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FIG 1. Functional MR imaging for a single participant, single session, as a function of increasing number of stimulated digits. This functional MR imaging study from a single volunteer shows the difference in activation pattern (red pixels) resulting from the stimulation of one through four fingers of the left hand. Overlays are shown on source echo-planar images (2000/69/1 [TR/TE/excitations]; flip angle, 60°); four sections are shown covering the expected primary somatosensory areas. Yellow pixels indicate areas of significant correlation with the stimulus presentation function (r > 0.3), which were deemed not primary contralateral somatosensory cortex by the radiologic reviewers (H.C.R. and H.A.R.). Although this example tends to show an increasing extent of cortical activation in line with expected somatotopic distribution in primary somatosensory cortex, results from other participants were less clearly demonstrative. Furthermore, increases in the number of activated pixels on progression from one to four stimulated fingers are non-monotonic (being especially diminished in response to three-finger stimulation in this example)
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