PMID- 20508919
OWN - NLM
STAT- MEDLINE
DCOM- 20100903
LR  - 20211020
IS  - 1432-1106 (Electronic)
IS  - 0014-4819 (Linking)
VI  - 204
IP  - 1
DP  - 2010 Jul
TI  - Repetitive doublet firing of motor units: evidence for plateau potentials in 
      human motoneurones?
PG  - 79-90
LID - 10.1007/s00221-010-2298-z [doi]
AB  - During voluntary muscle contraction, human motoneurones can exhibit specific 
      discharge patterns: single and repetitive doublets. Delayed depolarization has 
      been accepted as the mechanism underlying single doublets. Repetitive doublet 
      firing has been studied much less and its controlling mechanisms remain obscure. 
      The aim of the present study was to examine properties of repetitive doublets in 
      human motoneurones and to consider their underlying potential mechanisms. It was 
      found that 22 of 41 (53.7%) lower-threshold motor units (MUs) in the trapezius 
      and 15 of 42 (35.7%) MUs in triceps brachii displayed repetitive doublets with 
      the mean interspike intervals (ISIs) of 5.5 +/- 1.1 and 6.4 +/- 2.6 ms, 
      respectively. Each doublet was followed by a prolonged post-doublet ISI. The 
      analysis of properties of repetitive doublets showed that they were typically 
      initiated in quiescent motoneurones rather than in firing ones (appearing just at 
      recruitment in an all-or-none manner) and could only be maintained at a certain 
      level of muscle contraction. Repetitive doublets were interrupted either 
      voluntarily (by the subject), or spontaneously with sudden transition from 
      doublet firing to single discharges-the firing behaviour that may be referred to 
      as a firing-pattern "jump". The properties of doublet firing seem to be 
      consistent with traits of motoneurone firing in the presence of plateau 
      potentials reported in animal studies. It was suggested that the potential 
      mechanisms underlying repetitive doublet firing could include a delayed 
      depolarization as the primary determinant, which likely could become persistent 
      probably due to a plateau potential activated in parallel with a common synaptic 
      input.
FAU - Kudina, Lydia P
AU  - Kudina LP
AD  - Institute for Information Transmission Problems (Kharkevich Institute), Russian 
      Academy of Sciences, Moscow, Russia. kudina@iitp.ru
FAU - Andreeva, Regina E
AU  - Andreeva RE
LA  - eng
PT  - Journal Article
DEP - 20100528
PL  - Germany
TA  - Exp Brain Res
JT  - Experimental brain research
JID - 0043312
SB  - IM
MH  - Action Potentials
MH  - Adult
MH  - Arm/physiology
MH  - Electromyography
MH  - Humans
MH  - Middle Aged
MH  - Models, Neurological
MH  - Motor Neurons/*physiology
MH  - Muscle Contraction/*physiology
MH  - Muscle, Skeletal/*physiology
MH  - Shoulder/physiology
MH  - Time Factors
MH  - Volition
EDAT- 2010/05/29 06:00
MHDA- 2010/09/04 06:00
CRDT- 2010/05/29 06:00
PHST- 2010/01/11 00:00 [received]
PHST- 2010/05/07 00:00 [accepted]
PHST- 2010/05/29 06:00 [entrez]
PHST- 2010/05/29 06:00 [pubmed]
PHST- 2010/09/04 06:00 [medline]
AID - 10.1007/s00221-010-2298-z [doi]
PST - ppublish
SO  - Exp Brain Res. 2010 Jul;204(1):79-90. doi: 10.1007/s00221-010-2298-z. Epub 2010 
      May 28.