Representations of the pitch of complex tones in the auditory nerve

Previous studies of the coding of the pitch of complex tones in the auditory nerveand cochlear nucleus have documented a robust temporal representation based oninterspike interval distributions (Cariani and Delgutte, 1996; Rhode, 1995; Palmerand Winter, 1993). However, these studies have largely neglected possible rate-place cues to pitch available when individual harmonics are resolved by theperipheral auditory system. Stimuli used in these studies had fundamentalfrequencies in the range of human voice (100-300 Hz), which may produce few, ifany, resolved harmonics in typical experimental animals, which have a poorercochlear frequency selectivity compared to humans (Shera, Guinan and Oxenham,2002). Human psychophysical studies suggest that the low pitch produced bystimuli with resolved harmonics is stronger and less dependent on phaserelationships among the partials than the pitch based on unresolved harmonics(Shackleton and Carlyon, 1994).Here, we investigate the resolvability of harmonics of complex tones in the catauditory nerve, and compare the effectiveness of rate-place and interval-basedrepresentations of pitch over a much wider range of fundamental frequencies (110-3520 Hz) than in previous studies.