Drug-induced changes of spectral frequency content during d2 test. Time dependence of spectral frequency changes during performance of the d2 test in the presence of placebo or verum. Choice of electrode positions in concordance with statistically significant changes observed during this test condition (s. Figure 3). * corresponds to p < 0. 12; ** corresponds to p < 0. 076; *** corresponds to p < 0. 02.