They made significant progress and completed preliminary testing but did not receive enough funding or support from investors to continue: "The pair of longtime neurotech researchers had developed a device that might help people with brain injuries.

[14] At that time, Neuralink announced that it was working on a "sewing machine-like" device capable of implanting very thin (4 to 6 μm in width)[15] threads into the brain, and demonstrated a system that reads information from a lab rat via 1,500 electrodes.

[17] In September 2024, the company announced that its latest development effort, Blindsight, will allow those who would otherwise be blind to regain some level of vision, provided the visual cortex is undamaged.

[9][21] In April 2017, Neuralink announced that it was aiming to make devices to treat serious brain diseases in the short term, with the eventual goal of human enhancement, sometimes called transhumanism.

[23][24] Musk defined the neural lace as a "digital layer above the cortex" that would not necessarily require extensive surgical insertion but could be implanted through a vein or artery.

[31] By August 2020, only three of the eight founding scientists remained at the company, according to an article by Stat News that reported that Neuralink had seen "years of internal conflict in which rushed timelines have clashed with the slow and incremental pace of science.

"[32] As of 2020[update], Neuralink was headquartered in San Francisco's Mission District, sharing the Pioneer building with OpenAI, another company Musk co-founded.

[42] In 2018, Gizmodo reported that Neuralink "remained highly secretive about its work", although public records showed that it had sought to open an animal testing facility in San Francisco; it subsequently began doing research at the University of California, Davis.

[43] The probes, made mostly of polyimide, a biocompatible material, with a thin gold or platinum conductor, are inserted into the brain through an automated process performed by a surgical robot.

This system consists of 256 amplifiers that can be individually programmed, analog-to-digital converters within the chip, and peripheral circuit control to serialize the digitized information obtained.

[58][59] A removable[60][61] device the size of a coin (23 millimeters)[62][63] implanted in Gertrude's brain recorded signals from the neurons connected to her snout as it interacted with its environment, such as when it sniffed or touched things.

[64][65] The data showed that the technology could read and interpret brain signals, which is key to developing applications that could treat neurological conditions, enable brain-to-machine communication, or enhance human cognition.

In 2022, the Physicians Committee for Responsible Medicine (PCRM), an animal welfare advocacy group, alleged that Neuralink and UC Davis had mistreated several monkeys, subjecting them to psychological distress, extreme suffering, and chronic infections due to surgeries.

Additionally, a Reuters report cited claims by several Neuralink employees that testing was being rushed due to Musk's demands for fast results, which was leading to needless suffering and deaths among the animals.

[17] In 2022,[further explanation needed] after being rejected for human clinical trials by the FDA, Neuralink performed more tests on pigs to address safety concerns.

[86] In November 2023, U.S. lawmakers asked the Securities and Exchange Commission to investigate whether Neuralink deceived investors by omitting details about possible animal deaths.

He said it operates at low resolution that is expected to improve and that no monkey had died due to or been seriously injured by a Neuralink device, contradicting earlier reports.

It recruited people with quadriplegia due to cervical spinal cord injury or amyotrophic lateral sclerosis[92] under an investigational device exemption by the FDA.

[93][94] On January 29, 2024, Musk said that Neuralink had successfully implanted a brain computer interface (BCI) device the company named Telepathy in a human on the previous day and that the patient was recovering from the surgery.

[16] As it was a "first in human" and "early feasibility" trial to develop a concept, the company was not obligated to disclose details about the procedure or to prove safety or efficacy.

[101] The Wall Street Journal reported that Neuralink would proceed with a second trial participant,[101] with the FDA signing off on the company's proposed fixes for a problem that occurred with Arbaugh.

[107][108][109] MIT Technology Review accused the demonstration of having the main objective to "stir excitement", adding, "Neuralink has provided no evidence that it can (or has even tried to) treat depression, insomnia, or a dozen other diseases that Musk mentioned in a slide".

[107] In response to Musk's description of Neuralink's advancements as "profound", Andrew Jackson, a professor of neural interfaces at Newcastle University, said, "I don't think there was anything revolutionary in the presentation.

[111] He cited successful control of a robotic prosthetic arm by a man that gave him haptic feedback, which he used in 2016 to give President Obama a fist bump.

[111] Duke University researcher Miguel Nicolelis made similar criticism, saying that most of what Neuralink claims as "novelty" was already performed by his lab in the early 2000s; that there are ethical concerns about how the company markets and uses this technology; and that most patients don't want to undergo surgery to recover their movements, and so his team developed non-invasive techniques for BMI, as demonstrated in the opening ceremony of the 2014 FIFA World Cup, in the context of the Walk Again Project.