“…Previous fMRI studies of auditory-visual integration in STS (Beauchamp et al, 2004a;Beauchamp et al, 2004b;Hein et al, 2007;Van Atteveldt et al, 2004;van Atteveldt et al, 2007) and auditory-tactile integration in auditory cortex (Kayser et al, 2005) have also not observed super-additive changes in the BOLD signal, perhaps because only a few single neurons show super-additivity (Laurienti et al, 2005;Perrault et al, 2005). Supporting this idea, in single-unit recording studies, only a small fraction of STP neurons respond to both auditory and tactile stimulation (Bruce et al, 1981;Hikosaka et al, 1988); the same is true in multisensory regions of cat cortex (Clemo et al, 2007). Conversely, many single neurons may show no response to a sensory stimulus in isolation, but the same stimulus may modulate responses when presented with other sensory modalities .…”