Serial and parallel processing in the primate auditory cortex revisited

Abstract

Over a decade ago it was proposed that the primate auditory cortex is organized in a serial and parallel manner in which there is a dorsal stream processing spatial information and a ventral stream processing non-spatial information. This organization is similar to the "what"/"where" processing of the primate visual cortex. This review will examine several key studies, primarily electrophysiological, that have tested this hypothesis. We also review several human-imaging studies that have attempted to define these processing streams in the human auditory cortex. While there is good evidence that spatial information is processed along a particular series of cortical areas, the support for a non-spatial processing stream is not as strong. Why this should be the case and how to better test this hypothesis is also discussed.

Figure 1

Schematic illustration of the primate auditory cortex. The core area is made up of the primary auditory cortex (AI), the rostral field (R) and the rostrotemporal field (RT). The belt area is comprised of the caudolateral (CL), caudomedial (CM), middle medial (MM), rostromedial (RM), rostrotemporal medial (RTM) rostrotemporal lateral (RTL), anterolateral (AL) and middle lateral (ML) fields. Lateral to the lateral belt areas is the parabelt. The dual stream hypothesis posits that spatial processing will occur in a dorsal, or caudal stream (blue) and non-spatial processing will occur in the ventral, or rostral stream (red).