The shortest duration of an electrical stimulus where the threshold amplitude is twice the rheobase - the minimum required for eliciting an ACTION POTENTIAL at any time period. It is a measure of the excitability of nerve or muscle tissue, and is characteristic of types and/or condition of the nerve or muscle cells in the tissue.

Strength-duration relationship for intra- versus extracellular stimulation with microelectrodes. (1/4)

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Effect of pacing rate on the human atrial strength-duration curve. (2/4)

The effect of rapid pacing on the atrial constant voltage stimulation threshold in humans has not been defined at rates applicable to those of antitachycardia pacing. The effect of pacing rate on the atrial strength-duration relation was determined in 10 patients at pacing rates between 125 and 300 beats/min to explore excitability over the range of rates used for permanent antitachycardia pacing systems. Two points that define the strength-duration curve were measured at each pacing rate: rheobase voltage--the lowest stimulus voltage that results in capture at a pulse duration of 2 ms; and chronaxie pulse duration--the threshold pulse duration at twice rheobase voltage. A permanent, tined, J-shaped pacing lead with a high current density and low polarization electrode was positioned in the right atrial appendage for cathodal stimulation. A constant voltage output, incorporating a fast recharge pulse designed to minimize electrode polarization, was used for stimulation. There was a significant increase in rheobase voltage (p = 0.009), chronaxie pulse duration (p = 0.001) and minimal threshold stimulus energy (p = 0.05) at pacing rates greater than 225 beats/min. A rheobase voltage greater than 5 V occurred in three patients at pacing rates greater than or equal to 275 beats/min. At a pacing rate of 300 beats/min, rheobase voltage had increased in 8 of 10 patients.(ABSTRACT TRUNCATED AT 250 WORDS)  (+info)

Biophysical properties of the longitudinal smooth muscle of the guinea-pig rectum. (3/4)

1. The membrane properties of the longitudinal muscle layer of the guinea-pig rectum were studied in hypertonic solution (twice the normal Krebs by addition of sucrose) by the micro-electrode technique. To produce the electrotonic potential and spike, stimulating partitions were used.2. Hypertonic solution hyperpolarized the membrane and increased the membrane resistance. However, no change in the space constant was observed before and after treatment with hypertonic solution.3. The appearance and amplitude of the spike became regular after treatment with hypertonic solution and appearance of the overshoot was consistent.4. The characteristic constants and the conduction velocity were measured in hypertonic solution.(i) The space constant of the membrane was 0.81 mm, the time constant of the electrotonic potential was 83.7 msec and the time constant of the foot of the propagated spike was 8.8 msec.(ii) The conduction velocity of the excitation measured by insertions of the two micro-electrodes was 4.4 cm/sec.(iii) The chronaxie of the membrane was 71.3 msec.5. The results obtained from the present experiments were discussed in relation to the cable theory, and it was concluded that the passive properties of the membrane of the rectal smooth muscle could be explained by the cable equations.6. The specificities of the electrical properties of rectal smooth muscle were compared with muscle from other regions of the alimentary canal.  (+info)

Properties of two unmyelinated fibre tracts of the central nervous system: lateral Lissauer tract, and parallel fibres of the cerebellum. (4/4)

1. Monoplar tungsten micro-electrodes were used to stimulate and platinun plated tungsten micro-electrodes to record from single, unmyelinated cerebellar parallel fibres and lateral Lissauer tract axons in cats. 2. Stimulation of the lateral Lissauer tract resulted in the activation of a narrow, longitudinal 'beam', much as on the cerebellar surface. 3. Following impulse conduction, parallel and Lissauer tract fibres showed a supernormal conduction velocity (up to 25% increase) and increased excitability (up to 40% increase). No subnormality was encountered following supernormality. Some Lissauer tract fibres had prolonged relative refractory periods and no supernormal periods. 4. Chronaxies ranged from 155 to 380 microseconds. 5. Single fibres exhibited a remarkable increase in conduction velocity (up to 18% and excitability (up to 40%) following a single subthreshold stimulus. The duration of this effect (up to 20 msec) was much longer than expected from membrane time constant estimates.  (+info)

Chronaxie is a medical term that refers to the minimum amount of time or duration required for an electrical impulse to stimulate a nerve or muscle fibers. It is the measure of the excitability of excitable tissues, such as nerves and muscles, and is expressed in units of time, typically measured in microseconds (µs).

Chronaxie is used in the field of electrophysiology to determine the electrical properties of nerve and muscle fibers. It is a useful measure for setting the parameters of functional electrical stimulation (FES) devices, which are used to restore function to individuals with neuromuscular disorders or injuries. By adjusting the pulse width of the electrical stimulation to match the chronaxie of the target tissue, FES devices can more effectively activate nerves and muscles while minimizing discomfort and potential tissue damage.

