, 1997; Penny, 2004), other studies did not (Alain et al., 1989; Tarkka & Stokic, 1998). These controversial results might be due to a difference in stimulus presentation in the different experiments. These studies used repetition of a single tone as a stimulus and it might be difficult to create a steady perceptual unit from such simple stimuli, or the length of the unit could possibly be variable across the subjects. Therefore, the present study aimed to find the neural correlates for the attentive processing of perceptual grouping by using a sound omission in a tone sequence with a regular pattern, which is expected to create a stable

perceptual unit. In addition, numerous studies have found that musical training causes functional reorganisation MAPK inhibitor in the brain, such as the improvement of sensitivity for auditory processing (Münte et al., 2002). Because musical training normally includes the analysis of structure of musical pieces, we expected that musicians would be sensitive to the structure of a tone sequence that might be reflected by a specific distribution of brain activation. Thus, we also investigated the impact of musical

experience on the processing of omission and perceptual grouping. Eleven subjects selleck chemicals llc who played musical instruments regularly (musicians; six males and five females) and 10 subjects who did not have any experience in playing an instrument (non-musicians; seven males and three females) participated in the experiment. Musicians had experience playing the piano, guitar, or violin (average 10.5 ± 3.7 years, mean ± SD). All subjects were right-handed and the average age was 21.9 years (± 1.9 SD), and all gave written informed consent to participate in the experiment. The experiment was performed in accordance with the ethical standards in the declaration of Helsinki and the guidelines approved by the local ethics committee of the Graduate School of Medicine and Faculty of Medicine, Kyoto University. The sequence of tones was composed of pure tones (440 Hz, 50 ms, 5 ms rise/fall times) with

two different loudness levels, a louder tone (L) (75 dB sound pressure Thalidomide level) and a softer tone (S) (65 dB sound pressure level) as wave files. These tones were presented with a 350 ms ISI as a regular pattern of ‘LLS’ (group sequence, Fig. 1A) or randomly (random sequence, Fig. 1B). In the group sequence, the pattern appeared 595 times and, additionally, a pattern in which the L tones were omitted (100 times) was presented. There were two positions at which the L tones were omitted in this sequence: (i) for the within-group omission, an omission was inserted immediately after the first L tone of the ‘LLS’ pattern to violate it; and (ii) for the between-group omission, the omission was inserted between the groups and, as a result, the between-group omission did not violate the pattern in the sequence.