We hypothesize that due to these unforeseen and unexplored physiological consequences of the chronically cuffed vagus nerve in a rat, that inflammatory modulation and other vagal effects by VNS may become unreliable in chronic studies. Given our findings, we submit that it would benefit the VNS community to re-examine methods used in previous literature to verify the efficacy of the rat model for chronic VNS studies.

Vagus nerve stimulation (VNS) has been on the forefront of inflammatory disorder research and has yielded many promising results. Questions remain, however, about the biological mechanisms of such treatments and the inconsistencies in the methods used in research efforts. Here, we aimed to clarify the inflammatory response to intraperitoneal (IP) injections of lipopolysaccharide (LPS) in rats, while analyzing corresponding effects of electrical stimulation to subdiaphragmatic branches (anterior gastric, accessory celiac, and hepatic) of the left vagus nerve. We accomplished an in-depth characterization of the time-varying cytokine cascade response in the serum of 58 rats to an acute IP LPS challenge over a 330-minute period by utilizing curve-fitting and starting point-alignment methods. We then explored the post-LPS neuromodulation effects of electrically stimulating individually cuffed subdiaphragmatic branches. Through our analysis, we found there to be a consistent order of IP LPS cytokine response (IL-10, TNF-α, GM-CSF, IL-17F, IL-6, IL-22, INF-γ). Apart from IL-10, the IP cytokine cascade was more variable in starting time and occurred later than in previously recorded intravenous (IV) challenges. We also found distinct regulatory effects on multiple cytokine levels by each of the three subdiaphragmatic stimulation subsets. While the timevariability of IP LPS use in rats complicates its utility, we have shown it to be a practical, arguably more physiologically relevant method than IV in rats when our methods are used. More importantly, we have shown that selective subdiaphragmatic neurostimulation can be utilized to selectively induce specific effects on inflammation in the body.

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Implantable closed-loop neuromodulation devices for use in long-term chronic studies in a lab or clinical trial are expensive to acquire and difficult to modify for specific use cases. This article documents the design and fabrication of a wireless implantable device using only commercially available off-the-shelf (COTS) components. This device, called the Bionode, can record and transmit up to four channels of biopotential data while simultaneously providing biphasic constant-current stimulation. The Bionode is a viable, low-cost, reusable, and easily modifiable research tool with clinical implications that has gained widespread use in various research projects at Purdue University. CCS Concepts: • Hardware → Bio-embedded electronics; Wireless devices; • Computer systems organization → Firmware;

This study explores the characterization of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) downconversion using mathematical analysis. The SSS is an under-developed signal sampling methodology that can be used with military and industry radar receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and downconverts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, the main objective to be accomplished is the mathematical characterization of the effects of input, output, and filter coefficient parameters on the I/Q imbalances when using the SSS. We use Matlab to examine and to characterize the SSS to generate parameters suitable for an implementation with a digital circuit.