Faciotopy-A face-feature map with face-like topology in the human occipital face area.
Bottom Line: The responses in V1 were best explained by low-level image properties of the stimuli.OFA, and to a lesser degree FFA, showed evidence for faciotopic organization.Faciotopy would be the first example, to our knowledge, of a cortical map reflecting the topology, not of a part of the organism itself (its retina in retinotopy, its body in somatotopy), but of an external object of particular perceptual significance.
Affiliation: MRC Cognition and Brain Sciences Unit, Cambridge, UK; Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland. Electronic address: email@example.com.Show MeSH
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Mentions: We have now shown that V1, OFA and FFA respond to isolated face-features (Fig. 3), but do they also discriminate between the face features (e.g., an eye from a mouth)? Fig. 4a shows the results from linear discriminant analysis (Nili et al., 2014): the discriminability of each pair of face-feature stimuli was evaluated by fitting a Fisher linear discriminant to the response patterns from the first fMRI session and by testing the performance on the response patterns from the second fMRI session (same subject, different day, different stimulus presentation order, all stimulus layouts). The analyses were done on individual data and the results were pooled across the twelve subjects. The left column in Fig. 4a shows the linear-discriminant t-values, reflecting the discrimability of each pair of face-feature stimuli from the response patterns, and the right column shows the corresponding p-values. In V1, the response patterns discriminated each pair of face-feature stimuli, except the two hairlines from each other and the mouth from the chin (Fig. 4a, first row). In OFA, each pair of the face-feature stimuli could be discriminated from the response patterns (Fig. 4a, middle row). In addition, there appears to be a distinction between the inner (first five elements in the linear discriminant t-value and p-value matrices; e.g., the eyes) and outer face-features (elements 6–12 in the matrices; e.g., the ears), that is, the t-values are high for the discriminability of these stimulus pairs in OFA, and also in FFA. Moreover, in FFA, the symmetric face-features (the eyes, the hairlines, the ears, the jaw lines) evoked indistinguishable response patterns (bottom row in Fig. 4a; see the blue rectangles in the p-value matrix).
Affiliation: MRC Cognition and Brain Sciences Unit, Cambridge, UK; Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland. Electronic address: firstname.lastname@example.org.