How the Hippocampus Supports Visual Short-Term Memory: From iEEG Oscillations to Causal Stimulation
Jing Liu. Symposium presentation at BIOMAG 2026, Beijing, China, 23–25 August 2026.
While the hippocampus has traditionally been viewed as a specialized substrate for long-term episodic memory, emerging evidence suggests it plays a critical, yet underexplored, role in visual short-term memory (VSTM). Using intracranial EEG (iEEG) and intracranial electrical stimulation (iES) in patients performing a delayed match-to-sample task, we investigated the neural dynamics underlying VSTM. Our results showed that the VSTM task significantly modulated ripple rates in both the hippocampus and the lateral temporal lobe (LTL). Moreover, hippocampal ripple rates progressively ramped up during the maintenance delay, a phenomenon that predicted successful VSTM performance. These hippocampal ripples were temporally coupled with LTL ripples and tracked memory reactivation in the LTL. Finally, to establish a causal link, we applied high-frequency iES to the hippocampus and found that stimulation selectively enhanced VSTM performance under high-load conditions. Together, our findings suggest that the hippocampus coordinates VSTM representations.