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See detailThe SNARC effect – Does it depend on the level of mathematical training?
Hoffmann, Danielle UL; Mussolin, Christophe; Schiltz, Christine UL

Poster (2011)

Behavioural studies show a relation between numbers and space (DeHevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster ... [more ▼]

Behavioural studies show a relation between numbers and space (DeHevia et al., 2008). One instance of this link is the SNARC (Spatial Numerical Association of Response Codes) effect, consisting in faster reaction times responding to small/large digits with the left/right hand respectively (Dehaene et al. 1993). The SNARC effect has often been replicated, but it is also characterized by high inter-subject variability (Wood et al. 2006a,b). Although differences in mathematical skills are an obvious candidate source for SNARC variability, this variable has not yet been explored systematically. While in their seminal study Dehaene and colleagues had included two groups of participants differing in their field of study (science vs. literature), the differences in SNARC effect strengths indicated by the result figures were not tested formally (see also Fischer and Rottmann (2005)). The present study aims to assess the influence of mathematical training, as instantiated by the enrollment in study fields characterized by distinct levels of mathematical requirements, on the SNARC effect. We only included students of either a subject with a strong mathematical focus (e.g. mathematics, computer sciences), or no mathematical requirements at all (e.g. literature, philosophy). Results (N=36; 18/group) yielded a significant overall SNARC effect, i.e. interaction between digit magnitude and response side [F(1,35)=9.51; p=0.004], but no influence of study group on this interaction [F(1,35)=0.92; p=0.345]. Interestingly though, including gender in the ANOVA yielded a significant four-way interaction [F(1,35)=6.34; p=0.017]. These results replicate previous findings in children (Schweiter et al. 2005), interpreted as gender-related differences in mental strategy use. [less ▲]

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See detailCerebral lateralization of the face-cortical network in left-handers: only the FFA does not get it right
Bukowski, Henryk; Rossion, Bruno; Schiltz, Christine UL et al

in Journal of Vision (2010), 10(7),

Face processing is a function that is highly lateralized in humans, as supported by original evidence from brain lesion studies (Hecaen & Anguerlergues, 1962), followed by studies using divided visual ... [more ▼]

Face processing is a function that is highly lateralized in humans, as supported by original evidence from brain lesion studies (Hecaen & Anguerlergues, 1962), followed by studies using divided visual field presentations (Heller & Levy, 1981), neuroimaging (Sergent et al., 1992) and event-related potentials (Bentin et al., 1996). Studies in non-human primates (Perrett et al., 1988; Zangenehpour & Chaudhuri, 2005), or other mammals (Peirce & Kendrick, 2001) support the right lateralization of the function, which may be related to a dominance of the right hemisphere in global visual processing. However, in humans there is evidence that manual preference may shift or qualify the pattern of lateralization for faces in the visual cortex: face recognition impairments following unilateral left hemisphere brain damage have been found only in a few left-handers (e.g., Mattson et al., 1992; Barton, 2009). Here we measured the pattern of lateralization in the entire cortical face network in right and left-handers (12 subjects in each group) using a well-balanced face-localizer block paradigm in fMRI (faces, cars, and their phase-scrambled versions). While the FFA was strongly right lateralized in right-handers, as described previously, it was equally strong in both hemispheres in left-handers. In contrast, other areas of the face-sensitive network (posterior superior temporal sulcus, pSTS; occipital face area, OFA; anterior infero-temporal cortex, AIT; amygdala) remained identically right lateralized in both left- and right-handers. Accordingly, our results strongly suggest that the face-sensitive network is equally lateralized for left- and right-handers, and thus the face processing is not influenced by handedness. However, the FFA is an important exception since it is right-lateralized for right-handers but its recruitment is more balanced between hemispheres for left-handers. These observations carry important theoretical and clinical implications for the aetiology of brain lateralization depending on the left- or right-handedness and the neuropsychological undertaking of prosopagnosic patients. [less ▲]

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See detailCharacterizing the face processing network in the human brain: a large-scale fMRI localizer study
Dricot, Laurence; Hanseeuw, Bernard; Schiltz, Christine UL et al

in Journal of Vision (2010), 10(7),

A whole network of brain areas showing larger response to faces than other visual stimuli has been identified in the human brain using fMRI (Sergent, 1992; Haxby, 2000). Most studies identify only a ... [more ▼]

