An important avenue for future work is exploring the relative roles of these candidate musical features on ISS. Our results demonstrate that auditory structures of the temporal lobe, including HG, PT, PP and pSTG bilaterally, were highly synchronized across subjects during music listening. Interestingly, no differences were evident in auditory cortical synchronization for the Natural Music > Spectrally-Rotated comparison, although differences were evident for the Natural Music > Phase-Scrambled comparison (Fig. 4). Amplitude modulation in the Natural Music and Spectrally-Rotated conditions is one possible explanation Stem Cell Compound Library supplier for ISS across both tasks in the auditory cortex. This interpretation
is supported by previous studies which have shown auditory cortical sensitivity to low-frequency amplitude modulation in speech (Ahissar et al., 2001; Abrams et al., 2008, 2009; Aiken & Picton, 2008) and other auditory stimuli (Boemio et al., 2005), and is further supported by single and multi-unit activity measured in auditory cortex of animal models during the processing of spectro-temporally complex auditory stimuli (Wang et al.,
1995; Nagarajan et al., 2002). In this context it is noteworthy that a significant ISS difference was evident in auditory cortex for the Natural Music > Phase-Scrambled comparison (Fig. 4, right). These results indicate that despite the well-documented sensitivity of auditory cortex to spectral and harmonic information (Zatorre et al., 2002), which are Ureohydrolase present in the Phase-Scrambled condition, these features alone, in the absence of click here temporal patterns, are insufficient to drive ISS. Our results extend these previous findings by showing that the disruption of temporal patterns in music significantly reduces the consistency of auditory cortical activity measured across individuals. Moreover, our results point to the involvement of both primary and secondary auditory cortical structures, including HG, PP, PT and pSTG, in tracking the temporal structure of music across time periods lasting minutes. Additionally, a recent ISS study showed that activity in bilateral STG and HG are recruited during timbral
processing of a naturalistic musical stimulus, and bilateral STG and right-hemisphere HG are also active during rhythm processing (Alluri et al., 2012). ISS results in the current study also support a role for STG and HG in rhythm processing given that (1) ISS in these auditory cortical regions was only evident when temporal features were present in the stimuli (see Fig. 4), and (2) temporal features, such as amplitude modulation, are fundamental to the perception of rhythm (Sethares, 2007). An intriguing aspect of the results was the finding of differences in ISS for the Natural Music > Spectrally-Rotated condition in sub-cortical structures but not in auditory cortex. While both sub-cortical (Chandrasekaran et al., 2009) and cortical structures (Fecteau et al., 2004; Chait et al.