Research reportBehavioral and neuroimaging responses induced by mental imagery of threatening scenarios

- Imaginary of imminent threat scenarios increased fMRI signal of the dorsal midbrain.
- Activity in vmPFC was reduced during the imagination of imminent threat scenarios.
- Activation pattern was consistent with animal data and actual threat situations.
- Imminent and potential threats modulate brain structures related to fear and anxiety.
- Mental imagery is a reliable method to study the neurobiology of behavioral processes.

Functional neuroimaging studies have shown that actual situations of uncertain or distant threats increase the activity of forebrain regions, whereas proximal threats increase the activity of the dorsal midbrain. This experiment aimed at testing the hypothesis that brain activity elicited by imagined scenarios of threats with two different magnitudes, potential and imminent, resembles that found in response to actual threats. First, we measured subjective responses to imagined scenarios of potential and imminent threats compared with neutral and pleasant scenarios. The same scenarios were used as a paradigm in a functional magnetic resonance imaging experiment. Behavioral results show that the scenarios draw a gradient of hedonic valence and arousal dimensions. Both potential and imminent threat scenarios increased subjective anxiety; the imminent threat scenario also increased feelings of discomfort and bodily symptoms. The functional magnetic resonance imaging results revealed modulations of BOLD signal in the ventromedial prefrontal cortex by potential threat and in the periaqueductal gray matter by imminent threat. These results agree with previously reported evidence using actual threat situations, indicating that mental imagery is a reliable method for studying the functional neuroanatomy of relevant behavioral processes.