Abstract: Thought experiment: you’re starving, huddled in the fetal position in a hole in the ground, with no sense of the world around you, except that you are really, really cold. In fact, your internal temperature can go as low as –2.9°C, which is as dangerous as it sounds, and somehow, you are not freaking out. Actually, your heart rate is only two beats per minute, and you are breathing just a few shallow breaths every half hour or so. You’re not dead, so what are you? You’re hibernating. Hibernation is a form of torpor used by capable species to defend against the stressors of the winter months such as low ambient temperatures and low food availability. It is characterized by substantial decreases in metabolic rate, breathing and heart rates, and organ perfusion. For this reason, hibernator brains are unique and a little unusual, at least, unusual enough to tolerate and survive these inhospitable conditions. Despite brains being especially sensitive to changes in oxygen/nutrient availability and temperature, hibernators can withstand decreases in brain perfusion of ~90% compared to euthermic levels and changes in body temperatures (Tb) from ~37°C to as low as –2.9°C (Schwartz et al., 2013; Tessier et al., 2019). Yet, hibernators arise from their final torpor-arousal cycle in the spring with no signs of brain injury, almost immediately remembering how to forage for food and find summertime mates. How do hibernators prevent and reverse brain damage? We will describe the role of temperature and torpor in the preservation of hibernator brain integrity with a focus on the molecular aspects of dendritic reorganization.