Under fixed windows, a negative scene duration slope in 17 fMRI adults was not confirmed in 25 patients with hippocampal single units

We tested whether the hippocampal response at a scene boundary increases with prior scene duration. Public studies supplied separate cohorts and films: SUMMER single units during 500 Days of Summer, and hippocampal fMRI during Sherlock. A local plan fixed a post-minus-pre response, joint prior and following log-duration slopes, and person-level inference. Both positive shared tests failed. Negative BOLD slopes then set a reverse test before spike effects were viewed. The final spike sample had 25 patients, 399 single units and 598 person-boundary measurements. BOLD had 17 adults and 782 measurements. The prior-duration mean slope was -0.00881 in spikes, with a 95% person bootstrap interval of -0.03444 to +0.01828. It was -0.18314 in BOLD, with an interval of -0.24866 to -0.12412. Response units differ. The expanded negative shared test had Holm p=0.79268; the prior-minus-following test had p=0.48806. A 4.5 s earlier BOLD window kept the negative person slope but gave a scene-block interval that crossed zero. A fixed-amplitude hemodynamic simulation produced a positive duration slope without event-amplitude change. Post-window components had negative point estimates in both measures, but this is exploratory. The tests do not confirm a shared signed contrast slope or establish absent duration coding. Clinical sampling, source timing, baseline terms, different scene definitions, and one film per modality limit the scope. The package preserves code, source versions and hashes, local plans, all outcomes, uncertainty draws, figures, direct numerical checks and repeat instructions.

human hippocampus · single units · fMRI · event boundaries · scene duration · negative confirmation · source timing · reproducible analysis