Jans J E, Leon M
Physiol Behav. 1983 Jun;30(6):919-35. doi: 10.1016/0031-9384(83)90258-5.
Rat dams choose to care for their pups in a relatively warm area, apparently because they have an elevated thermal set point for the regulation of their body temperature. Since the duration of their contact bouts with their pups is limited by an acute hyperthermia that they experience while on the pups, their choice limits the time that they can spend with their pups. When dams could choose the temperature at which they cared for their young they spent only about half the time in contact with their offspring as did dams caring for their pups at the ambient temperature of the laboratory. We conclude that rat dams do not attempt to maximize the duration of their contact bouts with their offspring. Dams also do not attempt to minimize the amount of time that they spend away from their offspring. The duration of the intervals between contact bouts was influenced by the ability of the dams to dissipate the heat gained during the contact bout with the pups. Again, dams did not seek out a cool area in which to spend their interbout intervals, preferring to remain in relatively warm areas. Their thermal preference facilitated the retention of their body heat and prolongation of the interbout intervals. Dams may return to the nest periodically for brief bouts during which the state of the pups is monitored. Pups were found to play both passive and active roles in modulating the overall pattern of maternal contact, for dams maintained contact with pups if the pups were cool, but failure to attach to the nipples soon after contact was established frequently led to rapid bout termination, particularly with warm pups. Contact is maintained if the pups are cool or if they attach to the nipples. Finally, it was found that pups could actively curtail interbout intervals by emitting ultrasonic vocalizations.
大鼠母鼠会选择在相对温暖的区域照顾幼崽，显然是因为它们调节体温的热设定点升高了。由于它们与幼崽接触回合的持续时间受到趴在幼崽身上时所经历的急性体温过高的限制，它们的这种选择限制了它们与幼崽相处的时间。当母鼠能够选择照顾幼崽的温度时，它们与后代接触的时间仅为在实验室环境温度下照顾幼崽的母鼠的一半左右。我们得出结论，大鼠母鼠不会试图最大化与后代接触回合的持续时间。母鼠也不会试图最小化离开后代的时间。接触回合之间间隔的持续时间受到母鼠消散在与幼崽接触回合中获得的热量的能力的影响。同样，母鼠不会寻找凉爽的区域来度过它们的回合间隔，而是更喜欢待在相对温暖的区域。它们的热偏好有助于保持体温并延长回合间隔。母鼠可能会定期返回巢穴进行短暂的回合，在此期间监测幼崽的状态。发现幼崽在调节母鼠接触的总体模式中既扮演被动角色也扮演主动角色，因为如果幼崽凉爽，母鼠会与它们保持接触，但接触建立后如果幼崽未能很快附着在乳头上，通常会导致回合迅速结束，尤其是对于温暖的幼崽。如果幼崽凉爽或附着在乳头上，接触就会保持。最后，发现幼崽可以通过发出超声波叫声来主动缩短回合间隔。
