Inside Neuralink’s Human Trials: Progress, Setbacks, and the Future of BCI

Brain-computer interfaces (BCIs) have moved rapidly from science fiction to clinical reality over the last two years. While academic labs have experimented with these devices for decades, the entry of commercial heavyweights has accelerated the timeline for general availability. Leading this charge is Neuralink, the company founded by Elon Musk, which recently began its PRIME Study involving human patients.

This article examines the current status of Neuralink’s human trials, the specific engineering challenges they have faced, and how competitors like Synchron are approaching the same problem with different technology.

The PRIME Study: What Is It?

In May 2023, the FDA granted Neuralink approval to launch its first-in-human clinical study. This is officially known as the PRIME Study (Precise Robotically Implanted Brain-Computer Interface). The primary goal is to evaluate the safety of the implant and the surgical robot.

The study focuses on patients with quadriplegia due to cervical spinal cord injury or amyotrophic lateral sclerosis (ALS). The objective is to grant these individuals the ability to control external devices, such as a computer cursor or keyboard, using only their thoughts.

Unlike older BCI iterations that required bulky wired connections through the skull, the Neuralink device is fully implantable and wireless. It is designed to be cosmetically invisible once the surgical incision heals.

The Technology: The Link and the R1 Robot

To understand the trials, you must understand the hardware. Neuralink’s system consists of two main components:

  1. The N1 Implant (The Link): This coin-sized device replaces a small piece of the skull. It features 64 ultra-flexible threads that contain a total of 1,024 electrodes. These electrodes detect neural spikes (action potentials) from individual neurons.
  2. The R1 Robot: Human hands are not steady enough to insert threads that are thinner than a human hair. The R1 Robot acts as a surgical sewing machine. It uses cameras and sensors to insert the threads into specific regions of the motor cortex while avoiding blood vessels.

Patient One: Noland Arbaugh

In January 2024, Noland Arbaugh became the first human to receive the N1 Implant. Arbaugh, who was paralyzed from the shoulders down following a diving accident, provided the world with the first real-world look at the device’s capabilities.

The Successes: Within weeks of surgery, Arbaugh demonstrated the ability to control a mouse cursor on a screen. He appeared in livestreams playing chess and the strategy game Civilization VI. He reported being able to play for hours at a time, something that was previously impossible without assistance.

The Setback (Thread Retraction): About a month after surgery, the device began to lose data capture capability. Neuralink engineers discovered that several of the flexible threads had retracted (pulled back) from the brain tissue. This reduced the number of effective electrodes.

This issue highlighted a biological challenge: the brain moves inside the skull. It pulsates with every heartbeat and shifts when the head moves. The initial depth and tension of the threads did not fully account for this movement.

The Fix: Rather than removing the implant, Neuralink modified the recording algorithm. They made the software more sensitive to the remaining signals. This adjustment allowed Arbaugh to regain cursor control and continue using the system effectively.

Patient Two: "Alex"

In August 2024, Neuralink implanted its second participant, referred to as “Alex.” Learning from the issues with the first patient, the surgical team implemented specific mitigations to prevent thread retraction:

  • Reduced Gap: They minimized the space between the implant and the surface of the brain.
  • Insertion Depth: The threads were inserted at varying depths to anchor them more securely.

The Results: According to Neuralink’s updates, Alex has experienced no thread retraction. His cursor control has remained accurate and stable. He has used the implant to use CAD (computer-aided design) software to design a 3D mount for his charger and to play the first-person shooter game Counter-Strike 2.

This progression from patient one to patient two demonstrates the rapid iteration cycle characterizing the commercial BCI sector.

The Competition: Synchron and Blackrock Neurotech

While Neuralink captures the headlines, they are not the only player in the field. Other companies are pursuing different surgical approaches that may offer safety advantages.

Synchron

Synchron is arguably Neuralink’s closest commercial rival. Their device, the Stentrode, takes a vascular approach. Instead of drilling into the skull, the Stentrode is inserted through the jugular vein in the neck and pushed up into a blood vessel near the motor cortex.

  • Pros: No open brain surgery is required. It is less invasive.
  • Cons: The electrodes do not touch neurons directly (they sit inside the blood vessel wall), so the signal resolution is lower than Neuralink’s.
  • Status: Synchron has already implanted its device in multiple patients in the U.S. and Australia. It integrates with Apple products like the iPad to allow patients to text and email.

Blackrock Neurotech

Blackrock Neurotech is a veteran in the space. Their Utah Array has been used in research settings for nearly two decades. Unlike the flexible threads of Neuralink, the Utah Array uses rigid spikes.

  • History: Their technology has allowed patients to control robotic arms and feel sensations through haptic feedback.
  • Focus: They generally focus more on research applications and robotic limb control rather than the consumer-facing “telepathy” angle Neuralink pursues.

Future Applications: Blindsight and Beyond

Neuralink has stated that their next product application, after restoring digital agency (Telepathy), will be Blindsight. This initiative aims to restore vision to individuals who have lost it, or potentially even those who were born blind.

The concept involves stimulating the visual cortex directly. By bypassing the eyes and optic nerve, cameras could feed visual data straight to the brain. While this technology is still in early development compared to the motor control chip, it represents the long-term roadmap of high-bandwidth BCI technology.

Safety and Ethical Considerations

The rapid pace of these trials brings necessary scrutiny. The FDA monitors these studies closely to ensure patient safety. Key concerns include:

  1. Infection Risk: Any implant that breaks the skin or skull carries a risk of infection.
  2. Heat Generation: The device runs on a battery and processes data. It must not generate heat that could damage brain tissue.
  3. Longevity: Brain tissue creates scar tissue (gliosis) around foreign objects. It remains to be seen if the threads will continue to record clear signals for five or ten years.
  4. Upgradability: Technology becomes obsolete quickly. Unlike a smartphone, you cannot easily swap out a brain implant for next year’s model.

Conclusion

The data from Noland Arbaugh and Alex suggests that high-bandwidth, wireless brain-computer interfaces are viable. The ability to mitigate the thread retraction issue in the second patient is a significant engineering milestone.

For now, the technology remains in the investigational phase. However, with competitors like Synchron pushing for their own commercial approvals, the next five years will likely see BCIs transition from experimental novelties to prescribed medical devices for paralysis.

Frequently Asked Questions

How much does a Neuralink implant cost? The device is currently not for sale. It is only available through clinical trials. Neuralink has estimated the surgery could eventually cost around $40,000 in the early commercial stages, but this is speculative.

Can healthy people get a Neuralink? No. The current FDA approval covers only patients with severe paralysis (quadriplegia) or ALS. Consumer use for healthy individuals to “enhance” intelligence is likely decades away, if it happens at all.

How is the device charged? The N1 Implant charges wirelessly. The patient wears a custom cap that uses inductive charging (similar to how a wireless phone charger works) to power the battery inside the implant.

Is the surgery painful? The brain itself has no pain receptors. However, the surgery involves the scalp and skull, which requires anesthesia. Patients are under general anesthesia during the procedure and do not feel it happening.

What happens if the device breaks? This is a major part of the ongoing safety trials. If a device fails, it would likely need to be surgically removed or replaced. The safety of explanting (removing) the device is a key factor the FDA reviews.