Synchron's long road to reaching the brain through a blood vessel

By Inside BCI · Edited by Velco Dar · November 13, 2026

In December 2021, Philip O’Keefe, a 62-year-old Australian with ALS, took over Tom Oxley’s Twitter account and posted “Hello World” without moving his hands. Twenty months earlier, surgeons at the Royal Melbourne Hospital had guided Synchron’s Stentrode, a small tube of mesh lined with electrodes, up through a vein in his neck to a blood vessel on top of the part of his brain that controls movement. “It’s like learning to ride a bike,” O’Keefe said. “It takes practice, but once you’re rolling, it becomes natural.”

That tweet was one stop on a road that began with a cold email to the Pentagon’s research agency in 2011, and the company is still on it. This month Synchron confirmed it has paused enrolment in trials of its second-generation device while it upgrades the hardware. It says enrolment will resume once that work is done.

A cold email to DARPA

Oxley, a neurologist, says he had been thinking since 2007 about a tiny device, wired with electrodes, that could sit in a blood vessel next to the brain. In 2011, as a new PhD candidate at the University of Melbourne, he sent a cold email from a holiday in New York to Colonel Geoffrey Ling, who had just taken charge of the prosthetics programme at DARPA, the US Defense Advanced Research Projects Agency. Ling replied straight away and invited him in. Oxley sketched a presentation late into the night and caught an early bus to Washington.

Ling’s answer, as Oxley recalled it in 2016: “well, that’s interesting, no-one has been doing that at DARPA. Why don’t you go home and put a team together we’ll give you $1 million to build this thing.”

Back in Melbourne, Professor Terry O’Brien walked Oxley into the engineering department to meet Tony Burkitt and David Grayden, professors from the bionic eye and bionic ear projects, and later introduced him to Nicholas Opie, a biomedical engineer looking for a postdoctoral project. Oxley and Opie became joint leads, and co-founders. The DARPA money helped unlock a further grant from Australia’s National Health and Medical Research Council. The US Office of Naval Research Global, the Australian Defence Health Foundation, the Brain Foundation and the Royal Melbourne Hospital Neuroscience Foundation also funded the work. Synchron dates its founding to 2012 in Melbourne, by Oxley, Opie and Rahul Sharma. That year the team’s first company, SmartStent, was spun out of the university.

In February 2016 the team published its first results in Nature Biotechnology, a paper with 39 authors. Guided through blood vessels into a vein over the motor cortex of sheep, the stent-electrode recorded brain activity for up to 190 days, with signal bandwidth comparable to electrodes placed under the skull, and the vein stayed open throughout. The goal then was walking. Oxley called the device “a bionic spinal cord” that would let people with paralysis drive an exoskeleton by thought.

From sheep to people

Synchron bought SmartStent in 2016, and by April 2017 had raised a US$10 million Series A, led by Neurotechnology Investors, to start human studies. Oxley was by then in New York on a fellowship in endovascular neurosurgery at Mount Sinai, and Synchron later made New York its headquarters.

In December 2018 a second sheep study, in Nature Biomedical Engineering, showed that electrodes on a stent could also stimulate the brain from inside a blood vessel, producing responses in the animals’ facial muscles and limbs similar to those from surgically implanted electrodes. Synchron has since named Parkinson’s disease, epilepsy, depression and hypertension as possible future uses of its technology.

The first human study, SWITCH, opened at the Royal Melbourne Hospital on 27 May 2019, with neurointerventionist Peter Mitchell leading the procedures. Graham Felstead and Philip O’Keefe, both with motor neurone disease, were among its first participants. Surgeons reached the brain through the jugular vein and left the Stentrode, with its 16 electrodes, in the superior sagittal sinus, a large vein running along the top of the brain beside the motor cortex. A lead connected it to electronics placed under the skin of the chest, which sent signals wirelessly to an external unit that controlled a computer.

By then the goal had shifted from walking to the digital world. In October 2020 the team reported results from the first two participants in the Journal of NeuroInterventional Surgery. Using the implant to click and an eye tracker to move the cursor, both sent text messages, shopped online and managed their finances on their own. They typed about 14 and 20 correct characters a minute. Both were using the system at home without supervision within three months of surgery.

The FDA gave the Stentrode Breakthrough Device designation in August 2020. Khosla Ventures led a US$40 million Series B in June 2021. In July 2021 the FDA approved a US study, COMMAND, and in August the NIH backed it with a grant Synchron put at US$10 million, awarded through Carnegie Mellon University. In November 2021 TIME named the Stentrode one of its best inventions of the year.

In March 2022, ahead of the American Academy of Neurology’s annual meeting, the Melbourne team reported a year of follow-up: in four people with ALS there were no serious adverse events that led to disability or death, every device stayed in place and every vein stayed open. The full results were published in JAMA Neurology in January 2023.

Rodney Gorham, a former salesman from Melbourne with ALS, showed what that meant day to day. He used his implant to go online, send messages and play turn-based games. At the start, a click took about two and a half seconds after he thought of it; by 2023 it took half a second, a Synchron engineer told AFP. His wife, Carolyn, said the implant gave him a “slice of life”.

