Functional organisation of corticonuclear pathways to motoneurones of lower facial muscles in man |
| |
Authors: | B.-U. Meyer K. Werhahn J. C. Rothwell S. Roericht C. Fauth |
| |
Affiliation: | (1) MRC Human Movement and Balance Unit, Institute of Neurology, Queen Square, WC1N 3GB London, UK;(2) Neurologische Klinik der Technischen Universität, Moehlstrasse 28, D-81675 Munich, Germany;(3) Neurologische Klinik, Moorenstrasse 5, D-40225 Düsseldorf, Germany;(4) Neurologische Klinik der Charite, Schumannstrasse 20/21, D-10098 Berlin, Germany |
| |
Abstract: | EMG responses were recorded from lower facial muscles (depressor labii inferioris or depressor anguli oris) of 12 normal subjects after magnetic stimulation of the motor cortex. Using a figure-of-eight stimulating coil, the largest responses were obtained from points around 8–10 cm lateral to the vertex. Usually they were bilateral and had the same latency (11–12 ms) on both sides of the face. Patients with complete Bell's palsy had no response in muscles on the same side as the lesion, indicating that the ipsilateral component to cortical stimulation was not the result of recrossing in the periphery of nerve fibres from the contralateral side. Single-unit studies showed that cortical stimulation produced two phases of motoneuronal facilitation: a short-latency (central motor delay from contralateral cortex to the intracranial portion of the facial nerve, 7.6 ms), short-duration (1– to 2-ms duration peak in the post-stimulus time histogram) input, which was more commonly evoked by contralateral than ipsilateral stimulation; and a longer latency (central delay > 15 ms), long-duration input evoked equally well from either hemisphere. The former may represent activity in a predominantly contralateral oligosynaptic corticobulbar pathway; the latter, a polysynaptic indirect (e.g. co-rticotegmento-nuclear) bilateral pathway to lower facial muscles. |
| |
Keywords: | Magnetic stimulation Single motor units Lower facial muscles Corticobulbar connexions Human |
本文献已被 SpringerLink 等数据库收录! |
|