The Layer 7 Cortical Interface: A Scalable and Minimally Invasive Brain–Computer Interface Platform

May combine two claims.

For each electrode size, EIS showed the usual rise in cutoff frequency as size decreased, and 1 kHz impedance increased as expected with smaller electrodes.

“EIS measurements for each electrode size display typical positive shifts in cutoff frequencies with decreases in electrode size, and impedance magnitude at 1 kHz also follows the expected upward trend with decreasing electrode size (Figure 2b).”

May combine two claims.

The platform supported dense neural recording, localized cortical stimulation, and accurate decoding of neural signals.

“We further demonstrate the performance of this system for high-density neural recording, focal cortical stimulation, and accurate neural decoding.”

May combine two claims.

The strongest activation formed a ring about 1 mm in radius around the stimulating electrode, sparing the area immediately next to it.

“The most highly activated region formed an annulus of radius approximately 1 mm around, but not immediately surrounding the stimulating electrode.”

May combine two claims.

Each custom amplifier PCB contains eight RHD2164 64-channel amplifier chips and one RHS2116 16-channel stimulator/amplifier chip, enabling simultaneous recording from up to 528 channels and stimulation from up to 16 channels.

“The custom amplifier printed circuit boards (PCBs) used to interface with the implanted electrode arrays each contained eight of the RHD2164 64-channel amplifier chips and one of the RHS2116 16-channel stimulator/amplifier chips, allowing for simultaneous recording from up to 528 channels and stimulation from up to 16 channels.”

May combine two claims.

The authors defined a safe stimulation regime for thin-film surface microelectrodes, reached visual cortex minimally invasively, confirmed placement over working visual cortex, stimulated it, and recorded evoked activity.

“Here we characterize a safe operating regime for cortical stimulation from thin-film cortical surface microelectrodes, demonstrate the ability to access visual cortex in a minimally invasive fashion, electrophysiologically confirm array placement over functioning visual cortex, stimulate the cortical surface, and monitor stimulus-evoked cortical activity.”

May combine two claims.

The platform offers many channels, dense electrode coverage, and two-way function.

“The system provides high channel counts and high spatial densities of electrode coverage, as well as bidirectional functionality (both neural recording and neural stimulation).”

May combine two claims.

CV measurement placed the water window at about 1.85 V, with cathodic and anodic limits of 0.65 V and 1.2 V.

“Briefly, the water window was determined by CV measurement to be approximately 1.85 V (with a 0.65 V cathodic and 1.2 V anodic limit), and biphasic pulses were applied at 50 Hz to a test electrode within the range of anticipated stimulation parameters to confirm safe stimulation (Figure 7a).”

May combine two claims.

Impedance mapping in vivo indicated high electrode yield and uniform impedance.

“In vivo electrode impedance mapping results confirm high electrode yield and impedance uniformity (Figure 2b, inset).”

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The authors demonstrated three core functions: recording, decoding, and cortical stimulation.

“However, certain functions are commonly required of braincomputer interfaces, and we demonstrate three key functions here: neural recording, neural decoding, and cortical stimulation.”

May combine two claims.

Decoding with many electrodes across the whole array outperformed any single electrode, reaching 73% accuracy for the left and 67% for the right in offline analysis.

“Multichannel decoding using the large number of electrodes available from the entire array was more robust than decoding using any single electrode, with accuracies reaching 73% on the left and 67% on the right in off-line decoding.”

May combine two claims.

The implanted arrays recorded neural activity across many channels, including spontaneous cortical activity, somatosensory evoked responses, and visual evoked responses.

“Implanted arrays were used for multichannel neural recording using several paradigms, capturing both spontaneous cortical electrographic activity (Figure 5b) as well as somatosensory evoked potentials (Figure 5e) and visual evoked potentials (Figure 5f).”

May combine two claims.

The arrays can be linked modularly and inserted together at an effective rate above 40 s per cm2 of cortex.

“The effective area of the microelectrode arrays described here is 0.48 cm 2 per 529-channel module, and we have demonstrated that these arrays can be connected in a modular fashion and inserted simultaneously, at an effective rate exceeding 40 s per cm 2 of cortical surface.”

May combine two claims.

The team inserted double modules in vivo (1,058 channels over 0.96 cm2) and quadruple modules in vitro (2,116 channels each over 1.92 cm2).

“We performed in vivo insertions of doubly connected modules (1,058 channels over 0.96 cm 2 of cortical surface area), and in vitro insertions of quadruply connected modules (2,116 channels each covering 1.92 cm 2 of surface area).”

May combine two claims.

A double module halved the effective average insertion rate, and in vivo speeds reached under 20 ms per electrode.

