Anatomical and Pathophysiological Features of the Auditory Pathways

**3**

**Chapter 1**

**Abstract**

Attention and Working Memory in

Human sensory systems are organized into processing hierarchies within cortex, such that incoming sensory information is analyzed and compiled into our vivid sensory experiences. Computations that are common to these sensory systems include the abilities to maintain enhanced focus on particular aspects of incoming sensory information (i.e., attention) and to retain sensory information in a short-term memory store after such sensory information is no longer available (i.e., working memory). In at least the auditory and visual systems, the necessary computational steps to create these experiences take place in cloverleaf clusters of cortical field maps (CFMs). The human auditory CFMs represent the spectral (i.e., tones) and temporal (i.e., period) aspects of sound, which are represented along the cortical surface as two orderly gradients that are physically orthogonal to one another: tonotopy and periodotopy, respectively. Knowledge of the properties of such CFMs is the foundation for understanding the specific sensory computations carried out in particular cortical regions. This chapter reviews current research into auditory nonverbal attention, auditory working memory, and auditory CFMs, and introduces the next steps to measure the effects of attention and working memory

across the known auditory CFMs in human cortex using functional MRI.

cortical field maps, attention, working memory

**1. Introduction**

specialization (e.g., [18, 19, 21]).

**Keywords:** human auditory cortex, fMRI, tonotopy, periodotopy, cloverleaf cluster,

Mammalian sensory systems are composed in cortex of many functionally specialized areas organized into hierarchical networks [1–6]. The most fundamental sensory information is embodied by the organization of the sensory receptors, which is maintained throughout most of the cortical hierarchy of sensory regions with repeating representations of this topography in cortical field maps (CFMs) [5, 7–13]. Accordingly neurons with receptive fields situated next to one another in sensory feature space are positioned next to one another in cortex within a CFM. In auditory cortex, auditory field maps (AFMs) are identified by two orthogonal

sensory representations: tonotopic gradients from the spectral aspects of sound (i.e., tones), and periodotopic gradients from the temporal aspects of sound (i.e., period or temporal envelope) [5, 10, 14]. On a larger scale across cortex, AFMs are grouped into cloverleaf clusters, another fundamental organizational structure also common to visual cortex [8, 10, 15–20]. CFMs within clusters tend to share properties such as receptive field distribution, cortical magnification, and processing

Human Auditory Cortex

*Brian Barton and Alyssa A. Brewer*
