The Sub-Primary Range of firing is present in both cat and mouse spinal motoneurones and its relationship to force development is similar for the two species
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The Sub-Primary Range of firing is present in both cat and mouse spinal motoneurones and its relationship to force development is similar for the two species. / Jensen, Dennis Bo; Stecina, Katinka; Wienecke, Jacob; Hedegaard, Anne; Sukiasyan, Natalya; Hultborn, Hans; Meehan, Claire Francesca.
I: Journal of Neuroscience, Bind 38, Nr. 45, 2018, s. 9741-9753.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - The Sub-Primary Range of firing is present in both cat and mouse spinal motoneurones and its relationship to force development is similar for the two species
AU - Jensen, Dennis Bo
AU - Stecina, Katinka
AU - Wienecke, Jacob
AU - Hedegaard, Anne
AU - Sukiasyan, Natalya
AU - Hultborn, Hans
AU - Meehan, Claire Francesca
N1 - CURIS 2018 NEXS 379
PY - 2018
Y1 - 2018
N2 - In the motor system, force gradation is achieved by recruitment of motoneurons and rate modulation of their firing frequency. Classical experiments investigating the relationship between injected current to the soma during intracellular recording and the firing frequency (the I–f relation) in cat spinal motoneurons identified two clear ranges: a primary range and a secondary range. Recent work in mice, however, has identified an additional range proposed to be exclusive to rodents, the subprimary range (SPR), due to the presence of mixed mode oscillations of the membrane potential. Surprisingly, fully summated tetanic contractions occurred in mice during SPR frequencies. With the mouse now one of the most popular models to investigate motor control, it is crucial that such discrepancies between observations in mice and basic principles that have been widely accepted in larger animals are resolved. To do this, we have reinvestigated the I–f relation using ramp current injections in spinal motoneurons in both barbiturate-anesthetized and decerebrate (nonanesthetized) cats and mice. We demonstrate the presence of the SPR and mixed mode oscillations in both species and show that the SPR is enhanced by barbiturate anesthetics. Our measurements of the I–f relation in both cats and mice support the classical opinion that firing frequencies in the higher end of the primary range are necessary to obtain a full summation. By systematically varying the leg oil pool temperature (from 37°C to room temperature), we found that only at lower temperatures can maximal summation occur at SPR frequencies due to prolongation of individual muscle twitches.SIGNIFICANCE STATEMENT This work investigates recent revelations that mouse motoneurons behave in a fundamentally different way from motoneurons of larger animals with respect to the importance of rate modulation of motoneuron firing for force gradation. The current study systematically addresses the proposed discrepancies between mice and larger species (cats) and demonstrates that mouse motoneurons, in fact, use rate modulation as a mechanism of force modulation in a similar manner to the classical descriptions in larger animals
AB - In the motor system, force gradation is achieved by recruitment of motoneurons and rate modulation of their firing frequency. Classical experiments investigating the relationship between injected current to the soma during intracellular recording and the firing frequency (the I–f relation) in cat spinal motoneurons identified two clear ranges: a primary range and a secondary range. Recent work in mice, however, has identified an additional range proposed to be exclusive to rodents, the subprimary range (SPR), due to the presence of mixed mode oscillations of the membrane potential. Surprisingly, fully summated tetanic contractions occurred in mice during SPR frequencies. With the mouse now one of the most popular models to investigate motor control, it is crucial that such discrepancies between observations in mice and basic principles that have been widely accepted in larger animals are resolved. To do this, we have reinvestigated the I–f relation using ramp current injections in spinal motoneurons in both barbiturate-anesthetized and decerebrate (nonanesthetized) cats and mice. We demonstrate the presence of the SPR and mixed mode oscillations in both species and show that the SPR is enhanced by barbiturate anesthetics. Our measurements of the I–f relation in both cats and mice support the classical opinion that firing frequencies in the higher end of the primary range are necessary to obtain a full summation. By systematically varying the leg oil pool temperature (from 37°C to room temperature), we found that only at lower temperatures can maximal summation occur at SPR frequencies due to prolongation of individual muscle twitches.SIGNIFICANCE STATEMENT This work investigates recent revelations that mouse motoneurons behave in a fundamentally different way from motoneurons of larger animals with respect to the importance of rate modulation of motoneuron firing for force gradation. The current study systematically addresses the proposed discrepancies between mice and larger species (cats) and demonstrates that mouse motoneurons, in fact, use rate modulation as a mechanism of force modulation in a similar manner to the classical descriptions in larger animals
KW - Faculty of Science
KW - Motoneurone
KW - Cat
KW - Mouse
KW - Sub-Primary Range
U2 - 10.1523/JNEUROSCI.2898-17.2018
DO - 10.1523/JNEUROSCI.2898-17.2018
M3 - Journal article
C2 - 30249797
VL - 38
SP - 9741
EP - 9753
JO - The Journal of neuroscience : the official journal of the Society for Neuroscience
JF - The Journal of neuroscience : the official journal of the Society for Neuroscience
SN - 0270-6474
IS - 45
ER -
ID: 203048911