The present study was able to reproduce the behavioral results of Perruchet (1985) [31]. Although the results are not absolutely equal this may be a result of the modications of the task, . Thus, the validity of the behavioral task was conrmed.
For the ERPs a modulation of the amplitude dependent on the string-length and the condition was found although it was not situated at the right tem-poral source. The latency-eect at the cingulate-source shows an eect that would be expected in an experiment with two tones of dierent frequencies to be measured at temporal sources.
The amplitude of the aSSR shows signicant eects that are reected by the behavioral data and can be interpreted accordingly. The main question remaining is the amount of contribution of top-down or bottom-up inuences on the eects.
The analysis of the synchrony-measurements revealed the most consistent ef-fect of the study. Synchronicity increases with increasing repetitions between all possible sources, which can be accounted to the occupation of the whole brain in solving the task, and learning the right associations. There was also an eect depending on the condition as well as an interaction showing the relevance of right parietal sources in top-down processes.
In particular, the right parietal and the anterior cingulate sources are those regions that were aected most by the current experiment. Although there has been a great deal of research concerning the involvement of these sources in cognitive tasks the results of this study and the review of current and past literature have shown that much is still unknown about the relationship of these sources, especially in the auditory domain.
To sum up, the results of this study showed that many paramters of the aSSR and the ERP can be modulated by a design that uses only one stimulus, although it these modulations were not found primary auditory areas. Top-down modulation cannot be seen in primary auditory areas when bottom-up processes are kept to a minimum by only using one tone. Eects in other parts of the brain show that nonetheless the parameters of the aSSR and the ERP can be modulated by top-down processes. A special role seems to be played by the right parietal and anterior cingulate areas.
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Appendix A
Source-Montage
Source Coordinates
X Y Z
left temporal -0.68 0.00 0.06
right temporal 0.68 0.00 0.06
left frontal -0.36 0.65 0.09
right frontal 0.36 0.65 0.09
left parietal -0.51 -0.37 0.49
right parietal 0.51 -0.37 0.49
posterior -0.01 -0.67 0.08
anterior cingulum 0.00 0.33 0.59