Abstract
This experiment is intended to clarify the changes in the sleep cycle and EEG of rats exposed to toluene vapor. Chronically implanted electrodes were used to record the cortical and hippocampal EEGs, cervical EMG and pulse rate. The rats were exposed to 4000 ppm toluene vapor from 4 to 8 p.m. daily for four weeks. Polygraphs were recorded from noon to 4 p.m. before exposure, after four weeks' exposure and a week after the termination of exposure.
With regard to the sleep cycle, it was observed that the percent time of the wakefulness phase increased, while those of the slow-wave and paradoxical phases decreased, and the rhythm of the sleep cycle became irregular after four weeks' exposure.
As for the EEG patterns, it was noted that the spindle wave of the spindle phase changed in the appearance rate, shape and frequency, and the fast components of the cortical and hippocampal EEGs increased in the slow-wave phase after four weeks' exposure. The changes in the sleep cycle and EEGs continued for a week after the termination of exposure, although they became less marked.
It was thought that analysis of the changes in the sleep cycle and EEG would serve as an index of the effects of toluene on the central nervous system.
