Do F‐wave measurements detect changes in motor neuron excitability?

Lin, Jenny Z.; Floeter, Mary Kay

doi:10.1002/mus.20110

Cited by 73 publications

(45 citation statements)

References 33 publications

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“…No significant differences were found between the measurements measurements in this regard has limitations. The population of motoneurones tested by F-waves is probably not exactly the same as that activated by TMS, and there is even some doubt about the F-wave being a good indicator for short-term modulation of spinal motoneuronal excitability (Lin and Floeter 2004). The heterotopic SAI network during movement leads to enhanced corticospinal output in the representation of the target muscles, suggesting that a different mechanism is involved at rest than with homotopic stimulation.…”

Section: Discussionmentioning

confidence: 99%

Short-latency afferent inhibition during selective finger movement

et al. 2005

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During individual finger movement, two opposite phenomena occur at the level of the central nervous system that could affect other intrinsic hand muscle representations, unintentional co-activation, and surround inhibition (SI). At rest, excitability in the motor cortex (M1) is inhibited at about 20 ms after electric stimulation of a peripheral nerve [short-latency afferent inhibition (SAI)]. We sought to determine whether SAI changes during selective index finger movement. Effects were measured by the response to transcranial magnetic stimulation in two functionally distinct target muscles of the hand [abductor digiti minimi muscle (ADM), first dorsal interosseus muscle (FDI)]. An increase in SAI in the ADM during index finger movement compared to at rest could help explain the genesis of SI. Electrical stimulation was applied to either the little finger (homotopic for ADM, heterotopic for FDI) or the index finger (heterotopic for ADM, homotopic for FDI). During index finger movement, homotopic SAI was present only in the ADM, and the effect of peripheral stimulation was greater when there was less co-activation. Heterotopic SAI found at rest disappeared with movement. We conclude that during movement, homotopic SAI on the muscle in the surround of the intended movement may contribute to SI.

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Section: Discussionmentioning

confidence: 99%

Short-latency afferent inhibition during selective finger movement

et al. 2005

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“…Taken together, this suggests that the recruitment curve of Wrst discharges (i.e., the "input-output curve") was not aVected by the paradigms studied here. F-waves can serve as a measure of spinal motorneuronal excitability (Espiritu et al 2003;Lin and Floeter 2004;Mercuri et al 1996;Taniguchi et al 2007). They remained unchanged by the precision training protocol, but increased by force training.…”

Section: Discussionmentioning

confidence: 99%

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

et al. 2008

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Transcranial magnetic stimulation allows to study the properties of the human corticospinal tract noninvasively. After a single transcranial magnetic stimulus, spinal motor neurons (MNs) sometimes Wre not just once, but repetitively. The biological signiWcance of such repetitive MN discharges (repMNDs) is unknown. To study the relation of repMNDs to other measures of cortico-muscular excitability and to physiological measures of the skill for Wnely tuned precision movements, we used a previously described quadruple stimulation (QuadS) technique (Z'Graggen et al. 2005) to quantify the amount of repMNDs in abductor digiti minimi muscles (ADMs) on both sides of 20 right-handed healthy subjects. Skillfulness for Wnger precision movements of both hands was assessed using a Wnger tapping task. In 16 subjects, a follow-up examination was performed after training of either precision movements (n = 8) or force (n = 8) of the left ADM. The size of the QuadS response (amplitude and area ratios) was greater in the dominant right hand than in the left hand (QuadS amplitude ratio: 47.1 § 18.1 versus 37.7 § 22.0%, Wilcoxon test: P < 0.05; QuadS area ratio: 49.7 § 16.2% versus 36.9 § 23.0%, Wilcoxon test: P < 0.05), pointing to a greater amount of repMNDs. Moreover, the QuadS amplitude and area increased signiWcantly after Wnger precision training, but not after force training. This increase of repMNDs correlated signiWcantly with the increase in performance in the Wnger tapping task. Our results demonstrate that repMNDs are related to handedness and therefore probably reXect supraspinal excitability diVerences. The increase of repMNDs after skills training but not after force training supports the hypothesis of a supraspinal origin of repMNDs.

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“…8,13 The effects of voluntary contraction and vibration also indicate that the F wave, like the H reflex, provides a reliable index of spinal excitability. 12 Additionally, like F waves recorded from the hand muscles, inactivation of the calf muscle for 1-2 hours suppresses the amplitude of the H reflex, with a quick recovery after the subject has stood for 10 -20 min. 20 The history of activity of a muscle affects the persistence and average amplitude of F waves.…”

Section: Recorded From First Dorsal Interosseous (Fdi) and Abductor Dmentioning

confidence: 99%

Rest‐induced suppression of anterior horn cell excitability as measured by F waves: Comparison between volitionally inactivated and control muscles

et al. 2007

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To test the hypothesis that the anterior horn cells become hypoexcitable in the absence of central drive, we recorded F waves simultaneously from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) before and after volitionally inactivating one muscle (target) while periodically contracting the other muscle (control). In 14 healthy subjects, F waves recorded from the target muscle showed a progressive decrease in persistence and amplitude (whether counting all 100 trials or only detectable responses) after muscle relaxation for 1, 3, and 6 hours, followed by a quick recovery upon brief muscle contraction. We conclude that volitional inactivation suppresses the F waves of the target muscle without equally affecting the control muscle innervated by the same nerve. The history of activity of a muscle should therefore be taken into account in clinical testing, especially when the study of a paretic muscle shows abnormal F-wave excitability.

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Do F‐wave measurements detect changes in motor neuron excitability?

Cited by 73 publications

References 33 publications

Short-latency afferent inhibition during selective finger movement

Short-latency afferent inhibition during selective finger movement

Repetitive spinal motor neuron discharges following single transcranial magnetic stimulation: relation to dexterity

Rest‐induced suppression of anterior horn cell excitability as measured by F waves: Comparison between volitionally inactivated and control muscles

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