“We note that use of a doubly connected module halves the effective average insertion rate, and in this manner have achieved effective speeds as fast as <20 ms per electrode in vivo.”

May combine two claims.

The authors showed that high-density microelectrode arrays could be inserted safely and feasibly with a new minimally invasive cranial micro-slit method.

“We have demonstrated the safety and feasibility of inserting our high-density microelectrode arrays using a novel, minimally invasive “cranial micro-slit” technique (Figure 3).”

May combine two claims.

Delivering 50,000 pulses at 10 nC per phase and 100,000 at 20 nC per phase (50 and 100 μA, 200 μs width) left test electrode impedance unchanged and kept polarization potentials inside the water window.

“A total of 50,000 pulses of 10 nC per phase and 100,000 pulses of 20 nC per phase (50 and 100 µA respectively with a 200 µs pulse width) were found to cause no change in impedance on the test electrode, as well as polarization potentials within the water window, so stimulation currents in this range were determined to be acceptable for the 30 pulses per electrode used in vivo.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Intraoperative endoscopic view immediately following subdural placement of one thin-film array shows the electrode tail and traces entering the subdural space through a cranial slit.

“(b) Intraoperative endoscopic view immediately following subdural placement of one thin-film array, after shim removal, showing the electrode tail and traces entering the subdural space through a cranial slit”

Probably not a substantial claim: may not pass S3 (load-bearing).

Intraoperative fluoroscopic image shows four 529-electrode arrays in place, two over each hemisphere.

“(d) Intraoperative fluoroscopic image (dorsoventral projection) showing four 529-electrode arrays in place, two over each hemisphere.”

May combine two claims.

Somatosensory evoked potentials correspond to tactile stimulation of the left hindlimb, with traces spanning 1 s and maximum peak-to-peak signal approximately 80 μV.

“(e) Somatosensory evoked potentials corresponding to tactile stimulation of the left hindlimb.Traces span 1 s and the maximum peak-to-peak signal is approximately 80 µV.”

May combine two claims.

The Layer 7 Cortical Interface acquires neural activity and delivers stimulation.

“This schematic illustration shows how neural activity is acquired from and stimulated by the Layer 7 Cortical Interface.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The sampling rate for recording is set at 20 kHz per channel, generating data at a rate over 2.5 GB per minute for each set of 1,024 channels.

“The sampling rate for recording is set at 20 kHz per channel, generating data at a rate over 2.5 GB per minute for each set of 1,024 channels.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The recording computers interface with either controller via a custom configuration of Intan RHX Data Acquisition Software, allowing real-time event-triggered averaging.

“The recording computers interface with either controller via a custom configuration of the Intan Technologies RHX Data Acquisition Software, which allows for real-time event-triggered averaging in addition to base functionality.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Each amplifier board allows a hardware reference from one of 16 sites distributed across the array.

“In addition, each board allows for a hardware reference from one of 16 sites distributed across the array.”

May combine two claims.

More distant regions exhibit less evoked activity while still being responsive to stimulation.

“While still being responsive to stimulation, more distant regions exhibit less evoked activity.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Visual evoked potentials are obtained from photostimulation of the left eye.

“(f) Visual evoked potentials from photostimulation of the left eye.”

Classified as probably not a substantial claim.

Electrocorticography has facilitated capture of high-quality signals for effective use in brain-computer interfaces in several applications, including motor and speech neural prostheses.

“In practice, electrocorticography (ECoG) has already facilitated capture of high quality signals for effective use in brain-computer interfaces in several applications, including motor and speech neural prostheses 7,22,24,56,[64][65][66][67][68][69][70] .”

• cites 7,22,24,56,[64][65][66][67][68][69][70]Not checked yet

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May combine two claims.

Non-penetrating cortical surface microelectrodes are a potentially attractive alternative and form the basis of the described system.

“For this reason, non-penetrating cortical surface microelectrodes represent a potentially attractive alternative and form the basis of the system described here 53,63 .”

• cites [53] Wellman, S. M. et al. A Materials Roadmap to Functional Neural Interface Design. Adv. Funct. Mater. 28, 1701269 (2018). sourceNot checked yet

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• cites [63] 2017, Epidemiology of worldwide spinal cord injury: a literature review, JN sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

High-density microelectrode arrays have been replacing macroelectrode arrays, offering smaller features and improved spatial resolution.

“As a result, high-density microelectrode arrays have been replacing more traditional macroelectrode arrays, offering smaller features and improved spatial resolution [53][54][55][56][57][58] .”

• cites [53][54][55][56][57][58]Not checked yet

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May combine two claims.

