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Juha Silvanto - One of the best experts on this subject based on the ideXlab platform.
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Different neural representations for detection of symmetry in dot-patterns and in Faces: A state-dependent TMS study.
Neuropsychologia, 2020Co-Authors: Zaira Cattaneo, Silvia Bona, Juha SilvantoAbstract:The Occipital Face Area (OFA) has been shown to code the presence of symmetry in Faces and in vertically symmetric dot patterns. However, it is not clear whether symmetry processing of Face and non-Face stimuli involve overlapping neural mechanisms in OFA. This was assessed using state-dependent TMS by employing a priming paradigm. Specifically, we examined whether prior presentation of low-level symmetry affects the impact of TMS on discrimination of symmetry in subsequently presented Faces - indicating that the same neural mechanisms encode symmetry in both Face and non-Face stimuli. Participants performed a symmetry discrimination task on a series of Faces, each of which was preceded by either a vertically symmetric, a horizontally symmetric or a non-symmetric dot configuration (prime) while receiving stimulation over either the right OFA, the right Lateral Occipital Cortex (rLO) or over a control site (Vertex). Vertically symmetric dot patterns primed symmetry discrimination in Faces. The key finding was that the priming effect was not affected by TMS applied over OFA; stimulation of this site (but not of rLO) impaired the discrimination of facial symmetry regardless of prime type. Overall, these results suggest that distinct neural representations in OFA are involved in symmetry detection in Face and non-Face stimuli.
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TMS over right OFA affects individuation of Faces but not of exemplars of objects
Neuropsychologia, 2018Co-Authors: Silvia Bona, Juha Silvanto, Zaira CattaneoAbstract:In addition to its well-documented role in processing of Faces, the Occipital Face Area in the right hemisphere (rOFA) may also play a role in identifying specific individuals within a class of objects. Here we explored this issue by using fMRI-guided TMS. In a first experiment, participants had to judge whether two sequentially presented images of Faces or objects represented exactly the same exemplar or two different exemplars of the same class, while receiving online TMS over either the rOFA, the right lateral Occipital cortex (rLO) or the Vertex (control). We found that, relative to Vertex, stimulation of rOFA impaired individuation of Faces only, with no effect on objects; in contrast, TMS over rLO reduced individuation of objects but not of Faces. In a second control experiment participants judged whether a picture representing a fragment of a stimulus belonged or not to the subsequently presented image of a whole stimulus (part-whole matching task). Our results showed that rOFA stimulation selectively disrupted performance with Faces, whereas performance with objects (but not with Faces) was selectively affected by TMS over rLO. Overall, our findings suggest that rOFA does not contribute to discriminate between exemplars of non-Face objects.
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Not all visual symmetry is equal: Partially distinct neural bases for vertical and horizontal symmetry.
Neuropsychologia, 2017Co-Authors: Zaira Cattaneo, Silvia Bona, Juha SilvantoAbstract:Visual mirror symmetry plays an important role in visual perception in both human and animal vision; its importance is reflected in the fact that it can be extracted automatically during early stages of visual processing. However, how this extraction is implemented at the cortical level remains an open question. Given the importance of symmetry in visual perception, one possibility is that there is a network which extracts all types of symmetry irrespective of axis of orientation; alternatively, symmetry along different axes might be encoded by different brain regions, implying that there is no single neural mechanism for symmetry processing. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to compare the neural basis of the two main types of symmetry found in the natural world, vertical and horizontal symmetry. TMS was applied over either right Lateral Occipital Cortex (LO), right Occipital Face Area (OFA) or Vertex while participants were asked to detect symmetry in low-level dot configurations. Whereas detection of vertical symmetry was impaired by TMS over both LO and OFA, detection of horizontal symmetry was delayed by stimulation of LO only. Thus, different types of visual symmetry rely on partially distinct cortical networks.
