Neural Substrates of Duration Serial Dependence: Opposing Modulation in Basal Ganglia and Posterior Medial Cortex

Perceptual judgments are systematically biased toward recent experience, a phenomenon called serial dependence. The brain circuits underlying this effect in time perception remain unknown. Using fMRI, we identified the neural substrates of duration serial dependence and tested whether they overlap with those for motion direction. Twenty-seven participants reproduced either the duration or direction of a visual stimulus; a retro-cue revealed which feature to report 3-s after stimulus onset, separating memory-trace signals from task-switching signals. Duration serial dependence was robust and roughly four times stronger on task-repeat than task-switch trials; direction serial dependence was near zero. The previous duration produced opposing responses in the bilateral putamen (suppression) and in the posterior cingulate cortex and precuneus (reinstatement); no analogous signal emerged for direction. Task switching from direction to time task engaged the inferior frontal junction and the dorsolateral prefrontal cortex, which carried no serial dependence signal. The anatomical dissociation resolves the behavioral pattern: the duration trace is encoded in the putamen and posterior medial cortex on every trial, but task-set reconfiguration by the frontoparietal network gates its read-out into behavior, explaining the task repetition effect. These results reveal a dissociation between two functionally distinct circuits: the putamen and posterior cingulate/precuneus carry signals from the previous trial, whereas frontoparietal regions support task switching but carry little serial dependence information.