Introduction

Over the past decade, neuroimaging of metabolic activity related to brain function has advanced our understanding of how the human brain combines what we see and hear. This chapter examines studies designed to reveal human brain regions and mechanisms underlying audiovisual interactions using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). Our knowledge of the nature and location of audiovisual interactions and the neural mechanisms underlying such processing is inferred largely from animal experiments, for which we present a brief background. Extending these mechanisms and concepts to human hemodyamic neuroimaging, we then examine a variety of studies designed to expose sites of integration for different parameters shared between auditory and visual stimuli.