, 2001; Peretz et al., 2001; Itoh et al., 2003, 2010; Foss et al., 2007; Bidelman & Krishnan, 2009, 2011; Minati et al., 2009; Fujisawa & Cook, 2011). A region crucial to central processing during consonance/dissonance
is probably the inferior colliculus (IC). It is well documented that the IC, a prominent subcortical auditory relay, acts in a similar manner to the DZNeP critical bands of the cochlea (Merzenich & Reid, 1974; Schreiner & Langner, 1997). The majority of neurons in the central nucleus of the IC respond to binaural stimulation, with response characteristics that appear to be appropriate for the encoding of consonance and dissonance (Brückner & Rübsamen, 1995; Kuwada et al., 1997; Leroy & Wenstrup, 2000; McKinney et al., 2001; Bidelman & Krishnan, GSK1120212 order 2009). Despite findings suggesting a role of central processing
in the perception of consonance/dissonance, results obtained from a model of cat auditory nerve have indicated that sensory consonance/dissonance may be mediated by general cochlear and peripheral neural mechanisms basic to the auditory system (Bidelman & Heinz, 2011), identifying effects that were probably independent of musical training, long-term enculturation, and memory/cognitive capacity. The degree of dissonance correlates strongly with the percept of valence (pleasantness/unpleasantness). Hence the valence can be used to indirectly measure the perception of dissonance. Valence judgments index the perception of dissonance reliably in Western musicians, who are exposed to consonance/dissonance during their professional training, but also in Western non-musicians (Bugg, 1933; Plomp & Levelt, 1965; Blood et al., 1999). This is especially true for musical polyphonic stimuli where several chords
are presented in a sequence. Correlation of valence percept and degree of dissonance has even been observed in listeners never exposed to Western music (Fritz et al., 2009), which indicates that this is universally perceived and thus may correspond to some aspect Resminostat of the organisation of the auditory pathway. In the current study, we aimed to test behaviorally whether the cochlea is involved in the perception of dissonance in musical pieces that were more naturalistic than investigated in previous experiments. For this purpose, we dichotically presented dissonant music stimuli of several seconds duration, where a consonant track of a stereo file was presented to each ear, but both stereo tracks differed by a semitone in pitch. In this paradigm, a perception of dissonance arose only when participants listened to both tracks simultaneously – each track alone on each ear sounded consonant. Note that similar dichotic presentation paradigms have previously been successfully used as a means to study the role of a peripheral (cochlear) vs. central mechanism in consonance with simpler stimuli (Bidelman & Krishnan, 2009; McDermott et al., 2010).