Figure 4

Results of Series II: Experiments on plasticity expressed in stimulus–response maps. A An example from protocol II.3. Colored pixels represent changes in the average number of spikes on a given recording electrode 10–50 ms after a test pulse to a given stimulation electrode. The horizontal stripes of similar coloration reveal stimulation-site-specific changes. However, spontaneous changes (right) were comparable in magnitude to changes concomitant with tetani (left). B A direct comparison between stimulation-site-specific changes and recording-site-specific changes across tetani reveals that stimulation-site-specific changes were dominant in all experiments. Each point corresponds to one experiment. Plot symbols indicate tetanization protocols; arrows mark data points that fell outside the plot limits. C Direct comparison between stimulation-site-specific changes concomitant with tetanization and due to spontaneous drift reveals that tetanization does not cause enhanced change compared to drift. D Summary of data in B. All values were normalized by $n_{\text{base}}\equiv {\displaystyle {\sum }_{S,R}{n}_{\text{base}}^{SR}}$. Asterisks indicate significance: p < 0.05 (*) or p < 0.001 (***), two-tailed t-test, N = 8, 6, 6, 16, 16 for protocols II.1, II.2, II.5. E Summary of data in C, same normalization as in D. T-tests revealed no significant effects of tetanization.