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the causal role of the Occipital Face Area ofa and lateral Occipital lo cortex in symmetry perception
The Journal of Neuroscience, 2015Co-Authors: Silvia Bona, Juha Silvanto, Zaira CattaneoAbstract:Symmetry is an important cue in Face and object perception. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to shed light on the role of the Occipital Face Area (OFA), a key region in Face processing, and the lateral Occipital (LO) cortex, a key Area in object processing, in symmetry detection. In the first experiment, we applied TMS over the rightOFA, its left homolog (leftOFA), rightLO, and vertex (baseline) while participants were discriminating between symmetric and asymmetric dot patterns. Stimulation of rightOFA and rightLO impaired performance, causally implicating these two regions in detection of symmetry in low-level dot configurations. TMS over rightLO but not rightOFA also significantly impaired detection of nonsymmetric shapes defined by collinear Gabor patches, demonstrating that rightOFA responds to symmetry but not to all cues mediating figure-ground segregation. The second experiment showed a causal role for rightOFA but not rightLO in facial symmetry detection. Overall, our results demonstrate that both the rightOFA and rightLO are sensitive to symmetry in dot patterns, whereas only rightOFA is causally involved in facial symmetry detection.
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Investigating object representations during change detection in human extrastriate cortex.
The European journal of neuroscience, 2010Co-Authors: D. Samuel Schwarzkopf, Sharon Gilaie-dotan, Juha Silvanto, G. ReesAbstract:Detecting a change in a visual stimulus is particularly difficult when it is accompanied by a visual disruption such as a saccade or flicker. In order to say whether a stimulus has changed across such a disruption, some neural trace must persist. Here we investigated whether two different regions of the human extrastriate visual cortex contain neuronal populations encoding such a trace. Participants viewed a stimulus that included various objects and a short blank period (flicker) made it difficult to distinguish whether an object in the stimulus had changed or not. By applying transcranial magnetic stimulation (TMS) during the visual disruption we show that the lateral Occipital (LO) cortex, but not the Occipital Face Area, contains a sustained representation of a visual stimulus. TMS over LO improved the sensitivity and response bias for detecting changes by selectively reducing false alarms. We suggest that TMS enhanced the initial object representation and thus boosted neural events associated with object repetition. Our findings show that neuronal signals in the human LO cortex carry a sustained neural trace that is necessary for detecting the repetition of a stimulus.
Zaira Cattaneo - One of the best experts on this subject based on the ideXlab platform.
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Different neural representations for detection of symmetry in dot-patterns and in Faces: A state-dependent TMS study.
Neuropsychologia, 2020Co-Authors: Zaira Cattaneo, Silvia Bona, Juha SilvantoAbstract:The Occipital Face Area (OFA) has been shown to code the presence of symmetry in Faces and in vertically symmetric dot patterns. However, it is not clear whether symmetry processing of Face and non-Face stimuli involve overlapping neural mechanisms in OFA. This was assessed using state-dependent TMS by employing a priming paradigm. Specifically, we examined whether prior presentation of low-level symmetry affects the impact of TMS on discrimination of symmetry in subsequently presented Faces - indicating that the same neural mechanisms encode symmetry in both Face and non-Face stimuli. Participants performed a symmetry discrimination task on a series of Faces, each of which was preceded by either a vertically symmetric, a horizontally symmetric or a non-symmetric dot configuration (prime) while receiving stimulation over either the right OFA, the right Lateral Occipital Cortex (rLO) or over a control site (Vertex). Vertically symmetric dot patterns primed symmetry discrimination in Faces. The key finding was that the priming effect was not affected by TMS applied over OFA; stimulation of this site (but not of rLO) impaired the discrimination of facial symmetry regardless of prime type. Overall, these results suggest that distinct neural representations in OFA are involved in symmetry detection in Face and non-Face stimuli.
