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Scene Construction under Constraint: Neural Reorganization of Imagination in Limbic Encephalitis

Poster Session B - Sunday, March 8, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Julia Taube^1,2 (), Maren Bilzer³, Pitshaporn Leelaarporn^1,2, Sarah Dumitrescu^1,2, Tobias Baumgartner^1,2, Randi von Wrede¹, Rainer Surges¹, Christoph Helmstaedter¹, Cornelia McCormick^1,2; ¹University Hospital Bonn, ²German Center for Neurodegenerative Diseases, ³University Bonn

Imagining scenes is a core cognitive function, supporting our ability to recall autobiographical memories and simulate possible futures. Its disruption in temporal lobe epilepsy secondary to limbic encephalitis (LE) offers a rare insight into the mechanisms of constructive imagination and their reorganization. This study combined a behavioral assessment, neuropsychological profiling, and ultra-high-field 7 T fMRI to investigate how people with LE construct atemporal scenes. We hypothesized reduced scene construction, mediated by figural and verbal memory performance relative to controls, accompanied by compensatory recruitment of the ventromedial prefrontal cortex (vmPFC). Participants completed an imagined experiences task validated in other neurological populations, requiring them to visualize and verbally describe richly detailed atemporal scenes. During fMRI, they engaged in a visual imagery paradigm, in which they imagined objects, scenes, or scenarios cued by brief words validated in a pilot study to evoke consistent imagery across individuals, while the category identity was kept covert. The control condition was a nonword-counting task. Ten patients (age= 50 years; disease duration= 9 years) and twelve age-matched controls were included. Patients showed reduced SC (p=.04), correlating with figural (p=.04) and verbal memory (p=.04). During fMRI, patients generated fewer images within the intended scene category, accompanied by overlapping scene and scenario representations, in contrast to the discrete, task-specific networks observed in controls. This blurring of representational boundaries corresponded to increased recruitment of anterior hippocampal and vmPFC regions during scenario construction, suggesting a convergence of constructive processes that may underlie difficulties in recalling past experiences and imagining future events.

Topic Area: LONG-TERM MEMORY: Episodic