The sleep frequency

US patent 12,350,524 describes a device you strap to a patient’s head. It fires a focused ultrasound beam at the hippocampus, pulsing at one to four hertz. That frequency range is not arbitrary. It is the rate at which neurons fire during deep slow-wave sleep, the phase when the brain’s glymphatic system flushes cerebrospinal fluid through interstitial tissue, carrying away metabolic waste. The patent’s target waste product: amyloid plaque, the protein debris that accumulates in Alzheimer’s disease.

The assignee is Brainsonix Corporation, a small company in Los Angeles. The inventor is Alexander Bystritsky, a UCLA psychiatrist with over 200 published papers who spent the first half of his career running the university’s Anxiety Disorders Clinic. Somewhere in the middle, he became convinced that sound waves aimed at specific brain structures could do what drugs and electrodes could not: reach deep tissue non-invasively, with millimeter precision, and without surgery. He founded Brainsonix to test the idea.

That patent, granted July 8, 2025, encodes a specific bet: that if you replay the brain’s own cleaning rhythm using acoustic energy from outside the skull, you can trigger the waste-removal process on demand. If it works, it means an Alzheimer’s patient could sit in a chair for thirty to ninety minutes with a transducer on their head, and their brain would clear plaque the way a healthy brain does during deep sleep. No incision. No anesthesia. No antibody infusion at $26,000 per year.

The bet sounds speculative. The clinical data behind it is not.

144 trials and counting

Focused ultrasound aimed at the brain is not a single technology. It is one physical mechanism being dialed to different power levels for different effects, the way a garden hose can mist, stream, or blast.

At high intensity, focused ultrasound ablates tissue. Insightec, an Israeli company, won FDA approval in 2016 for its Exablate Neuro system, which uses MRI-guided focused ultrasound to destroy a small cluster of neurons in the thalamus that cause essential tremor. Patients go home the same day. In clinical trials, tremor and motor function improved by nearly 50 percent at three months. The FDA extended the approval to tremor-dominant Parkinson’s disease in 2018 and to bilateral treatment in 2022. For the roughly 7 million Americans with essential tremor who don’t respond to medication, this replaced brain surgery with sound.

At medium intensity combined with microbubbles injected into the bloodstream, focused ultrasound does something different: it temporarily opens the blood-brain barrier. The BBB is the molecular fence that keeps nearly all drugs out of the brain. It protects you from blood-borne pathogens, but it also blocks 98 percent of small-molecule therapeutics and essentially all large-molecule drugs like antibodies. This is why neurological diseases are so hard to treat. The drugs exist; they just can’t get in.

In January 2024, the New England Journal of Medicine published results from a trial combining focused ultrasound BBB opening with aducanumab, Biogen’s controversial amyloid-targeting antibody for Alzheimer’s. In the three patients treated, amyloid-beta levels dropped more in the brain regions where ultrasound had opened the barrier than in untreated regions. The sample was tiny, but the venue was the most selective medical journal in the world, and the implication was direct: focused ultrasound could make existing Alzheimer’s drugs work better by getting them to the tissue they’re designed to target.

A 2023 trial led by Jin Woo Chang at Korea University Anam Hospital in Seoul went further, testing whether BBB opening alone, without any antibody drug, could reduce amyloid. In four of six patients, it did. Chang’s team had opened the BBB in frontal brain regions repeatedly over multiple sessions and saw amyloid levels fall. Two patients didn’t respond, but this was the first trial to demonstrate plaque reduction from focused ultrasound alone, as reported in the Journal of Neurosurgery.

At low intensity, focused ultrasound modulates neurons directly. That’s where Bystritsky’s Brainsonix patent sits. The University of Minnesota holds a 2025 patent (US 12,329,991) for a wearable ultrasound patch that delivers continuous transcranial focused ultrasound from a lightweight, conformable device, moving the technology from an MRI suite to something a patient could wear at home. The clinical trial pipeline at this power level now includes treatment-resistant depression, epilepsy, schizophrenia, substance use disorders, and brain injury recovery.