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TMS over right OFA affects individuation of Faces but not of exemplars of objects
Neuropsychologia, 2018Co-Authors: Silvia Bona, Juha Silvanto, Zaira CattaneoAbstract:In addition to its well-documented role in processing of Faces, the Occipital Face Area in the right hemisphere (rOFA) may also play a role in identifying specific individuals within a class of objects. Here we explored this issue by using fMRI-guided TMS. In a first experiment, participants had to judge whether two sequentially presented images of Faces or objects represented exactly the same exemplar or two different exemplars of the same class, while receiving online TMS over either the rOFA, the right lateral Occipital cortex (rLO) or the Vertex (control). We found that, relative to Vertex, stimulation of rOFA impaired individuation of Faces only, with no effect on objects; in contrast, TMS over rLO reduced individuation of objects but not of Faces. In a second control experiment participants judged whether a picture representing a fragment of a stimulus belonged or not to the subsequently presented image of a whole stimulus (part-whole matching task). Our results showed that rOFA stimulation selectively disrupted performance with Faces, whereas performance with objects (but not with Faces) was selectively affected by TMS over rLO. Overall, our findings suggest that rOFA does not contribute to discriminate between exemplars of non-Face objects.
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Not all visual symmetry is equal: Partially distinct neural bases for vertical and horizontal symmetry.
Neuropsychologia, 2017Co-Authors: Zaira Cattaneo, Silvia Bona, Juha SilvantoAbstract:Visual mirror symmetry plays an important role in visual perception in both human and animal vision; its importance is reflected in the fact that it can be extracted automatically during early stages of visual processing. However, how this extraction is implemented at the cortical level remains an open question. Given the importance of symmetry in visual perception, one possibility is that there is a network which extracts all types of symmetry irrespective of axis of orientation; alternatively, symmetry along different axes might be encoded by different brain regions, implying that there is no single neural mechanism for symmetry processing. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to compare the neural basis of the two main types of symmetry found in the natural world, vertical and horizontal symmetry. TMS was applied over either right Lateral Occipital Cortex (LO), right Occipital Face Area (OFA) or Vertex while participants were asked to detect symmetry in low-level dot configurations. Whereas detection of vertical symmetry was impaired by TMS over both LO and OFA, detection of horizontal symmetry was delayed by stimulation of LO only. Thus, different types of visual symmetry rely on partially distinct cortical networks.
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the role of the Occipital Face Area in holistic processing involved in Face detection and discrimination a tdcs study
Neuropsychology (journal), 2015Co-Authors: Chiara Renzi, Chiara Ferrari, Susanna Schiavi, Alberto Pisoni, Costanza Papagno, Tomaso Vecchi, Andrea Antal, Zaira CattaneoAbstract:Objective: The aim of this study was to examine the role of Occipital Face Area (OFA) in mediating observers’ tendency to perceive Faces as “wholes” (holistic processing) both when detecting and discriminating Faces. To investigate this issue, we modulated OFA activity using transcranial direct current stimulation (tDCS). Method: In Experiment 1, participants performed a Face detection task (the Mooney Faces task) and a Face discrimination task (the Composite Faces task), which both assess holistic Face processing. In Experiment 2, participants were asked to detect both Mooney Faces and Mooney objects, to test Face selectivity of OFA. In each experimental session, the tasks were presented once before (pre) and once after (post) administration of 20 min of excitability increasing anodal tDCS (real) and sham stimulation over the putative OFA. Results: Compared with sham stimulation, we found that real anodal tDCS interfered with both Mooney Faces and objects detection, whereas it had no effect on holistic processing involved in Face discrimination, as measured by the Composite Faces task. Conclusions: Our results suggest that OFA is causally implicated in facial detection at least in degraded conditions (i.e., when the “Face” signal needs to be extracted from a noisy background). In turn, our data do not implicate OFA in holistic processing in Face discrimination. Finally, our data suggest a possible role of OFA in categorization of other nonFace stimuli, a conclusion that must be taken with caution, as stimulation over OFA may affect object-selective adjacent regions.
