Illustrations of relationships found between measures of transcallosal inhibition (TCI) derived from each hemisphere and age-related variations in unimanual performance in dexterity (A) and strength (B) tests. In both A and B, the relationships are given with respect to the direction of TCI induced from one hemisphere to the other and performance of the contralateral hand controlled by the stimulated hemisphere; so that left to right TCI is correlated with performance of the right hand. A. Relationships between onset latency of TCI and contralateral dexterity, as measured with the Grooved Pegboard Test after log-transformation of timed performance. B. Relationships between the ipsilateral silent period area (iSP) and contralateral grip strength, as measured with a pinch dynamometer. Note that correlational analysis omitted two subjects in the senior group, one with incomplete data and one detected as an outlier.