A whole network of brain areas showing larger response to faces than other visual stimuli has been identified in the human brain using fMRI (Sergent, 1992; Haxby, 2000). Most studies identify only a subset of this network, by comparing the presentation of face pictures to all kinds of object categories mixed up (e.g., Kanwisher, 1997), or to scrambled faces (e.g., Ishaï, 2005), using different statistical thresholds. Given these differences of approaches, the (sub)cortical face network can be artificially overextended (Downing & Wiggett, 2008), or minimized in different studies, both at the local (size of regions) and global (number of regions) levels. Here we conducted an analysis of a large set of right-handed subjects (40), tested with a new whole-brain localizer to control for both high-level and low-level differences between faces and objects. Pictures of faces, cars and their phase-scrambled counterparts were used in a 2x2 block design. Group-level (random effect) and single subject (ROI) analyses were made. A conjunction of two contrasts (F-SF and F-C) identified 6 regions: FFA, OFA, amygdala, pSTS, AIT and thalamus. All these regions but the amygdala showed clear right lateralization. Interestingly, the FFA showed the least face-selective response among the cortical face network: it presented a significantly larger response to pictures of cars than scrambled cars [t=9.3, much more than amygdala (t=2.6), AIT (t=2.1) and other regions (NS)], and was also sensitive to low-level properties of faces [SF - SO; t=5.1; NS in other areas]. These observations suggest that, contrary to other areas of the network, including the OFA, the FFA is a region that may contain populations of neurons that are specific to faces intermixed with populations responding more generally to object categories. More generally, this study helps understanding the extent and specificity of the network of (sub)cortical areas particularly involved in face processing. [less ▲]

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See detailAttentional shifts due to irrelevant numerical cues: Behavioral investigation of a lateralized target discrimination paradigm
Schiltz, Christine UL; Dormal, Giulia; Martin, Romain UL et al

in Journal of Vision (2010), 10(7),

Behavioural evidence indicates the existence of a link between numerical representations and visuo-spatial processes. A striking demonstration of this link was provided by Fischer and colleagues (2003 ... [more ▼]

Behavioural evidence indicates the existence of a link between numerical representations and visuo-spatial processes. A striking demonstration of this link was provided by Fischer and colleagues (2003), who reported that participants detect a target more rapidly in the left hemifield, if it is preceded by a small number (e.g. 2 or 3) and more rapidly in the right hemifield if preceded by a large number (e.g. 8 or 9). This is strong evidence that numbers orient visuo-spatial attention to different visual hemifields (e.g., left and right) depending on their magnitude (e.g., small and large, respectively). Here, we sought to replicate number-related attentional shifts using a discrimination task. The participants (n=16) were presented 1 digit (1,2 vs. 8,9) at the centre of the screen for 400ms. After 500ms, 1000ms or 2000ms, a target was briefly flashed in either the right or left hemifield and participants had to report its colour (red or green). They were told that the central digit was irrelevant to the task. We hypothesized that the attentional shift induced by the centrally presented numbers should induce congruency effects for the target discrimination task, so that small (or large) numbers would facilitate the processing of left (or right) targets. Our results confirmed this prediction, but only for the shortest digit-target interval (500ms). This is supported by a significant interaction between number magnitude (small/large) and target hemifield (left/right). The link between numerical and spatial representations further predicts a positive relation between number magnitude and the difference in RT between left and right targets. Regression slopes were computed individually and a positive slope was obtained for short number-target interval. These findings indicate that the attentional shifts induced by irrelevant numerical material are independent of the exact nature of target processing (discrimination vs. detection). [less ▲]

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See detailHolistic perception of individual faces in the right middle fusiform gyrus as evidenced by the composite face illusion
Schiltz, Christine UL; Dricot, Laurence; Goebel, Rainer et al

in Journal of Vision (2010), 10(2), 1-16

The perception of a facial feature (e.g., the eyes) is influenced by the position and identity of other features (e.g., the mouth) supporting an integrated, or holistic, representation of individual faces ... [more ▼]

