Bilateral connectivity in the brainstem respiratory networks of lampreys

Authors

  • Jean-François Gariépy,

    1. Groupe de Recherche sur le Système Nerveux Central (GRSNC), Département de Physiologie, Université de Montréal, Montréal, Québec, Canada H3T 1J4
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  • Kianoush Missaghi,

    1. Groupe de Recherche sur le Système Nerveux Central (GRSNC), Département de Physiologie, Université de Montréal, Montréal, Québec, Canada H3T 1J4
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  • Shannon Chartré,

    1. Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département de Kinanthropologie, Université du Québec à Montréal, Montréal, Québec, Canada H3C 3P8
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  • Maxime Robert,

    1. Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département de Kinanthropologie, Université du Québec à Montréal, Montréal, Québec, Canada H3C 3P8
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  • François Auclair,

    1. Groupe de Recherche sur le Système Nerveux Central (GRSNC), Département de Physiologie, Université de Montréal, Montréal, Québec, Canada H3T 1J4
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  • Réjean Dubuc

    Corresponding author
    1. Groupe de Recherche sur le Système Nerveux Central (GRSNC), Département de Physiologie, Université de Montréal, Montréal, Québec, Canada H3T 1J4
    2. Groupe de Recherche en Activité Physique Adaptée (GRAPA), Département de Kinanthropologie, Université du Québec à Montréal, Montréal, Québec, Canada H3C 3P8
    • Département de Kinanthropologie, Université du Québec à Montréal, C.P. 8888 Succ. Centre-ville, Montréal, Québec, Canada, H3C 3P8
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Abstract

This study examines the connectivity in the neural networks controlling respiration in the lampreys, a basal vertebrate. Previous studies have shown that the lamprey paratrigeminal respiratory group (pTRG) plays a crucial role in the generation of respiration. By using a combination of anatomical and physiological techniques, we characterized the bilateral connections between the pTRGs and descending projections to the motoneurons. Tracers were injected in the respiratory motoneuron pools to identify pre-motor respiratory interneurons. Retrogradely labeled cell bodies were found in the pTRG on both sides. Whole-cell recordings of the retrogradely labeled pTRG neurons showed rhythmical excitatory currents in tune with respiratory motoneuron activity. This confirmed that they were related to respiration. Intracellular labeling of individual pTRG neurons revealed axonal branches to the contralateral pTRG and bilateral projections to the respiratory motoneuronal columns. Stimulation of the pTRG induced excitatory postsynaptic potentials in ipsi- and contralateral respiratory motoneurons as well as in contralateral pTRG neurons. A lidocaine HCl (Xylocaine) injection on the midline at the rostrocaudal level of the pTRG diminished the contralateral motoneuronal EPSPs as well as a local injection of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and (2R)-amino-5-phosphonovaleric acid (AP-5) on the recorded respiratory motoneuron. Our data show that neurons in the pTRG send two sets of axonal projections: one to the contralateral pTRG and another to activate respiratory motoneurons on both sides through glutamatergic synapses. J. Comp. Neurol. 520:1442–1456, 2012. © 2011 Wiley Periodicals, Inc.

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