Whole-brain analysis of differences in intrasubject variability, response amplitude, and intersubject variability in older and younger adults.

<p>A: Regions that show a significant positive response (<i>t</i> >2 for all audiovisual syllables <i>vs.</i> baseline) to audiovisual speech in both older and younger adults. L: left hemisphere, R: right hemisphere. B: Differences in intrasubject variability (variability of the amplitude of the BOLD response to audiovisual speech within each subject) between older and younger subjects, masked by active regions in (A). Orange regions indicate areas with greater intrasubject variability in older adults. C: Differences in response amplitude. Green regions indicate no difference in response amplitude; blue regions indicate areas of greater response amplitude in younger adults. D: Differences in intersubject variability (variability of the amplitude of the BOLD response <i>across</i> subjects). Orange regions indicate areas with greater response variability in older adults.