The neural correlates of emotional memory in posttraumatic stress disorder.
BACKGROUND
Posttraumatic stress disorder (PTSD) is marked by intrusive, chronic, and distressing memories of highly emotional events. Previous research has highlighted the role of the amygdala and its interactions with the hippocampus in mediating the effect of enhanced memory for emotional information in healthy individuals. As the functional integrity of these regions may be compromised in PTSD, the current study examined the neural correlates of emotional memory in PTSD.


METHODS
We used functional magnetic resonance imaging and an event-related subsequent memory recognition paradigm to study amygdala and hippocampus activation in 18 individuals with PTSD and 18 trauma-exposed non-PTSD control participants.


RESULTS
Memory enhancement for negative, relative to neutral, pictures was found across all subjects, without significant differences between groups. Relative to the trauma-exposed non-PTSD group, the PTSD group showed exaggerated amygdala activation during the encoding of negative versus neutral pictures. This effect was even more pronounced when the analysis included data from only pictures that were subsequently remembered 1 week later. In the PTSD group, degree of amygdala activation during the encoding of negative versus neutral pictures was positively correlated with hippocampal activation and current PTSD symptom severity. The PTSD group also showed exaggerated hippocampal activation in response to negative pictures that were remembered versus forgotten. Finally, hippocampal activation associated with the successful encoding of negative relative to neutral pictures was significantly greater in the PTSD group.


CONCLUSIONS
Exaggerated amygdala activation during the encoding of emotionally negative stimuli in PTSD is related to symptom severity and to hippocampal activation.
Brohawn
Kathryn Handwerger
KH
Department of Psychology, Tufts University, Medford, Massachusetts 02155, USA. katiebrohawn@gmail.com
Offringa
Reid
R
Pfaff
Danielle L
DL
Hughes
Katherine C
KC
Shin
Lisa M
LM
D000328:Adult; D000679:Amygdala / Q000503:physiopathology*; D000704:Analysis of Variance; D001143:Arousal / Q000502:physiology; D001931:Brain Mapping; D004644:Emotions / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology* / Q000523:psychology