Silver Rae, Balsam Peter
Department of Psychology, Barnard College, New York City, New York, USA.
Sleep Biol Rhythms. 2010 Apr 1;8(2):120-136. doi: 10.1111/j.1479-8425.2010.00438.x.
Circadian rhythms are adjusted to the external environment by the light-dark cycle via the suprachiasmatic nucleus, and to the internal environment of the body by multiple cues that derive from feeding/fasting. These cues determine the timing of sleep/wake cycles and all the activities associated with these states. We suggest that numerous sources of temporal information, including hormonal cues such as corticoids, insulin, and ghrelin, as well as conditioned learned responses determined by the temporal relationships between photic and feeding/fasting signals, can determine the timing of regularly recurring circadian responses. We further propose that these temporal signals can act additively to modulate the pattern of daily activity. Based on such reasoning, we describe the rationale and methodology for separating the influences of these diverse sources of temporal information. The evidence indicates that there are individual differences in sensitivity to internal and external signals that vary over circadian time, time since the previous meal, time until the next meal, or with duration of food deprivation. All of these cues are integrated in sites and circuits modulating physiology and behavior. Individuals detect changes in internal and external signals, interpret those changes as "hunger," and adjust their physiological responses and activity levels accordingly.
昼夜节律通过视交叉上核，经由明暗周期与外部环境同步，并通过进食/禁食产生的多种信号与身体的内部环境同步。这些信号决定了睡眠/觉醒周期的时间以及与这些状态相关的所有活动。我们认为，包括皮质醇、胰岛素和胃饥饿素等激素信号在内的众多时间信息来源，以及由光信号与进食/禁食信号之间的时间关系所决定的条件性学习反应，都能够决定周期性出现的昼夜节律反应的时间。我们进一步提出，这些时间信号可以叠加作用，调节日常活动模式。基于上述推理，我们描述了区分这些不同时间信息来源影响的基本原理和方法。有证据表明，个体对内部和外部信号的敏感性存在差异，这种差异会随着昼夜时间、距上次进餐的时间、距下次进餐的时间或禁食持续时间而变化。所有这些信号都在调节生理和行为的位点及神经回路中整合。个体检测内部和外部信号的变化，将这些变化解读为“饥饿”，并相应地调整其生理反应和活动水平。
