Corticospinal excitability during painful self-stimulation in humans: a transcranial magnetic stimulation study.
We investigated changes in the corticospinal pattern of activity in healthy volunteers during sustained noxious and non-noxious mechanical stimulation of the first hand digit, resulting from active (self-stimulation) or passive (externally-induced) pressing against a sharp or blunted tip. The results indicate that, in order to press a finger onto a noxious stimulus with the same force generated to press onto a non-noxious one, the motor cortex adopts a peculiar strategy in terms of recruitment of motor units. This is reflected by an increase of corticospinal excitability (as revealed by motor potentials evoked by transcranial magnetic stimulation of the contralateral primary motor cortex) and EMG activity of agonist muscles, possibly related to an increase of motor unit synchronization.
Fadiga
Luciano
L
Department of Biomedical Sciences and Advanced Therapies, Section of Human Physiology, University of Ferrara, via Fossato di Mortara 17/19, 44100 Ferrara, Italy.
Craighero
Laila
L
Dri
Guanita
G
Facchin
Patrizia
P
Destro
Maddalena Fabbri
MF
Porro
Carlo A
CA
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology*; D000870:Anterior Horn Cells / Q000502:physiology; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009469:Neuromuscular Junction / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D010812:Physical Stimulation / Q000295:instrumentation / Q000379:methods; D011712:Pyramidal Tracts / Q000502:physiology*; D012016:Reference Values; D050781:Transcranial Magnetic Stimulation