Figure 1.

(A) Parietal lobe areas activated by roughness discrimination compared with a motor control (subjects their own controls). Horizontal section of the standard brain format 45 mm above the intercommissural plane (z = 45) showing the significant fields of activation in the postcentral gyrus in 10 subjects discriminating roughness with their right index fingers and thumbs (center of gravity, Talairach = HBA coordinates 32, −23, 51). The lateral parietal operculi also are activated (Table 2). The right side of the images presents the left side of the brain. (B) Coronal section 15 mm (y = −15) behind the vertical commissure anterior (VCA) plane (the plane that is a vertical tangent plane to the anterior commissure) showing significantly more parietal opercular fields activated bilaterally in roughness discrimination than in length discrimination (roughness − length, subjects their own controls). (C) Coronal section (y = −14) showing bilateral significantly more activated parietal opercular fields in roughness discrimination than in shape discrimination. No other parts of the parietal lobules were activated (roughness − shape, intergroup comparison). (D) Coronal section (y = −16) showing the left lateral parietal operculum more activated in roughness discrimination versus length and shape discrimination (image produced by multiplication of the cluster images of rough − length × rough − shape discrimination to give rough − length ∩ rough − shape). (E) Horizontal section of the standard brain format at z = 45, showing the significant increases in rCBF compared with control (cluster image) in nine subjects discriminating the shapes of ellipsoids in the postcentral gyrus, the cortex lining the postcentral sulcus, and the IPA. (F) Overlap between the cortical fields significantly activated by length discrimination and significantly activated by shape discrimination compared with the respective control measurements (i.e., cluster images shape − control ∩ length − control). Note consistent activation of the postcentral gyrus, the cortex lining the postcentral sulcus, and the IPA. Same section as A. (G) The IPA is significantly more activated by shape discrimination than by roughness discrimination (cluster image of shape − roughness, intergroup comparison). Same section as A. (H) Cluster images intersection superimposed on standard brain format of length − roughness × shape − roughness (to give shape − roughness ∩ length − roughness). Same section as A showing that shape discrimination activates IPA significantly and consistently more than does roughness discrimination.