Über Interferenzen zwischen zwei schwachen Reizen

Gildemeister, Martin

doi:10.1007/bf01677299

Cited by 18 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nitrous acid is the compound which oxidizes and is reduced primarily, nitric acid is reduced only secondarily by the reaction with nitric oxide obtained by reduction of nitrous acid. In the absence of nitrous acid therefore, nitric acid cannot easily be reduced by cathodic treatment and the current then reduces the passivating invisible surface oxide (3,4). In contrast, in the presence of nitrous acid the current will reduce nitric acid and therefore will be less effective in activating the passive wire.…”

Section: Refractory Statementioning

confidence: 99%

Activation of Passive Iron as a Model for the Excitation of Nerve

Bonhoeffer¹

1948

Journal of General Physiology

124

View full text Add to dashboard Cite

The activation by cathodic polarization of passive iron in concentrated nitric acid (d = 1.4) has been investigated. 1. For short current pulses (1 msec. or less) a transient activation occurs when the product of current density and time exceeds a certain value. This limiting value is here designated as the "threshold." It is of the order of magnitude of 200 x 10–6 coulomb/cm.2. 2. After activation and repassivation the threshold is temporarily several times higher than before. This "refractory state" is due to the presence of nitrous acid and of oxide layers. The return of the threshold to normal values occurs in seconds or minutes, depending on the variety of iron wire. 3. Immediately after a subthreshold current pulse the threshold is reduced (summation). However, if the second pulse occurs a certain interval of time after the first the wire exhibits a certain degree of refractoriness (Gildemeister effect). 4. Oscillographic measurements reveal the existence of a latent period between the application of the stimulating pulse and the establishment of the active state. The duration of this latent period depends on the strength of the current pulse. 5. There exists a minimum current density (rheobase) below which no activation occurs however long the current is applied. Depending on the variety of iron used this current density varies between about 1 and 10 ma./cm.2. To produce activation a current of rheobasic strength does not have to be applied for an infinite time but only for about 100 msec. (maximum utilization time). Activation becomes manifest some time after termination of the activating pulse. 6. With currents of slowly increasing strength it is possible to reach current strengths several times higher than rheobase without obtaining activation (accomodation). Accomodation to a large extent depends on the variety of iron used. Details are given for currents increasing with a time constant of 0.5 second. 7. Potential measurements on wires in the refractory state show the existence of after potentials. Wires in the refractory state which are cathodically polarized show peculiar oscillograms. Both types of experiments point to the formation of nitrous acid as an essential element in the course of events. 8. With current densities only slightly above rheobase all wires exhibit simple activations only. With higher current densities certain types of wires exhibit periodic activations. The range of current densities in which such periodic activations occur varies with the type of wire. The lower limit is sometimes quite close to the rheobase. 9. A theory of periodic activations is presented which is modelled on the theory of self-excitatory electrical oscillations. As variables describing the state of the wire, the "degree of activation" and the "degree of refractoriness" are introduced. In the physicochemical system an autocatalytic process corresponds to the "falling characteristic" of electrical oscillations. The theory leads to a rational view of the interrelations between threshold, rheobase, accomodafion, refractoriness, and rhythm. The phenomena of conduction are not discussed here but their relation to the theory is briefly touched upon.

show abstract

Section: Refractory Statementioning

confidence: 99%

Activation of Passive Iron as a Model for the Excitation of Nerve

Bonhoeffer¹

1948

Journal of General Physiology

124

View full text Add to dashboard Cite

show abstract

“…Kries & Sewall (1881), Gildemeister (1908), Lucas (1910), Rushton (1932), Katz (1937), and others reported the time-course of excitability changes, whereas Hodgkin (1937Hodgkin ( , 1938, Hodgkin & Rushton (1946), Katz (1947), and others analysed the course of local potential changes following application of currents.…”

Section: Membrane Time Constantmentioning

confidence: 99%

Stimulation of spinal motoneurones with intracellular electrodes

Frank¹,

Fuortes²

1956

The Journal of Physiology

291

156

View full text Add to dashboard Cite

“…The testing stimulus has been somewhat above maximal strength so that its effectiveness would not be diminished by the post-cathodal depression that follows just-subliminal stimulation of nerve by brief shocks (cf. Gildermeister, 1908;Erlanger & Blair, 1931). …”

Section: Triphasic Recordingmentioning

confidence: 99%

Analysis of the fast afferent impulses from thigh muscles

Bradley¹,

Eccles²

1953

The Journal of Physiology

156

111

View full text Add to dashboard Cite

Recently, when investigating the effect of graded stimulus strengths on the size of the conducted monophasic spike in muscle afferent fibres, Brock, Eccles & Rall (1951) found that with biceps-semitendinosus nerve the range of stimulus strengths from threshold to that giving the maximum group I spike was much larger than with other muscle nerves. There was a three-to fourfold increase of strength in contrast to an increment of 1-6-2-3 for other nerves. It has also been an almost invariable finding that, when recorded triphasically (a contact electrode against an indifferent electrode), an afferent volley from the biceps-semitendinosus or quadriceps nerves showed a double negative spike (cf. Brock, Coombs & Eccles, 1952, fig. 9), which was never observed for afferent volleys from the leg muscles-gastrocnemius, flexor digitorum longus, extensor digitorum longus, etc. Since the fast afferent fibres of muscle (the group I) are known to have two major components of quite different reflex function, which respectively may be designated group I a from the annulo-spiral endings and group I b from the Golgi tendon organs (Matthews, 1933;Barker, 1948;Granit, 1950; Granit & Strom, 1951; Hunt & Kuffler, 1951 a, b;Hunt, 1951 Hunt, , 1952Laporte & Lloyd, 1951, 1952Hagbarth & Naess, 1950), it was of interest to determine whether the double negative spike was attributable to this dual composition. If this was so, then the discrimination between the reflex functions of groups Ia and Ib would become simpler because the relative group I a and I b composition of an afferent volley would be directly determinable. METHODCats, anaesthetized with pentobarbitone sodium (Nembutal), have been used in all experiments. The method, and the dissection of nerves and their mounting on electrodes, have resembled in general those procedures described by Brock et al. (1951). Special precautions have been taken to ensure that the stimulus did not 'escape' to nerves other than those on the electrodes. For example the sartorius and saphenous components of the femoral nerve were dissected up and cut about 2 cm proximal to the cathodal electrode on quadriceps nerve. The stimuli were brief

show abstract

Über Interferenzen zwischen zwei schwachen Reizen

Cited by 18 publications

References 0 publications

Activation of Passive Iron as a Model for the Excitation of Nerve

Activation of Passive Iron as a Model for the Excitation of Nerve

Stimulation of spinal motoneurones with intracellular electrodes

Analysis of the fast afferent impulses from thigh muscles

Contact Info

Product

Resources

About