Direct structural connections between voice- and face-recognition areas

Currently, there are two opposing models for how voice and face information is integrated in the human brain to recognize person identity. The conventional model assumes that voice and face information is only combined at a supramodal stage (Bruce and Young, 1986; Burton et al., 1990; Ellis et al., 1997). An alternative model posits that areas encoding voice and face information also interact directly and that this direct interaction is behaviorally relevant for optimizing person recognition (von Kriegstein et al., 2005; von Kriegstein and Giraud, 2006). To disambiguate between the two different models, we tested for evidence of direct structural connections between voice and face processing cortical areas by combining functional and diffusion magnetic resonance imaging (fMRI and dMRI). We localized, at the individual subject level, three voice-sensitive areas in anterior, middle, and posterior superior temporal sulcus (STS) and face-sensitive areas in the fusiform gyrus (fusiform face area, FFA). Using probabilistic tractography, we show evidence that the FFA is structurally connected with voice-sensitive areas in STS. In particular, our results suggest that the FFA is stronger connected to middle and anterior than to posterior areas of the voice-sensitive STS. This specific structural connectivity pattern indicates that direct links between face- and voice-recognition areas could be used to optimize human person recognition