title: Ordered motor-unit firing behavior in acute cerebellar stroke.
abstract: It is known that at any given force level, the lower-threshold motor units generally fire at greater rates than the higher-threshold units during isometric tasks of extremity muscles. In addition to this hierarchical arrangement, firing rates of motor units fluctuate in unison with nearly no time delay; an observation that has led to the concept of common drive, a basic motoneuronal rule. Although it is established that the cerebellum plays a critical function in motor control, its role in the genesis, triggering, selection, and monitoring of motor-unit firing pattern discharges during isometric tasks is unknown. We applied an electromyographic (EMG) decomposition technique, known as precision decomposition, to accurately identify motor-unit firing times from the EMG signal recorded from the first dorsal interosseous muscle to unravel the features of motor-unit firings in three patients presenting a unilateral cerebellar stroke and exhibiting an acute cerebellar syndrome. We observed ataxic isometric force during visually guided abduction of the index finger on the affected side. However, the hierarchical response of individual motor units was spared. Furthermore, acute cerebellar ataxia was not associated with a loss of the common drive.
authors.affiliation: Université Libre de Bruxelles Erasme Neurologie, Fonds National de la Recherche Scientifique, 808, Route de Lennik, 1070 Brussels, Belgium.
authors.forename: Chloe
authors.initials: C
authors.lastname: Sauvage
authors.forename: Mario
authors.initials: M
authors.lastname: Manto
authors.forename: Alexander
authors.initials: A
authors.lastname: Adam
authors.forename: Rick
authors.initials: R
authors.lastname: Roark
authors.forename: Patrice
authors.initials: P
authors.lastname: Jissendi
authors.forename: Carlo J
authors.initials: CJ
authors.lastname: De Luca
mesh_terms: D000208:Acute Disease; D000368:Aged; D002524:Cerebellar Ataxia / Q000503:physiopathology / Q000523:psychology; D002526:Cerebellar Diseases / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004576:Electromyography; D004594:Electrophysiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000294:innervation / Q000503:physiopathology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D011999:Recruitment, Neurophysiological / Q000502:physiology; D020521:Stroke / Q000503:physiopathology*