While the 5% deviant responses were essentially as likely to be larger or smaller in the Random compared

to the Periodic condition (66/138, 48%), the majority of the responses to 20% deviants were larger in the Random compared to the Periodic condition (103/156, 66%); furthermore, the average response to the 20% deviants was significantly larger in the Random than in the Periodic condition. The responses to standards followed the reverse tendencies: the differences between the responses in the Periodic and Random conditions became less prominent with increasing deviant probability (and decreasing standard probability). Thus, while the LFP responses to Periodic standards were overwhelmingly smaller than the responses to Random standards for 5% deviant probability (99/124, 80%), the imbalance in the standard response was substantially smaller when deviant probability Apoptosis inhibitor MG-132 cell line was 20% (85/147, 58%). It has been previously shown that SSA has several timescales, from hundreds of milliseconds to tens of seconds (Ulanovsky et al., 2004). In order to examine the time course of the effects shown above, we calculated the average responses

to the standards with different time resolutions along the sequence. Figure 5 shows the average LFP responses to standards (Figure 5A) and deviants (Figure 5B), as a function of the sequential position of the stimulus within the sequence for the 5% (left) and 20% (right) deviant probabilities. In Figure 5A, the blue and green bars represent the average response to the standard stimuli at four ranges of trials along the sequence (1–19, 20–80, 81–278, 279–475 for the 5% conditions; 1–4, 5–19, 20–59, 60–100 for the 20% conditions) in the Random and Periodic conditions, respectively. In Figure 5B, the red and yellow bars represent

the average response to the deviant stimuli in four ranges of trials (1:3, 4:6, 8:16, 17:25) in the Random and Periodic conditions, Rutecarpine respectively. We analyzed the data with a three-way ANOVA on time bin and sequence type, with recording site as a random factor. The main effects of time bin were significant for all conditions [5%: standards F(3,2032) = 46.01, p < < 0.01; deviants F(3,2508) = 3.22, p = 0.022; 20%: standards F(3,3076) = 47.57, p < < 0.01; deviants F(3,3172) = 4.85 p = 2.3∗10−3]. The main effect of sequence type (Periodic versus Random) was significant for the standards in the 5% conditions [F(1,2032) = 52.75, p < < 0.01] but not for the deviants [F(1,2508) = 0.16 p = 0.69]. In contrast, in the 20% conditions the main effect of sequence type was significant for the deviants [F(1,3172) = 14.5 p = 1∗10−4] but not for the standards [F(1,3076) = 0.29 p = 0.59].