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Abstract

We used functional MRI to investigate the effects of tactile coactivation on the topographic organisation of the human primary somatosensory cortex (SI). Behavioural consequences of coactivation were studied in a psychophysical task assessing the mislocalization of tactile stimuli. Coactivation was applied to the index, middle and ring fingers of the right hand either synchronously or asynchronously. Cortical representations for synchronously coactivated fingers moved closer together, whereas cortical representations for asynchronously coactivated fingers became segregated. Behaviourally, this pattern coincided with an increased and reduced number of mislocalizations between coactivated fingers, respectively. Thus, both synchronous and asynchronous coupling of passive tactile stimulation is able to induce short-term cortical reorganization associated with functionally relevant changes.