Neuralink Wants to Expand Brain Chip Trial to Second Human Patient

Elon Musk’s Neuralink is signaling it’s ready to implant its brain chip in a second human patient after more than three months of tests with Noland Arbaugh, the first human subject. 

On Thursday, Musk tweeted: “Neuralink is accepting applications for the second participant. This is our Telepathy cybernetic brain implant that allows you to control your phone and computer just by thinking." His post retweets a Neuralink video intended to recruit eligible users for the second trial; it offers a glimpse of how the brain chip was surgically implanted in Arbaugh in January. 

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“It completely changed how I live,” Arbaugh says in the video, which shows how the technology has enabled him to move the cursor on his laptop remotely.  

Neuralink first called for human patients to test the brain chip in September, so the company may already have a database of eligible candidates. In particular, the startup is looking for quadriplegics like Arbaugh or people who’ve lost the ability to use their arms and legs.

The so-called N1 chip reads the user’s brain activity through 64 fine threads that contain 1,024 electrodes. These brain signals are then converted into Bluetooth-based remote commands to control an electronic device, like a mouse cursor. In Arbaugh’s case, the N1 chip has allowed him to control his laptop for eight-plus hours a day, play a variety of video games, and interact on social media. 

“I’m beating my friends in games that, as a quadriplegic, I should not be beating them in,” he told Neuralink last week. 

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There have been challenges. Neuralink last week disclosed that an unspecified number of electrode-laced threads attached to the N1 chip had “retracted" from Arbaugh’s brain a month after the surgery. This caused “a net decrease in the number of effective electrodes,” resulting in lower performance for the brain chip before Neuralink made software changes to compensate for the signal loss. 

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Since then, Arbaugh’s performance with the N1 chip has surpassed his initial benchmarks. Still, it's unclear why the threads retracted from his brain in the first place, although it appears to be a known problem. Bloomberg recently interviewed Arbaugh and said the threads attached to his brain had shifted more than Neuralink had seen while testing the chip with animals. 

One possible reason is that animal brains tend to be significantly smaller than human brains. Bloomberg also noted that Arbaugh possesses a “thicker-than-average skull,” which could have made it harder for the threads to settle into his brain tissue. What is clear is that Neuralink will no doubt try to address the thread-retraction issue when expanding the brain chip trials to more human patients.

Interested users can sign up for the Neuralink trials by visiting neuralink.com/patient-registry.