Altogether, our clinical trials database lists 144 registered studies involving focused ultrasound for brain conditions. The literature has kept pace: 855 academic papers since 2005 on transcranial focused ultrasound neuromodulation, growing from 8 per year to 146 in 2025. And 64 US patents have been granted, more than half of them since 2020.

Why the barrier matters most

The clinical applications are diverse, but the single most consequential use may be the simplest: opening a door.

The blood-brain barrier blocks drug delivery to the central nervous system. This fact shapes the entire pharmaceutical economics of neurology. Companies spend billions developing molecules that work in a dish but fail in a skull. Aducanumab costs roughly $26,000 a year and works poorly in part because so little of it reaches the brain tissue where amyloid lives. Focused ultrasound BBB opening doesn’t replace the drug. It makes the drug’s existing dose actually arrive where it’s needed.

If that scales, it changes the economics of every CNS drug in development. Not by inventing new molecules but by removing a delivery bottleneck that has constrained neurological pharmacology for decades. The pipeline of drugs waiting behind that bottleneck is enormous: antibodies for tau, for alpha-synuclein, for TDP-43, gene therapies for rare neurological conditions. Every one of them faces the same barrier problem. Solve it once with ultrasound and you have a platform, not a product.

From MRI suite to wearable patch

The practical bottleneck today is hardware. Insightec’s Exablate Neuro requires a full MRI scanner for guidance, which limits the procedure to major medical centers and costs $15,000 to $30,000 per treatment. The technology works, but it doesn’t scale to the 6.9 million Americans living with Alzheimer’s or the 10 million with Parkinson’s.

That’s what makes the Minnesota wearable patch patent significant. Their device uses a coarse-aperture transducer array with reduced channel count and full-duplex transmit-receive circuitry for real-time monitoring, all fitted into a conformable patch. If transcranial ultrasound can move from a shielded MRI room to an outpatient clinic or a living room, the addressable patient population changes by orders of magnitude.

Bystritsky’s Brainsonix is chasing the same goal from a different direction: a portable transducer system simple enough that a treatment session looks more like a sleep study than a surgical procedure. His deep-sleep-frequency approach requires no microbubbles, no MRI guidance, and no contrast agents. Just a sound wave tuned to the rhythm your brain already uses when it takes out the trash.

The origin and the opening

The ultrasound transducer has been in clinical use since the 1950s, when Ian Donald in Glasgow began using it to image fetuses. For sixty years it was a diagnostic instrument: sound goes in, echo comes back, you look at the picture. The idea that you could reverse the arrow, push enough acoustic energy through the skull to change what’s happening inside, seemed physically implausible. The skull is thick, irregularly shaped, and it scatters sound waves badly.

Sunnybrook Research Institute in Toronto, which holds seven US patents in this space, has spent years solving that scattering problem. Their most recent patent (US 12,318,637, granted June 2025) describes a system that dynamically corrects for skull-induced beam distortion in real time, compensating for the fact that the skull heats up during treatment and changes the speed of sound through bone. That kind of engineering detail is what separates an academic concept from a device that works on every patient’s skull, not just the ones with convenient anatomy.

Sixty-four patents, 144 clinical trials, 855 papers, and one FDA-cleared device already treating patients. A UCLA psychiatrist betting he can replay your sleep rhythm with a speaker pressed to your temple. The sound wave that used to show you a picture of your baby is learning to clean your brain.

Method note

Patent counts are from 9.3M US utility and design grants sourced from USPTO bulk grant XML, filtered by full-text search for “ultrasound” co-occurring with brain/neural/transcranial stimulation and modulation terms. Clinical trial counts are from a local mirror of 541K ClinicalTrials.gov studies, filtered by title keywords for focused or transcranial ultrasound and neurological conditions. Literature counts are from 357M scholarly works in OpenAlex. Insightec clinical outcomes from Practical Neurology and the Focused Ultrasound Foundation. NEJM trial results (aducanumab + FUS) published January 2024. Korean BBB-opening trial (Chang et al.) published in Journal of Neurosurgery, 2023. Brainsonix and Dr. Bystritsky background from company website and UCLA faculty records. The 2025 patent and literature counts are partial-year through late September.