Somatotopic organization of the hypoglossal nucleus: a HRP study in the rat

Krammer, Eva B.; Rath, Thomas; Lischka, Martin F.

doi:10.1016/0006-8993(79)90970-3

Cited by 178 publications

(98 citation statements)

References 11 publications

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“…In the rostrocaudal direction, motoneuron groups innervating single muscles span one to several spinal segments. Cranial, i.e., brain stem, motoneurons are not organized in a continuous column as in the spinal cord but form distinct nuclei, with an intrinsic somatotopic organization (297,664).…”

Section: Motoneurons a Embryonic Development And Anatomical Orgamentioning

confidence: 99%

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: Motoneurons a Embryonic Development And Anatomical Orgamentioning

confidence: 99%

Synaptic Control of Motoneuronal Excitability

Rekling

Funk

Bayliss

et al. 2000

Physiological Reviews

537

482

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“…ATP application over the dorsal aspect of the X II nucleus produced tonic excitation only. When it was injected over the ventromedial inspiratory (Remmers et al, 1978;Krammer et al, 1979) aspect of the X II nucleus, ATP consistently produced a significant increase of phasic inspiratory activity as well as tonic excitation.…”

Section: Methodsmentioning

confidence: 99%

P2 Receptor Excitation of Rodent Hypoglossal Motoneuron ActivityIn VitroandIn Vivo: A Molecular Physiological Analysis

et al. 1997

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The role of P2 receptors in controlling hypoglossal motoneuron (XII MN) output was examined (1) electrophysiologically, via application of ATP to the hypoglossal nucleus of rhythmically active mouse medullary slices and anesthetized adult rats; (2) immunohistochemically, using an antiserum against the P2X 2 receptor subunit; and (3) using PCR to identify expression of P2X 2 receptor subunits in micropunches of tissue taken from the XII motor nucleus. Application of ATP to the hypoglossal nucleus of mouse medullary slices and anesthetized rats produced a suramin-sensitive excitation of hypoglossal nerve activity. Additional in vitro effects included potentiation of inspiratory hypoglossal nerve output via a suramin-and pyridoxalphosphate-6-azophenyl-2Ј,4Ј-disulphonic acid (PPADS)-sensitive mechanism, XII MN depolarization via activation of a suraminsensitive inward current, decreased neuronal input resistance, and a slow-onset theophylline-sensitive reduction of inspiratory output likely resulting from hydrolysis of extracellular ATP to adenosine and activation of P1 receptors. Immunohistochemically, P2X 2 receptors were detected in inspiratory XII MNs that were labeled with Lucifer yellow. These data, combined with identification of mRNA for three P2X 2 receptor subunit isoforms within the hypoglossal nucleus (two of which have not been localized previously in brain) and the previous demonstration that P2X receptors are ubiquitously expressed in cranial and spinal motoneuron pools, support not only a role of P2 receptors in modulating inspiratory hypoglossal activity but a general role of P2 receptors in modulating motor outflow from the CNS.Key words: respiration; P2 receptor; hypoglossal motoneuron; ATP; suramin; PPADS; adenosine; medullary brain slice; rat; mouse ATP clearly has been established as a transmitter within the CNS (Edwards et al., 1992;Evans et al., 1992;Salter et al., 1993; Zimmerman, 1994;Burnstock, 1995). Its actions are mediated by two major receptor families Fredholm et al., 1994;Burnstock, 1995). P2X receptors are ligand-gated ion channels that mediate fast excitatory responses . P2Y receptors mediate slower responses via G-proteins (Dubyak and El-Moatassim, 1993;Burnstock, 1995). Purinergic synaptic signaling in the C NS is complicated further by the extracellular hydrolysis of ATP to adenosine, which modulates synaptic transmission via activation of P1 receptors (Burnstock, 1995).Widespread distribution of P2 receptors (Burnstock, 1995) in the brain, indicated by autoradiographic (Bo and Burnstock, 1994;Balcar et al., 1995), in situ hybridization (K idd et al., 1995;Collo et al., 1996;Kanjhan et al., 1996;Séguéla et al., 1996), and immunohistochemical studies (Kanjhan et al., 1996;Vulchanova et al., 1996), suggests involvement of ATP in many neuronal systems. It clearly is involved in sensory transduction , fast excitatory neurotransmission (Edwards et al., 1992;Evans et al., 1992;Harms et al., 1992;Tschöpl et al., 1992), modulation of glutamatergic synaptic transmission (Li and Perl, 19...

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“…The densely packed multipolar cells that together form the XII nucleus were identified under high-power optics using IR-DIC illumination and we selected for recordings large HMs that were located in the ventrolateral area of the nucleus, an area in which motoneurons that innervate the genioglossus tongue muscle are located (Krammer et al 1979). We targeted GFPϩ interneurons under epifluorescent illumination.…”

Section: Nonrhythmic Medullary Slice Preparationsmentioning

confidence: 99%

“…The immunostaining for glutamic acid decarboxylase (GAD) is most dense in the ventromedial part of the nucleus (Aldes et al 1988), a region that contains predominantly motoneurons that innervate the genioglossus muscle of the tongue (Krammer et al 1979). By combining patch-clamp recordings and immunocytochemistry it was shown that HMs from the ventrolateral part of the XII nucleus have spontaneous miniature inhibitory synaptic currents with a large GABA A receptor component and HMs in this part of the nucleus show more dense labeling for GABA A receptors than HMs in other parts of the nucleus (O'Brien and Berger 2001).…”

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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Somatotopic organization of the hypoglossal nucleus: a HRP study in the rat

Cited by 178 publications

References 11 publications

Synaptic Control of Motoneuronal Excitability

Synaptic Control of Motoneuronal Excitability

P2 Receptor Excitation of Rodent Hypoglossal Motoneuron ActivityIn VitroandIn Vivo: A Molecular Physiological Analysis

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

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