Introduction

Auditory cortex function beyond bottom–up feature detection

Until the 1980s the auditory cortex was mainly conceptualized as the neuronal structure implementing the top hierarchy level of bottom–up processing of physical characteristics (features) of auditory stimuli. In that respect, plastic changes in anatomical and functional principles were only considered relevant for developmental processes towards an otherwise stable adult brain. Presently, this view has been replaced by a conceptualization of auditory cortex as a structure holding a strategic position in the interaction between bottom–up and top–down processing (for review see Irvine, 2007; Scheich et al., 2007), in particular auditory learning (for review see Weinberger, 2004; Irvine and Wright, 2005; Ohl and Scheich, 2005).

In this chapter we review experimental evidence from gerbil and macaque auditory cortex that has led to this change of view about auditory cortex function. It will be argued that a fundamental understanding of the role of auditory cortex in learning has required to move beyond the study of simple classical conditioning and feature detection learning, for which auditory cortex does not seem to be a generally necessary structure (see below). Specifically, it will be elaborated that the abstraction from trained particular stimuli, as it is epitomized in the phenomenon of category learning (concept formation), is a complex but fundamental learning phenomenon for which auditory cortex is a relevant structure harboring the necessary functional organization.