Chapter 27 The metamodal organization of the brain

Abstract

To extract information derived from one sensory modality and used in another, shape can be known by touch and then can be identified correctly by sight. The chapter discusses the issue of internal versus experiential influences in the organization of the brain. The impressions generated by different sensory modalities can be integrated into a richer percept. The ventriloquism effect broadly refers to this phenomenon on which much of the knowledge of the world and an entire entertainment industry is based. Multimodal association areas that contain multisensory neurons are thought to provide a neural substrate for integrating sensory experiences, modulating the saliency of stimuli, assigning experiential and affective relevance, and providing the substrate for the true perceptual experience of the rich world. The chapter presents the hypothesis that the brain might actually represent a metamodal structure organized as operators that execute a given function or computation regardless of sensory input modality. Such operators might have a predilection for a given sensory input based on its relative suitability for the assigned computation. Such predilection might lead to operator-specific selective reinforcement of certain sensory inputs, eventually generating the impression of a brain structured in parallel, segregated systems processing different sensory signals.