The left fusiform gyrus hosts trisensory representations of manipulable objects

During object manipulation the brain integrates the visual, auditory, and haptic experience of an object into a unified percept. Previous brain imaging studies have implicated for instance the dorsal part of the lateral occipital complex in visuo-tactile and the posterior superior temporal sulcus in audio-visual integration of object-related inputs (Amedi et al., 2005). Yet it is still unclear which brain regions represent object-specific information of all three sensory modalities. To address this question, we performed two complementary functional magnetic resonance imaging experiments. In the first experiment, we identified brain regions which were consistently activated by unimodal visual, auditory, and haptic processing of manipulable objects relative to non-object control stimuli presented in the same modality. In the second experiment, we assessed regional brain activations when participants had to match object-related information that was presented simultaneously in two or all three modalities. Only a well-defined region in left fusiform gyrus (FG) showed an object-specific activation during unisensory processing in the visual, auditory, and tactile modalities. The same region was also consistently activated during multisensory matching of object-related information across all three senses. Taken together, our results suggest that this region is central to the recognition of manipulable objects. A putative role of this FG region is to unify object-specific information provided by the visual, auditory, and tactile modalities into trisensory object representations.