Fig. 4.

Brain regional networks that showed significant age-efficiency correlations across more than half of the range from 0.10 to 0.40 of connection densities for (A) dominant and (B) nondominant hand grip when considering 8 brain regions. In the upper and lower panels, red and blue indicate positive and negative correlations respectively between age and efficiency of the corresponding intra- or interregional networks. In the lower panel, boxes are used for intraregional network efficiency and lines for interregional network efficiency. Abbreviations: Cbl, cerebellar; Frn, frontal; Lmb, limbic and paralimbic; Occ, occipital; Prt, parietal; SC, subcortical; SM, sensorimotor; Tmp, temporal.