This paper considers neural signal processing applied to extracellular recordings, in particular, unsupervised action potential detection at a low signal-to-noise ratio. It adopts the basic framework of the multiresolution Teager energy operator (MTEO) detector, but presents important new results including a significantly improved MTEO detector with some mathematical analyses, a new alignment technique with its effects on the whole spike sorting system, and a variety of experimental results. Specifically, the new MTEO detector employs smoothing windows normalized by noise power derived from mathematical analyses and has an improved complexity by utilizing the sampling rate. Experimental results prove that this detector achieves higher detection ratios at a fixed false alarm ratio than the TEO detector and the discrete wavelet transform detector. We also propose a method that improves the action potential alignment performance. Observing that the extreme points of the MTEO output are more robust to the background noise than those of the action potentials, we use the MTEO output for action potential alignment. This brings not only noticeable improvement in alignment performance but also quite favorable influence over the classification performance. Accordingly, the proposed detector improves the performance of the whole spike sorting system. We verified the improvement using various modeled neural signals and some real neural recordings.
Selective depletion of overproduced nitric oxide (NO) with nanoscavengers is a promising approach for treating rheumatoid arthritis (RA), preventing both oxidative/nitrosative stress and the upregulation of immune cells. However, its practical applications are limited owing to the minimum time interval between intra‐articular injections and unwanted off‐target NO depletion. Herein, the rational design of an injectable in situ polymeric aggregate‐embodied hybrid NO‐scavenging and sequential drug‐releasing (M‐NO) gel platform for the combinatorial treatment of RA by incorporating a “clickable” NO‐cleavable cross‐linker (DA‐NOCCL) is reported. This network is held together with polymeric aggregates to achieve a self‐healing capability for visco‐supplementation and on‐demand dual drug (both hydrophilic and hydrophobic)‐releasing properties, depending on the NO concentration. Moreover, consecutive NO‐scavenging action reduces pro‐inflammatory cytokine levels in lipopolysaccharides‐stimulated macrophage cell lines in vitro. Finally, the intra‐articularly injected M‐NO gel with anti‐inflammatory dexamethasone significantly alleviates the symptoms of RA, with negligible toxicity, in animal models. It is believed that this novel M‐NO gel platform will provide a guideline for the combinatorial treatment of RA and various NO‐related diseases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.