Neural Correlates of Processing Syntax in Music and ... - PubMan

Experiment I 99
after stimulus onset (length of the final chord) with a baseline from -200 to 0 ms. Epoch
length and baseline values were chosen in accordance with earlier experiments using the
same paradigm (e.g., Koelsch et al., 2003; Koelsch et al., 2000).
Statistical evaluation
It was assured that variables used in the analyses did not deviate from a standard normal
distribution (with Kolmogorov-Smirnov tests; 0.11 ��p ��������������������������������
analysis of the ERPs, four regions of interest (ROIs) were computed: left-anterior (F3,
F7, FC3), right-anterior (F4, F8, FC4), left-posterior (P3, T7, CP5), and right-posterior
(P4, T8, CP6), and three time windows were evaluated: [1] 240 to 320 ms (ERAN), [2]
650 to 850 ms (N5), and [3] 120 to 200 ms after stimulus onset. In a first analysis, ERPs
were evaluated statistically by mixed-model ANOVAs for repeated measures containing
the within-subject factors chord function (regular [tonic] vs. irregular chords [supertonic,
Neapolitan sixth chord]), anterior-posterior distribution, and hemisphere (left vs.
right) and the between-subjects factor subgroup (supertonics vs. the Neapolitan sixth
chords as irregular chords). In a second analysis, the same ANOVA with an additional
between-subjects factor subgroup was employed to compare the ERP responses in the
children that were either at-risk or not at-risk for language impairment.
9.3 Results
Figure 9-2 and 9-3 present the ERP responses to the regular and the irregular chords.
They show that an ERAN was elicited in response to the irregular supertonics compared
to the regular tonics (Figure 9-2) and in response to the irregular Neapolitan sixth
chords compared to the regular tonics (Figure 9-3). The N5, that usually follows the
ERAN, had a very small amplitude size and could be observed only at few electrodes.
In addition, another unexpected ERP component was observed around 100 ms. Its short
latency indicates that it presumably reflects acoustic processing. Thus, this component
is termed early acoustic difference (EAD).
ERAN: For the first analysis, the data from both subgroups were pooled. An ERAN
was observed, peaking around 300 ms (see Figure 9-2 and 9-3). It was relatively broadly
distributed over the scalp. It was larger in the right compared to the left hemisphere and
in the anterior compared to the posterior ROIs (left-anterior: M = -0.61 μV, SEM =
0.39 μV; right-anterior: M = -0.94 μV, SEM = 0.42 μV; left-posterior: M = -0.47 μV,
SEM = 0.32 μV; right-posterior: M = -0.87 μV, SEM = 0.32 μV). However, the lateralization
of the ERAN was slightly different in the two subgroups: In the paradigm with
the Neapolitan sixth chords, the ERAN was rather right-lateralized (right-anterior: M =