The mean first-order autocorrelation at lag 1 (estimated from our data, and used for our Monte Carlo simulations) was 0.98 for the contralateral and 0.98 for the ipsilateral dataset. Statistical analyses of the mean amplitudes are compatible with these observations. In the P45 time-window, the overall analyses including Electrode Site, selleckchem Hemisphere and Posture showed main effects of Electrode Site (F2,22 = 33.964, P < 0.01) and Hemisphere (F1,11 = 30.047, P < 0.01). An interaction of Electrode Site × Hemisphere was also found
(F2,22 = 50.254, P < 0.01). In the N80 time-window, a main effect of Electrode Site was obtained (F2,22 = 50.352, P < 0.01), together with an interaction of Electrode Site × Hemisphere (F2,22 = 18.902, P < 0.01). Main effects of Electrode Site (F2,22 = 32.807,
P < 0.01) and Hemisphere (F1,11 = 25.231, P < 0.01), and an interaction of Electrode Site × Hemisphere (F2,22 = 4.689, P = 0.02) were also found in the P100 time-window. In the N140 time-window, main effects of Electrode Site (F2,22 = 31.764, P < 0.01) and Hemisphere (F1,11 = 43.445, P < 0.01) were obtained. The first effect of Posture was also found at the N140 (F1,11 = 8.682, P = 0.013) according to which crossing the arms enhanced the N140 amplitude (uncrossed – M = −0.64 μV, crossed – M = −0.79 μV). An interaction of Electrode Site × Hemisphere (F2,22 = 6.809, P < 0.01), and a marginal interaction of Posture × Hemisphere (F1,11 = 4.263, P = 0.06) were also observed at the N140. Planned comparisons (Bonferroni-corrected using P = 0.025) showed that the contralateral N140 was enhanced for crossed-hands posture in comparison with uncrossed-hands (t11 = 2.791, PARP activity P = 0.018; crossed – M = −1.1 μV; uncrossed – M = −0.85 μV). This effect was not found for the ipsilateral N140 (t11 = 0.596,
n.s.). The more contralateral distribution of the crossing effect can also be seen in Fig. 5, which shows the topographical maps of the voltage distribution over the scalp. Sclareol In the time-window between 180 and 400 ms post-stimulus, the anova computed to investigate longer latency effects showed a main effect of Hemisphere (F1,11 = 7.585, P = 0.019; contralateral – M = 0.12 μV; ipsilateral – M = −0.09 μV) and of Posture (F1,11 = 9.462, P = 0.011) (uncrossed – M = 0.09 μV; crossed – M = −0.06 μV). An interaction of Electrode Site × Hemisphere was also obtained (F2,22 = 6.809, P < 0.01). The participants in Experiment 1 were presented with tactile stimuli to their hands across blocks in which they were asked to adopt either crossed-hands or uncrossed-hands postures. Analyses of SEPs recorded from central, centroparietal and frontal sites indicated that posture affected somatosensory processing from 128 ms over the contralateral hemisphere. Posture effects were not observed over the ipsilateral hemisphere. Effects of posture on specifically contralateral somatosensory activity were also identified in Lloyd et al.