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the causal role of the Occipital Face Area ofa and lateral Occipital lo cortex in symmetry perception
The Journal of Neuroscience, 2015Co-Authors: Silvia Bona, Juha Silvanto, Zaira CattaneoAbstract:Symmetry is an important cue in Face and object perception. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to shed light on the role of the Occipital Face Area (OFA), a key region in Face processing, and the lateral Occipital (LO) cortex, a key Area in object processing, in symmetry detection. In the first experiment, we applied TMS over the rightOFA, its left homolog (leftOFA), rightLO, and vertex (baseline) while participants were discriminating between symmetric and asymmetric dot patterns. Stimulation of rightOFA and rightLO impaired performance, causally implicating these two regions in detection of symmetry in low-level dot configurations. TMS over rightLO but not rightOFA also significantly impaired detection of nonsymmetric shapes defined by collinear Gabor patches, demonstrating that rightOFA responds to symmetry but not to all cues mediating figure-ground segregation. The second experiment showed a causal role for rightOFA but not rightLO in facial symmetry detection. Overall, our results demonstrate that both the rightOFA and rightLO are sensitive to symmetry in dot patterns, whereas only rightOFA is causally involved in facial symmetry detection.
David Pitcher - One of the best experts on this subject based on the ideXlab platform.
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The Human Posterior Superior Temporal Sulcus Samples Visual Space Differently From Other Face-Selective Regions.
Cerebral cortex (New York N.Y. : 1991), 2019Co-Authors: David Pitcher, Amy Pilkington, Lionel Rauth, Chris I. Baker, Dwight J. Kravitz, Leslie G. UngerleiderAbstract:Neuroimaging studies show that ventral Face-selective regions, including the fusiform Face Area (FFA) and Occipital Face Area (OFA), preferentially respond to Faces presented in the contralateral visual field (VF). In the current study we measured the VF response of the Face-selective posterior superior temporal sulcus (pSTS). Across 3 functional magnetic resonance imaging experiments, participants viewed Face videos presented in different parts of the VF. Consistent with prior results, we observed a contralateral VF bias in bilateral FFA, right OFA (rOFA), and bilateral human motion-selective Area MT+. Intriguingly, this contralateral VF bias was absent in the bilateral pSTS. We then delivered transcranial magnetic stimulation (TMS) over right pSTS (rpSTS) and rOFA, while participants matched facial expressions in both hemifields. TMS delivered over the rpSTS disrupted performance in both hemifields, but TMS delivered over the rOFA disrupted performance in the contralateral hemifield only. These converging results demonstrate that the contralateral bias for Faces observed in ventral Face-selective Areas is absent in the pSTS. This difference in VF response is consistent with Face processing models proposing 2 functionally distinct pathways. It further suggests that these models should account for differences in interhemispheric connections between the Face-selective Areas across these 2 pathways.
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A functional dissociation of Face-, body- and scene-selective brain Areas based on their response to moving and static stimuli.
Scientific reports, 2019Co-Authors: David Pitcher, Geena Ianni, Leslie G. UngerleiderAbstract:The human brain contains Areas that respond selectively to Faces, bodies and scenes. Neuroimaging studies have shown that a subset of these Areas preferentially respond more to moving than static stimuli, but the reasons for this functional dissociation remain unclear. In the present study, we simultaneously mapped the responses to motion in Face-, body- and scene-selective Areas in the right hemisphere using moving and static stimuli. Participants (N = 22) were scanned using functional magnetic resonance imaging (fMRI) while viewing videos containing bodies, Faces, objects, scenes or scrambled objects, and static pictures from the beginning, middle and end of each video. Results demonstrated that lateral Areas, including Face-selective Areas in the posterior and anterior superior temporal sulcus (STS), the extrastriate body Area (EBA) and the Occipital place Area (OPA) responded more to moving than static stimuli. By contrast, there was no difference between the response to moving and static stimuli in ventral and medial category-selective Areas, including the fusiform Face Area (FFA), Occipital Face Area (OFA), amygdala, fusiform body Area (FBA), retrosplenial complex (RSC) and parahippocampal place Area (PPA). This functional dissociation between lateral and ventral/medial brain Areas that respond selectively to different visual categories suggests that Face-, body- and scene-selective networks may be functionally organized along a common dimension.
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Transient disruption in the Face perception network: combining TMS and fMRI.
