Biology subjects

Grupe, D. W.

Publications and source records attributed to Grupe, D. W..

3 recordsLinked to original sources

bioRxiv2018

A common neural substrate for elevated PTSD symptoms and reduced pulse rate variability in combat-exposed veterans

BackgroundPrevious studies have identified reduced heart rate variability (HRV) in posttraumatic stress disorder (PTSD), which may temporally precede the onset of the disorder. A separate line of functional neuroimaging research suggests that the ventromedial prefrontal cortex (vmPFC) -- a key aspect of a descending neuromodulatory system that exerts inhibitory control over heart rate -- shows functional and structural abnormalities in PTSD. No research to date, however, has simultaneously investigated whether altered vmPFC activation is associated with reduced HRV and elevated PTSD symptoms in the same individuals.\n\nMethodsWe collected fMRI data during alternating conditions of threat of shock and safety from shock in 51 male, combat-exposed veterans with either high or low levels of PTSD symptoms. Pulse rate variability (PRV) - an HRV surrogate calculated from pulse oximetry - was assessed during a subsequent resting scan. Correlational analyses tested for hypothesized relationships between vmPFC activation, PRV, and distinct dimensions of PTSD symptomatology.\n\nResultsRe-experiencing PTSD symptoms were inversely associated with high-frequency (HF)-PRV, thought to primarily reflect parasympathetic control of heart rate, in veterans with elevated PTSD symptoms. Lower HF-PRV was associated with reduced vmPFC activation for the contrast of safety-threat in a region that also showed an inverse relationship with re-experiencing symptoms.\n\nConclusionsReduced vmPFC responses to safety vs. threat were associated with both reduced HF-PRV and increased re-experiencing symptoms. These results tie together previous observations of reduced HRV/PRV and impaired vmPFC function in PTSD and call for further research on reciprocal brain-body relationships in understanding PTSD pathophysiology.

neuroscience↗

bioRxiv2018

Perceived threat bias and reduced hippocampal volume in combat veterans

BackgroundReduced hippocampal volume is frequently observed in posttraumatic stress disorder (PTSD), but the exact psychological processes associated with these alterations remain unclear. Given the role of the hippocampus in contextual representations of threat and memory, we investigated relationships between retrospectively reported combat exposure, perceived threat, and hippocampal volume in trauma-exposed veterans.\n\nMethodsT1-weighted anatomical MRI scans were obtained from 52 male veterans with a broad range of PTSD symptoms. Hippocampal volume was estimated using automatic segmentation tools in FreeSurfer. An index of perceived threat bias was calculated, reflecting the degree of discordance between subjective perceptions of threat while deployed and self-reported combat exposure. Hippocampal volume was regressed on perceived threat bias and PTSD symptoms on the Clinician-Administered PTSD Scale (CAPS).\n\nResultsPerceived threat bias was unrelated to overall CAPS symptoms, but was positively correlated with CAPS avoidance/numbing symptoms and symptoms of depression, anxiety, and worry. The degree of perceived threat bias was inversely correlated with hippocampal volume. Hippocampal volume was also inversely related to avoidance/numbing CAPS symptoms.\n\nConclusionsThese results indicate that volume of the hippocampus, a region involved in contextual threat processing and memory, is related to recalled associations between traumatic events and accompanying subjective threat appraisals. Future research should clarify the precise temporal milieu of these effects and investigate whether individual differences in hippocampal structure and function contribute to exaggerated threat appraisal at the time of trauma, or in subsequently biased memories or appraisals of traumatic events.

neuroscience↗

bioRxiv2017

Behavioral and neural indices of affective coloring for neutral social stimuli

Emotional processing often continues beyond the presentation of emotionally evocative stimuli, which can result in affective biasing or coloring of subsequently encountered events. Here, we describe neural correlates of affective coloring and examine how individual differences in affective style impact the magnitude of affective coloring. We conducted functional magnetic resonance imaging in 117 adults who passively viewed negative, neutral, and positive pictures presented 2s prior to neutral faces. Brain responses to neutral faces were modulated by the valence of preceding pictures, with greater activation for faces following negative (vs. positive) pictures in the amygdala, dorsomedial and lateral prefrontal cortex, ventral visual cortices, posterior superior temporal sulcus, and angular gyrus. Three days after the MRI scan, participants rated their memory and liking of previously encountered neutral faces. Individuals higher in trait positive affect and emotional reappraisal rated faces as more likable when preceded by emotionally arousing (negative or positive) pictures. Additionally, greater amygdala responses to neutral faces preceded by positively valenced pictures were associated with greater memory for these faces three days later. Collectively, these results reveal individual differences in how emotions spill over onto the processing of unrelated social stimuli, resulting in persistent and affectively biased evaluations of such stimuli.

neuroscience↗