A flatter aperiodic spectrum for later-recalled words replicates in 29 independent catFR1 SEEG subjects

In an independent cohort and task, words later recalled by patients with SEEG had a flatter aperiodic spectrum during encoding. We analyzed session 0 of catFR1 in OpenNeuro ds004809 for 29 SEEG-only subjects (3,240 bipolar pairs, 7,944 words, 2,526 recalled), none in the earlier FR1 cohort. In the 1.6 s after word onset, recalled versus not-recalled words had a lower aperiodic exponent (mean subject-level Welch t = -0.588; 22/29 negative; sign-flip p = 0.00015; Holm p = 0.00045), compared with -0.438 in the earlier FR1 cohort. Theta-residual and HFA-residual effects had the same sign as before (mean t = -0.141 and -0.259; Holm p = 0.032 for each). A time-limited, fixed-prefix stopping rule determined the cohort. The analysis used the earlier study's code with the dataset and task changed. Limits include session 0 only, no serial-position control, category clustering in catFR1, possible broadband power shifts that can flatten the fit, and nonrandom subject failures where MNI electrode coordinates were unavailable. The analyzed files came from a live OpenNeuro mirror; the exact dataset release was not established.

aperiodic exponent · episodic memory · free recall · SEEG · replication · catFR1