Journal of Vision, 2015Co-Authors: David PitcherAbstract:Abstract Faces contain structural information, for identifying individuals, as well as changeable information, that can convey emotion and direct attention. Neuroimaging studies reveal brain regions that exhibit preferential responses to invariant or changeable facial aspects but the functional connections between these regions are unknown. This issue was addressed by causally disrupting two Face-selective regions with thetaburst transcranial magnetic stimulation (TBS) and measuring the effects of this disruption in local and remote Face-selective regions with functional magnetic resonance imaging (fMRI). Participants were scanned, over two sessions, while viewing dynamic or static Faces and objects. During these sessions, TBS was delivered over the right Occipital Face Area (rOFA) or right posterior superior temporal sulcus (rpSTS). Disruption of the rOFA reduced the neural response to both static and dynamic Faces in the downstream Face-selective region in the fusiform gyrus. In contrast, the response to dynamic and static Faces was doubly dissociated in the rpSTS. Namely, disruption of the rOFA reduced the response to static but not dynamic Faces, while disruption of the rpSTS itself, reduced the response to dynamic but not static Faces. These results suggest that dynamic and static facial aspects are processed via dissociable cortical pathways that begin in early visual cortex, a conclusion inconsistent with current models of Face perception.
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Facial expression recognition takes longer in the posterior superior temporal sulcus than in the Occipital Face Area.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 2014Co-Authors: David PitcherAbstract:Neuroimaging studies have identified a Face-selective region in the right posterior superior temporal sulcus (rpSTS) that responds more strongly during facial expression recognition tasks than during facial identity recognition tasks, but precisely when the rpSTS begins to causally contribute to expression recognition is unclear. The present study addressed this issue using transcranial magnetic stimulation (TMS). In Experiment 1, repetitive TMS delivered over the rpSTS of human participants, at a frequency of 10 Hz for 500 ms, selectively impaired a facial expression task but had no effect on a matched facial identity task. In Experiment 2, participants performed the expression task only while double-pulse TMS (dTMS) was delivered over the rpSTS or over the right Occipital Face Area (rOFA), a Face-selective region in lateral Occipital cortex, at different latencies up to 210 ms after stimulus onset. Task performance was selectively impaired when dTMS was delivered over the rpSTS at 60-100 ms and 100-140 ms. dTMS delivered over the rOFA impaired task performance at 60-100 ms only. These results demonstrate that the rpSTS causally contributes to expression recognition and that it does so over a longer time-scale than the rOFA. This difference in the length of the TMS induced impairment between the rpSTS and the rOFA suggests that the neural computations that contribute to facial expression recognition in each region are functionally distinct.
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Stimulation of Category-Selective Brain Areas Modulates ERP to Their Preferred Categories
Current biology : CB, 2011Co-Authors: Boaz Sadeh, David Pitcher, Talia Brandman, Ami Eisen, Avner Thaler, Galit YovelAbstract:Neural selectivity to specific object categories has been demonstrated in extrastriate cortex with both functional MRI [1-3] and event-related potential (ERP) [4, 5]. Here we tested for a causal relationship between the activation of category-selective Areas and ERP to their preferred categories. Electroencephalogram (EEG) was recorded while participants observed Faces and headless bodies. Concurrently with EEG recording, we delivered two pulses of transcranial magnetic stimulation (TMS) over the right Occipital Face Area (OFA) or extrastriate body Area (EBA) at 60 and 100 ms after stimulus onset. Results showed a clear dissociation between the stimulated site and the stimulus category on ERP modulation: stimulation of the OFA significantly increased the N1 amplitude to Faces but not to bodies, whereas stimulation of the EBA significantly increased the N1 amplitude to bodies but not to Faces. These findings provide the first evidence for a specific and causal link between activity in category-selective networks and scalp-recorded ERP to their preferred categories. This result also demonstrates that the Face and body N1 reflects several nonoverlapping neural sources, rather than changes in Face-selective mechanisms alone. Lastly, because early stimulation (60-100 ms) affected selectivity of a later ERP component (150-200 ms), the results could imply a feed-forward connection between Occipital and temporal category-selective Areas.
