Twenty years of investigation with the case of prosopagnosia PS to understand human face identity recognition. Part I: Function

Neural computations in prosopagnosia

“…Non-face identity decoding. PS's impairments for individuation of visual objects are restrained to faces (Rossion, 2018(Rossion, , 2022a. As a standard of comparison to the neural face-identification decoders, we trained multiclass linear discriminant classifiers decoders to predict 8 within-category identities from non-face categories (i.e.…”

“…This closed head injury led to major lesions in the left middle fusiform gyrus, where the left Fusiform Face Area (lFFA) is typically located, and in the right inferior occipital gyrus, which typically locates the right Occipital Face Area (rOFA; see Gao et al 2019 for converging fMRI evidence). Both regions play a critical functional role within the face cortical network (Rossion, 2022a, 2022b). She also reported minor damages in the right middle temporal gyrus and left posterior cerebellum (for an exhaustive anatomical description and an illustration of her brain damages see, Sorger et al, 2007, Figures 2 and 3).…”

“…Patient PS is a very well-documented and described case of acquired prosopagnosia. She has been extensively studied over the last 20 years, leading to impactful scientific contributions that significantly enriched the theoretical models on human face perception (Rossion, 2008, 2014; for a complete case report see, Rossion, 2022a, 2022b; Rossion et al, 2003b).…”

“…Patient PS is a right-handed woman having sustained a closed head injury in 1992, leading to extensive bilateral occipitotemporal lesions encompassing the right OFA, left FFA, and a small region of the right middle temporal gyrus (Dricot et al, 2008;Sorger et al, 2007). She is perhaps the most studied case of acquired prosopagnosia, with more than 32 scientific publications in the last 20 years (see Rossion, 2022aRossion, , 2022b for recent reviews on this patient). The particular attention given to this case can be attributed to the relatively focal aspect of her lesions in the face network and the resulting highly specific impairment for face-identification (Busigny et al, 2010).…”

“…Overall, while her condition has been shown to affect a wide array of perceptual mechanisms (e.g. holistic processes, Ramon et al, 2016; the visual content of face representations in Caldara et al, 2005; Fiset et al, 2017; see also Rossion, 2022a), a direct characterisation of the neural computations behind her deficits has, to the best of our knowledge, never been attempted. A traditional proxy to the nature and level of brain computations affected in this patient, and in prosopagnosia in general, has been to consider the temporal dynamics and face-selectivity of the underlying neural activity.…”