Action potential

Too intensive training may lead to overreaching or overtraining. To study whether quantitative needle electromyography (QEMG) is more sensitive to detect training (mal)adaptation than muscle enzyme activities, 12 standardbred geldings trained for 32 wk in age-, breed-, and sex-matched fixed pairs. After a habituation and normal training (NT) phase ( phases 1 and 2, 4 and 18 wk, respectively), with increasing intensity and duration and frequency of training sessions, an intensified training (IT) group ( phase 3, 6 wk) and a control group (which continued training as in the last week of phase 2) were formed. Thereafter, all horses entered a reduced training phase ( phase 4, 4 wk). One hour before a standardized exercise test (SET; treadmill), QEMG analysis and biochemical enzyme activity were performed in muscle or in biopsies from vastus lateralis and pectoralis descendens muscle in order to identify causes of changes in exercise performance and eventual (mal)adaptation in skeletal m...

Analysis of mice with genetically altered expression of cardiac connexins can provide insights into the role of individual gap junction channel proteins in cell-to-cell communication, impulse propagation, and arrhythmias. However, conflicting results have been reported regarding conduction velocity slowing in mice heterozygous for a null mutation in the gene encoding connexin43 (Cx43). Methods: High-resolution optical mapping was used to record

A Turbo Pascal program for data acquisition and analysis is presented. The program detects incoming data as TTL pulses through the serial port of an IBM-PC and compatible computers and displays the instantaneous frequency plot and the interval histogram on-line. Novel features of this Pascal program are: (1) no special hardware requirements and (2) on-line analysis of more than one source at a time. No hardware additions to the supplied computer and easy operation make this program a valuable tool, directly useable in an IBM-PC and compatible computers.

The review focuses on the methods currently available for estimating muscle fibre conduction velocity (CV) from surface electromyographic (EMG) signals. The basic concepts behind the issue of estimating CV from EMG signals are discussed. As the action potentials detected at the skin surface along the muscle fibres are, in practice, not equal in shape, the estimation of the delay of

The central nervous system CNS acquired the control of the human body by to and fro transformation of information. The information is transferred from one neuron, the basic element of CNS to another neuron as electrical signals, called action potential. The axon a part of neuron acts as the medium for this propagation. The magnitude and duration of action potential remains the same throughout the propagation path. The process of propagation is termed as saltatory transmission or hopping. (Saltare means jump in Greek). This can be termed as lossless transmission in electrical engineering terms. At present, neuron is modeled as resistance-capacitance (RC) circuit in Hodkin Huxley model. To explain the lossless transmission, the transmission channel is to be modelled as an LC (Inductance- capacitance) circuit or a compensated RLC (resistance-Inductance-Capacitance) circuit. The current model can be changed to this form by the addition of an inductance, which is equivalent to the self-induced inductance in the neuron due to the flow of current through the neuron.

A comparatively simple apparatus allows even beginning students to observe action potentials in the cockroach leg. The recordings are made extracellularly by impaling the leg on two insect pins. Deflection of large spines on the leg, which are each innervated by one sensory neuron, initiates the action potentials. Using this technique, students observe the all-or-nothing nature of action potentials, their coding of information by frequency, and sensory adaptation.

Complex nerve models have been developed for describing the generation of action potentials in humans. Such nerve models have primarily been used to model implantable electrical stimulation systems, where the stimulation electrodes are close to the nerve (near-field). To address if these nerve models can also be used to model transcutaneous electrical stimulation (TES) (far-field), we have developed a TES model that comprises a volume conductor and different previously published non-linear nerve models. The volume conductor models the resistive and capacitive properties of electrodes, electrode-skin interface, skin, fat, muscle, and bone. The non-linear nerve models were used to conclude from the potential field within the volume conductor on nerve activation. A comparison of simulated and experimentally measured chronaxie values (a measure for the excitability of nerves) and muscle twitch forces on human volunteers allowed us to conclude that some of the published nerve models can be used in TES models. The presented TES model provides a first step to more extensive model implementations for TES in which e.g., multi-array electrode configurations can be tested.