Functional neuroimaging of emotionally intense autobiographical memories in post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) affects regions that support autobiographical memory (AM) retrieval, such as the hippocampus, amygdala and ventral medial prefrontal cortex (PFC). However, it is not well understood how PTSD may impact the neural mechanisms of memory retrieval for the personal past. We used a generic cue method combined with parametric modulation analysis and functional MRI (fMRI) to investigate the neural mechanisms affected by PTSD symptoms during the retrieval of a large sample of emotionally intense AMs. There were three main results. First, the PTSD group showed greater recruitment of the amygdala/hippocampus during the construction of negative versus positive emotionally intense AMs, when compared to controls. Second, across both the construction and elaboration phases of retrieval the PTSD group showed greater recruitment of the ventral medial PFC for negatively intense memories, but less recruitment for positively intense memories. Third, the PTSD group showed greater functional coupling between the ventral medial PFC and the amygdala for negatively intense memories, but less coupling for positively intense memories. In sum, the fMRI data suggest that there was greater recruitment and coupling of emotional brain regions during the retrieval of negatively intense AMs in the PTSD group when compared to controls

Schematic recapitulation of the hippocampal aspects according to the period of life (<i>p</i><.005, uncorrected, <i>k</i> = 50 voxels, including group, age, intracranial volume, and gender as nuisance covariates), including bilateral hippocampal engagement (A) for the ‘10–29 years’ period, (B) for the ‘30–59 years period, (C) for the ‘after 60 years’ period, and (D) for the ‘recent year’.

<p>Volumes and Talairach <i>y</i> coordinates are indicated for each period and side (L = left, R = right; Ant. = anterior, Post. = posterior).</p

VBM analyses showing brain areas of regional atrophy that correlate with the AbM deficit according to the score on the MCT ( <i>p</i><.005, uncorrected, <i>k</i> = 50 voxels, including group, age, intracranial volume, and gender as nuisance covariates), independently for each period of life: (A) for the ‘10–29 years’ period, (B) for the ‘30–59 years’ period, (C) for the ‘after 60 years’ period, and (D) for the “previous year".

<p>The clusters include (a) ventro-medial, ventro-lateral, orbial prefrontal cortex +/− anterior cingulate*, (b) left hippocampus +/− parahippocampus, retrosplenial cortex and/or amygdala*, (c) right hippocampus, (d) insula and temporal neocortex, (e) occipital neocortex (precuneus not shown). Talairach <i>z</i> coordinates are indicated for each slice.</p

Scores on the MCT for the two groups are shown for the five periods of life.

<p>Scores on the MCT for the two groups are shown for the five periods of life.</p

GM volume regions positively correlated to the score on the MCT in VBM including group, age, intracranial volume and gender as nuisance covariate, with a minimal cluster size (<i>k</i>) of 50 voxels and a threshold of <i>p</i><.005, uncorrected.

<p>g.: gyrus; L: left; R: right; <i>x, y, z</i>: Talairach coordinates; BA: Brodman Area.</p

VBM analyses showing brain areas of regional atrophy that correlate with the AbM deficit according to the score on the MCT (<i>p</i><0.005, uncorrected, <i>k</i> = 50 voxels, including group, age, intracranial volume, and gender as nuisance covariates), with clusters including (a) left and right ventromedial, ventrolateral, orbial prefrontal cortex and anterior cingulate (BA 11/25/47), (b) left hippocampus (<i>y</i> = −30 to <i>y</i> = −40), parahippocampus (BA 36/37), retrospenial cortex (BA 30), (c) right hippocampus (<i>y</i> = −22 to <i>y</i> = −40), (d) left cingulate gyrus, (e) right insula (BA13) and superior temporal gyrus (BA22), (f) right middle occipital gyrus (BA19), (e) left precuneus (BA7).

<p>Talairach <i>z</i> coordinates are indicated for each slice.</p

GM volume regions positively correlated to the global score on the MCT and independently for each life-period (‘0–9 years’, ‘10–29 years’, ‘30–59 years’, ‘after 60 years’, and ‘previous year’) in VBM including group, age, intracranial volume, and gender as nuisance covariates, with a minimal cluster size (<i>k</i>) of 50 voxels and a threshold of <i>p</i><.005, uncorrected.

<p>The regions are indicated with their side (L: left; R: right) within their belonging lobe, gyrus or region and Brodman area (BA, if applicable) for the global score on the MCT and independently for each period of life. Talairach <i>y</i> coordinates (Y) and volumes (in voxels, V) are indicated on both sides for the hippocampal involvement. Orb.: orbito-frontal; VL: ventro-lateral; Med.: medial; Parahipp.: parahippocampal gyrus; Amyg.: amygdala; Sup.: superior temporal gyrus; Mid.: middle temporal gyrus; Inf.: inferior temporal gyrus; Fus.: fusiform gyrus; Prc : precuneus; Psc : postcentral gyrus; II: cuneus or lingual gyrus; III: middle occipital gyrus.</p