Exploring the neural basis of fear produced by mental imagery: imaginal exposure in individuals fearful of spiders

Abstract

Imaginal exposure, i.e. reducing fear using exposure to mental imagery, is a widely used psychological treatment technique for dysfunctional fears. Yet, little is known about its underlying neural mechanisms. The present study examines the neural basis of imaginal exposure using a novel experimental procedure consisting of repeated exposure to flashpoint mental imagery of phobic (spiders) and neutral (gloves) stimuli. Whether the 10 min long imaginal exposure procedure could reduce fear responses was examined one week later. Thirty participants fearful of spiders underwent the experimental procedure. Neural activity was assessed using functional magnetic resonance imaging (session 1). Subjective fear and skin conductance responses were measured throughout the study (sessions 1 and 2). Imaginal exposure evoked intense fear and heightened skin conductance responses, and indicated robust activation in several brain regions, including amygdala, midcingulate cortex and insula. Findings demonstrate that neural activity in fear-processing brain areas can be elicited solely by generating a mental image of a phobic stimulus, that is, in the absence of the percept. Relevant for treatment development, results reveal that a single 10 min session of brief exposures to flashpoint mental imagery can lead to lasting reductions in phobic fear at both the subjective and physiological levels. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Keywords: functional magnetic resonance imaging; imaginal exposure; imaginal extinction; mental imagery; skin conductance responses.

Conflict of interest statement

The other authors declare no conflict of interest.

Figures

Figure 1.

Bar charts depict (a) subjective fear ratings (N = 29) and (b) mean skin conductance responses (N = 27) to mental imagery of phobic stimuli (spiders) and neutral stimuli (gloves) during the experimental procedure in sessions 1 and 2. Error bars represent standard error of mean. *p < 0.05, **p < 0.001.

Figure 2.

Results from whole-brain statistical parametrical mapping overlaid on a standard brain. Images are displayed at p < 0.05 family-wise error-corrected statistical threshold. Top panel depicts increased activity during imaginal exposure to phobic stimuli (phobic > neutral imagery) including the (a) left midcingulate gyrus, supplementary motor area, (b) bilateral amygdala and (c) bilateral insula. Bottom panel shows activity in areas associated with mental imagery production (neutral imagery > baseline) including (d) left dorsolateral and orbitofrontal cortex, (e) right cerebellum and (f) left inferior temporal gyrus. (Online version in colour.)