A reduction in chronaxie occurs during reinnervation. The published values for chronaxie have a wide range. If chronaxie is the ... The chronaxie times of grey matter were reported as being 380 +/- 191 ms and 200±700 ms. Interpretations of chronaxie times are ... Chronaxie varies across different types of tissue: fast-twitch muscles have a lower chronaxie, slow-twitch muscles have a ... Buchanan D. N.; Garven H. S. D. (1926). "Chronaxie in tetany. The effect on the chronaxie of thyreoparathyreoidectomy, the ...
Chronaxie Ashley, et al. "Determination of the Chronaxie and Rheobase of Denervated Limb Muscles in Conscious Rabbits". ... The x-intercept of the Weiss equation is equal to b x c, or rheobase times chronaxie. This equation suggests that a graph of ... Measurement of chronaxie and rheobase in sural sensory fibers has revealed mild reductions in excitability in diabetics, as ... Mathematically, rheobase is equivalent to half the current that needs to be applied for the duration of chronaxie, which is a ...
She was the author of many works on Chronaxie and the influence of insulin on the autonomic nervous system and became a ... Hurynowicz, J. (1933). Über die normale und pathologische Chronaxie der vasomotorischen Nerven. Pogoń. Hurynowicz, J. (1947). ...
While working on her doctorate, she worked in Louis and Marcelle Lapicque's Laboratory of Physiology, investigating chronaxie ...
... so called chronaxie). Typically, chronaxie of neural cells is in the range of 0.1-10 ms, so the sensitivity to electrical ...
Transcutaneous Electro-muscular stimulation Therapy and Relativity of Chronaxie. Invited lecture at International Conference on ...
Marcelle de Heredia Lapicque (1873 - 1960) was a French neurophysiologist known for her research on nerve impulses (chronaxie) ... and the effects of poisons, especially strychnine, on chronaxie. She was in charge of the Laboratoire des Hautes-Études General ...
This theory states that the frequency of the vocal fold vibration is determined by the chronaxie of the recurrent nerve, and ...
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Another factor is that cardiac tissue has a chronaxie (response time) of about 3 milliseconds, so electricity at frequencies of ...
... specialist of the nervous system and known for his discovery of the chronaxie. Marcel Mauss (1872-1950), father of French ...
Chronaxie in Frédéric Joliot-Curie page 578 by Michel Pinault (Editions Odile Jacob, 2000) Lapicque L (1907). "Recherches ... chronaxie, its meaning and its measure (1926) Nervous machine (1943) Neuromuscular isochronism and rythmogenic excitability ( ...
A reduction in chronaxie occurs during reinnervation. The published values for chronaxie have a wide range. If chronaxie is the ... The chronaxie times of grey matter were reported as being 380 +/- 191 ms and 200±700 ms. Interpretations of chronaxie times are ... Chronaxie varies across different types of tissue: fast-twitch muscles have a lower chronaxie, slow-twitch muscles have a ... Buchanan D. N.; Garven H. S. D. (1926). "Chronaxie in tetany. The effect on the chronaxie of thyreoparathyreoidectomy, the ...
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Testerman, R. L. Comments on Accuracy limitations of chronaxie values. IEEE Trans. Biomed. Eng. https://doi.org/10.1109/TBME. ...
The rheobase was used to determine the chronaxy for each of the 11 muscles in the 10 dogs; chronaxy values were compared with ... Results-Compared with values in humans, chronaxy values for stimulation of AA motor fibers in the biceps femoris and ... Objective-To determine the electrical impulse duration thresholds (chronaxy) for maximal motor contraction of various muscles ... Conclusions and Clinical Relevance-Application of the dog-specific chronaxy values when performing electrical stimulation for ...
The conductance and capacitance of the cable equation were modified to adjust the chronaxie value (Sweeney et al., 1987) using ...
... extracellular stimuli should more efficiently excite thin neuronal structures with small chronaxies, such as axons, than larger ...
Chronaxie ou ce désert acharnement de couleurs (1984) for percussion and tape was recorded on LP and CD by the percussionist ...
Electrical stimulation based on chronaxie reduces atrogin-1 and myoD gene expressions in denervated rat muscle. Muscle Nerve. ...
Chronaxie. Duration in which a stimulus twice the rheobase strength needs to be applied to elicit a biological response. ... Excitability is inversely proportional to chronaxie.. a.For nerve: 0.01 - 0.1 micro sec. b.For skeletal muscle: 0.5 - 1 micro ...
To make it as comfortable as possible for the affected person, use pulse widths equal to the chronaxies of the motor nerves of ...
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... with reference to chronaxie of subordination. American Journal of Physiology, 106, 721-737. Tente links no:* Google ...
