Abstract:
Birds have an electrophysiological sleep state that resembles mammalian rapid-eye-movement (REM) sleep. However, whether its regulation and function are similar is unclear. In the current experiment, we studied REM sleep regulation in jackdaws (Coloeus monedula) by exposing the birds to low ambient temperature, a procedure that selectively suppresses REM sleep in mammals. Eight jackdaws were equipped with electrodes to record brain activity and neck muscle activity and a thermistor to record cortical brain temperature. Recordings covered a three-day period starting with a 24 h baseline day at an ambient temperature of 21 °C, followed by a 12 h cold night at 4 °C, after which the ambient temperature was restored to 21 °C for the remaining recovery period. Cold exposure at night caused a significant drop in brain temperature of 1.4 °C compared to the baseline night. However, throughout the cold night, jackdaws expressed NREM sleep and REM sleep levels that were not significantly different from the baseline. Also, EEG spectral power during NREM sleep was unaffected by cold exposure. Thus, while cold exposure had a clear effect on brain temperature in jackdaws, it did not have the same REM sleep suppressing effect reported for mammals. These findings suggest that the REM-sleep-like state in birds, unlike REM sleep in mammals, is protected against the influence of low temperature.
摘要:
鸟类具有类似于哺乳动物快速眼动(REM)睡眠的电生理睡眠状态。然而,其调节和功能是否相似尚不清楚。在目前的实验中,我们通过将鸟类暴露在低环境温度下,研究了寒狼(Coloeusmonedula)的REM睡眠调节,一种选择性抑制哺乳动物REM睡眠的方法。八个寒风配备了电极以记录大脑活动和颈部肌肉活动,并配备了热敏电阻以记录皮质脑温度。记录涵盖为期三天,从环境温度为21°C的24小时基线日开始,随后是4°C的12小时寒冷夜晚,之后,在剩余的恢复期将环境温度恢复至21°C。与基线夜晚相比,夜间的冷暴露导致大脑温度显着下降1.4°C。然而,整个寒冷的夜晚,寒风表示NREM睡眠和REM睡眠水平与基线没有显着差异。此外,NREM睡眠期间的EEG频谱功率不受冷暴露的影响。因此,虽然寒冷暴露对寒狼的大脑温度有明显影响,它对哺乳动物没有相同的REM睡眠抑制作用。这些发现表明,鸟类的REM睡眠状态,与哺乳动物的REM睡眠不同,免受低温的影响。