Changes in selective brain cooling across the behavioral states of the ultradian wake-sleep cycle

In cats, the behavioral state-dependent negative correlation of the pontine-hypothalamic temperature difference, an indicator of selective brain cooling, with the hypothalamic-ear pinna temperature difference, which is an indicator of heat loss from the heat exchangers of the head, is suppressed after bilateral common carotid ligature. Behavioral state-dependent selective brain cooling may underlie a thermal feedback mechanism differentiating the relative influences of hypothalamic and extra-hypothalamic thermoreceptors on the thermoregulatory system during quiet wakefulness and NREM sleep.