Electrophysiological properties of hypoglossal motoneurons of guinea-pigs studied in vitro

Laursen, Arne Mosfeldt; Rekling, Jens C.

doi:10.1016/0306-4522(89)90156-5

Cited by 56 publications

(17 citation statements)

References 63 publications

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“…Because action potentials initiate in the unmyelinated initial axon segment, this region may have a higher concentration of Na i channels (34,66,141,200,240,861,1114). Normally, initial segment action potentials invade the somatodendritic membrane and give rise to action potentials, with inflections in typical intracellular recordings referred to as IS and SD spikes (66,240,454,870,919). Na + channels in the dendritic membrane have not been demonstrated directly in motoneurons in vivo or in acute brain slices, but there is evidence for backpropagating Na + -dependent spikes in dendrites of cultured spinal motoneurons (707,766).…”

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

“…A persistent, i.e., noninactivating, Na + current (I Na p ) is present in facial, hypoglossal, and trigeminal motoneurons (205,870,919). I Na p activates below spike threshold, which would accelerate subthreshold membrane depolarization to spike threshold.…”

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

“…It contributes to the falling phase of the action potential and the fast afterhyperpolarization (fAHP). External tetraethyl-ammonium (TEA) blocks the delayed rectifier, lengthening action potential duration and blocking fAHP in motoneurons (62,205,523,870,919,1113,1213,1311). Unitary K + currents of the delayed rectifier type, observed in patches from the soma of neonatal spinal motoneurons (1068), have a ~10-pS channel conductance (in normal Ringer solution), activate between −70 and 0 mV, and deactivate slowly (60 ms at −60 mV).…”

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

“…They are the result of large (BK) and small conductance (SK) K + channels gated by a rise in intracellular Ca 2+ , and in the case of the BK channels, also by voltage (1065). Both I K Ca(BK) and I K Ca(SK) are present in motoneurons (205,463,523,647,666,667,826,870,918,919,1070,1213,1291,1311). I K Ca(BK) , which also is called I c , is selective for K + and activates after an influx of Ca 2+ during an action potential.…”

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

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Synaptic Control of Motoneuronal Excitability

Rekling

Funk

Bayliss

et al. 2000

Physiological Reviews

537

482

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Movement, the fundamental component of behavior and the principal extrinsic action of the brain, is produced when skeletal muscles contract and relax in response to patterns of action potentials generated by motoneurons. The processes that determine the firing behavior of motoneurons are therefore important in understanding the transformation of neural activity to motor behavior. Here, we review recent studies on the control of motoneuronal excitability, focusing on synaptic and cellular properties. We first present a background description of motoneurons: their development, anatomical organization, and membrane properties, both passive and active. We then describe the general anatomical organization of synaptic input to motoneurons, followed by a description of the major transmitter systems that affect motoneuronal excitability, including ligands, receptor distribution, pre-and postsynaptic actions, signal transduction, and functional role. Glutamate is the main excitatory, and GABA and glycine are the main inhibitory transmitters acting through ionotropic receptors. These amino acids signal the principal motor commands from peripheral, spinal, and supraspinal structures. Amines, such as serotonin and norepinephrine, and neuropeptides, as well as the glutamate and GABA acting at metabotropic receptors, modulate motoneuronal excitability through pre-and postsynaptic actions. Acting principally via second messenger systems, their actions converge on common effectors, e.g., leak K + current, cationic inward current, hyperpolarization-activated inward current, Ca 2+ channels, or presynaptic release processes. Together, these numerous inputs mediate and modify incoming motor commands, ultimately generating the coordinated firing patterns that underlie muscle contractions during motor behavior.

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Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

Section: Active Membrane Properties Of Motoneuronsmentioning

confidence: 99%

See 2 more Smart Citations

Synaptic Control of Motoneuronal Excitability

Rekling

Funk

Bayliss

et al. 2000

Physiological Reviews

537

482

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“…HM axons do not possess collaterals (Mosfeldt Laursen and Rekling 1989;Withington-Wray et al 1988), suggesting that there is little or no feedback inhibition. The nature of the feedforward inhibitory network that controls the output of HMs to the tongue muscles is not well understood.…”

Section: Introductionmentioning

confidence: 99%

GAD67-GFP+ Neurons in the Nucleus of Roller: A Possible Source of Inhibitory Input to Hypoglossal Motoneurons. I. Morphology and Firing Properties