Existing brain-computer interfaces depend on invasive surgery or electrodes that penetrate the brain, which restricts the applications they can address and the number of patients eligible.

“Existing brain-computer interfaces rely on invasive surgical procedures or brain-penetrating electrodes, which limit addressable applications of the technology and the number of eligible patients.”

• cites 20,[59][60][61][62]Not checked yet

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Classified as probably not a substantial claim.

It is not yet clear whether softer penetrating electrodes offer a substantially different tradeoff.

“It is not yet clear whether approaches involving softer penetrating electrodes offer a substantially different tradeoff 20,59 .”

• cites [20] sourceNot checked yet

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• cites [59] Lamont, C. et al. Silicone encapsulation of thin-film SiO x, SiO x N y and SiC for modern electronic medical implants: a comparative long-term ageing study. J. Neural Eng. 18, 055003 (2021). sourceNot checked yet

  Not checked in the free run.

May combine two claims.

Penetrating microelectrode arrays enable high-spatial-resolution recordings for brain-computer interfaces but cause invasiveness and tissue damage that increase with the number of implanted electrodes.

“Microelectrode arrays that penetrate the brain have facilitated high-spatial-resolution recordings for brain-computer interfaces, but at the cost of invasiveness and tissue damage that scale with the number of implanted electrodes 20,[59][60][61][62] .”

• cites 20,[59][60][61][62]Not checked yet

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May combine two claims.

Surface micro-electrocorticography arrays offer an appealing balance between invasiveness and signal quality and are attractive alternatives or complements to penetrating arrays.

“For these reasons surface microarrays (micro-electrocorticography or µECoG arrays) embody an appealing tradeoff between invasiveness and signal quality, and are attractive as an alternative or complement to arrays of electrodes that penetrate the cortical surface.”

May combine two claims.

Penetrating microelectrode arrays enable single-cell recording but are more invasive and vary in tissue damage and long-term stability.

“Microelectrode arrays that penetrate the brain facilitate single-cell recordings, at the cost of greater invasiveness, with varying degrees of brain tissue damage and long-term stability [92][93][94] .”

• cites [92][93][94]Not checked yet

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May combine two claims.

The arrays are intended for subdural placement through 400 μm skull cuts made with a precision oscillating blade, with real-time imaging and fiberoptic endoscopy, at over 1,000 electrodes per minute.

“The microelectrode arrays are designed to be inserted into the subdural space through 400-micron-wide skull incisions made using a precision oscillating blade, guided by real-time imaging and fiberoptic endoscopy, at a rate of more than 1,000 electrodes per minute, and to provide 1,000-fold higher electrode density than standard cortical grids.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Recent studies have shown that high-density electrocorticography can decode speech representations, allowing words and short sentences to be articulated.

“More recent work has demonstrated the utility of high-density ECoG in decoding neural representations of speech, enabling the articulation of words and short sentences 6,69,99 .”

• cites [6] sourceNot checked yet

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• cites [69] Vomero, M. et al. Conformable polyimide-based μECoGs: Bringing the electrodes closer to the signal source. Biomaterials 255, 120178 (2020). sourceNot checked yet

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• cites [99] sourceNot checked yet

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May combine two claims.

Activity near kilohertz frequencies can be relatively uncorrelated even over short distances, which fits nearby but weakly coupled neurons.

“High-frequency activity approaching the kilohertz range can exhibit relatively uncorrelated activity even at short range, consistent with the coexistence of nearby but relatively uncoupled neurons.”

May combine two claims.

The platform may speed progress in decoding and encoding neural signals and may broaden the group of patients who could benefit from neural interfaces.

“Such a system promises to accelerate efforts to better decode and encode neural signals, and to expand the patient population that could benefit from neural interface technology.”

• AssumptionRests on an assumption: Safety and feasibility in Göttingen minipigs predict safety and feasibility in humans.

May combine two claims.

The Layer 7 Cortical Interface is a modular, scalable, and minimally invasive brain-computer interface platform.

“The system we describe here, the Layer 7 Cortical Interface, is a modular, scalable, minimally invasive brain-computer interface platform.”

Classified as probably not a substantial claim.

Electrocorticography and micro-electrocorticography have enabled high-resolution temporal and spatial recordings useful in vivo, including for brain-computer interfaces.

“In practice, however, electrocorticography (ECoG) and microelectrocorticography (µECoG) have facilitated high temporal-and spatial-resolution recordings for effective use in in vivo applications 56,64,65 , including brain-computer interfaces.”

