Audiovisual integration in human superior temporal sulcus: Inverse effectiveness and the neural processing of speech and object recognition

The superior temporal sulcus (STS) is a region involved in audiovisual integration. In non-human primates, multisensory neurons in STS display inverse effectiveness. In two fMRI studies using multisensory tool and speech stimuli presented at parametrically varied levels of signal strength, we show that the pattern of neural activation in human STS is also inversely effective. Although multisensory tool-defined and speech-defined regions of interest were non-overlapping, the pattern of inverse effectiveness was the same for tools and speech across regions. The findings suggest that, even though there are sub-regions in STS that are speech-selective, the manner in which visual and auditory signals are integrated in multisensory STS is not specific to speech.