The actions or reactions of persons or things in response to external or internal stimuli.

在有梦的睡眠中，动物根本不能动弹而且 对外界刺激没有反应。

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The idea that animalsact only in response to external stimuli has long been abandoned, andit is well established that they initiate behaviour on the basis oftheir internal states, as we do.

认为动物行为仅仅是对外部刺激(externalstimuli)的反射(response)的观点早就被摒弃了，取而代之的是，它们激发行为是建立在它们内部状态(internalstates)的基础之上的，就像我们做的那样。

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An external stimulus such as music can actually block some of the internal stimuli trying to reach the brain such as fatigue-related messages from muscles and organs.

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Using a technique called functional magnetic resonance imaging (fMRI), the researchers were able to record the brain's activity in response to internal and external stimuli such as eating and drinking.

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