Electroencephalography and clinical neurophysiology
-
Electroencephalogr Clin Neurophysiol · Nov 1949
Brain stem reticular formation and activation of the EEG.
1. Stimulation of the reticular formation of the brain stem evokes changes in the EEG, consisting of abolition of synchronized discharge and introduction of low voltage fast activity in its place, which are not mediated by any of the known ascending or descending paths that traverse the brain stem. The alteration is a generalized one but is most pronounced in the ipsilateral hemisphere and, sometimes, in its anterior part. 2. ⋯ The reticular response and the arousal reaction to natural stimuli have been compared in the "encéphale isolé", in which EEG synchrony was present during spontaneous relaxation or was produced by recruiting mechanisms, and the two appear identical. 9. The possibility that the cortical arousal reaction to natural stimuli is mediated by collaterals of afferent pathways to the brain stem reticular formation, and thence through the ascending reticular activating system, rather than by intra-cortical spread following the arrival of afferent impulses at the sensory receiving areas of the cortex, is under investigation. 10. The possibility is considered that a background of maintained activity within this ascending brain stem activating system may account for wakefulness, while reduction of its activity either naturally, by barbiturates, or by experimental injury and disease, may respectively precipitate normal sleep, contribute to anesthesia or produce pathological somnolence.