DARPA researchers to push the limits of reading and writing human brain neurons

DARPA brain neurons Stephenson's law
Credit: Thinkstock

This week neuroscientists met with DARPA in Arlington, Virginia, to embark on a project breaking Stevenson’s Law.


The Defense Advanced Research Projects Agency (DARPA) started a new project this week to dramatically increase the number of human brain neurons that can be read simultaneously, according to the MIT Technology Review. In four years, DARPA wants a breakthrough from neuroscientists that will record from 1 million neurons simultaneously. DARPA will spend $60 million under the broader Whitehouse BRAIN Initiative to fund research in the top neuroscience labs across the country. 

The applications for a brain computer interface (BCI) at this point is speculative. Achieving the project goal would significantly extend scientists’ ability to understand how the brain works, and would enable high-fidelity control of robotic limb and high-resolution electronic vision prosthetics. The report didn't provide any reason for a normal person to accept such an adaption, but this research would certainly be a game-changing development in human-computer interfaces and virtual reality.

The initiative stems from the disappointing predictions of progress in this field based on Stevenson’s Law. Similarly to how Moore’s Law has predicted exponential growth in the number of transistors on a silicon chip since 1965, Stevenson’s Law predicts exponential growth in the number of neurons that can be read simultaneously. According to Stevenson’s Law, the number of neurons that can be recorded simultaneously will double every seven years, and currently sits at about 500. DARPA’s goal of 1 million neurons will substantially break out from the limits of Stevenson’s Law.

mit chart MIT Technology Review

Delivering scientific research and breakthroughs quickly is DARPA’s purpose. DARPA is a 50-year-old Department of Defense agency with a budget of about $3 billion that’s charged with preventing strategic surprises from – and creating strategic surprises for – America’s adversaries. DARPA earned a reputation for producing high-impact results quickly. A few of DARPA’s innovations include the internet, global positioning satellites (GPS), drones, and micro-electro-mechanical systems (MEMS). 

Accompanying the goal of recording or “reading” brain neuron states is the goal to stimulate or “write to” at least 100,000 neurons in the brain. The stimulating device should be the size of a nickel or smaller and will operate wirelessly. Some of the research will involve studies on human subjects, requiring research teams to obtain investigational device exemptions from the FDA and follow the agency’s safety standards.

The Technology Review story lent some context to the importance of increasing the limits of the number of neurons that could be read and written to at once. Using sharp silicon needle arrays, researchers have been able to record 200 to 300 neurons in the brains of human volunteer subjects at research labs at Brown University and the University of Pittsburgh. It’s enough to read the intent of the subject’s thoughts to move an arm and hand. The Technology Review story set the boundaries of current research with a quote by Jonathan Wolpaw, an expert on brain-computer interfaces at the Wadsworth Center of the New York Department of Health:

“… they’re not anything that’s anywhere near ready to be taken out of the lab. There’s no BCI that you would now want to use to control a wheelchair on the edge of a cliff or to drive in heavy traffic.”

The small number of neurons that were read by the Brown and Pittsburgh teams don’t fully explain the connection between thought and movement because neuron cycle time is slow, spiking just twice a second. That’s not enough neurons firing fast enough to explain movement, Konrad Kording, a data scientist at Northwestern University with an interest in neuroscience, said in the Technology Review story.

“We need at least 1,000 times more neurons for an awesome prosthetic device, in my estimate,” Kording added, according to the report.

The research history and DARPA plan present the possibility many BCI applications, but little likelihood that this will become a standard for human computer interfaces.

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