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Brain–spine interfaces

A digital bridge around a spinal cord injury. Implants read movement intentions from the cortex and turn them into stimulation of the lumbar cord, so that a person with paralysis can stand and walk under their own control.

Updated 2026-10-024 sources

Depth:

Why it matters

A spinal cord injury interrupts communication between the brain and the part of the cord that produces walking [1]. A brain–spine interface tries to restore that communication with a digital bridge [1].

What it is

In the first published brain–spine interface, fully implanted recording and stimulation systems linked cortical signals to the modulation of epidural electrical stimulation of the cord regions that produce walking [1]:

  • Two cortical implants, each a grid of 64 electrodes, were placed epidurally over the sensorimotor cortex to record electrocorticographic (ECoG) signals [1].
  • A processing unit predicted motor intentions and translated them into changes to stimulation programs aimed at the dorsal root entry zones of the lumbosacral cord [1].
  • Stimulation was delivered by an implanted pulse generator through a 16-electrode paddle lead [1].

How it works

The decoder predicted which joint the person intended to move, the hip, knee or ankle on each side, or rest, and the direction and relative size of the movement [1]. These predictions updated joint-specific stimulation programs, constrained to preset ranges [1]. Wireless modules let the location and timing of stimulation change in real time with a latency of about 100 ms[1].

It builds on earlier work: stimulation targeting individual dorsal root entry zones of the lumbosacral cord can modulate specific leg motor pools, and spatiotemporal stimulation timed to intended movement re-established control of paralysed muscles during walking [1, 2].

The decoding used a recursive, exponentially weighted Markov-switching multi-linear model: a gating classifier chose the joint and experts predicted direction and amplitude [1]. The digital bridge lab simulates a simplified version and labels what it leaves out.

CortexDevicesLumbosacral cordLegsSensorimotor cortexintention to moveECoG implants64 electrodes eachDecoderjoint, directionPulse generator16-electrode paddleDorsal root entry zonesLeg muscles
Brain–spine interfaceCortical implants record movement intentions above the injury; a processing unit decodes them and updates stimulation of the lumbosacral cord below it, which activates the leg muscles.
  • Excitatory synapse (filled arrowhead)
  • Inhibitory synapse (bar)
  • Modulatory (open circle)
  • Signal or data flow, not a synapse (dashed)
  • Midline crossing (decussation)
Figure 1. Brain–spine interface. Cortical implants record movement intentions above the injury; a processing unit decodes them and updates stimulation of the lumbosacral cord below it, which activates the leg muscles.[1] Schematic
  • The stimulation could be adjusted in real time with a latency of about 100 ms.[1]
Text description of this diagram
  1. Cortical implants record movement intentions above the injury; a processing unit decodes them and updates stimulation of the lumbosacral cord below it, which activates the leg muscles.
  2. Sensorimotor cortex (midline, Cortex) to ECoG implants (midline, Devices); signal or data flow (not a synapse).
  3. ECoG implants (midline, Devices) to Decoder (midline, Devices); signal or data flow (not a synapse); wireless.
  4. Decoder (midline, Devices) to Pulse generator (midline, Lumbosacral cord); signal or data flow (not a synapse); stimulation update.
  5. Pulse generator (midline, Lumbosacral cord) to Dorsal root entry zones (midline, Lumbosacral cord); signal or data flow (not a synapse); epidural stimulation.
  6. Dorsal root entry zones (midline, Lumbosacral cord) to Leg muscles (midline, Legs); signal or data flow (not a synapse); motor pools.

The numbers

The trial participant was a 38-year-old man with an incomplete cervical (C5/C6) spinal cord injury from a cycling accident ten years earlier [1]. The interface could be calibrated within a few minutes, and its reliability stayed stable over one year, including during independent use at home [1].

In theatre and clinic

The participant reported natural control over his legs to stand, walk, climb stairs and cross complex terrain [1]. With rehabilitation supported by the interface, he regained the ability to walk with crutches overground even with it switched off [1]. These are results from one person in a clinical trial.

Frontier

Each entry shows its evidence tier and what it does not show [1, 3].

  • T1 peer-reviewed human studyA brain-spine interface lets a man with tetraplegia walk again2023-05 · as of 2026-10-02 · trial

    Two 64-electrode implants over the sensorimotor cortex read the intention to move a hip, knee or ankle; a decoder turns it into stimulation of the lumbosacral cord through an implanted paddle lead. The participant, with an incomplete cervical injury from ten years earlier, stood, walked and climbed stairs; the system stayed reliable for a year including use at home, and he regained some walking with crutches even with it switched off.

    What it does not show: One participant, with an incomplete injury and earlier stimulation training. It does not repair the cord, and it is not an approved treatment.

    Sources and details

The AI connection

The bridge is a decoder: a model fitted to map brain signals to intended movement and then to stimulation, much as brain–computer interfaces decode intended cursor or hand movements [1, 4].

Common misconceptions

Misconception: A brain–spine interface repairs the injured cord.

It bypasses the injury: it reads intentions above it and stimulates the cord below it [1].

Check yourself

Where were the cortical implants placed?

Epidurally over the sensorimotor cortex, one for each side's leg movements [1].

What does the stimulation target?

The dorsal root entry zones of the lumbosacral spinal cord [1].

Read next

References

  1. Lorach H, Galvez A, Spagnolo V, Martel F, Karakas S, Intering N, et al.. Walking naturally after spinal cord injury using a brain–spine interface. Nature. 2023;618(7963):126-133. doi:10.1038/s41586-023-06094-5
  2. Wagner FB, Mignardot JB, Le Goff-Mignardot CG, Demesmaeker R, Komi S, Capogrosso M, et al.. Targeted neurotechnology restores walking in humans with spinal cord injury. Nature. 2018;563(7729):65-71. doi:10.1038/s41586-018-0649-2
  3. Rowald A, Komi S, Demesmaeker R, Baaklini E, Hernandez-Charpak SD, Paoles E, et al.. Activity-dependent spinal cord neuromodulation rapidly restores trunk and leg motor functions after complete paralysis. Nature Medicine. 2022;28(2):260-271. doi:10.1038/s41591-021-01663-5
  4. Wolpaw JR, Birbaumer N, McFarland DJ, Pfurtscheller G, Vaughan TM. Brain–computer interfaces for communication and control. Clinical Neurophysiology. 2002;113(6):767-791. doi:10.1016/s1388-2457(02)00057-3

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