Functional organization of face processing in the human superior temporal sulcus: a 7T high-resolution fMRI study

The superior temporal sulcus (STS) is a major component of the human face perception network, implicated in processing dynamic changeable aspects of faces. However, it remains unknown whether STS holds functionally segregated subdivisions for different categories of facial movements. We used high-resolution functional magnetic resonance imaging (fMRI) at 7T in 16 volunteers to compare STS activation with faces displaying angry or happy expressions, eye-gaze shifts and lip-speech movements. Combining univariate and multivariate analyses, we show a systematic topological organization within STS, with gaze-related activity predominating in the most posterior and superior sector, speech-related activity in the anterior sector and emotional expressions represented in the intermediate middle STS. Right STS appeared to hold a finer functional segregation between all four types of facial movements, and best discriminative abilities within the face-selective posterior STS (pSTS). Conversely, left STS showed greater overlap between conditions, with a lack of distinction between mouth movements associated to speech or happy expression and better discriminative abilities (for gaze and speech vs emotion conditions) outside pSTS. Differential sensitivity to upper (eye) or lower (mouth) facial features may contribute to, but does not appear to fully account for, these response patterns.

Neural decoding of discriminative auditory object features depends on their socio-affective valence

Human voices consist of specific patterns of acoustic features that are considerably enhanced during affective vocalizations. These acoustic features are presumably used by listeners to accurately discriminate between acoustically or emotionally similar vocalizations. Here we used high-field 7T functional magnetic resonance imaging in human listeners together with a so-called experimental 'feature elimination approach' to investigate neural decoding of three important voice features of two affective valence categories (i.e. aggressive and joyful vocalizations). We found a valence-dependent sensitivity to vocal pitch (f0) dynamics and to spectral high-frequency cues already at the level of the auditory thalamus. Furthermore, pitch dynamics and harmonics-to-noise ratio (HNR) showed overlapping, but again valence-dependent sensitivity in tonotopic cortical fields during the neural decoding of aggressive and joyful vocalizations, respectively. For joyful vocalizations we also revealed sensitivity in the inferior frontal cortex (IFC) to the HNR and pitch dynamics. The data thus indicate that several auditory regions were sensitive to multiple, rather than single, discriminative voice features. Furthermore, some regions partly showed a valence-dependent hypersensitivity to certain features, such as pitch dynamic sensitivity in core auditory regions and in the IFC for aggressive vocalizations, and sensitivity to high-frequency cues in auditory belt and parabelt regions for joyful vocalizations.