Individualized attribution estimates which functional networks drive a model prediction for a given subject and is often proposed as an interpretable resting-state fMRI (rs-fMRI) biomarker, but its test-retest reliability is rarely quantified. We evaluate per-subject network-ablation attribution for a frozen resting-state functional connectivity (FC) predictor (Schaefer-200 FC predicting MMSE/ADAS-Cog13) trained on N=875 subjects from the Alzheimer's Disease Neuroimaging Initiative (ADNI), using, and (iii) a subject-level permutation null. Split-half reliability is near-ceiling (Spearman p=0.948/0.950) but drops on scan-rescan (p=0.609/0.616). Under the mismatched-subject null, correlations remain substantial (p0.46-0.47), indicating strong population-shared structure, yet matched pairs exceed this null (z6.6-6.9, p<=10-4). Thus, in ADNI, individualized network attribution contains a modest but non-zero person-specific component atop a strong population-shared pattern. We recommend reporting scan-rescan reliability together with a permutation-null control, rather than within-session proxies alone, to avoid overstating individual specificity.
Figures & tables
Figure 1: Top 6 of the 7 Yeo networks by group-level importance, visualized on anatomical MRI. Group-level importance is quantified by the drop in test-set explained variance when ablating each network, ΔR2=R2−R∖n2 , computed on the held-out test set and averaged over three independently trained runs (shown separately for MMSE and ADAS-Cog13). ΔR2 can exceed the total R2 when R∖n2<0 . The displayed “combined MMSE+ADAS-Cog13 rank” orders networks by the summed ΔR2 across the two targets. The 7th (lowest-ranked, Somatomotor) network is omitted for layout only; all 7 are used in every analysis.
Figure 2: Overview of the three progressively stricter reliability checks. (a) Within-session split-half: odd and even volumes of one session are each attributed and compared by Spearman ρ . (b) Scan–rescan: each subject’s baseline is compared with all repeat visits (median 24.4 months apart). (c) Permutation null: 10,000 subject-level derangements match each baseline with another subject’s repeat visits (kept as a block, no self-match); the observed mean Tobs is compared with this null.
Split-half
Scan–rescan
Statistic
MMSE
ADAS-Cog13
MMSE
ADAS-Cog13
Mean
0.948
0.950
0.609
0.616
95 % CI
0.929–0.964
0.934–0.964
0.553–0.663
0.571–0.660
Median
0.988
0.988
0.625
0.661
Std
0.101
0.085
0.242
0.198
10–90%
0.87–1.00
0.85–1.00
0.34–0.90
0.33–0.85
Table 1: Attribution reliability (Spearman ρ of the per-subject 7-network importance signature). The subject is the unit of analysis (split-half: n=132 ; scan–rescan: n=74 , with pairs averaged within subject). CIs are subject-level bootstrap intervals; “run SD” is the SD across 3 runs; “–” indicates not computed. Permutation-null rows use 10,000 subject-level derangements.
School of Medical Science and Technology · Department of Computer Science and Engineering at the Indian Institute of Technology Gandhinagar · Dr B C Roy Multi Speciality Medical Research Centre, Indian Institute of Technology Kharagpur, India