Neural mechanisms for the abstraction and use of pitch information in auditory cortex

Abstract

Experiments in animals have provided an important complement to human studies of pitch perception by revealing how the activity of individual neurons represents harmonic complex and periodic sounds. Such studies have shown that the acoustical parameters associated with pitch are represented by the spiking responses of neurons in A1 (primary auditory cortex) and various higher auditory cortical fields. The responses of these neurons are also modulated by the timbre of sounds. In marmosets, a distinct region on the low-frequency border of primary and non-primary auditory cortex may provide pitch tuning that generalizes across timbre classes.

Figure 1.

Schematics of auditory cortex across four species: A, Macaque; B, marmoset; C, cat; and D, ferret. In each panel, the top schematic shows an outline of the brain with auditory cortex indicted (dotted line, gray). The bottom schematic in each panel shows a closer view of the auditory cortex, with sulci (solid lines) and field boundaries (dotted lines). Core auditory cortex is shaded gray, and the orientations of known tonotopic maps are indicated with an arrow from low (L) to high (H) frequencies. A1, Primary auditory cortex; A2, secondary auditory area; AAF, anterior auditory field; ADF, anterior dorsal field; AL, anterolateral belt; CL, caudolateral belt; CM, caudomedial belt; DZ, dorsal zone; ML, mediolateral belt; MM, mediomedial belt; PAF, posterior auditory field; PPF, posterior pseudosylvian field; PSF, posterior suprasylvian field; r, rostral field; RM, rostromedial belt; RT, rostral temporal field; RTL, rostrotemporal lateral belt; RTM, rostrotemporal medial belt; VP, ventral posterior field.