The perception of a facial feature (e.g., the eyes) is influenced by the position and identity of other features (e.g., the mouth) supporting an integrated, or holistic, representation of individual faces in the human brain. Here we used an event-related adaptation paradigm in functional magnetic resonance imaging (fMRI) to clarify the regions representing faces holistically across the whole brain. In each trial, observers performed the same/different task on top halves (aligned or misaligned) of two faces presented sequentially. For each face pair, the identity of top and bottom parts could be both identical, both different, or different only for the bottom half. The latter manipulation resulted in a composite face illusion, i.e., the erroneous perception of identical top parts as being different, only for aligned faces. Release from adaptation in this condition was found in two sub-areas of the right middle fusiform gyrus responding preferentially to faces, including the “fusiform face area” (“FFA”). There were no significant effects in homologous regions of the left hemisphere or in the inferior occipital cortex. Altogether, these observations indicate that face-sensitive populations of neurons in the right middle fusiform gyrus are optimally tuned to represent individual exemplars of faces holistically. [less ▲]

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See detailWhen small is left and large is right : Behavioural evidence for attentional shifts due to irrelevant numerical cues
Hoffmann, Danielle UL; Goffaux, Valérie; Schiltz, Christine UL

Poster (2010)

Numerous behavioural studies indicate the existence of a link between numerical representations and visuo-spatial processes (for review see DeHevia et al., 2008). A striking demonstration of this link was ... [more ▼]

Numerous behavioural studies indicate the existence of a link between numerical representations and visuo-spatial processes (for review see DeHevia et al., 2008). A striking demonstration of this link was provided by Fischer and colleagues (2003), who reported that participants detect a target faster in the left hemifield, if preceded by a small number (e.g. 2 or 3) and faster in the right hemifield if preceded by a large number (e.g. 8 or 9). This is strong evidence that numbers orient visuo-spatial attention to the left or right hemifield, depending on their magnitude (e.g., small and large, respectively) (see also Galfano et al., 2006; Ristic et al., 2006). We designed a modified version of this target detection paradigm, by replacing the detection task with a target discrimination task (cf. Hommel et al., 2001). The participants (n=16) were presented 1 task irrelevant digit (1,2 vs. 8,9) for 400ms. After a variable inter-stimulus interval (500, 1000 or 2000ms), they had to discriminate the colour of a brief (100ms) lateral target. We hypothesized that the centrally presented numbers would induce an orientation of attention, in the same direction as the initial observations by Fischer et al. (2003). The current results indicate a significant effect, but only for the shortest digit-target interval (500ms). We observed a significant interaction between number magnitude (small/large) and side of target presentation (left/right) (F1,15 =7.784, p<0.014). These findings indicate that the attentional shifts induced by irrelevant numerical material are independent of the exact nature of target processing (discrimination vs. detection). [less ▲]

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See detailIs the cerebral processing of categorical and coordinate spatial relations based on different or identical but differentially activated functional networks?
Martin, Romain UL; Schiltz, Christine UL

Scientific Conference (2009, September)

The fundamental hypothesis related to the distinction between categorical and coordinate processing has been that these two types of spatial relations coding are qualitatively different. Based on ... [more ▼]

The fundamental hypothesis related to the distinction between categorical and coordinate processing has been that these two types of spatial relations coding are qualitatively different. Based on Kosslyn’s initial hemispheric specialization theory, they also are hypothesized to rely on different functional networks in the brain which are supposed to have evolved in a way to take advantage of more fundamental hemispheric specializations in order to adapt these hemispheric strengths to the processing of the two different types of spatial relations. (...) [less ▲]

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See detailTemporal dynamics of face spatial frequency processing: An fmri masking experiment
Goffaux, Valerie; Peters, Judith; Schiltz, Christine UL et al

Poster (2009, May)

When processing a face stimulus, the human visual system tends to strongly integrate its constituent features (eyes, nose, mouth, etc) in a so-called holistic representation. Such feature integration ... [more ▼]

