Mrittika Dey^1,2 (), Jolien P Schuurmans^1,2, Valerie Goffaux^1,2; ¹Psychological Sciences Research Institute, UCLouvain, ²Institute of Neuroscience, UCLouvain

Human observers identify faces best based on horizontal cues. This horizontal tuning is disrupted when the face is inverted, highlighting the importance of horizontal information for the specialized processing of the upright face stimulus. Face-preferring regions like the fusiform face area (FFA) are selectively tuned to horizontal content of upright face information. Orientation selectivity is a fundamental characteristic of neural coding in the primary visual cortex (V1). It is also shown to interact recurrently with high-level visual regions to refine visual representations. The present fMRI study investigates whether high-level face-specialized mechanisms influence orientation-selective coding in V1. Using correlation, we compared orientation selectivity in V1 and FFA for upright, inverted, and scrambled faces, filtered in restricted orientation bands (0°,30°,60°,90°,120°,150°). In a separate identity-matching task, we measured face identification performance at the same orientations. For all stimulus types, V1 univariate response follows a negatively-curved profile dipping in the horizontal range, suggesting response suppression in this range. FFA response peaked in the horizontal range for upright faces only. This horizontal tuning was eliminated by inversion, mirroring face identification performance. The correlation between FFA and V1 responses also peaked in the horizontal range for upright faces only, suggesting an increased V1/FFA communication for the face-specialized processing of horizontal information. Identification behavior and V1 response correlated more negatively in the horizontal range and with inversion, suggesting a potential influence of V1 coding on the horizontal tuning of recognition behavior. Multivoxel pattern analysis (MVPA) revealed that stimulus class significantly impacts V1 orientation selectivity, as orientation decoding was best for cardinal orientations for faces but not scrambled images. These findings suggest that V1 orientation selectivity is influenced by downstream face-specialized processing stages. This supports the view of V1 as an active blackboard, updating its orientation-selective coding under the influence of higher-level visual regions to facilitate perceptual behavior.