FIG 3. Variation of derived measures of the extent of cortical activation with increasing numbers of stimulated digits: intra- and interparticipant.

A, Area of activation derived by functional MR imaging shows considerable intraparticipant variability and no trend toward increasing areas of activation with increasing numbers of stimulated digits, for averaged data for each individual. Measures of cortical activation are shown as a function of increasing numbers of stimulated digits with intraparticipant variability represented by the dispersion of like-colored dots. Mean individual participant trends are shown as solid lines.

B, Evoked field amplitude as determined by magnetoencephalography. Despite overlap in the range of evoked fields elicited by each stimulation type across participants, the data from each individual are relatively clustered for each stimulation type; clear trends indicating increased activation with increased numbers of stimulated digits are seen for every individual participant. Measures of cortical activation are shown as a function of increasing numbers of stimulated digits with intraparticipant variability represented by the dispersion of like-colored dots. Mean individual participant trends are shown as solid lines.

C, There is no evident correlation between functional MR imaging and magnetoencephalographic measures.