Psychiatry - Research Publications
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ItemIntrusive Memories of Distressing Information: An fMRI Study(PUBLIC LIBRARY SCIENCE, 2016-09-29)Although intrusive memories are characteristic of many psychological disorders, the neurobiological underpinning of these involuntary recollections are largely unknown. In this study we used functional magentic resonance imaging (fMRI) to identify the neural networks associated with encoding of negative stimuli that are subsequently experienced as intrusive memories. Healthy partipants (N = 42) viewed negative and neutral images during a visual/verbal processing task in an fMRI context. Two days later they were assessed on the Impact of Event Scale for occurrence of intrusive memories of the encoded images. A sub-group of participants who reported significant intrusions (n = 13) demonstrated stronger activation in the amygdala, bilateral ACC and parahippocampal gyrus during verbal encoding relative to a group who reported no intrusions (n = 13). Within-group analyses also revealed that the high intrusion group showed greater activity in the dorsomedial (dmPFC) and dorsolateral prefrontal cortex (dlPFC), inferior frontal gyrus and occipital regions during negative verbal processing compared to neutral verbal processing. These results do not accord with models of intrusions that emphasise visual processing of information at encoding but are consistent with models that highlight the role of inhibitory and suppression processes in the formation of subsequent intrusive memories.
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ItemAssociation of FKBP5 polymorphisms and resting-state activity in a frontotemporal-parietal network(SPRINGERNATURE, 2016-10-18)The FKBP5 polymorphism is a key regulator of the glucocorticoid system underpinning stress responsivity, and risk alleles can increase vulnerability for developing posttraumatic stress disorder. To delineate the specific role of FKBP5 risk alleles unencumbered by the confounds of psychopathology, this study investigated whether high-risk alleles of the FKBP5 polymorphism are characterized by distinctive neural activity during resting state. Thirty-seven healthy participants were selected on the basis of four SNPs in the FKBP5 gene region (rs3800373, rs9296158, rs1360780 and rs9470080) to determine participants who were carriers of the FKBP5 high- and low-risk alleles. Spatial maps, power spectra and connectivity in neural networks active during resting state were assessed with functional magnetic resonance imaging (fMRI). During resting-state fMRI, FKBP5 low-risk allele group displayed more power in the low frequency range (<0.1 Hz) than the high-risk allele group, who had significantly more power in higher frequency bins (>0.15 Hz). This difference was apparent only in a frontotemporoparietal network underpinning salience detection and emotion processing. This study provides initial evidence that the risk alleles of the FKBP5 polymorphism are associated with different resting-state activity in a frontotemporal-parietal network, and may point to mechanisms underpinning high-risk carriers' vulnerability to severe stress reactions.