The tech multibillionaire said his company, Neuralink, was seeking government approval to test his device in people, and predicted it could happen in six months. Others have been conducting similar tests for years, but no device has been marketed commercially.In a presentation showcasing the Neuralink implant that Elon Musk hopes will someday connect the human brain to a computer, two monkeys were reportedly moving computer cursors with their brains.The feat was first documented by others in a human in 2006 in the pre-YouTube era and with technology that is far more cumbersome, mooring patients to a computer with a cord.Mr. Musk’s presentation on Wednesday night offered little that was significantly new from previous demonstrations of the device. He continued to claim that the implant could make computer control possible for people with paralysis outside of a lab setting. But experts in the field questioned whether the demonstration showed major progress with the device, especially given the breadth of work underway nationwide.“These are incremental advances,” Daniel Yoshor, a neurosurgeon and neuroscientist at the Perelman School of Medicine at the University of Pennsylvania who has worked with similar devices, said after watching the presentation. “The hardware is impressive but does not represent a dramatic advance in restoring or enhancing brain function.”Neuralink does not have approval from the Food and Drug Administration to sell the device. Mr. Musk said on Wednesday that the company had submitted most of its paperwork to the agency to seek permission to implant its device in a human. He predicted a test in humans in six months, but any step toward trials in people would be up to the F.D.A. after a full evaluation of the risks of surgical implantation and safety of the device.Neuralink originally scheduled the event for the end of October, before Mr. Musk, a multibillionaire, postponed the presentation amid one of the more chaotic months of his career. He recently completed his off-again, on-again purchase of Twitter, which has commanded much of his attention — and generated considerable controversy — over management of the social media company.While Mr. Musk juggles that and other duties — he also oversees the electric carmaker Tesla and the rocket company SpaceX — Neuralink is emerging from a period of change. Last year, Max Hodak, the company’s president and one of its co-founders, left to launch his own venture in the field. Neuralink’s chief executive is officially Jared Birchall, a wealth manager who runs Mr. Musk’s family office.Wednesday night’s presentation focused on the “Link” device, which resembles an inch-wide stack of several coins with hundreds of hair-thin threads. A surgical robot would cut a hole in the skull and slip the electrode threads into the gray matter of the brain, according to Mr. Musk’s 2020 company presentation. The coin-like piece would sit flush with the skull.Leaders in the field of brain-computer interface technology have been closely watching Neuralink’s investment in a device that operated without protruding wires or hardware. Yet Mr. Musk’s presentations thus far have concerned and underwhelmed many of them.A 2021 Neuralink presentation of a monkey playing the video game Pong with his mind was similar to a primate demonstration at Brown University in 2001, though it had a far clunkier system.A diagram showing different steps of the Neuralink implantation process.NeuralinkIn a 2020 presentation showcasing a pig with the implant, Mr. Musk suggested the device could “solve” conditions including paralysis and insomnia and could even give a user “superhuman vision.” Such applications sound like science fiction to scientists who are singularly focused on restoring basic functions, like typing, speaking or lifting a fork, to those who have lost them after a spinal cord injury or a dire diagnosis. For such patients, the benefits weigh favorably against the small, but serious, risk of brain surgery.“No one is talking about implanting able-bodied people,” said Cindy Chestek, an associate professor of biomedical engineering at the University of Michigan whose lab is working on restoring function to amputees.On Wednesday night, Mr. Musk said plans for his device included making the blind see and giving someone with a severed spinal cord “full-body functionality.” The claims drew applause from the audience, but do not reflect the state of the field.“I would not say that with confidence,” Dr. Yoshor said after Mr. Musk had claimed the Neuralink device would give sight to people who have never seen before. “I would be highly unsure of this kind of device in a patient with congenital blindness.”Safety will be the F.D.A.’s primary concern in considering whether the device could be tested in humans, said Cristin Welle, an associate professor of neuroscience at the University of Colorado, who helped draft F.D.A. guidance on brain-computer implants before leaving the agency in 2016.Dr. Welle said regulators will focus on whether the device would damage the brain or present unreasonable risks to patients. She said device durability would also be considered, given the potential for brain fluids to eat through insulation coating the hundreds of hairlike electrodes on the Link device.So far, Neuralink has tested the device on sheep, pigs and primates, according to records filed with the Agriculture Department.Several other companies and scientists have already obtained approval from the F.D.A. to study similar devices in humans. In 2004, researchers conducted human trials with the Utah array, a device the size of a baby aspirin and fitted with spikes that is surgically placed on the brain. It connects through a wire to a small computer installed on the head that transmits to a computer. This neural interface system is called BrainGate.Gertrude the pig and her brain activity charted by a Neuralink implant in the 2020 presentation.NeuralinkWith the pieces in place, scientists seek patterns in the electrical current of neurons that signal the brain’s intention to type letters or lift a hand. The code, in turn, commands a computer or robot to perform the task.Nearly three dozen patients have undergone testing with the Utah array device. Using the technology, people with paralysis or other disabilities have lifted a cinnamon latte with a robotic arm in 2011, typed letters quoting Shakespeare in 2012 and lifted forkfuls of mashed potatoes in 2016.But the Utah array is not suited to long-term use. It rises up out of the skull, tethers users to a cord linked to a computer and exposes them to the risk of a brain infection. For these and other reasons, companies like Neuralink are working to build devices that are fully implanted.