Stimulation Of Nervous Tissue Research Articles

Graphene-based nanomaterials for peripheral nerve regeneration.

Emerging nanotechnologies offer numerous opportunities in the field of regenerative medicine and have been widely explored to design novel scaffolds for the regeneration and stimulation of nerve tissue. In this review, we focus on peripheral nerve regeneration. First, we introduce the biomedical problem and the present status of nerve conduits that can be used to guide, fasten and enhance regeneration. Then, we thoroughly discuss graphene as an emerging candidate in nerve tissue engineering, in light of its chemical, tribological and electrical properties. We introduce the graphene forms commonly used as neural interfaces, briefly review their applications, and discuss their potential toxicity. We then focus on the adoption of graphene in peripheral nervous system applications, a research field that has gained in the last years ever-increasing attention. We discuss the potential integration of graphene in guidance conduits, and critically review graphene interaction not only with peripheral neurons, but also with non-neural cells involved in nerve regeneration; indeed, the latter have recently emerged as central players in modulating the immune and inflammatory response and accelerating the growth of new tissue.

Peripheral Neuromodulation to Treat Postamputation Pain.

Some of the more common peripherally mediated pain disorders are postamputation stump pain and phantom pain. These disabling conditions have proven difficult to treat. Here we aim to illustrate an option to treat postamputation pain using peripheral neurostimulation techniques. Traditional peripheral neuromodulation techniques use standard stimulation parameters and work by stimulation of nerve tissues which are then felt by the patient as a tingling sensation or paresthesia. Recently introduced high-frequency (10 kHz) electrical nerve block [HFAC (high-frequency alternating current) block] via a surgically implanted peripheral nerve cuff electrode results in true conduction block which actually blocks action potentials emanating from the painful neuroma and thus suppresses pain without tingling or paresthesia felt by the patient. In a recently completed 10-patient pilot study, the average pain level decreased from a score of 5.7 to 1.4 (out of 10) after HFAC block therapy with 85% of all testing sessions yielding a >50% pain reduction; a very significant reduction in the use of opioid and other analgesics was also noted, with all tested patients either stopping or decreasing their analgesic intake significantly. Patients achieved meaningful and significant pain reduction throughout the study, and patients who had phantom pain (in addition to stump pain) that responded to local anesthetic injections also responded favorably with HFAC block, presumably because in these particular patients, the phantom symptoms were peripherally generated. Each of the tested patients reported that HFAC block provided the most significant amount of pain reduction they had ever experienced when compared to other pain modalities tried since their amputations. The high-frequency electric nerve block technique is currently investigational pending FDA clearance. The next step for this modality is a pivotal trial, with the goal of having this therapy available to the mass market upon FDA clearance.

A theoretical framework for studying the electromagnetic stimulation of nervous tissue.

In this paper we present a model for calculating the electric field, and its spatial derivatives, produced by arbitrarily shaped, oriented and placed coils carrying time-varying currents. The model has been validated by comparing its results with those obtained using FEM simulations. The model provides a simple and fast computation framework to investigate the electromagnetic stimulation of neural tissues. Some example applications are also provided.

Batteries Not Included: A Mat-Based Wireless Power Transfer System for Implantable Medical Devices As a Moving Target

Implantable devices have become increasingly popular in modern medicine. These devices have a wide range of applications, such as health monitoring, disease prevention, delivery of a therapeutic regimen, and biomimetic prosthesis. For example, electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders [1]-[5]. Being able to record neural activity from awake animals with observable behavior has greatly advanced our understanding of the neural mechanisms that mediate behavior. Conventional microelectrode recording techniques typically require a percutaneous connector, which is associated with infection risks. Generally, in order to obtain stable recordings, animals must be trained to accept some degree of restraint (e.g., head fixation). Not only is the mobility of the animal subject limited, but the results obtained under such restricted conditions may not reflect the full repertoire of brain activity that occurs during natural behaviors [2]. This issue can be addressed with implantable electronics to record neural activity and wirelessly transmit this data through the skin to an external device. A wireless technique is then required to transmit both data and power, connecting the external system and the implanted devices.

Charge and energy minimization in electrical/magnetic stimulation of nervous tissue

In this work we address the problem of stimulating nervous tissue with the minimal necessary energy at reduced/minimal charge. Charge minimization is related to a valid safety concern (avoidance and reduction of stimulation-induced tissue and electrode damage). Energy minimization plays a role in battery-driven electrical or magnetic stimulation systems (increased lifetime, repetition rates, reduction of power requirements, thermal management). Extensive new theoretical results are derived by employing an optimal control theory framework. These results include derivation of the optimal electrical stimulation waveform for a mixed energy/charge minimization problem, derivation of the charge-balanced energy-minimal electrical stimulation waveform, solutions of a pure charge minimization problem with and without a constraint on the stimulation amplitude, and derivation of the energy-minimal magnetic stimulation waveform. Depending on the set stimulus pulse duration, energy and charge reductions of up to 80% are deemed possible. Results are verified in simulations with an active, mammalian-like nerve fiber model.

Capacitive stimulatory effect in magnetic stimulation of nerve tissue

Two related contactless stimulating methods were examined using frog nerve-muscle preparations. One stimulates the nerve by means of voltage pulses through windings on a permalloy core through which the nerve bundle is threaded. The pulse strength-duration curve was measured, and found to give at chronaxy of 20 μsec, which is shorter by one decade than the 0.3 msec for galvanic stimulation. The other method excites the nerve by means of a high-frequency magnetic field generated in the airgap of a ferrite core driven by burst signals. The voltage threshold for nerve excitation was minimum near 1 kHz. These phenomena are explained by an equivalent circuit of the magnetic circuit and nerve bundle.

Contactless nerve stimulating transducer.

Stimulation of nervous tissue by means of an induced electric field produced by a contactless device is described. The unit is unique because it lends itself to surgical implantation.

Stimulation of intestinal nervous elements by angiotensin.

The stimulation of nervous elements in the intestine by the polypeptide angiotensin has been examined. Comparisons between nicotine, a neurotropic agent, acetylcholine which exerts principally a musculotropic action and angiotensin have been made by examining their interactions with hexamethonium and the anticholinesterase 1,5-di-(p-N-allyl-N-methylaminophenyl)pentan-3-one dibromide in both the rabbit and guinea-pig ileum. The effect of atropine on the responses of the guinea-pig ileum and botulinum toxin on the responses of the rabbit ileum to angiotensin was also tested. The results show that angiotensin causes most of its contractile response in both the guinea-pig and rabbit ileum by an indirect action, through the stimulation of nervous tissue.