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... based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased ... based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased ... based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased ... based on the similar chronaxies and rheobases); (3) following spinal cord compression the chronaxie and rheobase increased ...
NED was diagnosed by the stimulus electrodiagnosis test when chronaxie was ≥1000µs. The muscle structure (thickness and ...
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In electrical stimulation, the most energy-optimal PW setting is the chronaxie setting [86, 87]. ...
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Chronaxie of Defibrillation: a Pathway Toward Further Optimization of Defibrillation Waveform?. Journal of Cardiovascular ...
Fits to the data using standard strength-duration equations were qualitatively similar, but the resulting chronaxie and ...
Chronaxie data were found to be linearly dependent on rheobase data and so are not reported and were not used for subsequent ... chronaxie (C50), and peak isometric force (Po) were determined as described in detail [5,8]. Specific Po was calculated by ...
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  • Chronaxie is the minimum time required for an electric current double the strength of the rheobase to stimulate a muscle or a neuron. (wikipedia.org)
  • The terms chronaxie and rheobase were first coined in Louis Lapicque's famous paper on Définition expérimentale de l'excitabilité that was published in 1909. (wikipedia.org)
  • For the formulation of numeric indices of excitability, the rheobase is defined as the minimal current strength below which response cannot occur even if the current continues, and the chronaxie is defined as the minimal duration of a current required to evoke the potential at twice the rheobase strength. (elsevierpure.com)
  • The strength-duration curve, the chronaxie and the rheobase may be useful in assessing spinal cord function. (elsevierpure.com)
  • Chronaxie is the tissue-excitability parameter that permits choice of the optimum stimulus pulse duration for stimulation of any excitable tissue. (wikipedia.org)
  • Chronaxie (c) is the Lapicque descriptor of the stimulus pulse duration for a current of twice rheobasic (b) strength, which is the threshold current for an infinitely long-duration stimulus pulse. (wikipedia.org)
  • The minimum energy occurs with a pulse duration equal to chronaxie. (wikipedia.org)
  • Objective -To determine the electrical impulse duration thresholds (chronaxy) for maximal motor contraction of various muscles without stimulation of pain fibers in dogs. (avma.org)
  • Some conditions affecting intensity and duration thresholds in motor nerves, with reference to chronaxie of subordination. (bvsalud.org)
  • The chronaxies and rheobases were calculated from the constructed strength-duration curves. (elsevierpure.com)
  • The purpose of this study is to produce strength-duration curves and to evaluate the utility of chronaxies and rheobases for SCEPs. (elsevierpure.com)
  • This example of the preponderating influence which the condition of the skin and the underlying tissues may exert compels caution in judging the results of chronaxie measurements by percutaneous stimulation. (wikipedia.org)
  • Results -Compared with values in humans, chronaxy values for stimulation of AA motor fibers in the biceps femoris and semitendinosus muscles and muscles of the more distal portions of limbs were lower in dogs. (avma.org)
  • Conclusions and Clinical Relevance -Application of the dog-specific chronaxy values when performing electrical stimulation for strengthening muscles or providing pain relief is likely to minimize the pain perceived during treatment in dogs. (avma.org)
  • To make it as snug as attainable for the patient, use pulse widths equal to PulSe widtH the chronaxies of the motor nerves of the muscular tissues within the lumbar region. (suzumgerecleri.com)
  • Chronaxie varies across different types of tissue: fast-twitch muscles have a lower chronaxie, slow-twitch muscles have a higher one. (wikipedia.org)
  • chronaxy values were compared with those reported for the corresponding muscles in humans. (avma.org)
  • For the other muscles evaluated, chronaxy values did not differ between dogs and humans. (avma.org)
  • The chronaxie of this action current in Blepharipoda and Randallia is 0.8{sigma} and is about the same as that found for the action current of the nerve. (caltech.edu)
  • Chronaxie values increase resulting from hyperventilation can be ascribed to a change in skin impedance, the physiological factors responsible for this change being under the influence of the autonomic nervous system. (wikipedia.org)
  • Chronaxie varies across different types of tissue: fast-twitch muscles have a lower chronaxie, slow-twitch muscles have a higher one. (wikipedia.org)
  • Activation characteristics of the heart and phrenic nerve are different with higher chronaxie for the heart. (medscape.com)
  • Etude sur les modifications de la chronaxie neuromusculaire par refroidissement d'un membre chez l'homme normal. (nih.gov)