At the end of August, Musk's press conference with three piglets shocked the brain science community. As for the progress and limitations of Musk's intrusive brain-computer interface technology, Han Bicheng, PhD in brain science and founder of BrainCo, Harvard University, and Yang Jinchen, a scientist at Harvard Medical School and head of brain science at Kangpu Ruiqi, made an exclusive interpretation.

On the afternoon of August 28, US time, Elon Musk, founder of intrusive brain-computer interface company Neuralink and technology hero "Silicon Valley Iron Man", held a press conference he jokingly called "three Little Pigs."

Through the way of "walking the pig", it announced and demonstrated to the world the research and development achievements of the Neuralink team in the past year, and once again pushed the concept of "brain-computer interface" to the focus of global attention. Many people were first surprised by the appearance of the pig and were excited to hear the "sound" of the discharge of pig brain cells at the press conference. In fact, this is a routine operation in the field of neuroscience. Electrophysiological researchers have been listening to recorded nerve cell discharges into sound waves in the laboratory for decades.

The pig's head is very large, so it is an ideal experiment for nerve implantation. For example, a 2015 MIT doctoral thesis study implanted devices in pigs that could record and diagnose epileptic brain waves for a long time (see below, source https://dspace.mit.edu/, author Bruno G. Do Valle). It is similar to the release of Elon Musk, including pig walking.

But there is no doubt that brain-computer interface is an area with high technical difficulty and complexity. From the perspective of brain-computer interface entrepreneurs and brain science practitionersMusk's newly released Link V0.9 technology can be said to have three advances and three limitations.

First of all.Three developments。

First of all, Link V0.9 enables external wireless。Although the invasive operation of inserting a microelectrode wire attached to the signal processor into the brain tissue has not changed, the junction box placed behind the ear in the schematic diagram released at the press conference last year is missing.

In the latest scheme, a small hole will be dug out of the brain skull, and the signal processor containing components such as an amplifier, analog-to-digital converter, will be made into a large coin-shaped cylinder with a diameter of 23 mm and a thickness of 8 mm (the size of an one-yuan coin in China is 25 mm in diameter and 1.85 mm in thickness). The realization of external wireless improves the aesthetics and application possibility.

The second development isBy decoding the brain waves recorded by Link V0.9It can better predict the dynamic position of the joints of the limbs of pigs when they are moving on the treadmill. It should be pointed out that the sample size of this experiment is only one pig, which belongs to the pre-experiment.

And similar motion decoding techniques have been successfully applied to decode the movement of vocal organs and subsequent speech synthesis by a research team at the University of California, San Francisco, funded by Facebook Inc. Relevant papers have been published in academic journals such as Nature in 2019 and early this year. Musk's team's research has not yet been officially published through peer review.

The third development is，Musk announced that Link V0.9 had been approved as a breakthrough device by the U.S. Food and Drug Administration (FDA) in July.Human implant testing is expected in the near future after obtaining the remaining necessary approvals and safety tests. Only after a large number of human safety and effectiveness tests, a medical device can be approved for application. Therefore, the identification of FDA is a solid first step for the device to eventually be applied to the human body.

One of the cores of scientific thinking is critical thinking. From a professional point of view, Neuralink's intrusive brain-computer interface technology includesThree limitations.

FirstThe microelectrode wires connected under the circuit board embedded in the skull need to be inserted into the brain tissue, except for the parietal lobe motor cortex and other relatively convenient implantation, slightly deeper brain tissue is very difficult to implant, unless a traditional craniotomy is used. However, no matter how thin the inserted electrode is, it may still lead to a serious decline or even loss of electrode signal quality due to the scab formation of glial cells.

SecondlyFDA in the United States expects the implanted human material to last in the body for at least 10 years. Neuralink electrode wire is made of a new flexible polymer material, which may take 10 years to test to show FDA whether the new material meets the standard. Moreover, Musk did not give a specific timetable for clinical trials of any of the diseases listed in his PPT.

Last pointAt the technical level. The brain is actually a vast small universe with nearly 100 billion neurons, and a single neuron is connected to other neurons through as many as 10,000 synapses.

The way the brain works is that the whole is greater than the sum of the parts, and wisdom and soul are produced in the brain but not in a specific synaptic gap. To directly record the discharges of 1000 (at Neuralink's current level) or 100000 (Neuralink's target) neurons, the idea used is reductionism, and the resulting data are essentially sampled. And, as Professor Desimone, director of the McGovern brain Research Institute at the Massachusetts Institute of Technology, pointed out in a paper published in Neuron earlier this year, both brain stimulation and photogenetic techniques inevitably cause man-made disturbance to the brain activity they want to measure.

In order to truly realize the interpretation of the advanced mental operation, and even realize the download and upload of consciousness and memory, it is necessary to combine a large number of data at the system and behavioral level, through the idea of holism, which is the advantage of non-invasive brain-computer interface technology.

Musk said at this press conference that "you need an electrical thing to solve the circuit problem of the brain's neural system," which is correct, as long as the electrical thing-- brain-computer interface technology-- can not stay at the reductionist level. and can meet the medical and social ethics of the human body for safety and effectiveness and other requirements.