Reduced hippocampal volume is associated with overgeneralization of negative context in individuals with PTSD

Einat Levy-Gigi, Csilla Szabo, Gal Richter-Levin, S. Kéri

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Objective: Previous studies demonstrated reduced hippocampal volume in individuals with posttraumatic stress disorder (PTSD). However, the functional role the hippocampus plays in PTSD symptomatology is still unclear. The aim of the present study was to explore generalization learning and its connection to hippocampal volume in individuals with and without PTSD. Animal and human models argue that hippocampal deficit may result in failure to process contextual information. Therefore we predicted associations between reduced hippocampal volume and overgeneralization of context in individuals with PTSD. Method: We conducted MRI scans of bilateral hippocampal and amygdala formations as well as intracranial and total brain volumes. Generalization was measured using a novel-learning paradigm, which separately evaluates generalization of cue and context in conditions of negative and positive outcomes. Results: As expected, MRI scans indicated reduced hippocampal volume in PTSD compared to non-PTSD participants. Behavioral results revealed a selective deficit in context generalization learning in individuals with PTSD, F(1, 43) = 8.27, p <.01, ηp2 = .16. Specifically, as predicted, while generalization of cue was spared in both groups, individuals with PTSD showed overgeneralization of negative context. Hence, they could not learn that a previously negative context is later associated with a positive outcome, F(1, 43) = 7.33, p = .01, ηp2 = .15. Most importantly, overgeneralization of negative context significantly correlated with right and left hippocampal volume (r = .61, p = .000; r = .5, p = .000). Finally, bilateral hippocampal volume provided the strongest prediction of overgeneralization of negative context. Conclusions: Reduced hippocampal volume may account for the difficulty of individuals with PTSD to differentiate negative and novel conditions and hence may facilitate reexperiencing symptoms.

Original languageEnglish
Pages (from-to)151-161
Number of pages11
JournalNeuropsychology
Volume29
Issue number1
DOIs
Publication statusPublished - 2015

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Post-Traumatic Stress Disorders
Learning
Cues
Hippocampus
Magnetic Resonance Imaging
Overgeneralization
Amygdala
Animal Models
Generalization (Psychology)
Brain

Keywords

  • Context
  • Generalization
  • Hippocampus
  • PTSD
  • Structural brain imaging

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Arts and Humanities (miscellaneous)

Cite this

Reduced hippocampal volume is associated with overgeneralization of negative context in individuals with PTSD. / Levy-Gigi, Einat; Szabo, Csilla; Richter-Levin, Gal; Kéri, S.

In: Neuropsychology, Vol. 29, No. 1, 2015, p. 151-161.

Research output: Contribution to journalArticle

Levy-Gigi, Einat ; Szabo, Csilla ; Richter-Levin, Gal ; Kéri, S. / Reduced hippocampal volume is associated with overgeneralization of negative context in individuals with PTSD. In: Neuropsychology. 2015 ; Vol. 29, No. 1. pp. 151-161.
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