pong with their minds.

History

Neuralink was originally founded in 2016, and publicly introduced in 2017 but did not receive significant attention until its CEO, Elon Musk, announced its existence during a livestream presentation. Before the company could be founded however, its founders had to purchase its name, NeuraLink, fromm a pair of BMI researchers who had copyrighted the name back in 2013. The pair first met in 2011, Mohseni, a biomedical engineer, and Nudo, a neuroscientist, had been prototyping a BMI in rats that would restore communication between damaged brain regions. The pair eventually sold the rights to the name in 2015 to Elon after being unable to hurdle many of the obstacles that stand in front of BMI development. The main hurdle that the pair faced was the lack of profitability in their business model. The engineering complexity and bureaucratic red tape that surrounds a medical device that will be implanted in the brain meant many investors were reluctant to invest without solid proof of concept. In addition, even if a promising product was produced, there is a fairly limited pool of patients that could benefit from these devices. The pair were optimistic in Musk's endeavor however, as they believe his wealth of capital and plan to make the device applicable to the general public will overcome the hurdles that their predecessors could not. The core of Neuralink's team consist of industry experts in the fields of neuroscience and engineering. Notable members of this team include Flip Sabes and Tim Gardner who both left tenured positions at UC San Francisco and Boston University to be apart of Neuralink. As of now Neuralink hopes to start testing its product in humans in 2022, 2 years later than its original goal of 2020.

Technology

Background on BMIs

BMIs use mathematical transformations to collect and interpret multi neuron signals from the motor cortex and the frontal and parietal lobes. There have been multiple important breakthroughs in BMI technology. One of the first is parallel recording instead of serial recording. Serial recording would involve recording from the same neuron multiple times to detect a discernable pattern that could be correlated with a certain stimulus. Parallel recording would instead look at multiple neurons at a single time. Another break through was the idea of distributed coding. Distributed coding is the idea that the single neuron is not the key functional unit but it is the collection of multiple neurons in a population that encode information. When BMIs were first being developed the consensus in the neuroscience community was that the information from a single neuron had enough predictive power to describe physiological phenomena. Finally, modern computational models are used to simultaneously extract various motor parameters (such as arm position and velocity, or hand gripping force) in real time from the extracellular activity of frontal and parietal cortical neurons. These models are often first trained to predict motor movements by observing modulations in the neuronal ensemble activity of animals as they perform certain tasks.

Listed below is a rough timeline of crucial developments in neuroscience and engineering that eventually lead to the development of BMIs.
~1802: Thomas Young proposes population coding
~1950s: First multi electrode recording experiments
~1980s: Modern approach of sampling extracellular activity from neurons
~1990s: Expansion of electrophysiology and imaging methods
~2010s: Introduction of companies specific to brain machine interfaces

Innovations

Neuralink's website list multiple areas of innovation that separate its product from the current BMIs that are on the market. The first area that Neuralink focuses on is the application of its product compared to other BMIs. Neuralink explains how most of the popular BMIs such as deep brain stimulation are used to for recording or stimulating the brain only. The Link, Neuralink's flagship product, will be able to record and interpret neuronal signals as well as communicate with them. The second area of innovation that was stated by Neuralink was the number and size of electrodes. Due to the mechanisms of current BMIs, the devices themselves require relatively few electrodes, with the electrodes themselves being fairly large. Neuralink states how its device will have 1024 electrodes, and each one will be extremely small yet flexible.

Another innovation of Neuralink is centered around the electrodes themselves. Classic electrodes are made of metals so they are rigid enough to allow easy penetration into the brain. However, this rigid nature makes the electrodes stand out as a foreign insert within the brain and thus elicit quick and heavy immune responses. These immune responses can hinder the ability of the electronics to pick up clear neuronal signals. The limited flexibility also prevents the amount of neuronal populations that can be reached and recorded from as the probes can not by pass important brain structures. Neuralink attempts to solve this issue by creating flexible probes that are made of flexible and biocompatible materials with good conducting properties. However, their long term efficacy in biological environments is still not clear.

