Author/Editor		Liščić, R; Zidar, J; Prevec, TS
Title		Activation of the corticobulbar tract to the lower facial muscles by magnetic stimulation: a study of motor unit responses
Type		članek
Source		Neurol Croat
Vol. and No.		Letnik 43, št. 2
Publication year		1994
Volume		str. 65-74
Language		eng
Abstract		The influence of transcranial magnetic stimulation (TMS) of the motor cortex on the discharge patterns of motor units in the orbicularis oris (OOR) muscle in healthy volunteers was studied and compared to that of the first dorsal interosseous (FDI) muscle using poststimulus time histograms (PSTH). With PSTH, the primary (PP) and secondary peaks (SP), and respective subspeaks, were defined. Latency variation (jitter) of evoked single muscle fibre motor unit responses was measured for each of the subspeaks within the PP. A relatively small latency variation of the motor unit responses to TMS for the FDI muscle suggests a predominantly monosynaptic projection to the spinal motorneurons. Latency variation (SD-jitter) of the evoked responses in the OOR muscle was by 1.6 times larger in comparison with the FDI muscle. The difference in the latency variation of motor unit responses for the P1 subpeak measured in the FDI and OOR muscles was statistically significant (P less th. 0.05). This finding implies that the corticobulbar projection to the OOR muscle is more complex than that to the FDI muscles. A less synchronized excitation volley may also explain the discharge characteristics in the OOR muscle.
Descriptors		PYRAMIDAL TRACTS MOTOR CORTEX SYNAPTIC TRANSMISSION NEUROMUSCULAR JUNCTION MAGNETICS ELECTRIC STIMULATION