Activation properties of trigeminal motoneurons in participants with and without bruxism

Jessica M. D'Amico, S. Utku Yavuz, Ahmet Saraçoǧlu, Elif Sibel Atiş, Monica A. Gorassini, Kemal S. Türker

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)
2 Downloads (Pure)

Abstract

In animals, sodium and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of F values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent "onion skin effect" during the moderately sized contractions (<20% of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4-7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities such as eating, nonnutritive chewing, clenching, and yawning.

Original languageEnglish
Pages (from-to)2863-2872
Number of pages10
JournalJournal of neurophysiology
Volume110
Issue number12
DOIs
Publication statusPublished - 15 Dec 2013
Externally publishedYes

Fingerprint

Bruxism
Motor Neurons
Mastication
Serotonin
Motor Activity
Sleep Bruxism
Yawning
Masseter Muscle
Isometric Contraction
Onions
Fatigue
Norepinephrine
Eating
Sodium
Calcium
Skin
Drive

Keywords

  • Motoneurons
  • Pain
  • Plateaus
  • Sleep bruxism

Cite this

D'Amico, J. M., Yavuz, S. U., Saraçoǧlu, A., Atiş, E. S., Gorassini, M. A., & Türker, K. S. (2013). Activation properties of trigeminal motoneurons in participants with and without bruxism. Journal of neurophysiology, 110(12), 2863-2872. https://doi.org/10.1152/jn.00536.2013
D'Amico, Jessica M. ; Yavuz, S. Utku ; Saraçoǧlu, Ahmet ; Atiş, Elif Sibel ; Gorassini, Monica A. ; Türker, Kemal S. / Activation properties of trigeminal motoneurons in participants with and without bruxism. In: Journal of neurophysiology. 2013 ; Vol. 110, No. 12. pp. 2863-2872.
@article{a727538b01b04524912db05584289d49,
title = "Activation properties of trigeminal motoneurons in participants with and without bruxism",
abstract = "In animals, sodium and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of F values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent {"}onion skin effect{"} during the moderately sized contractions (<20{\%} of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4-7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities such as eating, nonnutritive chewing, clenching, and yawning.",
keywords = "Motoneurons, Pain, Plateaus, Sleep bruxism",
author = "D'Amico, {Jessica M.} and Yavuz, {S. Utku} and Ahmet Sara{\cc}oǧlu and Atiş, {Elif Sibel} and Gorassini, {Monica A.} and T{\"u}rker, {Kemal S.}",
year = "2013",
month = "12",
day = "15",
doi = "10.1152/jn.00536.2013",
language = "English",
volume = "110",
pages = "2863--2872",
journal = "Journal of neurophysiology",
issn = "0022-3077",
publisher = "American Physiological Society",
number = "12",

}

D'Amico, JM, Yavuz, SU, Saraçoǧlu, A, Atiş, ES, Gorassini, MA & Türker, KS 2013, 'Activation properties of trigeminal motoneurons in participants with and without bruxism' Journal of neurophysiology, vol. 110, no. 12, pp. 2863-2872. https://doi.org/10.1152/jn.00536.2013

Activation properties of trigeminal motoneurons in participants with and without bruxism. / D'Amico, Jessica M.; Yavuz, S. Utku; Saraçoǧlu, Ahmet; Atiş, Elif Sibel; Gorassini, Monica A.; Türker, Kemal S.

In: Journal of neurophysiology, Vol. 110, No. 12, 15.12.2013, p. 2863-2872.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Activation properties of trigeminal motoneurons in participants with and without bruxism

AU - D'Amico, Jessica M.

AU - Yavuz, S. Utku

AU - Saraçoǧlu, Ahmet

AU - Atiş, Elif Sibel

AU - Gorassini, Monica A.

AU - Türker, Kemal S.

PY - 2013/12/15

Y1 - 2013/12/15

N2 - In animals, sodium and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of F values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent "onion skin effect" during the moderately sized contractions (<20% of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4-7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities such as eating, nonnutritive chewing, clenching, and yawning.

AB - In animals, sodium and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of F values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent "onion skin effect" during the moderately sized contractions (<20% of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4-7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities such as eating, nonnutritive chewing, clenching, and yawning.

KW - Motoneurons

KW - Pain

KW - Plateaus

KW - Sleep bruxism

UR - http://www.scopus.com/inward/record.url?scp=84890376931&partnerID=8YFLogxK

U2 - 10.1152/jn.00536.2013

DO - 10.1152/jn.00536.2013

M3 - Article

VL - 110

SP - 2863

EP - 2872

JO - Journal of neurophysiology

JF - Journal of neurophysiology

SN - 0022-3077

IS - 12

ER -