BRAIN IMAGINGEffects of co-activation on cortical organization and discrimination performancePilz, Karin1 2; Veit, Ralf1; Braun, Christoph1 3; Godde, Ben1 4 CA Author Information 1Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Gartenstr. 29, 72074 Tübingen 2Max-Planck Research School and Graduate School of Neural and Behavioral Sciences, Tübingen 3MEG Center, University Hospital Tübingen, Germany 4Cognitive Neuroscience Sector, International School for Advanced Studies (SISSA), Trieste, Italy CACorresponding Author and Address: [email protected] Received 8 September 2004; accepted 18 October 2004 NeuroReport: December 3, 2004 - Volume 15 - Issue 17 - p 2669-2672 Buy Abstract We used fMRI to investigate the effects of tactile co-activation on the topographic organization of the human primary somatosensory cortex (SI). Behavioral consequences of co-activation were studied in a psychophysical task assessing the mislocalization of tactile stimuli. Co-activation was applied to the index, middle and ring fingers of the right hand either synchronously or asynchronously. Cortical representations for synchronously co-activated fingers moved closer together, whereas cortical representations for asynchronously co-activated fingers became segregated. Behaviorally, this pattern coincided with an increased and reduced number of mislocalizations between synchronously and asynchronously co-activated 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. © 2004 Lippincott Williams & Wilkins, Inc.