Factors determining the frequency content of the electromyogram

1983 ◽  
Vol 55 (2) ◽  
pp. 392-399 ◽  
Author(s):  
H. Kranz ◽  
A. M. Williams ◽  
J. Cassell ◽  
D. J. Caddy ◽  
R. B. Silberstein
Keyword(s):  
Electrical Activity ◽  
Action Potentials ◽  
Nerve Fibers ◽  
Frequency Content ◽  
Muscle Properties ◽  
Spectral Content ◽  
Unit Discharge ◽  
Compound Action Potentials ◽  
Motor Unit Discharge ◽  
Compound Action

The contribution of central and peripheral factors to the frequency content of the electromyogram was examined in 10 subjects performing maximal 45-s contractions of thenar muscles. The median frequencies (Fm) of surface-recorded electromyograms and compound action potentials were similar early (P greater than 0.6) and late (P greater than 0.5) in the contractions. There was a mean decrease in the Fm during contraction of 39% for electromyograms and 35% for compound potentials (P greater than 0.1). The Fm of electromyograms increased 11% (P less than 0.02) in only the 1st s of contraction as force was raised from 25 to 100% of maximum. Only one of five subjects showed evidence of increasing synchronization of motor unit discharge during contraction. There was no evidence that delay or dispersion of action potential propagation in terminal nerve fibers or at the neuromuscular junction had a significant effect on frequency content. The findings indicated that the spectral content of muscle electrical activity, and its shift during contraction, primarily reflects intrinsic muscle properties.

Reflexes, fictive respiration and cell division in the brain and spinal cord of the newborn opossum, Monodelphis domestica, isolated and maintained in vitro

1990 ◽  
Vol 152 (1) ◽  
pp. 1-15
Author(s):  
J. G. Nicholls ◽  
R. R. Stewart ◽  
S. D. Erulkar ◽  
N. R. Saunders
Keyword(s):  
Spinal Cord ◽  
Electrical Activity ◽  
Action Potentials ◽  
Monodelphis Domestica ◽  
Spinal Reflexes ◽  
Bathing Solution ◽  
Proliferative Zone ◽  
Compound Action Potentials ◽  
Compound Action

1. The entire central nervous system (CNS) was isolated from 1- to 4-day-old newborn South American opossums (Monodelphis domestica). At this stage the CNS has only an embryonic forebrain (two-layered) and no cerebellum and corresponds to a 14-day rat embryo. Its eyes, ears and hind-limbs are only at an early stage of formation. The isolated CNS preparations continue to develop and to produce electrical signals for up to 4 days in oxygenated Krebs' fluid at 23 degrees C. 2. The longitudinal axis of the CNS showed markedly different stages of development. More neuroblast cells were present in the proliferative zone in lumbosacral than in cervical or thoracic regions of the cord. 3. The progeny of dividing cells were labelled in isolated preparations by applying bromodeoxyuridine (BrdU) to the bathing solution for 2 h. Stained precursor cells were observed in CNS that had been left in Krebs' fluid for 4 days before applying BrdU and also in CNS that had been exposed to BrdU shortly after dissection and then left for 4 days. 4. Compound action potentials were evoked from the isolated CNS by stimulation with extracellular electrodes. Compound action potentials increased in amplitude with stronger stimulation and showed discrete peaks of conduction velocity. All electrical activity was eliminated reversibly by 0.1 mumol l-1 tetrodotoxin applied to the bathing solution. Block and recovery occurred with a half-time of approximately 5 min. High concentrations of magnesium (20 mmol l-1) reversibly blocked slower components of the volley. 5. Reflexes in cervical and thoracic segments of the spinal cord continued to function in isolated preparations. Stimulation of a dorsal root evoked bursts of impulses in the appropriate ventral root. Spontaneous and evoked activity in ventral roots was eliminated reversibly by 20 mmol l-1 magnesium. 6. In thoracic segments, spontaneous rhythmical bursts of action potentials were recorded. Burst activity was correlated with respiratory movements of the ribs in semi-intact preparations in which a few ribs and muscles were left attached to the isolated CNS. 7. At raised temperatures of 28 degrees C compared to 23 degrees C both spontaneous and evoked electrical activity were reversibly reduced. 8. Together these results show that the isolated CNS of the newborn opossum survives well in culture. The preparation offers advantages for pharmacological and physiological studies of spinal reflexes, for analysis of the mechanisms underlying rhythmical respiratory activity and for following the time course of CNS development in vitro.

Stretch of mammalian nerve in vitro: Effect on compound action potentials

2000 ◽  
Vol 5 (4) ◽  
pp. 227-235 ◽  
Author(s):  
Sidney Ochs ◽  
Rahman Pourmand ◽  
Kenan Si ◽  
Richard N. Friedman
Keyword(s):  
Action Potentials ◽  
Compound Action Potentials ◽  
Vitro Effect ◽  
Mammalian Nerve ◽  
Compound Action

scholarly journals Site of cochlear stimulation and its effect on electrically evoked compound action potentials using the MED-EL standard electrode array

2009 ◽  
Vol 8 (1) ◽  
pp. 40 ◽  
Author(s):  
Stefan Brill ◽  
Joachim Müller ◽  
Rudolf Hagen ◽  
Alexander Möltner ◽  
Steffi-Johanna Brockmeier ◽  
...  
Keyword(s):  
Action Potentials ◽  
Electrode Array ◽  
Compound Action Potentials ◽  
Compound Action

Using Evoked Compound Action Potentials to Assess Activation of Electrodes and Predict C-Levels in the Tempo+ Cochlear Implant Speech Processor

2010 ◽  
Vol 31 (1) ◽  
pp. 134-145 ◽  
Author(s):  
Isaac Alvarez ◽  
Angel de la Torre ◽  
Manuel Sainz ◽  
Cristina Roldán ◽  
Hansjoerg Schoesser ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Action Potentials ◽  
Speech Processor ◽  
Compound Action Potentials ◽  
Compound Action

Synaptic transmission in the chronically decentralized middle cervical and stellate ganglia of the dog

1983 ◽  
Vol 61 (10) ◽  
pp. 1149-1155 ◽  
Author(s):  
J. A. Armour
Keyword(s):  
Central Nervous System ◽  
Action Potentials ◽  
Autonomic Nerves ◽  
Autonomic Ganglia ◽  
Afferent Nerves ◽  
Stellate Ganglia ◽  
Compound Action Potentials ◽  
The Central Nervous System ◽  
Compound Action ◽  
Stimulation Of

Afferent stimulation of one thoracic cardiopulmonary nerve generated compound action potentials in the efferent axons of other ipsilateral cardiopulmonary nerves in dogs, 14 days after their thoracic autonomic ganglia had been decentralized. The compound action potentials were influenced by the frequency of activation and (in 5 of 12 dogs) by pharmacological autonomic blocking agents (hexamethonium, atropine, phentolamine, and propranolol). Moreover, they were abolished transiently when chymotrypsin was injected locally into the ganglia, and extendedly when manganese was injected. Thus, synapses that can be activated by stimulation of afferent nerves exist in chronically decentralized thoracic autonomic nerves and ganglia. It is proposed that regulation of the heart and lungs occurs in part via thoracic autonomic neural elements independent of the central nervous system.

Sign in / Sign up

Export Citation Format

Share Document