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Intrusive memories to traumatic footage: The neural basis of their encoding and involuntary recall

Intrusive memories to traumatic footage: The neural basis of their encoding and involuntary recall
Intrusive memories to traumatic footage: The neural basis of their encoding and involuntary recall
Background
A hallmark symptom after psychological trauma is the presence of intrusive memories. It is unclear why only some moments of trauma become intrusive, and how these memories involuntarily return to mind. Understanding the neural mechanisms involved in the encoding and involuntary recall of intrusive memories may elucidate these questions.

Method
Participants (n = 35) underwent functional magnetic resonance imaging (fMRI) while being exposed to traumatic film footage. After film viewing, participants indicated within the scanner, while undergoing fMRI, if they experienced an intrusive memory of the film. Further intrusive memories in daily life were recorded for 7 days. After 7 days, participants completed a recognition memory test. Intrusive memory encoding was captured by comparing activity at the time of viewing ‘Intrusive scenes’ (scenes recalled involuntarily), ‘Control scenes’ (scenes never recalled involuntarily) and ‘Potential scenes’ (scenes recalled involuntarily by others but not that individual). Signal change associated with intrusive memory involuntary recall was modelled using finite impulse response basis functions.

Results
We found a widespread pattern of increased activation for Intrusive v. both Potential and Control scenes at encoding. The left inferior frontal gyrus and middle temporal gyrus showed increased activity in Intrusive scenes compared with Potential scenes, but not in Intrusive scenes compared with Control scenes. This pattern of activation persisted when taking recognition memory performance into account. Intrusive memory involuntary recall was characterized by activity in frontal regions, notably the left inferior frontal gyrus.

Conclusions
The left inferior frontal gyrus may be implicated in both the encoding and involuntary recall of intrusive memories.

0033-2917
505 - 518
Clark, I.A.
59c2bf1b-d47d-4878-9338-8a5948ffbe4a
Holmes, E.A.
a6379ab3-b182-45f8-87c9-3e07e90fe469
Woolrich, M.W.
6ebed264-7648-4b79-bb4c-2cf411d6f389
Mackay, C.E.
bbe52259-edcf-43fc-854f-eb9893320883
Clark, I.A.
59c2bf1b-d47d-4878-9338-8a5948ffbe4a
Holmes, E.A.
a6379ab3-b182-45f8-87c9-3e07e90fe469
Woolrich, M.W.
6ebed264-7648-4b79-bb4c-2cf411d6f389
Mackay, C.E.
bbe52259-edcf-43fc-854f-eb9893320883

Clark, I.A., Holmes, E.A., Woolrich, M.W. and Mackay, C.E. (2015) Intrusive memories to traumatic footage: The neural basis of their encoding and involuntary recall. Psychological Medicine, 46 (3), 505 - 518. (doi:10.1017/S0033291715002007).

Record type: Article

Abstract

Background
A hallmark symptom after psychological trauma is the presence of intrusive memories. It is unclear why only some moments of trauma become intrusive, and how these memories involuntarily return to mind. Understanding the neural mechanisms involved in the encoding and involuntary recall of intrusive memories may elucidate these questions.

Method
Participants (n = 35) underwent functional magnetic resonance imaging (fMRI) while being exposed to traumatic film footage. After film viewing, participants indicated within the scanner, while undergoing fMRI, if they experienced an intrusive memory of the film. Further intrusive memories in daily life were recorded for 7 days. After 7 days, participants completed a recognition memory test. Intrusive memory encoding was captured by comparing activity at the time of viewing ‘Intrusive scenes’ (scenes recalled involuntarily), ‘Control scenes’ (scenes never recalled involuntarily) and ‘Potential scenes’ (scenes recalled involuntarily by others but not that individual). Signal change associated with intrusive memory involuntary recall was modelled using finite impulse response basis functions.

Results
We found a widespread pattern of increased activation for Intrusive v. both Potential and Control scenes at encoding. The left inferior frontal gyrus and middle temporal gyrus showed increased activity in Intrusive scenes compared with Potential scenes, but not in Intrusive scenes compared with Control scenes. This pattern of activation persisted when taking recognition memory performance into account. Intrusive memory involuntary recall was characterized by activity in frontal regions, notably the left inferior frontal gyrus.

Conclusions
The left inferior frontal gyrus may be implicated in both the encoding and involuntary recall of intrusive memories.

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e-pub ahead of print date: 9 December 2015

Identifiers

Local EPrints ID: 507927
URI: http://eprints.soton.ac.uk/id/eprint/507927
ISSN: 0033-2917
PURE UUID: 728c247d-60b0-45d2-96cb-02989590399b
ORCID for E.A. Holmes: ORCID iD orcid.org/0000-0001-7319-3112

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Date deposited: 07 Jan 2026 17:57
Last modified: 08 Jan 2026 03:28

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Contributors

Author: I.A. Clark
Author: E.A. Holmes ORCID iD
Author: M.W. Woolrich
Author: C.E. Mackay

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