title: First steps in using machine learning on fMRI data to predict intrusive memories of traumatic film footage.
abstract: After psychological trauma, why do some only some parts of the traumatic event return as intrusive memories while others do not? Intrusive memories are key to cognitive behavioural treatment for post-traumatic stress disorder, and an aetiological understanding is warranted. We present here analyses using multivariate pattern analysis (MVPA) and a machine learning classifier to investigate whether peri-traumatic brain activation was able to predict later intrusive memories (i.e. before they had happened). To provide a methodological basis for understanding the context of the current results, we first show how functional magnetic resonance imaging (fMRI) during an experimental analogue of trauma (a trauma film) via a prospective event-related design was able to capture an individual's later intrusive memories. Results showed widespread increases in brain activation at encoding when viewing a scene in the scanner that would later return as an intrusive memory in the real world. These fMRI results were replicated in a second study. While traditional mass univariate regression analysis highlighted an association between brain processing and symptomatology, this is not the same as prediction. Using MVPA and a machine learning classifier, it was possible to predict later intrusive memories across participants with 68% accuracy, and within a participant with 97% accuracy; i.e. the classifier could identify out of multiple scenes those that would later return as an intrusive memory. We also report here brain networks key in intrusive memory prediction. MVPA opens the possibility of decoding brain activity to reconstruct idiosyncratic cognitive events with relevance to understanding and predicting mental health symptoms.
authors.affiliation: University Department of Psychiatry, Warneford Hospital, University of Oxford, United Kingdom.
authors.forename: Ian A
authors.initials: IA
authors.lastname: Clark
authors.affiliation: Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Niehaus
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, United Kingdom.
authors.forename: Eugene P
authors.initials: EP
authors.lastname: Duff
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom.
authors.forename: Martina C
authors.initials: MC
authors.lastname: Di Simplicio
authors.affiliation: Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
authors.forename: Gari D
authors.initials: GD
authors.lastname: Clifford
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, United Kingdom.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Smith
authors.affiliation: University Department of Psychiatry, Warneford Hospital, University of Oxford, United Kingdom.
authors.forename: Clare E
authors.initials: CE
authors.lastname: Mackay
authors.affiliation: Oxford Centre for Human Brain Activity (OHBA), Department of Psychiatry, Warneford Hospital, University of Oxford, United Kingdom.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Woolrich
authors.affiliation: Medical Research Council Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom; Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: emily.holmes@mrc-cbu.cam.ac.uk.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Holmes
mesh_terms: D000293:Adolescent; D000328:Adult; D001185:Artificial Intelligence; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D010775:Photic Stimulation; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology / Q000523:psychology*; D055815:Young Adult
keywords: Flashback; Functional magnetic resonance imaging; Intrusive memories; MVPA; Machine learning; Mental imagery; Trauma