Baldwin B A, Lipton J M
Acta Neurobiol Exp (Wars). 1973;33(2):433-47.
Pigs aged about 8 weeks will learn to operate infra-red heaters at ambient temperatures of 20 degree Celsius but not at 25 degree Celsius. Hypothalamic temperature, cortical EEG and skin temperatures have been recorded in pigs exposed to ambient temperatures of 0, +10 or +20 degree Celsius in both heat reinforcement and heat escape situations. The amount of heating received decreased with increasing ambient temperature but at any given ambient temperature there was no significant difference between the duration of heating obtained in the heat reinforcement or heat escape situations. At O degree Celsius, in both situations, the pigs tended to maintain the temperature of their skin which was nearest the heaters at higher levels than they did at +10 degree Celsius. Skin temperatures rarely exceeded 45 degree Celsius. The temperature of the preoptic region was variable but did not change systematically with respect to the behaviour. Observation of the pigs and cortical EEG revealed that during periods of infra-red heating the pigs often became drowsy, but "post reinforcement synchrony" was not seen in the EEG. Cooling the preoptic region by means of an implanted thermode increased the duration of heating in a heat reinforcement situation at 0 degree Celsius and resulted in skin temperatures reaching levels of 45-47 degree Celsius.
约8周龄的猪在环境温度为20摄氏度时会学会操作红外加热器，但在25摄氏度时则不会。在热强化和热逃避两种情况下，对暴露于0、+10或+20摄氏度环境温度下的猪记录了下丘脑温度、皮层脑电图和皮肤温度。随着环境温度升高，所接受的加热量减少，但在任何给定的环境温度下，热强化或热逃避情况下获得的加热持续时间之间没有显著差异。在0摄氏度时，在两种情况下，猪倾向于将最靠近加热器的皮肤温度维持在比在+10摄氏度时更高的水平。皮肤温度很少超过45摄氏度。视前区的温度是可变的，但相对于行为没有系统性变化。对猪和皮层脑电图的观察表明，在红外加热期间，猪经常变得困倦，但脑电图中未观察到“强化后同步”。在0摄氏度的热强化情况下，通过植入的热电极冷却视前区会增加加热持续时间，并导致皮肤温度达到45 - 47摄氏度。
