The presented method is robust to impedance changes, independent of the electrode's relative position, does not compromise the nerve and can run on implantable, ultra-low power signal processors.
Electrical stimulation of afferent nerve fibers originating from pressure sensors can trigger the baroreflex to reduce blood pressure and might be an alternative to treat patients with hypertension. In this study, baroreceptor compound activity was detected using multi-channel cuff-electrode recordings on rat vagal nerve. In order to isolate the vagal nerve signals from external potentials (such as ECG- and EMG-coupling), a tripolar measuring technique was applied. To eliminate noise and neural signals corresponding to other organs, coherent averaging was used. The baroreceptor-correlated signals appear predominantly in one of the electrode channels, presumably close to the corresponding neural substrate. This localization was done in real-time.
The therapy of refractory hypertension is an increasing problem for health care systems and a frontend in research in both pharmacology and neuroelectronic engineering. Overriding the baroreceptive information of afferent nerve fibers, originating from pressure sensors in the aortic arch, can trigger the baroreflex, a systemic control system that lowers the blood pressure (BP) almost instantaneously. Using a multichannel cuff electrode, wrapped around a rat vagal nerve, we were able to regulate the BP using selective, tripolar stimulation. The tripolar stimulation was sufficiently selective to not trigger any unwanted side effects like bradycardia or bradypnea. The BP was reduced best with charge balanced stimulation amplitudes of 1 mA and pulse duration of 0.3 ms. The stimulation frequency had only a mild influence on the effectiveness of the stimulation and did work best at 40 Hz. We found that the BP took up to five times the stimulation period to recover to the value prior to stimulation.
Simultaneous stimulation and recording of retinal nerve cells with penetrating three dimensional multi-electrode arrays (MEA) on a localized area is a demanding challenge in next generation retina implant research. Within the scope of this research we developed a device to stimulate a network of bi-polar cells and record retinal ganglion cells with a slight time gap to overcome long recording dead times and switching artifacts in common stimulation-and recording systems. The device contains a four channel stimulator capable of pushing arbitrary bi-polar charges into the tissue and a 16 channel commercial electrophysiology interface chip. The device is a miniaturized front-end for our former developed embedded wireless communicating sensor node. First tests in in-vitro retina slices on adult rat with our device show reliable recordings of ganglia cell activity below 1ms after the bi-polar cell stimulation. Index Terms-functional electrical stimulation, neuronal recording, retina implant, embedded system
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.