time interaction against 18

Contributed by dkumral on June 24, 2026

Collection: Learning sculpts microstructure in real time: evidence from dense temporal sampling of diffusion MRI

Description: We first defined a linear decrease contrast across all 22 acquired sessions using a whole-brain flexible factorial analysis with a group × time interaction, comparing the learning group against the control group. To further explore the temporal trajectories of learning-induced MD changes across the whole brain, we contrasted the MD change from baseline (t1) to each subsequent time point (t2-22) against the corresponding change in the control condition. This was implemented as an interaction contrast (i.e., [learning_tn − learning_t1] - [control_tn − control_t1]), resulting in 21 comparisons (puncorrected<.001, k=20). For these contrasts, the corresponding control scans were defined by using temporally corresponding session(s). For time points of t11-t19, where no temporally matching control sessions were available, the final DW-MRI acquisition (t10) during the learning interval was used. By subtracting the control-related change from the learning-related change, these contrasts isolate MD changes specific to learning while accounting for nonspecific temporal effects.

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