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Titolo:
Concurrent inhibition and excitation of phrenic motoneurons during inspiration: Phase-specific control of excitability
Autore:
Parkis, MA; Dong, XW; Feldman, JL; Funk, GD;
Indirizzi:
Univ Auckland, Fac Med & Hlth Sci, Dept Physiol, Auckland, New Zealand Univ Auckland Auckland New Zealand Dept Physiol, Auckland, New Zealand Schering Plough Corp, Res Inst, Kenilworth, NJ 07033 USA Schering Plough Corp Kenilworth NJ USA 07033 st, Kenilworth, NJ 07033 USA Univ Calif Los Angeles, Dept Neurobiol, Syst Neurobiol Lab, Los Angeles, CA Univ Calif Los Angeles Los Angeles CA USA 90095 biol Lab, Los Angeles, CA Univ Calif Los Angeles, Dept Physiol Sci, Los Angeles, CA 90095 USA Univ Calif Los Angeles Los Angeles CA USA 90095 Los Angeles, CA 90095 USA
Titolo Testata:
JOURNAL OF NEUROSCIENCE
fascicolo: 6, volume: 19, anno: 1999,
pagine: 2368 - 2380
SICI:
0270-6474(19990315)19:6<2368:CIAEOP>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
MEDULLARY RESPIRATORY NEURONS; MEMBRANE-POTENTIAL CHANGES; SPINAL-CORD; RECURRENT INHIBITION; DECEREBRATE CAT; HYPOGLOSSAL MOTONEURONS; SYNAPTIC INHIBITION; FICTIVE LOCOMOTION; RENSHAW CELLS; FUNCTIONAL ASSOCIATIONS;
Keywords:
phrenic motoneuron; brainstem; spinal cord; respiration; GABA; neonatal rat;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
73
Recensione:
Indirizzi per estratti:
Indirizzo: Parkis, MA Univd,uckland, Fac Med & Hlth Sci, Dept Physiol, Private Bag 92019, Aucklan Univ Auckland Private Bag 92019 Auckland New Zealand Aucklan
Citazione:
M.A. Parkis et al., "Concurrent inhibition and excitation of phrenic motoneurons during inspiration: Phase-specific control of excitability", J NEUROSC, 19(6), 1999, pp. 2368-2380

Abstract

The movements that define behavior are controlled by motoneuron output, which depends on the excitability of motoneurons and the synaptic inputs theyreceive. Modulation of motoneuron excitability takes place over many time scales. To determine whether motoneuron excitability is specifically modulated during the active versus the quiescent phase of rhythmic behavior, we compared the input-output properties of phrenic motoneurons (PMNs) during inspiratory and expiratory phases of respiration. In neonatal rat brainstem-spinal cord preparations that generate rhythmic respiratory motor outflow, we blocked excitatory inspiratory synaptic driveto PMNs and then examined their phase-dependent responses to superthreshold current pulses. Pulses during inspiration elicited fewer action potentials compared with identical pulses during expiration. This reduced excitability arose from an inspiratory-phase inhibitory input that hyperpolarized PMNs in the absence of excitatory inspiratory inputs. Local application of bicuculline blocked this inhibition as well as the difference between inspiratory and expiratory firing. Correspondingly, bicuculline locally applied to the midcervical spinal cord enhanced fourth cervical nerve (C4) inspiratoryburst amplitude. Strychnine had no effect on C4 output. Nicotinic receptorantagonists neither potentiated C4 output nor blocked its potentiation by bicuculline, further indicating that the inhibition is not from recurrent inhibitory pathways. We conclude that it is bulbospinal in origin. These data demonstrate that rapid changes in motoneuron excitability occurduring behavior and suggest that integration of overlapping, opposing synaptic inputs to motoneurons is important in controlling motor outflow. Modulation of phasic inhibition may represent a means for regulating the transfer function of PMNs to suit behavioral demands.

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Documento generato il 28/11/20 alle ore 20:00:56