Into the United States

In May 2022 Synchron partnered with the ALS charity Team Gleason to bring input from people living with ALS and their caregivers into the Stentrode’s development. Oxley set out the company’s case on the TED stage the same year, in a talk titled “A brain implant that turns your thoughts into text”.

In July 2022, neurointerventional surgeon Shahram Majidi implanted the first US patient at Mount Sinai West in New York, working in an angiography suite. The patient went home 48 hours later.

In August, Reuters reported that Elon Musk had approached Oxley about a potential investment, at a time when Neuralink had not yet begun human trials. Synchron, based in Brooklyn with about 60 staff, declined to comment, and no deal was announced. Bloomberg reported that at a Neuralink meeting in July 2022, Musk said: “We should be far exceeding the Stentrode.” Reuters also reported that Max Hodak, a Neuralink co-founder who stepped down as its president in 2021, had become a Synchron investor. In October, COMMAND began enrolling at the University of Pittsburgh.

In December 2022 ARCH Venture Partners led an oversubscribed US$75 million Series C. Bill Gates’s Gates Frontier, Jeff Bezos’s Bezos Expeditions and Reliance Digital Health joined, taking total funding to US$145 million. In 2023 Andy Rasdal, a former chief executive of the glucose-monitor maker DexCom, joined Synchron’s board.

COMMAND implanted six people at Mount Sinai, the Gates Vascular Institute in Buffalo and UPMC in Pittsburgh, in collaboration with Carnegie Mellon University’s College of Engineering. The tenth and last person to receive the first-generation Stentrode across both studies was Mark, a man with ALS implanted in August 2023.

In February 2024 Synchron took a minority stake in Acquandas, a German manufacturer that layers the metals in one component of its implant, with exclusive access to that technology for medical devices. “There are millions of people with paralysis who we think are in need of this technology, and we’re preparing to produce in high volumes,” Oxley said. It also announced a registry for people with limb or motor impairment to keep up with its trials.

In September 2024 COMMAND met its primary endpoint: none of the six participants had a device-related serious adverse event that led to death or permanent increased disability within a year. The device was placed correctly in every case, with a median deployment time of 20 minutes. A preprint posted a year later reported that motor signals recorded from five of the participants stayed distinguishable from rest throughout their first year, and that electrode impedance and resting signal power on most channels did not change significantly.

Plugging into everyday technology

From 2024 Synchron linked the implant to a run of mainstream consumer products, and Mark became its test pilot.

In July 2024 Synchron announced a chat feature built on OpenAI models that suggests replies while users text. “Rather than me typing single words, I’m hitting one or two buttons or clicks, if you will, and I’ve got the majority of a sentence done,” Mark told CNBC. Oxley said the partnership was not exclusive and that Synchron shares no brain data with OpenAI. Later that month Synchron said Mark had become the first person to use an Apple Vision Pro with an implanted brain-computer interface. In September he used Amazon’s Alexa on a Fire tablet to control his home, with preset actions for lights, video calls, music, Kindle books and shopping.

In January 2025 Synchron announced a collaboration with NVIDIA, using its Holoscan platform for faster decoding on the device. At NVIDIA’s GTC conference in March, it set out a roadmap to Chiral, which it calls a foundation model of human cognition, to be trained on deidentified brain data. Synchron said it had accumulated 20 patient-years of implant experience since its clinical programme began in 2019. A video shown there featured Rodney, a Melbourne participant with ALS, using his implant and a Vision Pro to adjust lighting, play music, set the temperature and feed his dog. “This is possible because of our ability to scale large datasets, by making BCI as common as a stent insertion,” Oxley said.

On 13 May 2025 Apple announced a protocol that lets its operating systems take brain signals as a native input. Synchron says it was the first brain-computer interface company to integrate it and that it co-developed the Bluetooth-based protocol. In August, Synchron released what it called the first public demonstration of an iPad controlled entirely by thought, with Mark at the controls. “When I lost the use of my hands, I thought I had lost my independence,” he said. “Now, with my iPad, I can message my loved ones, read the news, and stay connected with the world, just by thinking.”

The same month Synchron brought in medical-device veterans for the commercial stage. Rasdal took on a full-time role as chief of staff while staying on the board, and Mark Brister, an engineer with senior research and development roles at Guidant, Medtronic and DexCom behind him, became vice-president of R&D.

The second generation

In November 2025 Synchron raised US$200 million in a Series D led by Double Point Ventures, taking total funding to US$345 million. ARCH, Khosla, Bezos Expeditions, NTI and METIS invested again. New investors included Australia’s National Reconstruction Fund Corporation, which took a A$54 million stake, the Qatar Investment Authority, IQT, T.Rx Capital, K5 Global and Protocol Labs. WIRED reported an estimated valuation of nearly US$1 billion. “We’ve built the first non-surgical brain-computer interface designed for everyday life for people with paralysis,” Oxley said.

The money was earmarked for pivotal trials, preparation for commercial launch, an expanding Cognitive AI division in New York and a new engineering hub in San Diego. Oxley said the round would also speed development of “a next-generation, transcatheter high-channel whole-brain interface”. In March 2026 Fast Company ranked Synchron eighth among its most innovative data science companies of the year.

