Investigating the effect of goal-directed eye movements during extinction on amygdala activity and long-term expression of fear memory

Eye movement desensitization and reprocessing (EMDR) is seen as a promising treatment option for fear-related psychiatric diseases such as post-traumatic stress disorder (PTSD). Indeed, experimental studies have shown that performing goal-directed eye movements following recall of autobiographical episodic memories can reduce the vividness and emotionality of these memories. However, the effect of goal-directed eye movements on retention of fear memory has not been tested directly, and critically, the mechanisms by which eye movements may affect mnemonic processes remain poorly understood. Previous research suggests that performing tasks involving endogenous attention suppresses neural activity in the default mode network (DMN), a large-scale brain network which includes the ventromedial prefrontal cortex (vmPFC) and medial temporal lobe regions such as the amygdala and hippocampus. These regions are also critically implicated in fear and safety learning. We therefore hypothesized that deployment of endogenous attention during goal-directed eye movements suppresses activity in these regions and might thereby affect fear retention. To address this hypothesis, twenty-four healthy volunteers were tested in a Pavlovian fear conditioning paradigm, the most widely used experimental laboratory model of fear and safety learning, which is used in both animal and human research. Participants came to the lab on three consecutive days for an acquisition, an extinction, and a recall phase. During fear acquisition, two stimuli (CS+) were associated with a mild electrical shock, while two other stimuli (CS-) were never reinforced. During extinction, one CS+ and one CS- was always followed by a block of goal-directed eye movements. Blood Oxygenation Level-Dependent functional MRI data, pupil dilation, and skin conductance responses were recorded throughout all phases of the experiment. Preliminary results show that during eye movement blocks, there is suppression in the amygdala, hippocampus, and vmPFC relative to baseline compared to the fixation blocks. Further analyses will focus on whether this temporary suppression of brain regions supporting fear acquisition and extinction may affect retention of fear memories.

Conference

English

L. D. de Voogd
W. Kanen
K. Roeslofs
G. Fernandez
E. J. Hermans

de Voogd, L. D., Kanen, W., Roselofs, F., Fernandez, G., & Hermans, E. J. (October, 2015). Investigating the effect of goal-directed eye movements during extinction on amygdala activity and long-term expression of fear memory. Poster presented at the Society for Neuroscience Annual Meeting, Washington, DC