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Propriospinal transmission of part of the corticospinal excitation in humans
Author(s) -
PierrotDeseilligny Emmanuel
Publication year - 2002
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.1240
Subject(s) - neuroscience , inhibitory postsynaptic potential , excitatory postsynaptic potential , motor cortex , pyramidal tracts , afferent , primary motor cortex , corticospinal tract , biology , anatomy , medicine , magnetic resonance imaging , stimulation , radiology , diffusion mri
In humans a substantial part of corticospinal excitation to upper limb motoneurons is mediated through cervical premotoneurons located rostral to motoneurons, analogous to the feline system of C3–C4 propriospinal neurons. The indirect (disynaptic) component of the corticospinal command passing through the propriospinal relay may be updated by the extensive convergence at this level of afferent inputs (both excitatory and inhibitory) from the moving limb. Propriospinal neurons are potently inhibited by feedback inhibitory interneurons facilitated from the motor cortex, and this explains why artificial volleys delivered to the pyramidal system by itself have failed to demonstrate this indirect corticospinal projection. The strength of this indirect corticospinal projection may be estimated in routine practice by the amount of suppression elicited by a cutaneous volley on the ongoing electromyogram of extensor carpi radialis, and is increased in patients recovering from hemiplegia and in early Parkinson's disease. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 155–172, 2002