Repetitive doublets of human motoneurones: analysis of interspike intervals and recruitment pattern

Kudina, Lydia P.; Alexeeva, Natalia

doi:10.1016/0168-5597(92)90112-o

Cited by 48 publications

(47 citation statements)

References 5 publications

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“…The results of this study show that the amplitude of the second MUAP of doublet discharges was smaller than the amplitude of the first, as has been suggested previously (Bawa and Calancie 1983;Kudina and Alexeeva 1992). Because of the short period of time between MUAPs in a doublet discharge, incomplete recovery of Na ϩ and/or K ϩ channels may reduce the amplitude of the second MUAP.…”

Section: Amplitude Of Doublet Muapssupporting

confidence: 58%

“…These values closely match reports by Griffin et al (1998) who suggest that those units that showed doublet discharges had recruitment threshold ranging from 20 to 50% MVC. Previous reports have suggested that doublets are more likely to occur in "higher-threshold" motor units (Bawa and Calancie 1983;Garland and Griffin 1999;Kudina and Alexeeva 1992). It is important to note, however, that these studies, like this study, have used protocols that typically do not require force production above 50% MVC.…”

Section: Motor Unit Typesmentioning

confidence: 63%

“…Such doublet discharges are typically followed by a longer than average ISI, often lasting Ͼ100 ms (Bawa and Calancie 1983;Garland and Griffin 1999). This firing behavior has been described in numerous muscles of both the upper and lower limbs of healthy, young individuals (Bawa and Calancie 1983;Griffin et al 1998;Kudina and Alexeeva 1992;Partanen and Lang 1978;Van Cutsem et al 1998). However, the majority of studies to date have focused on muscles of the upper limb; doublet discharges have not been as well characterized in muscles of the lower limb.…”

Section: Introductionmentioning

confidence: 99%

“…Initial activation of the axon hillock of the motoneuron results in subthreshold antidromic signals traveling back toward the dendrites. The antidromic invasion of the dendrites increases the resting membrane potential of the dendrites, making them more susceptible to synaptic input, and thereby increases the likelihood of a second action potential (Calvin and Schwindt 1972;Granit et al 1963;Kudina and Alexeeva 1992;Kudina and Churikova 1990).…”

Section: Introductionmentioning

confidence: 99%

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Doublet Discharges in Motoneurons of Young and Older Adults

Christie

Kamen²

2006

Journal of Neurophysiology

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Christie, Anita and Gary Kamen. Doublet discharges in motoneurons of young and older adults. J Neurophysiol 95: 2787-2795, 2006. First published February 1, 2006 doi:10.1152/jn.00685.2005. The purpose of this study was to investigate the occurrence of motor unit doublet discharges in young and older individuals at different rates of increasing force. Participants included eight young (21.9 Ϯ 3.56 yr) and eight older (74.1 Ϯ 8.79 yr) individuals, with equal numbers of males and females in each group. Motor unit activity was recorded from the tibialis anterior during isometric dorsiflexion using a fourwire needle electrode. Subjects performed three ramp contractions from zero to 50% maximal voluntary contraction (MVC) force at each of three rates: 10, 30, and 50% MVC/s. Overall, the occurrence of doublets was significantly higher in the young than in the older individuals. However, neither group showed differences in the occurrence of doublets across the three rates of force production. Doublet firings were observed in 45.6 (young) and 35.1% (old) of motor units at 10% MVC/s; 48.6 (young) and 22.5% (old) of motor units at 30% MVC/s; and 48.4 (young) and 31.4% (old) at 50% MVC/s. The maximal firing rate was significantly higher and the force at which the motor units were recruited was significantly lower for those units that fired doublets than those that did not. The force at which doublets occurred ranged from 3.42 to 50% MVC in the young subjects and from 0 (force onset) to 50% MVC in the older subjects. The results of this study suggest that the occurrence of doublets is dependent on both motor unit firing rate and force level. The lower incidence of doublets in older individuals may be attributable to changes in the intrinsic properties of the motoneurons with aging, which appear to play a role in doublet discharges.

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Section: Amplitude Of Doublet Muapssupporting

confidence: 58%

Section: Motor Unit Typesmentioning

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Doublet Discharges in Motoneurons of Young and Older Adults

Christie

Kamen²

2006

Journal of Neurophysiology

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“…These functions include absorbing the resting slack of the muscle to enable linear isometric force production, increasing series elastic stiffness for greater force transmission (Binder-Macleod and Kesar 2005;Parmiggiani and Stein 1981;Wilson and Larimer 1968), or rapid summation of MU twitch tensions to increase the rate of isometric torque production (Desmedt and Godaux 1978;Mrǒwczyński et al 2011;Van Cutsem et al 1998). Although DDs have been observed periodically in long trains of MU action potentials (Bawa and Calancie 1983;Kudina and Alexeeva 1992;Westad et al 2004) and at termination of isometric force production (Kudina and Alexeeva 1992;Kudina and Churikova 1990;Stephenson and Maluf 2010), they are more often found at or near minimal firing rates (Bawa and Calancie 1983;Calvin and Schwindt 1972) when MUs are first recruited during low isometric torque contractions (Bawa and Calancie 1983;Denslow 1948;Kudina 1974;Kudina and Churikova 1990), or preceding fast ballistic isometric contractions (Bawa and Calancie 1983;Desmedt and Godaux 1977). Similarly, short ISIs have been noted preceding moderately fast (Ͻ250°/s) dynamic contractions in 97% of triceps brachii MUs recorded (Griffin et al 1998).…”

mentioning

confidence: 99%