Reanimating paralyzed hands using an implantable, brain-controlled functional electrical stimulation neuroprosthesis

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Project Summary The long-term goal of this study is to reanimate paralyzed hands using a fully implantable brain-controlled functional electrical stimulation neuroprosthesis for spinal cord injured patients to use at any time. The overall objective of this proposal, which is the next step toward attainment of the long-term goal, is to present an implantable brain-controlled hand neuroprosthesis in non-human primates that returns function to paralyzed musculature through electrical stimulation and does not sacrifice performance. Previous brain-controlled functional electrical stimulation neuroprostheses required hundreds of wires connected to towers of computers that consume power at rates unreasonable for portability to obtain the presented decode performance, rendering usage of the neuroprostheses restricted to the laboratory (Bouton et al. 2016, Ajiboye et al. 2017). The central hypothesis is that the 300-1,000 Hz spiking band power (SBP) feature will allow safely implantable power levels while maintaining the decode performance of 30 kSps threshold crossings. The rationale of the proposed research is that the 15x bandwidth reduction over conventional recording paradigms and single unit specificity of SBP dramatically cut the power needed to extract features without any loss in single-unit performance. In the first aim, a low-power multiple degree of freedom decoding method will be developed on an embedded platform. Irwin et al. demonstrated that SBP can predict open-loop finger position with high performance (Irwin et al. 2016). However, the monkey performed a single degree of freedom two target acquisition task. It remains unknown if SBP will maintain high performance when decoding complex movements. Consequently, SBP will be used to decode the more complicated center-out multiple finger task on the low-power embedded device presented in Bullard, Nason et al. 2018 (in submission). It is hypothesized that SBP decoders will perform better than threshold crossing decoders in closed-loop multiple finger tasks, even on the embedded device. The purpose of the second aim is to investigate closed-loop functional electrical stimulation of hand muscles using the embedded neural signal processor and the Networked Neuroprosthesis in a non-human primate. To date, the Networked Neuroprosthesis developed at Case Western Reserve University has been unable to provide intuitive multiple finger control to cervical level spinal cord injury patients. It is hypothesized that a brain interface is required to make the Networked Neuroprosthesis intuitive, but there exists no fully implantable solution yet. The device from the first aim will be used to present an implantable hand neuroprosthesis ready for human clinical trials. The contribution of this work is expected to be an implantable, intuitive, brain-controlled functional electrical stimulation hand neuroprosthesis to return some independence to spinal cord injured patients. This contribution will be significant because it will provide a hand neuroprosthesis that patients can take home with them for full- time use. The proposed research is innovative, in the opinion of the researchers, because it is the first system capable of acquiring signals specific to single units using an order of magnitude less power than the standard.