Gyula Kovács - One of the best experts on this subject based on the ideXlab platform.
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Inhibition of the Occipital Face Area modulates the electrophysiological signals of Face familiarity positively: a combined cTBS-EEG study
2020Co-Authors: Charlotta Marina Eick, Géza Gergely Ambrus, Gyula KovácsAbstract:The Occipital Face Area (OFA) is hierarchically one of the first stages of the Face processing network. It has originally been thought to be involved in early, structural processing steps, but currently more and more studies challenge this view and propose that it also takes part in higher Face processing, such as identification and recognition. Here we tested whether the OFA is involved in the initial steps of recognition memory and plays a causal role in the differential processing of familiar and unfamiliar Faces. We used an offline, inhibitory continuous theta-burst stimulation (cTBS) protocol over the right OFA and the vertex as control site. An electroencephalographic (EEG) recording of event-related potentials (ERPs), elicited by visually presented familiar (famous) and unfamiliar Faces was performed before and after stimulation. We observed a difference in ERPs for famous and unfamiliar Faces in a time-window corresponding to the N250 component. Importantly, this difference was significantly increased by cTBS of the right OFA, suggesting its causal role in the differential processing of familiar and unfamiliar Faces. The enhancement occurred focally, at electrodes close to the right hemispheric cTBS site, as well as over similar occipito-temporal sites of the contralateral hemisphere. To the best of our knowledge, this is the first study showing the causal role of the rOFA in the differential processing of familiar and unfamiliar Faces, using combined cTBS and EEG recording methods. These results are discussed with respect to the nature of familiar Face representations, supported by an extensive, bilateral network.
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The Occipital Face Area is causally involved in identity-related visual-semantic associations
Brain Structure and Function, 2020Co-Authors: Charlotta Marina Eick, Gyula Kovács, Sophie-marie Rostalski, Lisa Röhrig, Géza Gergely AmbrusAbstract:Faces are processed in a network of Areas within regions of the ventral visual stream. However, familiar Faces typically are characterized by additional associated information, such as episodic memories or semantic biographical information as well. The acquisition of such non-sensory, identity-specific knowledge plays a crucial role in our ability to recognize and identify someone we know. The Occipital Face Area (OFA), an early part of the core Face-processing network, is recently found to be involved in the formation of identity-specific memory traces but it is currently unclear if this role is limited to unimodal visual information. The current experiments used transcranial magnetic stimulation (TMS) to test whether the OFA is involved in the association of a Face with identity-specific semantic information, such as the name or job title of a person. We applied an identity-learning task where unfamiliar Faces were presented together with a name and a job title in the first encoding phase. Simultaneously, TMS pulses were applied either to the left or right OFA or to Cz, as a control. In the subsequent retrieval phase, the previously seen Faces were presented either with two names or with two job titles and the task of the participants was to select the semantic information previously learned. We found that the stimulation of the right or left OFA reduced subsequent retrieval performance for the Face-associated job titles. This suggests a causal role of the OFA in the association of Faces and related semantic information. Furthermore, in contrast to prior findings, we did not observe hemispherical differences of the TMS intervention, suggesting a similar role of the left and right OFAs in the formation of the visual-semantic associations. Our results suggest the necessity to reconsider the hierarchical Face-perception models and support the distributed and recurrent models.
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TMS of the Occipital Face Area modulates cross-domain identity priming
Brain Structure and Function, 2019Co-Authors: Géza Gergely Ambrus, Catarina Amado, Laura Krohn, Gyula KovácsAbstract:Accumulating evidence suggests that besides its function in early facial feature processing, the role of the right Occipital Face Area (rOFA) extends to higher level, image-independent processing. Recent studies hint at the possibility that the activity of this region can be modulated by semantic information as well. To test whether the OFA is sensitive to semantic information in a functionally relevant way, we implemented a cross-domain, name-Face priming paradigm combined with state-dependent transcranial magnetic stimulation, whereby stimulation preferentially facilitates the processing of attributes encoded by less active neural populations. Our volunteers performed a familiarity decision task for target Face images preceded by primes that were either the name of the same identity (congruent), a name of a different person (incongruent), or the character string ‘XXXXX’ (no prime). Stimulating the rOFA at target stimulus onset, we observed the disappearance of the behavioral disadvantage of incongruent primes, compared to the vertex control condition. Performance in the congruent and no prime conditions remained intact. This result suggests the existence of neural populations in the rOFA that take part in the semantic processing of identity, probably in interplay with other nodes in the extended Face network.