Brederode

Yanagawa

Berger

2011

Journal of Neurophysiology

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van Brederode JFM, Yanagawa Y, Berger AJ. GAD67-GFPϩ neurons in the Nucleus of Roller: a possible source of inhibitory input to hypoglossal motoneurons. I. Morphology and firing properties. J Neurophysiol 105: 235-248, 2011. First published November 3, 2010 doi:10.1152/jn.00493.2010. In this study we examined the electrophysiological and morphological properties of inhibitory neurons located just ventrolateral to the hypoglossal motor (XII) nucleus in the Nucleus of Roller (NR). In vitro experiments were performed on medullary slices derived from postnatal day 5 (P5) to P15 GAD67-GFP knock-in mouse pups. ON cell recordings from GFPϩ cells in NR in rhythmic slices revealed that these neurons are spontaneously active, although their spiking activity does not exhibit inspiratory phase modulation. Morphologically, GFPϩ cells were bi-or multipolar cells with small-to medium-sized cell bodies and small dendritic trees that were often oriented parallel to the border of the XII nucleus. GFPϩ cells were classified as either tonic or phasic based on their firing responses to depolarizing step current stimulation in whole cell current clamp. Tonic GFPϩ cells fired a regular train of action potentials (APs) throughout the duration of the pulse and often showed rebound spikes after a hyperpolarizing step. In contrast, phasic GFPϩ neurons did not fire throughout the depolarizing current step but instead fired fewer than four APs at the onset of the pulse or fired multiple APs, but only after a marked delay. Phasic cells had a significantly smaller input resistance and shorter membrane time constant than tonic GFPϩ cells. In addition, phasic GFPϩ cells differed from tonic cells in the shape and time course of their spike afterpotentials, the minimum firing frequency at threshold current amplitude, and the slope of their current-frequency relationship. These results suggest that GABAergic neurons in the NR are morphologically and electrophysiologically heterogeneous cells that could provide tonic inhibitory synaptic input to HMs.

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Morphology of developing rat genioglossal motoneurons studied in vitro: Changes in length, branching pattern, and spatial distribution of dendrites

Nuñez-Abades

Barrionuevo

et al. 1994

J of Comparative Neurology

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The aim of this study is to describe the postnatal change in dendritic morphology of those motoneurons in the hypoglossal nucleus that innervate the genioglossus muscle. Forty genioglossal (GG) motoneurons from four age groups (1-2, 5-6, 13-15, and 19-30 postnatal days) were labeled by intracellular injection of neurobiotin in an in vitro slice preparation of the rat brainstem and were reconstructed in three-dimensional space. The number of primary dendrites per GG motoneuron was approximately 6 and remained unchanged with age. The development of these motoneurons from birth to 13-15 days was characterized by a simplification of the dendritic tree involving a decrease in the number of terminal endings and dendritic branches. Motoneurons lost their 6th-8th order branches, in parallel with an elongation of their terminal dendritic branches maintaining the same combined dendritic length. The elongation of terminal branches was attributed to both longitudinal growth and the apparent lengthening caused by resorption of distal branches. The elimination of dendritic branches tended to increase the symmetry of the tree, as revealed by topological analysis. Later, between 13-15 days and 19-30 days, there was a reelaboration of the dendritic arborization returning to a configuration similar to that found in the newborn. The length of terminal branches was shorter at 19-30 days, while the length of preterminal branches did not change, suggesting that the proliferation of branches at 19-30 days takes place in the intermediate parts of terminal branches. The three-dimensional distribution of dendrites was analyzed by dividing space into six equal volumes (hexants). This analysis revealed that GG motoneurons have major components of their dendritic tree oriented in the lateral, medial, and dorsal hexants. Further two-dimensional polar analysis (consisting of eight sectors) revealed a reconfiguration of the tree from birth up to 5-6 days involving resorption of dendrites in the dorsal, dorsomedial, and medial sectors and growth in the lateral sector. Later in development (between 13-15 days and 19-30 days), there was growth in all sectors, but of a greater magnitude in the dorsomedial, medial, and dorsolateral sectors.

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Electrophysiological properties of hypoglossal motoneurons of guinea-pigs studied in vitro

Cited by 56 publications

References 63 publications

Synaptic Control of Motoneuronal Excitability

Synaptic Control of Motoneuronal Excitability

GAD67-GFP+ Neurons in the Nucleus of Roller: A Possible Source of Inhibitory Input to Hypoglossal Motoneurons. I. Morphology and Firing Properties

Morphology of developing rat genioglossal motoneurons studied in vitro: Changes in length, branching pattern, and spatial distribution of dendrites

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