Linked Life Data

10706434

Source:http://linkedlifedata.com/resource/pubmed/id/10706434

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2000-3-29
pubmed:abstractText
The possibility was investigated that changes in heteronymous recurrent inhibition (RI) from quadriceps (Q) to soleus (Sol) and tibialis anterior (TA) motoneurons (MNs) occur during postural tasks requiring cocontraction of Q with one of these muscles. Stimulation of the femoral nerve (FN), which elicited a Q H-reflex discharge, was used to activate Renshaw cells. The resulting inhibition of TA and Sol MNs was assessed using three test responses: (1) the rectified and averaged ongoing electromyogram (EMG) activity in TA or Sol; (2) the motor-evoked potential (MEP) elicited by cortical stimulation in these muscles; and (3) the Sol H reflex. The characteristics of the depression (appearance and increase with the conditioning reflex discharge, short central delay and long duration) are consistent with a Renshaw origin. In addition, results obtained in control experiments (no change in the EMG suppression after an ischaemic blockade of group-I afferents from the leg, time course of the FN-induced depression of the MEP similar to that of the ongoing EMG) made a significant contribution from other pathways activated by FN stimulation unlikely. Posture-related heteronymous RI from Q was compared in different postural tasks at matched levels of background EMG activity: voluntary co-contraction of Q and of the relevant ankle muscle while sitting (control situation), postural co-contraction of Q and TA (while leaning backwards during stance), or contraction of Sol with (preparation for hopping) and without (standing on tip of toes and leaning forwards during stance) associated contraction of the Q. During stance, heteronymous RI from Q was reduced to TA (but not to Sol) while leaning backwards and to Sol in preparation for hopping, but not in the other situations. Thus, RI from Q to TA or Sol was specifically decreased when a co-contraction of the Q and of the relevant muscle operating at the ankle was required to maintain bipedal stance. It is argued that this control of Renshaw cells is descending in origin and contributes to selection of the appropriate synergism in various postural tasks.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0014-4819
pubmed:author
pubmed:issnType
Print
pubmed:volume
130
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
345-61
pubmed:dateRevised
2009-11-11
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Posture-related changes in heteronymous recurrent inhibition from quadriceps to ankle muscles in humans.
pubmed:affiliation
Laboratoire de Neurophysiologie Clinique, Rééducation, Hôpital de la Salpêtrière, Paris, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't