An Electrophysiological Study on the Thresholds of Arousal Reaction and Evoked Muscular Discharge
1969 Volume 21 Issue 3 Pages 26-53
Details
1969 Volume 21 Issue 3 Pages 26-53
An electrophysiological study was made of the thresholds of arousal reaction and evoked muscular discharge following stimuli on the midbrain reticular formation in unanesthetized rabbits.
1. The threshold of arousal reaction developing on the cerebral cortex and hippocampus due to a 100 c/s stimulation on the midbrain reticular formation appeared at 0.2-0.8 volt, especially at 0.4 volt and 0.6 volt. Generally the threshold of arousal reaction in the cerebral cortex was similar to or slightly higher than that in the hippocampus.
2. Following a 100 c/s stimulation on the midbrain reticular fo rmation, arousal reaction appeared in EEG simultaneously with evoked muscular discharge from the fore and hind extremities. Generally the threshold of arousal reaction due to stimuli on the same site of the midbrain reticular formation was similar or slightly less than that of evoked muscular discharge.
3. A histological pursuance was made of relations between the site of stimulation and threshold in the midbrain reticular formation. As a result it was likely that sits of stimulation having comparatively high thresholds of arousal reaction and evoked muscular discharge were frequently found in the central area of the midbrain reticular formation while those having low thresholds were often found in the area above the center of the midbrain reticular formation.
4. The influence of various pharmaceutical agents on the thresholds of arousal reaction and evoked muscular discharge studied resulted in rather an easy access to the clarification of the agents' action on both sensory and motor systems.
5. In view of changes in arousal reaction depending upon the kind of agents administered it was found that changes in extent of the threshold in the cerebral cortex were in same cases proportional to and in other cases unproportional to those in the hippocampus and that the latter cases suggested a possible habit forming of agents administered.