When processing a face stimulus, the human visual system tends to strongly integrate its constituent features (eyes, nose, mouth, etc) in a so-called holistic representation. Such feature integration mainly occurs in face-sensitive regions located in bilateral fusiform gyrii. Behavioural studies showed that feature integration relies on the extraction of low spatial frequencies (LSF) while high SF (HSF) underlie more local aspects of feature analysis. Following coarse-to-fine models of vision, we propose that the LSF-driven feature integration is an early and fast stage of face perception, in contrast to the longer-lasting extraction of detailed feature cues in HSF. By means of an event-related fMRI design, the present study investigated the temporal dynamics of face LSF and HSF processing in the network of face-sensitive cortical regions. Faces were flashed at 75, 150, or 300 msec, followed by a Gaussian mask. They were band-pass filtered to preserve low or high SF. At short stimulus durations, face-sensitive regions located in bilateral fusiform gyrii and superior temporal sulci responded more strongly to LSF than HSF faces. At longer durations, the same regions were more active for HSF than LSF faces. This pattern did not replicate for phase-scrambled versions of the stimuli. Taken together our findings suggest that face perception proceeds following a coarse-to-fine scenario, with an early and fast LSF-driven feature integration being relayed by the slower accumulation of HSF local information. [less ▲]

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See detailFace inversion disrupts the perception of vertical relations between features in the right human occipito-temporal cortex
Goffaux, Valerie; Rossion, Bruno; Sorger, Bettina et al

in Journal of Neuropsychology (2009), 3

The impact of inversion on the extraction of relational and featural face information was investigated in two fMRI experiments. Unlike previous studies, the contribution of horizontal and vertical spatial ... [more ▼]

The impact of inversion on the extraction of relational and featural face information was investigated in two fMRI experiments. Unlike previous studies, the contribution of horizontal and vertical spatial relations were considered separately since they have been shown to be differentially vulnerable to face inversion (Goffaux & Rossion, 2007). Hence, inversion largely affects the perception of vertical relations (e.g. eye or mouth height) while the processing of features (e.g. eye shape and surface) and of horizontal relations (e.g. inter-ocular distance) is affected to a far lesser extent. Participants viewed pairs of faces that differed either at the level of one local feature (i.e. the eyes) or of the spatial relations of this feature with adjacent features. Changes of spatial relations were divided into two conditions, depending on the vertical or horizontal axis of the modifications. These stimulus conditions were presented in separate blocks in the first (block) experiment while they were presented in a random order in the second event-related (ER) experiment. Face-preferring voxels located in the right-lateralized middle fusiform gyrus (rMFG) largely decreased their activity with inversion. Inversion-related decreases were more moderate in left-lateralized middle fusiform gyrus (lMFG). ER experiment revealed that inversion affected rMFG and lMFG activity in distinct stimulus conditions. Whereas inversion affected lMFG processing only in featural condition, inversion selectively affected the processing of vertical relations in rMFG. Correlation analyses further indicated that the inversion effect (IE) observed in rMFG and right inferior occipital gyrus (rIOG) reliably predicted the large behavioural IE observed for the processing of vertical relations. In contrast, lMFG IE correlated with the weak behavioural IE observed for the processing of horizontal relations. Our findings suggest that face configuration is mostly encoded in rMFG, whereas more local aspects of face information, such as features and horizontal spatial relations drive lMFG processing. These findings corroborate the view that the vulnerability of face perception to inversion stems mainly from the disrupted processing of vertical face relations in the right-lateralized network of face-preferring regions (rMFG, rIOG). [less ▲]

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See detailRelations between numerical and visuospatial competencies
Wantz, Marc UL; Reuter, Robert UL; Martin, Romain UL et al

Scientific Conference (2009)

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See detailGender and mathematical competencies!?
Wantz, Marc UL; Brunner, Martin UL; Martin, Romain UL et al

Scientific Conference (2008, September 04)

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See detailThe roles of "face" and "non-face" areas during individual face perception: Evidence by fmri adaptation in a brain-damaged prosopagnosic patient
Dricot, Laurence; Sorger, Bettina; Schiltz, Christine UL et al

in NeuroImage (2008), 40(1), 318-332

Two regions in the human occipito-temporal cortex respond preferentially to faces: 'the fusiform face area' ('FFA') and the 'occipital face area' ('OFA'). Whether these areas have a dominant or exclusive ... [more ▼]

