Zanutto B Silvano, Staddon John E R
Instituto de Ingeniería Biomédica-Universidad de Buenos Aires, Buenos Aires, Argentina.
PLoS Comput Biol. 2007 May;3(5):e97. doi: 10.1371/journal.pcbi.0030097.
Rats, people, and many other omnivores eat in meals rather than continuously. We show by experimental test that eating in meals is regulated by a simple bang-bang control system, an idea foreshadowed by Le Magnen and many others, shown by us to account for a wide range of behavioral data, but never explicitly tested or tied to neurophysiological facts. The hypothesis is simply that the tendency to eat rises with time at a rate determined by satiety signals. When these signals fall below a set point, eating begins, in on-off fashion. The delayed sequelae of eating increment the satiety signals, which eventually turn eating off. Thus, under free conditions, the organism eats in bouts separated by noneating activities. We report an experiment with rats to test novel predictions about meal patterns that are not explained by existing homeostatic approaches. Access to food was systematically but unpredictably interrupted just as the animal tried to start a new meal. A simple bang-bang model fits the resulting meal-pattern data well, and its elements can be identified with neurophysiological processes. Hypothalamic inputs can provide the set point for longer-term regulation carried out by a comparator in the hindbrain. Delayed gustatory and gastrointestinal aftereffects of eating act via the nucleus of the solitary tract and other hindbrain regions as neural feedback governing short-term regulation. In this way, the model forges real links between a functioning feedback mechanism, neuro-hormonal data, and both short-term (meals) and long-term (eating-rate regulation) behavioral data.
大鼠、人类以及许多其他杂食动物都是按餐进食，而非持续进食。我们通过实验测试表明，按餐进食受一种简单的开关控制系统调节，这一观点由勒马涅等人预先提出，我们已证明它能解释广泛的行为数据，但此前从未经过明确测试，也未与神经生理学事实联系起来。该假设很简单，即进食倾向会随着时间推移，以由饱腹感信号决定的速率上升。当这些信号降至设定点以下时，进食以开关方式开始。进食的延迟后果会增加饱腹感信号，最终停止进食。因此，在自由条件下，生物体以进食时段与非进食活动交替的方式进食。我们报告了一项对大鼠的实验，以测试关于进食模式的新预测，这些预测无法用现有的稳态方法来解释。当动物试图开始新的一餐时，系统地但不可预测地中断其获取食物的机会。一个简单的开关模型能很好地拟合由此产生的进食模式数据，并且其要素可以与神经生理过程相对应。下丘脑输入可以为后脑的比较器进行的长期调节提供设定点。进食的延迟味觉和胃肠道后效应通过孤束核和其他后脑区域起作用，作为控制短期调节的神经反馈。通过这种方式，该模型在一个起作用的反馈机制、神经激素数据以及短期（进餐）和长期（进食速率调节）行为数据之间建立了真实的联系。
