Dynamical mean-field theory of spiking neuron ensembles: response to a single spike with independent noises

Dynamics of an ensemble of $N$-unit FitzHugh-Nagumo (FN) neurons subject to white noises has been studied by using a semi-analytical dynamical mean-field (DMF) theory in which the original $2 N$-dimensional {\it stochastic} differential equations are replaced by 8-dimensional {\it deterministic} differential equations expressed in terms of moments of local and global variables. Our DMF theory, which assumes weak noises and the Gaussian distribution of state variables, goes beyond weak couplings among constituent neurons. By using the expression for the firing probability due to an applied single spike, we have discussed effects of noises, synaptic couplings and the size of the ensemble on the spike timing precision, which is shown to be improved by increasing the size of the neuron ensemble, even when there are no couplings among neurons. When the coupling is introduced, neurons in ensembles respond to an input spike with a partial synchronization. DMF theory is extended to a large cluster which can be divided into multiple sub-clusters according to their functions. A model calculation has shown that when the noise intensity is moderate, the spike propagation with a fairly precise timing is possible among noisy sub-clusters with feed-forward couplings, as in the synfire chain. Results calculated by our DMF theory are nicely compared to those obtained by direct simulations. A comparison of DMF theory with the conventional moment method is also discussed.Comment: 29 pages, 2 figures; augmented the text and added Appendice

The Basis of Sensation

Adrian, E.D. The basis of sensation. London: W.W. Norton & Co., 1928 The author summarizes work that has been in progress for the last two years under the following headings: the function of the nerve fiber, the recording of impulses in sensory nerve fibers, the mechanism of the end organ, sensory discharges from various types of receptor, the efficiency of the sense organs (adaptation), and nervous impulses and sensation. Most of the work was carried out with a capillary electrometer plus a three or four-valve amplifier. Brief descriptions are given of the apparatus. Records have been made of the discharge of sensory impulses produced by the following stimuli: tension on a muscle, pressure, touch, movement of hairs, and pricking with a needlepoint. With constant stimulation, the discharge from the end organs in the skin declines in frequency much more rapidly than from a muscle or a pressure organ. This difference in the adaptation rate of the end organs corresponds with the different types of reflex action which they produce, and the end organs may be classified, like the reflexes, as \u27postural\u27 or \u27phasic.\u27 The impulses produced by a pain stimulus are of the usual type and have the usual range of frequency, but there is some evidence that the discharge must have a certain mass (duration and intensity) if it is to evoke the pain reaction. The central nervous system (whose fibers carry impulses of the usual type) derives all of its information concerning the stimulus applied to a single end-organ from the rate at which the end organ becomes adapted to a constant stimulus. The intensity of sensation is proportional to the frequency of impulses in the nerve fiber. Sensation quality depends upon central connections. Visual adaptation and protopathic and epicritic sensitivity are discussed. 31 figures, but no bibliography. -PsycINFO Database Record (c) 2016 APA, all rights reservedhttps://digitalcommons.rockefeller.edu/jason-brown-library/1039/thumbnail.jp

The Physical Background of Perception

Adrian, E.D. The Physical Background of Perception. Oxford: At the Clarendon Press, 1947 The Waynflete lectures Book review Full texthttps://digitalcommons.rockefeller.edu/jason-brown-library/1040/thumbnail.jp

Flexible dry electrode for recording surface electromyogram

A new type of flexible dry electrode is examined for its suitable for surface electromyography (SEMG). SEMG signals were collected from the both biceps of a subject, using the dry electrodes and standard AgAgCl electrodes, during three tasks: 1) rest, 2) an isometric contraction, and 3) a dynamic contraction. Signal quality indices (signal-to-motion artifact ratio, maximumto- minimum drop in power ratio, signal to noise ratio, and power spectrum deformation) were computed to assess the SEMG. Results show that the dry electrodes can acquire SEMG signals that are nearly indistinguishable from the SEMG signals acquired using the AgAgCl electrodes. The dry electrodes did appear to exhibit a slightly high susceptibility to motion artifact; however, the motion artifact remained below 10 Hz, which can be filtered out for most SEMG applications

Surface electromyographic signals using a dry electrode

A new flexible, dry electrode is examined for recording surface electromyographic signals and compared to a conventional Ag/AgCl electrode. A suitable dry electrode would enable practical implementation of wearable mobility monitoring systems. Results from a preliminary experiment are presented in this paper. Measurements were performed on the right tibialis anterior during a series of small and large contractions. The effects of skin preparation, which included shaving and cleaning with isopropyl alcohol, are also examined. Results show that the dry electrode is sensitive enough to detect the small, unloaded muscle contractions. The dry electrode signal strength was similar to the Ag/AgCl electrode; however, the noise level was higher by approximately 13.5±1.3 %. Skin preparation reduced the noise level by approximately 7.9% for the dry electrodes and 8.1% for the Ag/AgCl electrodes

Surface electromyographic signals using dry electrodes

For many electromyography (EMG) applications, a suitable dry electrode would simplify practical implementation of an EMG recording system. Wearable mobility monitoring is an example of such a system. Therefore, surface EMG signals, from Fraunhofer Institute for Biomedical Engineering (IBMT) flexible dry electrodes and Orbital Research electrodes, were compared to signals from conventional Ag/AgCl electrodes. EMG measurements were performed on the right tibialis anterior for a range of different activities, such as light twitches, isometric contractions, jumping, and walking. Signal feature comparisons, skin preparation effects (i.e., cleaning with isopropyl alcohol), and impedance-noise analyses were performed. Results showed that both dry electrodes had comparable sensitivity to the standard Ag/AgCl electrodes for detecting small unloaded muscle contractions and large loaded contractions. Results also showed that noise content and impedance are weakly correlated and skin preparation methods did not have a positive effect on skin/electrode impedance