Integration of Neural Decoding in Prosthesis

            The clinical applications of neural innervation in prosthetics are limited by two main factors: invasiveness of neural surgery and the pattern recognition limitations of the current software to decode neural communication patterns. The article, “Neural Prosthesis Using Brain Activity to Decode Speech,” addresses recent breakthroughs in overcoming such limitations. They introduce a new machine learning model that utilizes intracranial EEG electrodes to decode speech patterns. This breakthrough surpasses prior methods that require outside devices such as keyboards or microphones to decode speech patterns and utilizes BCI processing which is controlled directly by the brain. 

Prior to the most recent breakthrough, the challenge in utilizing neural prosthesis is that the surgery required to implant electrodes into brain tissue is both highly invasive and dangerous. This required a surgery that used a vast amount of electrodes to cover a large area of the cortical surface. In the long term, this is not feasible and has a great amount of risk associated with it. The article discusses a new way in achieving the same effect as neural prosthesis by utilizing a smaller surface and less electrodes which minimizes the invasiveness of the procedure. Using sEEG’s, a two stage architecture for internal speech representations can be extracted from records of brain activity to produce log-mel spectral coefficients with a 55% accuracy rate from 5 channels of electrodes and 70% with 8 electrode channels. 

“Robotic Leg Control with EMG Decoding in an Amputee with nerve transfers” discusses a similar approach to neural innervation from a prosthetic standpoint, but focuses on re-innervating nerves and then using EMG signaling to derive meaning from the re-innervated nerves. This then utilizes a pattern recognition algorithm to decode the neural communication patterns from the 8 natively innervated residual muscle tissues which must be trained on the spot. This technique relies heavily on high quality EMG signal recordings through electrodes which must remain in contact with the residual limb the entire time during walking. This poses a challenge in itself as this can be uncomfortable for the amputee as well as hard to consistently ensure. 

Both articles lean into the neural innervation or decoding aspect of prosthetics to linearize the connection between the amputee and their prosthetic. By utilizing the neurological pathways, communication between the amputee and their prosthetic can mimic that of the average human being. It also helps the amputee to establish more efficient routines in their daily life. 

Hargrove, L. J.; Simon, A. M.; Young, A.; Lipschutz, R. D.; Finucane, S. B.; Smith, D. G.; Kuiken, T. A. Robotic Leg Control with EMG Decoding in an Amputee with Nerve Transfers. The New England Journal of Medicine 2013, 369 (13), 1237–1242. https://doi.org/10.1056/nejmoa1300126. 

News, N. Neural Prosthesis Uses Brain Activity to Decode Speech - Neuroscience News. Neuroscience News. https://neurosciencenews.com/speech-decoding-neuroprosthetic-22304/ (accessed 2023-12-13).

A Look Forward: Research in Angiogenesis and Neural Regeneration Lay a Promising Foundation for Future Studies

In the field of medicine/healthcare some of the most intriguing yet heartbreaking ailments that some individuals deal with are neurodegenerative disorders. Diseases such as Parkinson’s, Huntington’s, ALS, and Motor Neuron Disease (among many others) are at the forefront of many researchers’ inquisitions. Any sort of degeneration of the nervous system/surrounding vasculature can be detrimental to an individual’s health and could lead to symptoms such as pain, weakness, numbness, or any series of cognitive deficits; all of which could lead to a dramatic decrease in one’s quality of life.

Many people outside the realm of scientific research tend to hold the belief that these diseases of the nervous system have no cure or are essentially death sentences—a sense of hopelessness seems to coincide with the diagnosis of many of them. I argue that there is hope to be had—although a cure to many of these disorders is not immediately attainable, remarkable progress is being made in the field of neuroscience and clinical research!

In the realm of clinical research (having to do with spinal cord contusion specifically, a form of neurodegeneration characterized by injury to the spinal cord and subsequent damage which is allowed by minimal endogenous neural regeneration), Li et al., in their 2020 paper titled The effect of a nanofiber-hydrogel composite on neural tissue repair and regeneration in the contused spinal cord, provide evidence that shows that an engineered, injectable nanofiber-hydrogel with interfacial bonding can be used to regenerate tissue in rats with spinal cord contusions. Furthermore, this injectable nanofiber-hydrogel (NHC) treatment can “imitate biological features of native extracellular matrix, which may facilitate tissue regeneration and repair…[and] could serve as scaffolds for axonal growth” (Li 2). This fascinating finding shows many promising results, and could lead to further research that may indeed allow similar techniques to be used in the brain itself.

In the article titled Interfer(on)-ing with vascular repair after acute brain injury, Jeremy R. Hermann and Dennis W. Simon looked at results found by Mastorakos et al. in their research in mice regarding immune response and the pathophysiology of vascular repair in the brain. Overall, their primary finding provided insight into “the pathophysiology of vascular repair after acute brain injury” where they reveal, “the importance of secondary infections as an immune-modulating event that triggers faulty tissue repair and impairs functional outcomes” (Hermann 2). By focusing on immune response to traumatic brain injury, they lay the groundwork for future inquiries as to how a mediated immune response in the brain could lead to findings in preventative measures and regenerative abilities of certain signaling systems, such as IFN-I and INF-β administration in the brain and spinal cord, respectively. Although specificity in the amount administered, and a few other drawbacks prevent these findings from having any immediate clinical implications, the initial findings (as mentioned before) could have major implications in the regeneration of blood vessels and brain vasculature, and further prevent secondary neurological damage once further investigated.

A similar theme of both the paper by Li et al. and the analysis of the findings of Mastoraks et al. by Hermann and Simon is both neural regeneration, and angiogenesis—two major players in the prevention of brain damage. Although neither can solely prevent/cure any neurodegenerative brain disorders, both findings have implications that could one day lead to a prevention/cure. The field of neuroscience is astonishing and making remarkable progress in the (relatively) short amount of time it has existed apart from other scientific sects. When there seems to be little hope, it is always important to remember progress is progress, and we as a species are making remarkable strides in the right direction.

References:

Herrmann, J.R., Simon, D.W. Interfer(on)-ing with vascular repair after acute brain injury. Nat Immunol 22, 1205–1206 (2021). https://doi.org/10.1038/s41590-021-01034-9

Li, Xiaowei, et al. “The Effect of a Nanofiber-Hydrogel Composite on Neural Tissue Repair and Regeneration in the Contused Spinal Cord.” Biomaterials, vol. 245, 2020, p. 119978., https://doi.org/10.1016/j.biomaterials.2020.119978.