Two regions in the human occipito-temporal cortex respond preferentially to faces: 'the fusiform face area' ('FFA') and the 'occipital face area' ('OFA'). Whether these areas have a dominant or exclusive role in face perception, or if sub-maximal responses in other visual areas such as the lateral occipital complex (LOC) are also involved, is currently debated. To shed light on this issue, we tested normal participants and PS, a well-known brain-damaged patient presenting a face-selective perception deficit (prosopagnosia) [Rossion, B., Caldara, R., Seghier, M., Schuller, A. M., Lazeyras, F., Mayer, E. (2003). A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing. Brain 126 2381-2395.], with functional magnetic resonance imaging (fMRI). Of particular interest, the right hemisphere lesion of the patient PS encompasses the 'OFA' but preserves the 'FFA' and LOC [Sorger, B., Goebel, R., Schiltz, C., Rossion, B. (2007). Understanding the functional neuroanatomy of acquired prosopagnosia. NeuroImage 35, 836-852.]. Using fMRI-adaptation, we found a dissociation between the coding of individual exemplars in the structurally intact 'FFA', which was impaired for faces but preserved for objects in the patient PS's brain. Most importantly, a larger response to different faces than repeated faces was found in the ventral part of the LOC both for normals and the patient, next to the right hemisphere lesion. Thus, following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited for compensatory or residual individual face perception. Overall, these observations indicate that several high-level visual areas in the human brain contribute to individual face perception. However, a subset of these areas in the right hemisphere, those responding preferentially to faces ('FFA' and 'OFA'), appear to be critical for this function. [less ▲]

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See detailGender and mathematical competencies!?
Wantz, Marc UL; Brunner, Martin; Martin, Romain UL et al

Scientific Conference (2008)

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See detailEvidence for individual face discrimination in non-face selective areas of the visual cortex in acquired prosopagnosia
Dricot, Laurence; Sorger, Bettina; Schiltz, Christine UL et al

in Behavioral Neurology (2008), 19(1-2), 75-79

Two areas in the human occipito-temporal cortex respond preferentially to faces: 'the fusiform face area' ('FFA') and the 'occipital face area' ('OFA'). However, it is unclear whether these areas have an ... [more ▼]

Two areas in the human occipito-temporal cortex respond preferentially to faces: 'the fusiform face area' ('FFA') and the 'occipital face area' ('OFA'). However, it is unclear whether these areas have an exclusive role in processing faces, or if sub-maximal responses in other visual areas such as the lateral occipital complex (LOC) are also involved. To clarify this issue, we tested a brain-damaged patient (PS) presenting a face-selective impairment with functional magnetic resonance imaging (fMRI). The right hemisphere lesion of the prosopagnosic patient encompasses the 'OFA' but preserves the 'FFA' and LOC. Using fMRI-adaptation, we found a larger response to different faces than repeated faces in the ventral part of the LOC both for normals and the patient, next to her right hemisphere lesion. This observation indicates that following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited to subtend residual perception of individual faces. [less ▲]

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See detailIs there continuity between categorical and coordinate spatial relations coding? Evidence from a grid/no-gridworking memory paradigm
Martin, Romain UL; Houssemand, Claude UL; Schiltz, Christine UL et al

in Neuropsychologia (2008), 46(2), 576-594

We ask the question whether the coding of categorical versus coordinate spatial relations depends on different neural networks showing hemispheric specialization or whether there is continuity between ... [more ▼]

We ask the question whether the coding of categorical versus coordinate spatial relations depends on different neural networks showing hemispheric specialization or whether there is continuity between these two coding types. The `continuous spatial coding' hypothesis would mean that the two coding types rely essentially on the same neural network consisting of more general-purpose processes, such as visuo-spatial attention, but with a different weighting of these general processes depending on exact task requirements. With event-related fMRI, we have studied right-handed male subjects performing a grid/no-grid visuo-spatial working memory task inducing categorical and coordinate spatial relations coding. Our data support the `continuous spatial coding' hypothesis, indicating that, while based on the same fronto-parieto-occipital neural network than categorical spatial relations coding, the coding of coordinate spatial relations relies more heavily on attentional and executive processes, which could induce hemispheric differences similar to those described in the literature. The results also show that visuo-spatial working memory consists of a short-term posterior store with a capacity of up to three elements in the parietal and extrastriate cortices. This store depends on the presence of a visible space categorization and thus can be used for the coding of categorical spatial relations. When no visible space categorization is given or when more than three elements have to be coded, additional attentional and executive processes are recruited, mainly located in the dorso-lateral prefrontal cortex. [less ▲]

