Neural signatures of contextual memory in post-traumatic stress disorder

• Applicant: Dr. James Moran
• Subject Area: Personality Psychology, Clinical and Medical Psychology, Methodology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 470285225

People with posttraumatic stress disorder (PTSD) often have deficits in different aspects of memory processing, including fragmented and overgeneralized autobiographical memory, intrusions of traumatic memory, and working memory (WM) impairments. These disparate problems could be manifestations of common underlying problems in contextual processing. That is, a reduced ability to bind individual elements of memory into a coherent whole. Research has revealed the role of neural oscillations, as measured by electroencephalography (EEG) in binding elements of memory. Frontal and parietal theta (4-7 Hz) and gamma (> 30 Hz) oscillations, and their cross-frequency interactions are particularly important in this regard. Gamma oscillations reflect local activation of sensory elements, and theta acts as a temporal window, coordinating the activation and integration of these individual elements. This project will apply insights into oscillatory correlates of memory to people with PTSD, to test for abnormalities in memory processing. In a series of 3 experiments, we will examine memory-related PTSD symptoms, comparing a group of people with PTSD to a demographically matched trauma exposed control group (TE). We will examine contextual memory processing with EEG during contextual sequence binding in a WM task and during item-context binding in a contextual subsequent memory task. We will use individualized autobiographical and non-autobiographical related negative-emotional and neutral stimuli and will employ multivariate pattern analysis to validate activation of intrusion related stimuli. All oscillatory outcomes will be investigated in relation to intrusion measures. In a third experiment, we target sites of dysfunctional oscillations using transcranial Alternating Current Stimulation (tACS) to improve WM performance in people with PTSD. This project will provide insight into the neuronal mechanisms mediating impaired contextual memory processing in PTSD. In particular, it will shed light on the potential role of different oscillatory phenomena in PTSD symptomatology. This includes intra- and interregional phase coherence, oscillatory power differences, and cross-frequency theta-gamma interplay. Crucially, the project will also test whether non-invasive tACS manipulation, specifically targeted at abnormal frequency bands, can improve aberrant memory processing in PTSD. This would also provide a theoretical basis to optimize non-invasive brain stimulation as a potential therapeutic tool in the treatment of PTSD. Overall, the project seeks to apply established knowledge of dynamic neural processes underlying memory to its potential dysfunction in people with PTSD. This will yield both theoretical insights as well as having potential therapeutic utility by demonstrating the feasibility of non-invasive brain stimulation for the treatment of memory deficits in PTBS.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Daniel Senkowski; Professor Dr. Surjo R. Soekadar