Bypass eyes and ears. Read intent from cortex, write signals back. Once medical-only — now an arms race.
Each neuron fires action potentials at variable rates — millivolt spikes lasting roughly a millisecond. Cognition emerges from the patterns across populations.
No surgery, no risk — but the bone and scalp blur the signal. You measure populations of millions, not individual neurons.
All four trade fidelity for safety. None will give you a smooth cursor.
Reading isn't telepathy. It's measuring intent — the motor signals that would have moved a hand or shaped a sound — and translating them into text or motion.
Send pulses into nerve or cortex, the brain learns to read them as sound, sight, or sensation. Write-mostly BCIs are the oldest commercial neurotech — and the most successful.
The Stentrode is a mesh of electrodes placed via blood vessels — threaded up the jugular into the superior sagittal sinus, sitting against motor cortex from inside a vein.
Founded by Neuralink co-founder Ben Rapoport. Lays a thin polyimide film with 1,024 microelectrodes onto the cortical surface — through a slit-like incision, no penetration of brain tissue.
Trade-off: ECoG-class signal — not single neurons, but huge spatial coverage. The "safe upgrade" pitch.
Also: epilepsy responsive stimulation, treatment-resistant depression trials, tinnitus suppression. The medical track record is real and growing.
The gap between "works in a lab on five patients" and "costs $300 at Best Buy" is wider than the marketing suggests.
Two completely different timelines collapsed into one word.
Medical BCI works. Paralysis, speech, deafness, Parkinson's — measurable wins, multi-decade track record. The science is competitive, well-funded, and shipping.
Consumer BCI — meaningful enhancement of a healthy brain — is decades away. Surgery risk, signal density, biocompatibility, and FDA pathways all bind. Don't believe the demo reels.
The right framing: BCI is a medical revolution that will eventually spill into consumer use. We are early, and the early stories are the medical ones.
Companies cited: Neuralink, Synchron, Precision Neuroscience, BrainGate consortium, Medtronic (DBS), Cochlear Ltd. Decoding speech: UCSF / Stanford labs (Chang, Henderson, Shenoy).