Tests for Conditioned Anxiety

Another behavioral approach used to assess aspects of anxiety in animals relies on conflict paradigms in combination with punishment, mostly induced by electric foot shock. Due to ethical and also ethological considerations, paradigms based on electric shock are less often used than tests for unconditioned anxiety. However, it has been hypothesized that behavioral expressions displayed in tests for unconditioned and conditioned anxiety may reflect profoundly different aspects of anxiety (File 1995 Griebel 1996 Millan and Brocco 2003). Thus, shock paradigms are quite frequently included in behav- 

Referred to as a conditioned fear paradigm, the fear potentiated startle response was first described by Brown et al. (1951). In the original test, an acoustic stimulus is presented in the presence of a conditioned stimulus that has previously been paired with an aversive, unconditioned stimulus. The amplitude of the acoustic startle response is thought to indicate the degree of conditioned anxiety, which can be reduced by anxiolytic drugs (Davis et al. 1993 Hijzen et al. 1995). 

Comprehensive studies based on rodent models of anxiety have not only underlined that anxiety in itself represents a complex behavioral system but also that it is determined by both genetic and environmental factors as well as by the interaction between both. The examples used in this section have been selected to illustrate both the potential and the caveats of current models and the emerging possibilities offered by gene technology. These examples are thought to be representative of the different concepts followed in generating animal models. 

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