Results suggest that inter-fascicular selectivity could be achieved by properly orienting and positioning the coil with respect to the nerve. Neural excitation of a nerve fiber was implemented by an equivalent cable model and Frankenhaeuser-Huxley equations using NEURON software. We leveraged the multi-resolution impedance method and a heterogeneous multifascicular anatomical model of rat sciatic nerve to explore the possibility of selective stimulation as well. parallel coil connections) on the stimulation threshold. same direction of coil currents and series vs. We also examined the effect of coil design parameters (number of layers and turns) and different coil electrical configurations (opposite vs. Specifically, we investigated different orientations and positions of the figureof- eight coils for neural stimulation of the rat sciatic nerve. Utilizing numerical simulations in this work, we optimized the design parameters, orientation, and positioning of magnetic coils with respect to the peripheral nerve for improved stimulation efficacy. The orientation and location of the coil with respect to the stimulation site play a critical role in determining the stimulation threshold and stimulation selectivity. Here, we review the literature on possible technologies for precise modulation to highlight progress along with limitations with the goal of suggesting future directions for this field.Īlthough magnetic neural stimulation has many advantages over electrical neural stimulation, its main disadvantages are higher energy requirement and poor stimulation selectivity. However, few precise modulation strategies are available, and the long-term safety and efficacy of these strategies need to be confirmed. Such studies appear particularly promising as they may not only allow us to probe affected brain areas during TMS but also seem to predict underlying research directions that may enable us to precisely target and remodel impaired cortices or circuits. ![]() Developments in TMS have been accompanied by advances in combining TMS with neuroimaging techniques, including electroencephalography, functional near-infrared spectroscopy, functional magnetic resonance imaging, and positron emission tomography. These differential effects are important when designing precise modulatory strategies for clinical or research applications. ![]() The literature provides strong evidence that the modulatory effects of TMS vary depending on device components and stimulation protocols. Unfortunately, current modulation strategies are only modestly effective. Transcranial magnetic stimulation (TMS) is a popular modulatory technique for the noninvasive diagnosis and therapy of neurological and psychiatric diseases. In addition, the reduced inductance of the Slinky coil decreases the power requirement thus, the improved efficiency of the system may allow the generation of bursts of pulses, and expand the utilization of the system to possible functional activation of certain neuro-muscular structures when peripheral nerves are stimulated. Improved focality permits the current through the coil to be reduced for the same effect. The distribution of eddy currents was analyzed using Matlab, following Faraday's Law of Induction. This renders the Slinky coil more selective than conventional coils used for magnetic stimulation. The coil, due to its geometry, generates a unique distribution of eddy currents in nearby tissues which is favorable compared to a solenoid type stimulator. The loops are bunched at the axis of the torus. The actual device is formed by winding different numbers of loops forming a helical coil on a half torus. The basic structure of the device is derived from the popular "Slinky" toy. ![]() ![]() This coil improves the focal effect of a magnetic stimulator, and it reduces its inductance, hence the efficiency of the system is improved. A novel coil design for inductive electromagnetic stimulation of neural cells has been simulated and experimentally tested.
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