Person: Anzellotti, Stefano
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Anzellotti
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Stefano
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Anzellotti, Stefano
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Publication Person- and Place-Selective Neural Substrates for Entity-Specific Semantic Access(Oxford University Press (OUP), 2013) Fairhall, S. L.; Anzellotti, Stefano; Ubaldi, S.; Caramazza, AlfonsoObject-category has a pronounced effect on the representation of objects in higher level visual cortex. However, the influence of category on semantic/conceptual processes is less well characterized. In the present study, we conduct 2 fMRI experiments to investigate the semantic processing of information specific to individual people and places (entities). First, during picture presentation, we determined which brain regions show category-selective increases during access to entity-specific semantic information (i.e., nationality) in comparison to general-category discrimination (person vs. place). In the second experiment, we presented either words or pictures to assess the independence of entity-specific category-selective semantic representations from the processes used to access those representations. Convergent results from these 2 experiments show that brain regions exhibiting a category-selective increase during entity-specific semantic access are the same as those that show a supramodal (word/picture) category-selective response during the same task. These responses were different from classical “perceptual” category-selective responses and were evident in the medial precuneus for people and in the retrosplenial complex as well as anterior/superior sections of the transverse occipital sulcus and parahippocampal gyrus for places. These results reveal the pervasive influence of object-category in cortical organization, which extends to aspects of semantic knowledge arbitrarily related to physical/perceptual properties.Publication Decoding Representations of Face Identity That are Tolerant to Rotation(Oxford University Press (OUP), 2013) Anzellotti, Stefano; Fairhall, Scott L.; Caramazza, AlfonsoIn order to recognize the identity of a face we need to distinguish very similar images (specificity) while also generalizing identity information across image transformations such as changes in orientation (tolerance). Recent studies investigated the representation of individual faces in the brain, but it remains unclear whether the human brain regions that were found encode representations of individual images (specificity) or face identity (specificity plus tolerance). In the present article, we use multivoxel pattern analysis in the human ventral stream to investigate the representation of face identity across rotations in depth, a kind of transformation in which no point in the face image remains unchanged. The results reveal representations of face identity that are tolerant to rotations in depth in occipitotemporal cortex and in anterior temporal cortex, even when the similarity between mirror symmetrical views cannot be used to achieve tolerance. Converging evidence from different analysis techniques shows that the right anterior temporal lobe encodes a comparable amount of identity information to occipitotemporal regions, but this information is encoded over a smaller extent of cortex.Publication The representation of person identity in the human brain(2014-06-06) Anzellotti, Stefano; Caramazza, Alfonso; Xu, Yaoda; Nakayama, Ken; Greene, JoshuaEvery day we encounter a variety of people, and we need to recognize their identity to interact with them appropriately. The most common ways to recognize a person's identity include the recognition of a face and of a voice. Recognizing a face or a voice is effortless, but the neural mechanisms that enable us to do so are complex. The face of a same person can look very different depending on the viewpoint and it can be partly occluded. Analogously, a voice can sound very different when it is saying different words. The neural mechanisms that enable us to recognize a person's identity need to abstract away from stimulus differences that are not relevant for identity recognition. Patient studies indicate that this process is executed with the contribution of multiple brain regions (Meadows, 1974; Tranel et al., 1997). However, the localization accuracy allowed by neuropsychological studies is limited by the lack of control on the location and extent of lesions. Neuroimaging studies individuated a set of regions that show stronger responses to faces than other objects (Kanwisher et al., 1997; Rajimehr et al., 2009), and to voices than other sounds (Belin et al., 2000). These regions do not necessarily encode information about a person's identity. In this thesis, a set of regions that encode information distinguishing between different face tokens were individuated, including ventral stream regions located in occipitotemporal cortex and the anterior temporal lobes, but also parietal regions: posterior cingulate and superior IPS. Representations of face identity with invariance across different viewpoints and across different halves of a face were found in the right ATL. However, representations of face identity and of voice identity were not found to overlap in ATL, indicating that in ATL representations of identity are organized by modality. For famous people, multimodal representations of identity were found in association cortex in posterior STS.Publication Differential Activity for Animals and Manipulable Objects in the Anterior Temporal Lobes(Massachusetts Institute of Technology Press, 2011) Anzellotti, Stefano; Mahon, Bradford Z.; Schwarzbach, Jens; Caramazza, AlfonsoNeuropsychological evidence has highlighted the role of the anterior temporal lobes in the processing of conceptual knowledge. That putative role is only beginning to be investigated with fMRI as methodological advances are able to compensate for well-known susceptibility artifacts that affect the quality of the BOLD signal. In this article, we described differential BOLD activation for pictures of animals and manipulable objects in the anterior temporal lobes, consistent with previous neuropsychological findings. Furthermore, we found that the pattern of BOLD signal in the anterior temporal lobes is qualitatively different from that in the fusiform gyri. The latter regions are activated to different extents but always above baseline by images of the preferred and of the nonpreferred categories, whereas the anterior temporal lobes tend to be activated by images of the preferred category and deactivated (BOLD below baseline) by images of the nonpreferred category. In our experimental design, we also manipulated the decision that participants made over stimuli from the different semantic categories. We found that in the right temporal pole, the BOLD signal shows some evidence of being modulated by the task that participants were asked to perform, whereas BOLD activity in more posterior regions (e.g., the fusiform gyri) is not modulated by the task. These results reconcile the fMRI literature with the neuropsychological findings of deficits for animals after damage to the right temporal pole and suggest that anterior and posterior regions within the temporal lobes involved in object processing perform qualitatively different computations.