The second-generation Stentrode has fewer electrodes and is fully wireless, connecting over Bluetooth. Oxley told the Herald Sun in March 2026 that it could recognise up to 16 different commands. Three Synchron studies started this year, matching the trials WIRED describes: FOCUS-CAN at two Toronto hospitals on 18 March, INTENT at five US sites on 7 May, and FOCUS-AUS on 22 May at the Royal Melbourne Hospital, where SWITCH had opened seven years earlier.

November 2026: the pause

In November WIRED reported that the trials had paused enrolment after the new device did not perform as expected in early participants. Synchron said it paused voluntarily “after identifying a performance issue involving the lead, the cable that carries signals from the Stentrode to the implanted electronics.” The company said the problem does not involve the Stentrode itself and that no safety issues related to the device have been found. It said the FDA did not direct the pause. It has brought design and manufacturing of the lead in-house, is upgrading the whole Stentrode system, and will resume enrolment when the upgrades are complete. “We will continue to support participants with Stentrode devices across their lifetime,” it said.

The registry entry for the Canadian study lists it as terminated in September for insufficient recruitment, with one participant enrolled. WIRED also reported that Synchron is cutting jobs and scaling back in New York while it builds up the San Diego team. Synchron’s careers page, checked on 13 November, listed 13 open roles in San Diego and described the next system as reaching “all regions of the brain through a catheter, not a hole in the skull”.

“We still have strong confidence that it has the potential to be a first-line therapy,” Oxley said of the Stentrode.

The significance of Synchron’s approach

Synchron’s founding bet is that the brain can be reached with the catheter techniques commonly used to treat stroke, and that a brain-computer interface placed that way could one day be as routine as a stent. Fifteen years in, it has reported safety results from the ten people who received its first-generation device, made the implant work with mainstream consumer devices, and drawn investors from the United States, Australia, Qatar and India.

Neuralink had its own early hardware problem: weeks after its first implant in 2024, several of the device’s threads came out of the brain, and the company restored cursor control by changing its recording software. Synchron’s current problem sits in the lead of the second-generation device. The company says it will upgrade the hardware and restart enrolment. These early studies come before the larger pivotal trial the FDA needs before it can approve the device for sale.

Forward Radar: What to watch from here

Whether the INTENT and FOCUS-AUS registry entries return to recruiting, and when.

What the San Diego team’s whole-brain device turns out to be, and how it is placed.

Whether Synchron publishes data from Chiral or from its home-use trial participants.

When the pivotal trial starts, and how many sites it uses.

Key dates

2011: Tom Oxley emails DARPA from New York and is offered US$1 million to build the device.
2012: SmartStent is spun out of the University of Melbourne. Synchron dates its founding to this year.
February 2016: The sheep study appears in Nature Biotechnology.
2016: Synchron buys SmartStent.
2017: A US$10 million Series A funds the move to human studies.
December 2018: A second sheep study shows a stent-mounted electrode can stimulate the brain from inside a vein.
27 May 2019: The SWITCH study opens at the Royal Melbourne Hospital.
April 2020: Philip O’Keefe receives his implant.
August 2020: The FDA grants Breakthrough Device designation.
October 2020: First results from two participants are published.
June 2021: Khosla Ventures leads a US$40 million Series B.
July 2021: The FDA approves the US COMMAND study.
August 2021: The NIH backs COMMAND.
November 2021: TIME lists the Stentrode among its best inventions.
December 2021: O’Keefe posts “Hello World” by thought.
March 2022: Twelve-month safety results from four Melbourne patients are released.
May 2022: Team Gleason partnership begins.
July 2022: The first US patient is implanted at Mount Sinai West.
August 2022: Reuters reports Elon Musk’s approach.
December 2022: ARCH leads a US$75 million Series C, with Gates Frontier and Bezos Expeditions.
January 2023: SWITCH results appear in JAMA Neurology.
August 2023: Mark becomes the tenth first-generation patient.
February 2024: Synchron takes a stake in Acquandas.
July 2024: OpenAI-powered chat feature announced; first Vision Pro use.
September 2024: Alexa integration; COMMAND meets its primary endpoint.
January 2025: Collaboration with NVIDIA announced.
March 2025: The Chiral roadmap is unveiled at NVIDIA GTC.
May 2025: Apple announces its brain-computer interface protocol, which Synchron says it co-developed.
August 2025: First public iPad demonstration; Andy Rasdal and Mark Brister join the executive team.
November 2025: Double Point Ventures leads a US$200 million Series D.
March 2026: Synchron’s Canadian study begins.
May 2026: US and Australian studies begin.
November 2026: WIRED reports the enrolment pause, and Synchron confirms it while it upgrades the hardware.

Sources

Origins:

Clinical studies:

Funding, partners and people:

The pause:

Cross-reference to prior InsideBCI coverage:

market Synchron Stentrode Tom-Oxley Nicholas-Opie DARPA University-of-Melbourne Royal-Melbourne-Hospital Mount-Sinai SWITCH COMMAND Apple BCI-HID Chiral NVIDIA endovascular-BCI Australia