Process timing and its relation to the coding of tonal harmony

Advances in auditory research suggest that gamma-band synchronization of frequency-specific cortical loci could be responsible for the integration of pure tones (harmonics) into harmonic complex tones. Thus far, evidence for such a mechanism has been revealed in neurophysiological studies, with little corroborative psychophysical evidence. In six experiments, we observed a rate- and time-specific response-time advantage for a sequence of target pips when the defining frequency of the target was a fractional multiple of a priming frequency. The effect was only observed when the prime and target sequences were presented at 33 pips per second and when the interstimulus interval was approximately 100 and 250 ms. This evidence implicates oscillatory gamma-band activity in the representation of harmonic complex tones and suggests that synchronization with precise temporal characteristics is important for disambiguating related harmonic templates. An outline of a model is presented, which accounts for these findings in terms of fast resynchronization of relevant neuronal assemblies.