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Assessing fear and anxiety in humans using the threat of predictable and unpredictable aversive events (the NPU-threat test)

Abstract

The threat of predictable and unpredictable aversive events was developed to assess short-duration (fear) and long-duration (anxiety) aversive states in humans. A typical experiment consists of three conditions: a safe condition (neutral (N)), during which participants are safe from aversive stimuli, and two threat conditions—one in which aversive events are administered predictably (P) (i.e., signaled by a threat cue), and one in which aversive stimuli are administered unpredictably (U). During the so-called NPU-threat test, ongoing change in aversive states is measured with the startle reflex. The NPU-threat test has been validated in pharmacological and clinical studies and can be implemented in children and adults. Similar procedures have been applied in animal models, making the NPU-threat test an ideal tool for translational research. The procedure is relatively short (35 min), simple to implement and generates consistent results with large effect sizes.

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Figure 1: Visual material presented during the experiment by cue/no cue status and condition.
Figure 2: Schematic representation of sequences of stimulus presentation during each condition in one block of the NPU-threat test.
Figure 3: Blue line represents EMG of the orbicularis oculi.
Figure 4: Mean EMG magnitude during the cue and in the absence of the cue in the no shock, predictable and unpredictable conditions.

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Acknowledgements

This research was supported by the Intramural Research Program of the NIMH (MH002798 and MH002804-09).

Author information

Authors and Affiliations

Authors

Contributions

C.G. developed the NPU-threat test and edited the protocol. A.S. drafted the manuscript and contributed to paradigm modifications.

Corresponding author

Correspondence to Anja Schmitz.

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Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Methods 1

Questionnaire (PDF 90 kb)

Supplementary Table 1

This table shows an example of the timing of all stimuli for a block. The table starts with 4 startle stimuli followed by the sequence PNUNUNP. Note that ITI stands for inter trial interval, which refers to the period without cue (PDF 170 kb)

Supplementary Methods 2

Instructions (PDF 23 kb)

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Schmitz, A., Grillon, C. Assessing fear and anxiety in humans using the threat of predictable and unpredictable aversive events (the NPU-threat test). Nat Protoc 7, 527–532 (2012). https://doi.org/10.1038/nprot.2012.001

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