Abstract
Tools are often compared to a part of our own “body”. Since the end of the 20th century, neuroscientists and psychologists have accumulated evidence suggesting that the “tool as a part of the body” is not just a metaphor, but is a fact in the brain. In the introduction of this article, we review a neurophysiological study on the monkey brain that achieved a breakthrough in this area of research. Subsequently, we review studies in humans. In the first section, we explain the psychophysical studies that suggest the perceptual assimilation of tools and hands and neuroimaging reports regarding the neural correlates of perceptual tool-hand assimilation. In the second section, we describe the spatial action capability with tools or extracorporeal objects based on behavioral studies regarding locomotion, such as load-carriage and wheelchair-use. Based on these findings, we discuss current and future research issues regarding the tool-body interaction in the context of neural mechanisms and applications.
