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International audience; Introduction: In the framework of two clinical trials involving participants with chronic spinal cord injury, we intend to take advantage of the remaining brain motor activity to drive effectors to compensate motor handicap. To this aim, we developed WIMAGINE a fully implantable battery-less device able to record ECoG signals on 64 channels through the duramater.In BCI & tetraplegia clinical trial (NCT02550522), tetraplegic participants are trained to drive an exoskeleton to walk in the lab or to reach and grasp objects from the daily life whereas in STIMO-BSI clinical trial (NCT04632290), a paraplegic participant is also implanted with a spinal neurostimulator to elicit motor activity of their lower limbs.Results: When we started the design of the WIMAGINE implant, there was a great challenge on such a Brain Computer approach based on epidural signals. Indeed, the signals might have been too weak or their quality might have lessened dramatically after several months due to fibrotic reaction. However, based on our clinical data, we have demonstrated the great interest of our approach and device. The analysis of the signal stability (based on ECoG signal magnitude (RMS), signal to noise ratio, band power levels of the signal spectrum) was performed on three participants. The signal stability of the 1st participant has highlighted an outstanding signal stability even over a three years implantation period. For the two following participants with a respective follow-up duration of 1.5 year and 6 months, the signal stability follows the same trend.Thanks to this good stability performance, we can foresee uses of the WIMAGINE ECoG recorder during rehabilitation period or for chronic use in the participant's daily life. Note that these implants embedded in the skull thickness can be considered as passive/inert devices once the head-set providing the power thanks to the inductive link at 13.56 MHz.Outlook: So far, the WIMAGINE implants coupled proprietary decoding algorithms[1], [2] have demonstrated their interest for long-term recording and/or decoding of the ECoG signals. This system is compliant with the MDR 2017/745 regulation and is easy to implant. So far, we have demonstrated that it can be used in implantable BCI projects to drive external or implantable effectors.References:[1] A. Moly et al, An adaptive closed-loop ECoG decoder for long-term and stable bimanual control of an exoskeleton by a tetraplegic, DOI: 10.1088/1741-2552/ac59a0.[2] A. L. Benabid et al., An exoskeleton controlled by an epidural wireless brain-machine interface in a tetraplegic patient: a proof-of-concept demonstration, DOI: 10.1016/S1474-4422(19)30321-7.

Brain-computer interfaces (BCIs) include stimulators, infusion devices, and neuroprostheses. They all belong to functional neurosurgery. Deep brain stimulators (DBS) are widely used for therapy and are in need of innovative evolutions. Robotized exoskeletons require BCIs able to drive up to 26 degrees of freedom (DoF). We report the nanomicrotechnology development of prototypes for new 3D DBS and for motor neuroprostheses. For this complex project, all compounds have been designed and are being tested. Experiments were performed in rats and primates for proof of concepts and development of the electroencephalogram (EEG) recognition algorithm.

This preliminary study constitutes a proof of concept for seizure-triggered neuromodulation in a genetic rat model of absence epilepsy (GAERS) using the BioMEA™ system. BioMEA™ is a 256-channel MEA system with integrated electronics (ASIC) allowing simultaneous recording and stimulation of neural networks in vitro. It is based on parallel architecture of 64-channel ASICs with recording and stimulation capabilities for each channel. Here, we show that BioMEA™ can also be used to develop adaptive protocols of neurostimulation in vivo. In epileptic rats, a seizure detection algorithm delivered online command to BioMEA™ for bilateral stimulation of the substantia nigra pars reticulata which aborted spike-and-wave discharges in many instances, within 1 second following seizure onset.

A spinal cord injury interrupts the communication between the brain and the region of the spinal cord that produces walking, leading to paralysis(1,2). Here, we restored this communication with a digital bridge between the brain and spinal cord that enabled an individual with chronic tetraplegia to stand and walk naturally in community settings. This brain-spine interface (BSI) consists of fully implanted recording and stimulation systems that establish a direct link between cortical signals(3) and the analogue modulation of epidural electrical stimulation targeting the spinal cord regions involved in the production of walking(4-6). A highly reliable BSI is calibrated within a few minutes. This reliability has remained stable over one year, including during independent use at home. The participant reports that the BSI enables natural control over the movements of his legs to stand, walk, climb stairs and even traverse complex terrains. Moreover, neurorehabilitation supported by the BSI improved neurological recovery. The participant regained the ability to walk with crutches overground even when the BSI was switched off. This digital bridge establishes a framework to restore natural control of movement after paralysis.