Figure 2.

Summary diagram of ICMS-induced changes in OPMs. (a) Changes in the relative sizes of iso-orientation domains. Mean values and SDs are shown for different stimulus orientations relative to the orientation preference of the ICMS site (red squares, preferred orientation; green circles, oblique orientations; blue diamonds, orthogonal orientations) at different recording sessions (pre-ICMS, post-ICMS, after recovery). Note the significant enlargement of domains representing the orientation at the ICMS site at the cost of domains representing neighboring and orthogonal orientations (ANOVA, F_4,103 = 8.75, P < 0.0001; posthoc t tests, P < 0.001 for the preferred orientation and P < 0.05 for the other orientations). Representational areas after recovery were not significantly different from the precondition (P > 0.6). In this and all following figures, significance is indicated with: **, P < 0.01; *, P < 0.05; and n.s., not significant. (b) Average two-dimensional cross-correlation coefficients describing map similarity between two pre-ICMS maps (pre-pre, n = 10), pre- and post-ICMS maps (pre-post, n = 10), preICMS maps and maps after the recovery period (pre-rec, n = 6), and pre- and post-sham stimulation (pre-sham, n = 2). Means, black dots; SEs, boxes; and SDs, whiskers. Univariate ANOVA (F_3,24 = 8.27, P < 0.0006) and posthoc t tests revealed that the correlation coefficient for pre-post comparison (0.24) was significantly lower than that for comparison of two pre maps (0.48, P < 0.005). After several hours of termination of ICMS, the correlation coefficient had an intermediate value (0.34), which was not significantly different from the pre-pre condition (P = 0.18). Sham stimulation had no effect (0.50, P = 0.99).