Table 1.
Participant details.
Figure 1.
Time-domain event-related potentials by condition.
Panel A: 2 Hz condition. Panel B: 1.5 Hz condition. Topographic headplots show the contingent negative variation (CNV) for both groups and the difference between the groups. Electrode showing significant amplitude difference in the prestimulus −50 to 0 ms interval after correcting for false positives are marked with larger disk. ERP traces are shown from the most significant electrode (marked with larger disk).
Figure 2.
Time-frequency plots, 2 hz condition.
The two lower panels show ITC across frequencies from 0 to 40(right panel) and controls (left panel). Dashed vertical lines indicate the time of stimulus arrival. Statistical analysis revealed significant group differences in the delta frequency range (∼0.5–4 Hz) in the prestimulus interval (−40–0 ms). Topographic headplots show ITC values over the whole head for both groups and the difference between the groups. Electrodes with significant group difference are marked with disks.
Figure 3.
Distribution of Reaction Times (RTS) by group, 2 hz condition.
Middle square indicates median RT; Box indicates the middle 75% of the distribution; Tails indicate min/max.
Figure 4.
Phase entrainment of prestimulus delta oscillation by group.
Panel A: Phase distribution in the 2 Hz condition is plotted as a rose diagram (from the electrode approximately corresponding to FCz in the 10–20 electrode location system, see figure 1), with the radial extent of the petals representing the probability of a given phase range. Top row depicts controls, bottom row depicts dyslexics. The red petal indicates the mean angle for each group. Panel B: Upper: Phase angle (depicted via π) of the delta oscillation along the whole epoch (from −800 to 800 ms) for both groups. Lower: Average EEG trace showing the delta oscillation along the whole epoch (from −800 to 800 ms) illustrating the ongoing nature of the delta oscillation for both groups. Panel C and D show analogous plots to Panel A and B, but for the 1.5 Hz condition.
Figure 5.
Task performance correlated with delta phase by conditions.
Panel A: 2 Hz condition. Panel B: 1.5 Hz condition. Both panels show RT-phase correlations from the most representative electrode (from the electrode approximately corresponding to FCz in the 10–20 electrode location system, see Figure 1). Trials are sorted according to their phase angle in ascending order. Trials with a prestimulus delta phase of –π are followed by trials with prestimulus delta phase ascending towards +π. The phase angle across the trials is represented by the green line. The corresponding RT value is represented by the blue line. The non-linearity of the blue line with respect to the green line for the control participants indicates that prestimulus delta phase predicts RT. For visualisation purposes the RT plots are smoothed using a 500 point sliding window.
Figure 6.
Correlation between ITC and CNV.
CNV (in µV) values as a function of coherence (ITC) in the 2 Hz condition. The solid line indicates the regression line.
Table 2.
Pearson correlations between ITC strength, CNV amplitude and the language measures for the two rhythmic presentation rates (2 Hz, 1.5 Hz).