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Striatal and hippocampal theta neuromodulation split human timing

Poster Session C - Sunday, March 8, 2026, 5:00 – 7:00 pm PDT, Fairview/Kitsilano Ballroom

Chenyang (Leo) Lin¹ (), Wen Wen¹, Wai Zeng¹, Anna (Xinze) Zhang¹, Rui Cao^1,2, Sara Bissell¹, Shrey Grover¹, Jiating (Sophie) Zhu¹, Seth Schallies¹, Robert M.G. Reinhart¹; ¹Boston University, ²University of Tennessee Knoxville

Human interval timing is widely attributed to deep subcortical circuits, yet these mechanisms have been hard to test causally without surgery. Here we used biophysically optimized transcranial temporal-interference stimulation (tTIS) to focally modulate either the right putamen or the left hippocampus while participants performed temporal estimation and reproduction, two mechanistically distinct timing tasks. Theta (5 Hz) tTIS over the right putamen selectively and transiently degraded temporal precision in estimation, increasing Weber fractions without shifting the point of subjective equality, whereas beta-band stimulation and theta over the left putamen were ineffective, demonstrating frequency- and hemisphere-specific striatal involvement. In reproduction, the pattern reversed across sites: putaminal theta biased responses toward over-reproduction, whereas hippocampal theta biased them toward under-reproduction, revealing a double dissociation between striatal and hippocampal theta in human timing. Concurrent pupillometry mapped these behavioral effects onto distinct physiological signatures: striatal theta amplified cue-locked, decision-related pupil bursts linked to temporal comparison, whereas temporal principal component analysis (PCA) of duration-scaled pupil signals showed that hippocampal theta selectively altered an encoding component that predicted subsequent reproduction bias. A mechanistic Laplace-timeline model with decaying (“past”) and ramping (“future”) units reproduced these bidirectional effects when striatal versus hippocampal dynamics were selectively slowed, providing a single computational account of the dissociation. Together, these results show that human interval timing can be fractionated into complementary theta-sensitive subcortical computations and establish tTIS as a noninvasive route to deep, circuit-level causal tests in time cognition.

Topic Area: PERCEPTION & ACTION: Other