• cites [56] Deku, F. et al. Amorphous silicon carbide ultramicroelectrode arrays for neural stimulation and recording. J. Neural Eng. 15, 016007 (2018). sourceNot checked yet

  Not checked in the free run.

• cites [64] 2021, A Systematic Review of the Incidence, Prevalence, Costs, and Activity and Work Limitations of Amputation, Osteoarthritis, Rheumatoid Arthritis, Back Pain, Multiple Sclerosis, Spinal Cord Injury, Stroke, and Traumatic Brain Injury in the United States: A 2019 Update. Archives of Physical Medicine and RehabilitationNot checked yet

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• cites [65] sourceNot checked yet

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Probably not a substantial claim: may not pass S4 (based).

The platform is intended to bring high-density, high-channel-count neural interfaces to the many millions of neurologic patients who could benefit.

“The system is designed to deliver the benefits of high-density, high-channel-count neural interfaces to the millions of patients with neurologic disorders who stand to benefit from this technology.”

Probably not a substantial claim: may not pass S4 (based).

The arrays are intended to give 1,000 times the electrode density of standard cortical grids.

“The microelectrode arrays are designed to be inserted into the subdural space through 400-micron-wide skull incisions made using a precision oscillating blade, guided by real-time imaging and fiberoptic endoscopy, at a rate of more than 1,000 electrodes per minute, and to provide 1,000-fold higher electrode density than standard cortical grids.”

May combine two claims.

Brain-computer interface decoding can work with multiunit activity, local field potentials, or micro-electrocorticography, and does not require single-unit spikes.

“Effective neural decoding for brain-computer interfaces can be achieved using multiunit activity, local field potentials, or micro-electrocorticography, without relying on single-unit action potentials 22,[84][85][86][87][88][89][90][91] .”

• cites 22,[84][85][86][87][88][89][90][91]Not checked yet

  Not checked in the free run.

May combine two claims.

The platform can be deployed quickly and minimally invasively over large cortical areas, reversibly and without trauma.

“Here we have described a modular and highly scalable brain-computer interface platform capable of rapid, minimally invasive surgical deployment over multiple large areas of the cortical surface in a reversible and atraumatic manner.”

May combine two claims.

New thin-film micro-electrocorticography arrays have safely conformed to the brain for months and reliably recorded multi-unit and single-unit activity in some locations.

“Recently developed thin-film µECoG arrays have demonstrated the ability to conform to the brain surface safely for several months while reliably recording multi-unit and single-unit activity in certain anatomic settings 53,57 .”

• cites [53] Wellman, S. M. et al. A Materials Roadmap to Functional Neural Interface Design. Adv. Funct. Mater. 28, 1701269 (2018). sourceNot checked yet

  Not checked in the free run.

• cites [57] Li et al. Ultra-Long-Term Reliable Encapsulation Using an Atomic Layer Deposited HfO2/Al2O3/HfO2 Triple-Interlayer for Biomedical Implants. Coatings 9, 579 (2019). sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

Multiple groups have used surface arrays to link neural activity to motor function for controlling prostheses in patients with physical impairment.

“Several groups have used surface array techniques to correlate neural activity with motor function for the control of neural prostheses in physically impaired patients 7,67,68,[95][96][97][98] .”

• cites 7,67,68,[95][96][97][98]Not checked yet

  Not checked in the free run.

May combine two claims.

Surface-conforming arrays are much less invasive, easier to insert and remove without tissue damage, and possibly more stable long-term, though being farther from neurons may limit single-cell communication.

“Microelectrode arrays that conform to the brain surface are considerably less invasive, more easily inserted and removed without damage to brain tissue, and potentially more stable in the long-term, but their greater distance from target neurons may limit single-cell communication.”

Probably not a substantial claim: may not pass S4 (based).

General anesthesia was maintained with isoflurane at levels sufficient to produce analgesia without suppressing electrocorticographic activity.

“General anesthesia was maintained with isoflurane at levels sufficient to produce analgesia without suppressing electrocorticographic activity, a balance that was facilitated by the minimally invasive nature of the procedure.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A stimulation waveform was used for in vitro confirmation of safe polarization potential.

“(a) Stimulation waveform used for in vitro confirmation of safe polarization potential, with the 100 µA current overlaid on the waveform for reference.”

May combine two claims.

The microelectrode arrays provide multichannel data used in electrophysiologic paradigms for recording spontaneous and stimulus-evoked neural activity, decoding, and focal stimulation across functional brain regions.

“The microelectrode arrays provide multichannel data that is used in a variety of electrophysiologic paradigms to perform neural recording of both spontaneous and stimulus-evoked neural activity as well as decoding and focal stimulation of neural activity across a variety of functional brain regions.”