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Titolo:
THE RELATIONSHIP BETWEEN ESTIMATES OF IA-EPSP AMPLITUDE AND CONDUCTION-VELOCITY IN HUMAN SOLEUS MOTONEURONS
Autore:
AWISZUS F; FEISTNER H;
Indirizzi:
HANNOVER MED SCH,NEUROPHYSIOL ABT OE4230,POSTFACH 610180 W-3000 HANNOVER 61 GERMANY HANNOVER MED SCH,NEUROL KLIN NEUROPHYSIOL KLIN W-3000 HANNOVER 61 GERMANY
Titolo Testata:
Experimental Brain Research
fascicolo: 2, volume: 95, anno: 1993,
pagine: 365 - 370
SICI:
0014-4819(1993)95:2<365:TRBEOI>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
SINGLE MOTOR UNITS; STIMULUS-DURATION; MACRO-EMG; H-REFLEX; NEURONS; CAT; EXCITABILITY; STIMULATION; POTENTIALS; EXTENSOR;
Keywords:
MOTONEURONS; SIZE PRINCIPLE; IA EPSP; CONDUCTION VELOCITY; HUMAN;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
F. Awiszus e H. Feistner, "THE RELATIONSHIP BETWEEN ESTIMATES OF IA-EPSP AMPLITUDE AND CONDUCTION-VELOCITY IN HUMAN SOLEUS MOTONEURONS", Experimental Brain Research, 95(2), 1993, pp. 365-370

Abstract

There are several parameters associated with motoneuron size, among which are the conduction velocity of the axon as well as the size of the excitatory post-synaptic potential (EPSP) induced by stimulation of Ia afferents in the corresponding muscle nerve. In particular, it has been established in animal experiments that small motoneurons with a low conduction velocity exhibit large Ia EPSPs, whereas large motoneurons with a high conduction velocity show small Ia EPSPs. Thus small motoneurons are recruited earlier than large ones. In this study, we investigated whether such a relationship between motoaxon conduction velocity and size of the Ia EPSPs could also be found for human soleus motoneurons. In total, 36 motor units from six healthy volunteers were activated by a slight voluntary contraction and exposed to 200 stimuli ofthe tibial nerve in the popliteal fossa. Stimuli were delivered usinga special stimulus protocol ensuring a constant pre-stimulus spike density along with a constant rate of discharge of the investigated unit. From the stimulus-correlated spike train data a measure of Ia-EPSP amplitude was obtained, along with the single-unit H-reflex latency. Additionally, for each unit, the so-called surface macro EMG was recorded, which measures the complete electrical activity attributable to theunit investigated. From the macro EMG, the intramuscular delay from arrival of each action potential at the soleus muscle and the detectionof the muscle-fiber action potential picked up by the recording needle electrode were measured. All single-unit H-reflex latencies were corrected for the corresponding intramuscular delays. From the corrected latencies, single-unit conduction velocities were obtained. It was found that there was a highly significant negative correlation between the estimate of the single-unit conduction velocity and the inferred size of the Ia EPSP. Thus, it was found that Ia-EPSP amplitudes in human soleus motoneurons follow the size principle.

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Documento generato il 28/11/20 alle ore 04:54:57