Sensory-evoked potentials (EPs) were studied in male Long-Evans and Fischer-344 rats in order to characterize the electrophysiological consequences of chronic inhalation exposure to trichloroethylene (TCE). Groups of ten Long-Evans rats were exposed to air or 1600 ppm or 3200 ppm TCE for twelve weeks and evaluated periodically with a multisensory test battery. Brainstem auditory-evoked response (BAER) amplitudes were depressed by TCE, whereas somatosensory and visual potentials remained normal. The effects on BAERs, which varied with tone intensity and frequency, suggested that TCE causes a predominantly high-frequency hearing loss. Comparable effects were obtained in both strains of rats and were like those previously observed following exposure to toluene.

Animals↗

PubMedDate not supplied

Functional cerebral asymmetry and performance. I. Reaction time to words and dot patterns as a function of EEG alpha asymmetry.

Alpha activity in left and right hemispheres was recorded while subjects performed in verbal and nonverbal target detection/reaction time tasks. Alpha in the right hemisphere was paradoxically enhanced during the nonverbal task, but RT varied as a function of differential hemispheric arousal in the expected manner--e.g., RT to words was fastest in the performance set showing greatest relative left hemisphere arousal.

Alpha Rhythm↗

PubMedDate not supplied

Functional cerebral asymmetry and performance II. Individual differences in reaction time to word and pattern stimuli triggered by asymmetric alpha bursts.

The difference in mean square values of EEG alpha in left and right hemispheres recorded from parietal scalp regions of 5 female and 6 male human Ss was used to trigger 50 msec presentations of words or random dot patterns, and reaction times to correctly detected target stimuli were obtained. In 9 of 11 Ss the effect of left and right triggering was opposite for word and pattern stimuli, although in only 4 Ss were results consistent with a simple interpretation of alpha as an "idling" rhythm. The results support the hypothesis of complementary hempheric specialization and indicate that overt performance depends on the state of functional cerebral asymmetry.

Alpha Rhythm↗

PubMedDate not supplied

Effects of inhaled carbon disulfide on sensory-evoked potentials of Long-Evans rats.

Peripheral nerve conduction time and parameters of potentials evoked from brain by somatosensory, auditory, and visual stimulation were studied as a function of the concentration of carbon disulfide (CS2) chronically inhaled by female Long-Evans rats. Thirty rats were divided into three groups of ten each and exposed to air or 400 or 800 ppm CS2 7 hours per day, 7 days per week, for 11 weeks. Stimuli consisted of tail shock, clicks, tone pips, light flashes, and reversing visual patterns to evoke multisensory potentials. Effects were observed on conduction time in the periphery, in brainstem auditory pathways and in the visual system. The effects on pattern-reversal potentials were greater than those on flash-evoked potentials.

Action Potentials↗