Our body is not only an extended object in external space, but also the basis of our sense of self. Proprioceptive signals from muscle spindle organs, specifying body position, play a key role in this unique dual quality of body representation, as they define a 'here' or set of locations, where 'I' am located [1]. Position information from muscle spindles can be manipulated by vibrating the muscle tendon, generating illusions of position and movement [2]. For example, biceps vibration generates illusions of elbow extension, while triceps vibration generates illusions of flexion. Here we report that proprioceptive conflict induced by simultaneous vibration of antagonistic biceps and triceps muscle tendons alters representation of the body in a way qualitatively different from single vibrations. Rather than relocation or movement, this incoherent conflict of location produces perceived telescoping of the arm towards the elbow. Loss of coherent information about body position in space seems to produce contraction of the body representation itself. Our result suggests that basic sensory signals about body posture also play an essential role in representing the self as an extended object in space.

DOI: 10.1016/j.cub.2009.07.024
Version: za2963e q8zac q8zbf q8zc1 q8zd0 q8zef q8zfd q8zg6