Linked Life Data

10066287

Source:http://linkedlifedata.com/resource/pubmed/id/10066287

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1999-4-13
pubmed:abstractText
The movements that define behavior are controlled by motoneuron output, which depends on the excitability of motoneurons and the synaptic inputs they receive. 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 drive to 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) inspiratory burst amplitude. Strychnine had no effect on C4 output. Nicotinic receptor antagonists 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 occur during 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.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0270-6474
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
19
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2368-80
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Concurrent inhibition and excitation of phrenic motoneurons during inspiration: phase-specific control of excitability.
pubmed:affiliation
Department of Physiology, Faculty of Medicine and Health Sciences, University of Auckland, Auckland, New Zealand.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't