Spatial processing of touch in sighted and congenitally blind humans

Abstract

We easily interact with our environment in daily life. For instance, when an object touches our hands, we can quickly localize it and look at it for further exploration. This seemingly effortless act poses a remarkable challenge for the brain. The tactile information about skin location on the hand is, yet, not enough to localize the origin of the tactile event in external three-dimensional space, because the hand could be anywhere around the body, for example, in front of the body or behind the back. Thus, to successfully localize touch the brain needs to integrate somatosensory skin-based information and posture-related proprioceptive, visual, and vestibular information about body parts. Yet, despite a large body of research we do not know exactly how the brain integrates such multisensory information for tactile localization. Here, I approach this question in several ways. The thesis begins with a general overview about how the brain may integrate signals coming from multiple senses to construct a coherent percept of the world (Chapter 2). Then, a description of how multisensory integration contributes to tactile localization follows, together with background information on the specific hypotheses of the present studies (Chapter 2, Section 2.2-2.7). Subsequently, I provide a detailed description of the conducted studies (Chapters 3–6) and end with concluding the thesis in a general discussion of the reported findings (Chapter 7).

CONTENTS

Chapter 1: Summary

Chapter 2: Introduction

Chapter 3: Oscillatory activity reflects differential use of spatial reference frames by sighted and blind individuals in tactile attention

Chapter 4: Alpha‐band oscillations reflect external spatial coding for tactile stimuli in sighted, but not in congenitally blind humans

Chapter 5: Task context effects on tactile reference frame weighting in sighted and congenitally blind humans

Chapter 6: Influences of movement planning on tactile perception

Chapter 7: Discussion

References Acknowledgements