The cholinergic system-dependent myoclonus of the baboon Papio papio is a reticular reflex myoclonus.
Neurophysiological studies were performed on four Papio papio baboons presenting with nonepileptic myoclonus (a startle response resembling stimulus-sensitive jerk). Investigations of the EEG, back-averaged EEG, and somatosensory evoked potentials revealed the absence of cortical correlates preceding the jerks, and exclusion of cerebral cortex involvement. No long-latency reflexes could be recorded in these animals. The jerks were symmetric when evoked by unilateral stimulation in normal baboons as well as in a split-brain animal. Polymyographic records showed that the first muscle involved during the jerk was the trapezius; other muscles were involved with latencies increasing in both cranial and caudal directions. From these data, nonepileptic myoclonus of baboons can be classified as a reticular reflex myoclonus. The involvement of cranial nerves did not follow the layout of the nuclei in the brainstem, indicating that the jerk is most likely generated as a complete movement. The generating structure is probably under cholinergic control. Finally, the Papio papio baboon, which was already known as a model for cortical myoclonus elicited by intermittent photic stimulation in predisposed animals, can also be considered a model for the study of the reticular reflex myoclonus.
Rektor
I
I
Laboratoire de Physiologie Nerveuse, C.N.R.S. Gif-sur-Yvette, France.
Svejdová
M
M
Silva-Barrat
C
C
Menini
C
C
D000818:Animals; D001933:Brain Stem / Q000503:physiopathology; D002799:Cholinergic Fibers / Q000502:physiology*; D003391:Cranial Nerves / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D008297:Male; D009132:Muscles / Q000294:innervation; D009207:Myoclonus / Q000503:physiopathology*; D009474:Neurons / Q000502:physiology; D010215:Papio; D012018:Reflex / Q000502:physiology*; D012154:Reticular Formation / Q000503:physiopathology*