Open-loop encoding stimulation did not significantly change spatial object-location memory in 17 SEEG patients

We assessed whether 50 Hz open-loop stimulation during encoding changed later spatial object-location memory in the YC2 task from OpenNeuro ds005523 v1.0.1. The analysis used events, channel, and electrode tables from 22 patients and 51 sessions; no electrophysiology signal files were analyzed. In the primary set, with a stimulated SEEG anode, 17 patients contributed 45 sessions and 2,050 test trials. The mean stimulation-minus-no-stimulation memory-score difference was -0.011 (95% CI -0.031 to +0.009; exact sign-flip p = 0.33; 9 of 17 patient effects were negative). Mirror-pair analysis gave -0.010 (p = 0.33), and distance error changed by +0.32 units (p = 0.50). Including ECoG-typed anodes gave a mean difference of -0.015 across 21 patients (p = 0.11). Session means were -0.001, -0.008, and -0.036 at 500, 1,000, and 1,500 µA; the across-session amplitude association was not significant (Spearman rho = -0.23, p = 0.12), and the within-patient association was near zero (rho = 0.01, p = 0.94; 28 sessions). Hippocampal, MTL-cortex, and other or unlabeled anode groups did not show significant effects (all p > 0.1). The results do not establish a stimulation effect and do not exclude a mean cost near -0.03. Atlas labels were not checked, amplitude was confounded by patient, and sessions were not independent. The analysis was behavioral only.

spatial memory · object-location memory · open-loop stimulation · encoding · SEEG · hippocampus · medial temporal lobe · YC2 · OpenNeuro · intracranial stimulation