A 72-subject SEEG subset showed no leftward HFA memory effect; leftward theta effects remained exploratory

We compared anatomical left and right subsequent memory effects (SMEs) in bipolar SEEG recordings during delayed free recall. Archived per-word features covered 72 subjects from OpenNeuro ds004789, FR1 session 0; electrode-coordinate files for all subjects had SHA-256 values matching the earlier feature archive. In bilateral subjects, the primary paired tests found no leftward asymmetry in 70–150 Hz high-frequency activity: hippocampus L−R = +0.010 z (95% CI −0.051 to +0.068; n=29; Holm p=1.0) and ventral temporal cortex L−R = +0.011 z (95% CI −0.041 to +0.061; n=21; Holm p=1.0). The apparent left-only hippocampal HFA result across all implanted subjects was not present in the within-subject comparison. Exploratory 3–8 Hz theta SMEs were more negative on the left (hippocampus L−R = −0.093 z; ventral temporal cortex L−R = −0.097 z; both p=0.038), but post hoc Holm-adjusted p=0.076 for the two theta tests and p=0.15 across four paired tests. Findings are limited to anatomical side, a subset of about 155 eligible subjects, and small bilateral samples (29 hippocampal and 21 ventral temporal). Language dominance was unavailable. Theta results need confirmation.

subsequent memory effect · SEEG · free recall · hippocampus · ventral temporal cortex · hemispheric asymmetry · high-frequency activity · theta · OpenNeuro ds004789