Volumetric and correlational implications of brain parcellation method selection: a 3-way comparison in the frontal lobes.

Objective: To compare distinct brain frontal lobe parcellation methods across 90 brain MRI scans, and examine their associations with cognition in older age. Methods: Three parcellation methods (Manual, FreeSurfer and Stereology) were applied to T1-weighted MRI of 90 older men, aged ~73 years. A measure of general fluid intelligence (gf) associated with dorsolateral frontal regions was also derived from a contemporaneous psychological test battery. Results: In spite of highly discordant raw volumes for the same nominal regions, Manual and FreeSurfer (but not Stereology) left dorsolateral measures were significantly correlated with gf (r > .22), whereas orbital and inferior lateral volumes were not, consistent with the hypothesised frontal localisation of gf. Conclusions: Individual differences in specific frontal lobe brain volumes - variously measured – show consistent associations with cognitive ability in older age. Importantly, differences in parcellation protocol for some regions that may impact the outcome of brain-cognition analyses are discussed.