Autocorrelation pitch schemes lack neural evidence for periodicity-tuned neurons

Evidence

A robust but implicit code for pitch exists in the AN in the form of an across-fiber pooled interspike interval (ISI) distribution (Cariani and Delgutte 1996a , 1996b ; Meddis and Hewitt 1991a , b ), which resembles the stimulus autocorrelation. An unsolved question is how and whether this implicit temporal representation is transformed into a more explicit representation. Following an early model (Licklider 1951 ), various autocorrelation-type schemes have been proposed, in which periodicity-tuning is generated by some combination of coincidence detection and a source of delay. It is generally assumed that such a computation is implemented at a brainstem level, where responses are temporally precise over a broad range of frequencies. However, recordings have not revealed convincing evidence for level-invariant, periodicity-tuned neurons or sources of delay that cover a sufficiently broad temporal range (Neuert et al. 2005 ; Sayles et al. 2013 ; Sayles and Winter 2008a , 2008b ; Verhey and Winter 2006 ; Wang and Delgutte 2012 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 4495

Categorization

• DEFINE: Clarifies the autocorrelation-type scheme: coincidence detection combined with a source of delay.