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See detailThe spatio-temporal correlates of holistic face perception
Schiltz, Christine UL; Jacques, Corentin; Rossion, Bruno

Poster (2007, May)

It is well known that faces are perceived holistically: their parts are integrated into a global or so-called holistic individual representation. Here we clarify where and how early in time individual ... [more ▼]

It is well known that faces are perceived holistically: their parts are integrated into a global or so-called holistic individual representation. Here we clarify where and how early in time individual holistic representations are extracted from the visual stimulus, by means of an event-related identity adaptation paradigm in fMRI (study 1; 10 subjects) and ERPs (study 2; 16 subjects). During blocks, subjects were presented with trials made of two sequentially presented faces and performed a same/different judgement on the top parts of each pair of faces. Face parts were presented either aligned or misaligned. For each face pair, the identity of top and bottom parts could be (a) both identical, (b) both different, (c) different only for the bottom part. The latter manipulation resulted in a strong face composite illusion behaviourally, i.e. the perception of identical top parts as being different, only in the aligned format. In the face-sensitive area of the middle fusiform gyrus (‘fusiform face area’) we observed a stronger response to the top part perceived as being different (release from adaptation), but only when the top and the bottom parts were aligned. It is consistent with the illusion of viewing different top parts of faces, and this release from fMR-adaptation is similar to the one observed in the ‘different’ condition for both aligned and misaligned parts. The same observations were made in ERPs as early as 150 ms, the amplitude of the electrophysiological response at occipito-temporal sites to the second face stimulus being reduced for identical relative to different top face parts, and to identical top parts perceived as different (aligned - bottom different). With both methods, the effects were stronger in the right hemisphere. Altogether, these observations indicate that individual faces are perceived holistically as early as 150 ms in the occipito-temporal cortex. [less ▲]

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See detailInvestigation of featural versus configural processing of faces in the middle fusiform gyrus
Goffaux, Valerie; Sorger, Bettina; Schiltz, Christine UL et al

Poster (2007, May)

Inverting a face affects the processing of the vertical relations between features (e.g. eye height) more than the processing of horizontal relations (e.g. interocular distance) and of local features (e.g ... [more ▼]

Inverting a face affects the processing of the vertical relations between features (e.g. eye height) more than the processing of horizontal relations (e.g. interocular distance) and of local features (e.g. eye shape and surface). Inversion also decreases hemodynamic responses (HR) in face-sensitive regions in the middle fusiform gyrus (MFG), presumably because it reduces face distinctiveness and leads to larger adaptation. Here we tested the hypothesis that inversion affects the perception of vertical metric distances between features in the MFG. In the present fMRI study, twelve subjects were presented with short blocks of upright and inverted pairs composed either of identical faces (‘same’ condition), or of faces that differed at the level of ‘vertical’ relations, ‘horizontal’ relations, the shape of all inner feature (‘different’), or the shape of one single ‘feature’. In rMFG, smaller HR were observed for ‘same’ as compared to ‘different’ condition when faces were presented upright; due to HR adaptation. ‘Vertical’, ‘horizontal’ and ‘featural’ conditions led to HR close to ‘same’ condition. Inversion decreased HR in all conditions except the ‘same’ condition, thus replicating previous findings. The largest inversion-related decrements measured in rMFG were observed for vertical relations. In the left MFG, all conditions led to larger HR than the ‘same’ condition at upright. Inversion decreased HR in vertical and horizontal conditions only. These results suggest different roles of the MFG across hemispheres. rMFG may code ecological face differences, since release from adaptation was only observed for completely different faces in this region. Moreover, rMFG may be sensitive to face configuration as suggested by the generalised inversion-related HR decrease. In contrast, lMFG may code any kind of physical difference between faces irrespective of orientation, except for relational differences. [less ▲]

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See detailFmri evidence for multiple face processing pathways in the human brain
Dricot, Laurence; Schiltz, Christine UL; Sorger, Bettina et al

Poster (2007, May)

Two regions in the occipito-temporal cortex respond more strongly to faces than to objects and are thought to be important for face perception: ‘the fusiform face area’ (‘FFA’) and the ‘occipital face ... [more ▼]

