The brain's fingers and hands
Poster Presentation

Marisa Taylor-Clarke
Institute of Cognitive Neuroscience, University College London

Clare Press

Keiko Kitadono
Department of Psychology, University College London

Patrick Haggard
Institute of Cognitive Neuroscience, University College London

     Abstract ID Number: 80
     Full text: Not available
     Last modified: March 20, 2005

Abstract
The brain keeps track of the changing positions of body parts in space using a spatial body schema. When subjects localise a tactile stimulus on the skin, they might either use a somatotopic body map, or use a body schema to identify the location of the stimulation in external space. Healthy subjects were touched on the fingertips, with the hands in a range of postures: the right hand could be vertically above the left, or the fingers of both hands interwoven. In addition the right palm could face the left or the right. Subjects made speeded verbal responses to identify either the finger or the hand that was touched. Interweaving the fingers significantly impaired hand identification across several experiments, but had no effect on finger identification. Our results suggest that finger identification involves a somatotopic representation or finger schema. Hand identification uses a general body schema, and is influenced by external spatial location. This dissociation implies that touches on the finger can only be identified with a particular hand after a process of assigning fingers to hands, based on proprioceptively-sensed external spatial location. Our results suggest a role of the proprioceptive body schema in the organisation and interpretation of touch.