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From a technical point of view, Pavlovian fear conditioning is well-established in animals, and fear expression (usually measured with freezing) can be readily quantified. Since anxiety is highly associated with various psychiatric diseases (such as post-traumatic stress disorder and phobia), a better understanding of this question using animals is of great importance. Anxiety disorder is one of the most prevalent psychiatric disorders, the lifetime prevalence of human population is up to 30%, and is also highly comorbid with other mental disorders. Evidences suggest that a standard extinction procedure with repeated expose to non-reinforced conditioned stimulus (CS) may reduce fear responses to the CS, but anxiety associated with or caused by the fearful experience remains. In this regard, fear is directed at something specific and concrete, while anxiety to something diffuse and abstract in nature. One prevailing view is that fear is specific to responses directed to a present threat (i.e., when facing a threat) associated with specific cues (such as a sound that predicts the incoming of a foot shock), while anxiety is in preparation for threats of future-oriented. In both literatures of clinical psychiatry and basic neuroscience, the distinction between anxiety and fear is ambiguous, and often one is used to define the other. Thus, under our experimental conditions, CS presentations likely reduce anxiety level in the fear-conditioned mice. Calcium responses in the lateral hypothalamus-projecting vCA1 neurons showed a steady decay during CS suggesting a reduced anxiety. Heart rate measures suggested a small reduction in anxiety during CS. Injection of an inhibitory peptide of PKMzeta (ZIP) into the basolateral amygdala almost entirely abolished CS-triggered fear expression and reduced anxiety to basal level. Diazepam reduced basal anxiety level but had no effect during the presentation of conditioned stimulus (CS). We found that the occurrence of fear significantly interfered with anxiety measurements under various conditions. In this study, we measured anxiety in mice that received discriminative fear conditioning using behavioral, heart rate and calcium (Ca 2+) responses in the ventral hippocampal CA1 (vCA1) neurons. Although it has been claimed that both processes can be measured with certain independence of each other, it is unclear how exactly they differ. It is generally believed that fear is rapidly triggered by a distinct cue while anxiety onset is less precise and not associated with a distinct cue.