Experience-dependent rapid structural changes in the human brain: A systematic review.
Level 1 - systematic review of randomized trials
Systematic review of 30 human experimental neuroimaging studies
PubMed 42105826 · doi:10.1016/j.neubiorev.2026.106736
What was done
Authors conducted a systematic review synthesizing human neuroimaging evidence on rapid structural gray matter alterations occurring within short intervals (<2 hours). Thirty studies were identified examining diffusion-weighted MRI (DW-MRI) and T1-weighted MRI (T1W-MRI, including voxel-based morphometry [VBM] and cortical thickness [CT]) after interventions such as motor and spatial learning, perceptual and language training, acute stress, exercise, and pharmacological manipulations.
What was found
Across the 30 included studies, DW-MRI consistently showed rapid decreases in mean diffusivity within task-relevant brain areas, including the hippocampus, cerebellum, and primary motor cortex. T1W-MRI studies reported short-term increases in cortical thickness or gray matter volume, typically emerging within one hour of the intervention. However, studies utilizing perfusion-sensitive modalities (e.g., arterial spin labeling and functional MRI) showed that some observed volume changes may reflect transient shifts in cerebral blood flow or extracellular fluid rather than cellular structural remodeling. Exact pooled effect sizes or numerical statistics were not provided in the abstract.
Why it matters
This review challenges the traditional view that human structural brain plasticity requires days to weeks, demonstrating that detectable gray matter changes occur within hours of experience. It highlights the necessity of controlling for non-structural physiological variables in acute neuroimaging paradigms.
Limits
The abstract notes substantial heterogeneity in task durations and imaging timing across studies, hindering direct comparisons. Furthermore, conventional structural MRI sequences cannot cleanly distinguish true cellular morphological remodeling from transient hemodynamic, metabolic, or extracellular fluid fluctuations.
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