Two regions in the occipito-temporal cortex respond more strongly to faces than to objects and are thought to be important for face perception: ‘the fusiform face area’ (‘FFA’) and the ‘occipital face area’ (‘OFA’). Whether these areas responding preferentially to faces play a dominant or exclusive role in face processing or if sub-maximal responses in other areas of the ventral stream such as the lateral occipital complex (LOC) are also involved is currently debated. To clarify this issue, we tested a brain-damaged patient presenting a face-selective deficit, prosopagnosia, with functional magnetic resonance imaging (fMRI). Using fMRI-adaptation, we found a dissociation between the coding of identity in the structurally intact ‘FFA’, which was impaired for faces but preserved for objects. This observation complements recent fMRI findings that the ‘FFA’ reflects averaging of heterogeneous highly selective neural populations for faces and objects, by showing here that the responses of these populations can be functionally independent. Most importantly, a larger response to different faces than repeated faces was found in the ventral part of the LOC both for normals and the patient, next to the right hemisphere lesion. Following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited to subtend residual individual face discrimination. Overall, these observations indicate that faces are processed through a network of visual areas in the human brain, with a subset of these areas responding preferentially to faces being critical for efficient face recognition. [less ▲]

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See detailUnderstanding the functional neuroanatomy of acquired prosopagnosia
Sorger, Bettina; Goebel, Rainer; Schiltz, Christine UL et al

in NeuroImage (2007), 35(2), 836-852

One of the most remarkable disorders following brain damage is prosopagnosia, the inability to recognize faces. While a number of cases of prosopagnosia have been described at the behavioral level, the ... [more ▼]

One of the most remarkable disorders following brain damage is prosopagnosia, the inability to recognize faces. While a number of cases of prosopagnosia have been described at the behavioral level, the functional neuroanatomy of this face recognition impairment, and thus the brain regions critically involved in normal face recognition, has never been specified in great detail. Here, we used anatomical and functional magnetic resonance imaging (fMRI) to present the detailed functional neuroanatomy of a single case of acquired prosopagnosia (PS; Rossion, B., Caldara, R., Seghier, M., Schuller, A.-M., Lazeyras, F., Mayer, E., 2003a. A network of occipito-temporal face-sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing. Brain 126, 2381-95; Rossion, B., Joyce, C.A., Cottrell, G.W., Tarr, M.J., 2003b. Early lateralization and orientation tuning for face, word, and object processing in the visual cortex. Neuroimage 20, 1609-24) with normal object recognition. First, we clarify the exact anatomical location and extent of PS' lesions in relation to (a) retinotopic cortex, (b) face-preferring regions, and (c) other classical visual regions. PS' main lesion - most likely causing her prosopagnosia - is localized in the posterior part of the right ventral occipitotemporal cortex. This lesion causes a left superior paracentral scotoma, as frequently observed in cases of prosopagnosia. While the borders of the early visual areas in the left hemisphere could be delineated well, the extensive posterior right-sided lesion hampered a full specification of the cortical representation of the left visual field. Using multiple scanning runs, face-preferring activation was detected within the right middle fusiform gyrus (MFG) in the so-called 'fusiform face area' ('FFA'), but also in the left inferior occipital gyrus (left 'OFA'), and in the right posterior superior temporal sulcus (STS). The dorsal part of the lateral occipital complex (LOC) and the human middle temporal cortex (hMT+/V5) were localized bilaterally. The color-preferring region V4/V8 was localized only in the left hemisphere. In the right hemisphere, the posterior lesion spared the ventral part of LOC, a region that may be critical for the preserved object recognition abilities of the patient, and the restriction of her deficit to the category of faces. The presumptive functions of both structurally damaged and preserved regions are discussed and new hypotheses regarding the impaired and preserved abilities of the patient during face and non-face object processing are derived. Fine-grained neurofunctional analyses of brain-damaged single cases with isolated recognition deficits may considerably improve our knowledge of the brain regions critically involved in specific visual functions, such as face recognition. [less ▲]

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See detailVisuelle Wahrnehmung und arithmetische Kompetenzen
Wantz, Marc UL; Martin, Romain UL; Schiltz, Christine UL

in Motorik (2007), 4

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