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The relationship between repetition suppression and Face perception
Brain Imaging and Behavior, 2017Co-Authors: Petra Hermann, Gyula Kovács, Mareike Grotheer, Zoltán VidnyánszkyAbstract:Repetition of identical Face stimuli leads to fMRI response attenuation (fMRI adaptation, fMRIa) in the core Face-selective occipito-temporal visual cortical network, involving the bilateral fusiform Face Area (FFA) and the Occipital Face Area (OFA). However, the functional relevance of fMRIa observed in these regions is unclear as of today. Therefore, here we aimed at investigating the relationship between fMRIa and Face perception ability by measuring in the same human participants both the repetition-induced reduction of fMRI responses and identity discrimination performance outside the scanner for upright and inverted Face stimuli. In the correlation analysis, the behavioral and fMRI results for the inverted Faces were used as covariates to control for the individual differences in overall object perception ability and basic visual feature adaptation processes, respectively. The results revealed a significant positive correlation between the participants’ identity discrimination performance and the strength of fMRIa in the core Face processing network, but not in the extrastriate body Area (EBA). Furthermore, we found a strong correlation of the fMRIa between OFA and FFA and also between OFA and EBA, but not between FFA and EBA. These findings suggest that there is a Face-selective component of the repetition-induced reduction of fMRI responses within the core Face processing network, which reflects functionally relevant adaptation processes involved in Face identity perception.
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The Occipital Face Area is causally involved in the formation of identity-specific Face representations.
Brain structure & function, 2017Co-Authors: Géza Gergely Ambrus, Maria Dotzer, Stefan R. Schweinberger, Gyula KovácsAbstract:Transcranial magnetic stimulation (TMS) and neuroimaging studies suggest a role of the right Occipital Face Area (rOFA) in early facial feature processing. However, the degree to which rOFA is necessary for the encoding of facial identity has been less clear. Here we used a state-dependent TMS paradigm, where stimulation preferentially facilitates attributes encoded by less active neural populations, to investigate the role of the rOFA in Face perception and specifically in image-independent identity processing. Participants performed a familiarity decision task for famous and unknown target Faces, preceded by brief (200 ms) or longer (3500 ms) exposures to primes which were either an image of a different identity (DiffID), another image of the same identity (SameID), the same image (SameIMG), or a Fourier-randomized noise pattern (NOISE) while either the rOFA or the vertex as control was stimulated by single-pulse TMS. Strikingly, TMS to the rOFA eliminated the advantage of SameID over DiffID condition, thereby disrupting identity-specific priming, while leaving image-specific priming (better performance for SameIMG vs. SameID) unaffected. Our results suggest that the role of rOFA is not limited to low-level feature processing, and emphasize its role in image-independent facial identity processing and the formation of identity-specific memory traces.
Jennifer K. E. Steeves - One of the best experts on this subject based on the ideXlab platform.
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Early monocular enucleation selectively disrupts neural development of Face perception in the Occipital Face Area.
Experimental eye research, 2018Co-Authors: Krista R. Kelly, Brenda L. Gallie, Jennifer K. E. SteevesAbstract:Retinoblastoma generally occurs before 5 years of age and often requires enucleation (surgical removal of one eye) of the cancerous eye. We have previously shown using behavioural methods that this disruption in binocular vision during the critical period of visual development results in impaired Face perception. In this case series study, we sought to determine the underlying neural correlates of this Face perception deficit by examining brain activity in regions of cortex that preferentially respond to visual images of Faces and places in 6 adults who had one eye enucleated early in life due to retinoblastoma. A group of 10 binocularly-intact adult controls were recruited for comparison. