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Figure. Effect of aging on brain regional activity during chewing. (A) The task paradigm used. (B,C,D) Significant signal increases associated with gum-chewing in a young adult subject (B), a middle-aged subject (C), and an aged subject (D). Upper section: Activated areas superimposed on a template (p < 0.05, corrected for multiple comparisons). Lower section: Activated regions superimposed on a T1 weighted MRI (p < 0.001, uncorrected for multiple comparisons). Abbreviations: smc, primary sensorimotor cortex; sma, supplementary motor area; i, insula; t, thalamus; c, cerebellum; pfa, prefrontal area. Arrowheads: Activated regions in the parietal, temporal, or occipital association cortices. Color scale: t value (degrees of freedom = 87.12). (E) Percentage increase in the fMRI signal in the young adult (Y, n = 10), middle-aged (M, n = 8), and aged (A, n = 10) groups. Each column represents the mean ± SE. *p < 0.05 compared with young adults. **p < 0.0001 compared with young adults.
