Cardiac Rhythms and Variation in Hibernating Arctic Ground Squirrels

Methods to estimate body temperature and energy expenditure dynamics in fed and fasted laboratory mice: effects of sleep deprivation and light exposure

“…However, a similar linear fit provided a far less accurate description of energy expenditure during daily torpor in food deprived mice (R 2 = 0.463 ± 0.121; mean ± SD; T core > 35 °C is excluded). Visual inspection of the recordings presented here supports the notion that an alternative ‘hysteresis’ description of the relationship between T core and energy expenditure provides a more reliable estimation of energy expenditure during daily torpor (Geiser et al 2014 ; Swoap & Gutilla 2009 ; Zanetti et al 2023 ). In this description the relationship between T core and energy expenditure is partitioned into three distinct components: (1) periods during which T core decreases, (2) an initial stage when T core increases, and (3) a sustained terminal stage of increasing T core during which the increase of energy expenditure is less rapid than during stage 2 (Fig.…”

“…The estimation of energy expenditure during daily torpor based on a hysteresis-model using T core measurements (Geiser et al 2014 ; Swoap & Gutilla 2009 ; Zanetti et al 2023 ) provides a substantially better estimate compared to traditional models based on a simple linear fit. This improvement is especially pronounced at the initiation and termination of torpor bouts where energy expenditure changes much more rapidly compared to the relatively slow change in T core .…”