The Excitability Change of Motoneurones Due to Electrotonus and Its Relations to the Effects of Repetitive Stimulation

Otani, Takuzo; Iwata, Shunji; Furukawa, Taro

doi:10.2170/jjphysiol.2.154

Cited by 5 publications

(6 citation statements)

References 7 publications

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“…The great sensitivity of neurons to small voltage differences tends to support the views already suggested to the effect that electric field actions can play a role in the determination of probability of firing of units in ganglionic masses within the central nervous system,49-56 at least in synchronizing cells,6' 7 -5 and that currents adequate to exert an effect are physiologically available.7' 16,19,[65][66][67][68][69][70][71][72][73][74] If this is true, the considerations adduced here emphasize the significance of the morphology of the cell, since the geometric relations between the portions of the cell or dendritic membrane specially sensitive to the transmembrane changes, or the regions sensitive to difference in potential between different points on the surface with relation to the external field, acquire an overriding importance. Even more, the view here expressed emphasizes the importance of the architectural arrangements of groups of neurons and of their complex dendritic ramifications, which will be, as it were, antennae oriented with respect to the direction of currents of physiological significance to these cell masses.…”

Section: Discussionsupporting

confidence: 53%

Measurement of Imposed Voltage Gradient Adequate to Modulate Neuronal Firing

Terzuolo

Bullock

1956

Proc. Natl. Acad. Sci. U.S.A.

213

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results when the protein intake is 24 per cent is any higher than the level of calcium which gives the best results when the protein intake is 14 per cent. The present studies seem to indicate that the most beneficial level of calcium intake when the protein intake is liberal lies in the range of 0.4-0.6 per cent, or two to three times the level of minimal adequacy. In earlier studies,8 where calcium alone was added to Diet A, the level of optimum intake appeared to be at least three, and perhaps as much as four, times the level of minimal adequacy. Finally, it would seem justifiable to conclude that a diet liberal both in calcium and in protein is clearly superior to a diet liberal only in protein. * This work has been aided by grants to Columbia University, at first from the John and Mary Markle Foundation, more recently from the Nutrition Foundation, Inc., the Williams-Waterman Fund in the Research Corporation, and Swift and Company. t Deceased October 7, 1955. ' A comparison will soon be published of the life-histories of such late-generation Diet A animals with those of their ancestors whose families had been on the diet only about half as many generations and with those of their early forebears whose families had only recently been transferred to the diet.

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Section: Discussionsupporting

confidence: 53%

Measurement of Imposed Voltage Gradient Adequate to Modulate Neuronal Firing

Terzuolo

Bullock

1956

Proc. Natl. Acad. Sci. U.S.A.

213

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“…of the electrode and ceased to discharge in a short time. In fact, it has been known from studies on ventral root potential that the excised toad's spinal cords discharge not infrequently considerable spontaneous impulses over the ventral roots, especially when the motoneurones are in a state of cathodal polarization (2,16). Inspite of this, the micro-electrodes never met these motoneurones in the present research, which showed a sustained spontaneous discharge.…”

Section: Spontaneous Discharge Of Motoneuronesmentioning

confidence: 48%

“…The electrodes for the application of constant currents were placed, one on a ventral root including the axon of motoneurone to be tested and the other on a ventral surface near the upper end of the spinal cord, which had been lifted beforehand above the surface of the Ringer bath. The arrangements of the electrodes were the same as those once adopted by Otani, Iwata and Furukawa (16) in their studies of ventral root potential. When the electrode on the cord surface was an anode, i.e., the motoneurones were polarized anodally, both resting and spike potentials were augmented, so long as the polarizing currents remained below certain limit ( fig.…”

Section: Excitation Of Internuncialmentioning

confidence: 99%

The Electrical Activities of Single Motoneurones in Toad's Spinal Cord, Recorded With Intracellular Electrodes

1952

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“…(12) that the repetitive stimulation of an afferent pathway sets up a similar state at motoneurone soma as catelectrotonus. The positive wave began most frequently from the time-point 16-18 msec.…”

Section: Positive Wave In the Initial Part Of Vrpmentioning

confidence: 99%

On the Nature of Positive Waves in Ventral Root Potential

Iwata

Araki

1952

Jpn.J.Physiol

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The ventral root potential (VRP) is recorded in general as a slow negative deflection, which indicates the negativity in the proximal portion of the ventral root in reference to its distal portion. We are already familiar with the positive slow potential in the sympathetic ganglia (5, 6, 10), but nothing has been reported concerning positive waves in VRP except the studies performed by Bernhard and Skoglund (1). They succeeded, by medullary stimulation, in obtaining positive VRP accompanied by predominant responses in extensor muscles, while the negative VRP was found to be always accompanied by responses predominant in the flexors. Some possible causes which may lead to these results were suggested by them, but no satisfactory account has yet been given for the reversal of the potential sign.In the course of the authors' research about the influence of polarizing currents on VRP, positive sloW potentials were found on occasion under certain experimental conditions. The findings seem to be worth reporting, because they might furnish a clue for the bearings of positive VRP on the mechanism of synaptic transmission. METHODSToads were used in all experiments. The spinal cord with attached roots was excised from the animal body and placed in an airtight chamber through which moist oxygen (sometimes 5% CO2 was added) was passed. The VRP and in some cases also the dorsal root potential (DRP) evoked by dorsal root stimulation were recorded routinely by means of a RC-coupled amplifier (half time : 0.5 sec.) and an oscilloscope. For stimulation, a thyratron stimulator coupled with an induction coil was used, which relayed electrically to the sweep circuit. In order to polarize motoneurones, constant currents were made to flow along a ventral root and the spinal cord ( fig. 1). The previous reports (8, 12) must be read for details. RESULTSThe occurrence of positive waves in VRP seemed to be facilitated firstly by cathodal polarization of motoneurone somata and secondly by its repeated orthodromic excitation. Also the intensity of the stimuli delivered to a dorsal root was proved to have some bearings on it. These conditions, however, were

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The Excitability Change of Motoneurones Due to Electrotonus and Its Relations to the Effects of Repetitive Stimulation

Cited by 5 publications

References 7 publications

Measurement of Imposed Voltage Gradient Adequate to Modulate Neuronal Firing

Measurement of Imposed Voltage Gradient Adequate to Modulate Neuronal Firing

The Electrical Activities of Single Motoneurones in Toad's Spinal Cord, Recorded With Intracellular Electrodes

On the Nature of Positive Waves in Ventral Root Potential

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