Besides the BMI itself another area of innovation in Neuralink's design is how they plan to implant the device. Due to the extremely small scale of the electrodes, each one being 5 microns wide (a human hair is 70 microns wide), the company has developed a surgical robot that will help assist surgeons during implantation. The company hopes that in the near future the robot will be able to completely automate the procedure. Neuralink's scientist and engineers created the technology that allows the robot to function however they outsourced the aesthetic design and user interface of the robot to a third party company, Woke Studio. The company focused heavily on making the robot have an "anthroprmorphic characteristic". The principle behind the design was to minimize the invasiveness of the procedure by having the robot that was doing the procedure be aesthetically pleasing. The robot is split into 3 different sections, the head, body, and base. The head holds the head of the patient and holds all the surgical tools needed for the procedure along with a host of sensors for mapping the head and brain. The body holds all of the mechanical machinery that allows the robot to move and the base holds the computational hardware. The robot currently has a autoinsertion mode and can insert up to 6 probes a minute, however, the surgeon can intervene at any point and make manual adjustments.

Neuralink vs DBS

One of the most popular BMIs used today is deep brain stimulation (DBS). Its efficacy in treating neurological disorders such as Parkinson's and essential tremor has made it a mainstay in clinically used BMIs. However, DBS is a technology that is already two decades old and has not seen much innovation. DBS uses 4 electrodes, with each one being 1.27 mm in diameter . This limits the efficacy of DBS by offering low spatial resolution, the electrodes can not stimulate very precise regions of brain, and by limiting the amount of endemic neural signaling that can be recorded. This latter limitation means DBS can not be individualized to each patient's unique symptoms and pathology. Future discussion of how DBS should evolve draws various parallels with the current Neuralink design. A need for better spatial resolution means having smaller and more plentiful electrodes.

Another defining characteristic of DBS is the implantable pulse generator, the device that powers the DBS electrodes inserted into the patient's brain. This implantable pulse generator is regularly inserted under the collar bone of the patient, similar to where a pacemaker would be placed. The device is two inches in diameter and one half inch thick and often produces a notable bump in the skin. Since the device is a battery it will eventually run out of power. Thus patients are given the option of a non rechargeable battery that last 3-5 years or a rechargeable one. The rechargeable battery is charged by holding a device over the site and must be charged several times a week. The surgery that implants the DBS electrodes and implantable pulse generator requires 6 steps and takes around 4 hours.The size and surgery of deep brain stimulation are areas that Neuralink's technology has innovated. Compared to the two by one half inch implantable pulse generator, Neuralink's device is 23 millimeters by 8 millimeters and will sit in the skull so there will be no visible protrusion. The company also says that the device can be implanted into a patient under one hour without general anesthesia and that the patient would be able to leave the the hospital on the same day.

Issues

Technological

One of the first issues surrounding Neuralink's technology is the materials that are being used to make the threads that will be inserted into the brain. In order to improve the electrophysiological properties of the miniscule threads and have better recording features they were coated with poly-ethylenedioxythiophene doped with polystyrene sulfonate. The issue with this polymer is since it is so novel there is limited research on it biocompatibility and what type of immune response it could generate once inside the brain. Another issue is centered around the robot that is used for implanting the device. Although the robot has impressive speed, its first 19 surgeries had a 87.1 percent success rate with a standard deviation of 12.6% . Considering the fact that these surgeries were not done on human patients but on mammals with much less complex neural anatomy, the accuracy of the robot may be brought into question. The invasiveness of the procedure means that patients will unlikely be comfortable with anything less than absolute accuracy during the procedure. Neuralink has also been criticized for its recent demos that involved its device being implanted into animals such as monkeys and pigs. Among the critics are tenured neuroscientists that express doubt over the novelty of the demonstration. Andrew Jackson, a professor at Newcastle University remarked how the 1024 recording electrodes was not necessarily impressive for today's standards, but did say how the ability to relay their information wirelessly was impressive. The professor went on to remark how the largest limitation that brain machine interface technology has encountered is not recording information from the brain but finding ways to interpret it. He remarked how the Neuralink demo displayed encoding methods and technologies that have been displayed before. He also expressed doubt to the more exotic claims that were presented by Neuralink, such as the ability to write information to the brain and replay memories. He says that there are fundamental limitations around electrical stimulation and how it can convey information to the brain. Overall Dr. Jackson stated that neuralink demonstrated, "good engineering but mediocre neuroscience".