TY - JOUR
T1 - Cutaneomotor integration in human hand motor areas
T2 - Somatotopic effect and interaction of afferents
AU - Tamburin, S.
AU - Manganotti, P.
AU - Zanette, G.
AU - Fiaschi, A.
PY - 2001
Y1 - 2001
N2 - The aim of this study was to elucidate sensori-motor integration in human hand motor areas, its time course, somatotopy and the interaction of sensory fields arising from two different fingers. We studied the influence of different intensities of electrical digital stimulation of two different fingers on motor-evoked potentials elicited in hand muscles by transcranial magnetic stimulation (TMS). Single conditioning electrical stimuli were applied to the right second (D2) and fifth fingers (D5) individually and also to both fingers (D2+D5) simultaneously in six normal volunteers. Magnetic tests, adjusted to produce a response in the abductor digiti minimi muscle of the right hand, were delivered using a circular and a focal coil. The digital stimuli were delivered to the finger at the sensory threshold (ST), at 3 and 5 times the ST, and over the pain threshold at interstimulus intervals (ISIs) ranging from 10 to 100 ms. In order to define the anatomical level of the sensorimotor interactions, the effect of the digital stimulation on TMS was compared to the effect on transcranial electrical stimulation. When the peripheral stimulation was delivered at the ST a small inhibitory effect was found only when stimulating both fingers. At 3 times the ST we detected a topographic distribution of motor-evoked potential inhibition, which partially disappeared at higher intensity (5 times the ST); two types of convergence effects took place at different ISIs. When conditioning stimuli were painful, somatotopy and convergence were lost. Sensorimotor integration shows somatotopy and interaction of afferents at different sites. The intensity of the conditioning stimulus plays an important role in topography and sensory convergence. The importance of these mechanisms in physiology and physiopathology is discussed.
AB - The aim of this study was to elucidate sensori-motor integration in human hand motor areas, its time course, somatotopy and the interaction of sensory fields arising from two different fingers. We studied the influence of different intensities of electrical digital stimulation of two different fingers on motor-evoked potentials elicited in hand muscles by transcranial magnetic stimulation (TMS). Single conditioning electrical stimuli were applied to the right second (D2) and fifth fingers (D5) individually and also to both fingers (D2+D5) simultaneously in six normal volunteers. Magnetic tests, adjusted to produce a response in the abductor digiti minimi muscle of the right hand, were delivered using a circular and a focal coil. The digital stimuli were delivered to the finger at the sensory threshold (ST), at 3 and 5 times the ST, and over the pain threshold at interstimulus intervals (ISIs) ranging from 10 to 100 ms. In order to define the anatomical level of the sensorimotor interactions, the effect of the digital stimulation on TMS was compared to the effect on transcranial electrical stimulation. When the peripheral stimulation was delivered at the ST a small inhibitory effect was found only when stimulating both fingers. At 3 times the ST we detected a topographic distribution of motor-evoked potential inhibition, which partially disappeared at higher intensity (5 times the ST); two types of convergence effects took place at different ISIs. When conditioning stimuli were painful, somatotopy and convergence were lost. Sensorimotor integration shows somatotopy and interaction of afferents at different sites. The intensity of the conditioning stimulus plays an important role in topography and sensory convergence. The importance of these mechanisms in physiology and physiopathology is discussed.
KW - Convergence
KW - Digital nerve stimulation
KW - Sensorimotor integration
KW - Somatotopy
KW - Transcranial magnetic stimulation
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U2 - 10.1007/s002210100859
DO - 10.1007/s002210100859
M3 - Article
C2 - 11713634
AN - SCOPUS:0034750569
VL - 141
SP - 232
EP - 241
JO - Experimental Brain Research
JF - Experimental Brain Research
SN - 0014-4819
IS - 2
ER -