A study has been made of d-c potential changes in the brain during various states of sleep and wakefulness in the unrestrained unanesthetized rabbit with chronically implanted electroencephalogram and d-c electrodes. In preliminary acute experiments with an occipital bone reference electrode, the direction of the d-c potential change induced by stimulation of the midbrain reticular formation was the same in cortical and subcortical sites. With frontal and occipital bones as reference points the cortical d-c potential changes were similar to one another, but arousal stimuli readily elicited positive d-c shifts with the frontal reference electrode. In the chronic rabbit with an occipital reference electrode, cortical and hypothalamic d-c potentials shifted strongly to the positive side during slow-wave sleep and after injection of pentobarbital; from these conditions stimulation of the reticular formation induced a marked negative shift. During paradoxical sleep both cortical and subcortical d-c electrodes showed negative shifts similar to those seen during an arousal reaction. Grooming and eating elicited strong positive shifts in both cortical and hypothalamic d-c electrodes.
