The functional anatomy of visual-tactile integration in man: a study usingpositron emission tomography

The integration of neural signals from different sensory modalities is a pr erequisite for many cognitive and behavioural functions. In this study, we have mapped the functional anatomy of the integration of sensory signals ac ross the tactile and visual modalities. Using the PET radiotracer (H2O)-O-1 5, regional cerebral blood flow (rCBF) changes were measured in eight norma l volunteers performing crossmodal recognition of simultaneously presented visual and tactile stimuli using a modified version of the 'arc-circle test '. Whilst intramodal matching within the visual modality led to relative rC BF increases in the visual association cortex, crossmodal matching (visual- tactile), when compared to intramodal matching, was accompanied by relative rCBF increases in the anterior cingulate cortex, inferior parietal lobules , the left dorsolateral prefrontal cortex (DLPFC) and the left claustrum/in sular cortex. The pattern of brain activation is congruent with areas of he teromodal and supramodal cortex and indicates that activation of multimodal areas is required to solve the crossmodal problem. (C) 1999 Elsevier Scien ce Ltd. All rights reserved.