Bilateral electrodermal activity during sleep and waking in the cat

Electrodermal activity (EDA) was recorded as skin potential responses (SPRs), on the hindpaws of cats during waking and sleep. SPRs recorded on both paws showed an overall parallelism during all stages of vigilance. SPRs on both paws significantly decreased in amplitude and in frequency from wakefulness to sleep. Most SPRs were synchronous but showed bilateral differences larger than 0.1 mV. However, this asymmetry did not show any significant variation as a function of sleep stages. Electrical stimulation of the reticular central tegmental field at levels below the thresholds for behavioral and cortical arousal thresholds evoked SPRs during wakefulness and all stages of sleep. Bilateral differences between evoked SPR amplitudes did not show significant variations as a function of the stages of vigilance. Moreover, the bilateral asymmetry of the evoked SPRs was significantly lower than that of the spontaneous SPRs. These results are discussed in relation to the variations in bilateral EDA recorded in humans during waking and sleep; the influence of central and peripheral factors on EDA laterality is also discussed.