Fig. 4.

The cutaneous locations of the centers of activity of the PLs of SAs and RAs to objects of differing curvature and orientation stroked in different directions over the fingerpad. Thestar-shaped figures show the PLs of the SAs (middle) and RAs (bottom) for strokes in the eight different directions for each object (top, schematically outlined). The 1 × 5 mm (A,C) and 3 × 5 mm (B,D) toroidal objects were stroked either orthogonal (A, B) or parallel (C,D) to the direction of motion. Because a sphere (E) is without a major axis, only one star burst figure is presented. The PLs were calculated after every 0.2 mm of movement of the object during the 7 mm stroke. Solid lines, The PLs for stroke directions of 0, 45, 90, and 135°, in which 90° refers to the tip of the fingerpad (Fig. 1).Dotted lines, The locations of the PLs for stroke directions of 180, 225, 270, and 315°. Open circles, The center of each stroke trajectory. Line, The 7 mm stroke. Scale bar, 1 mm.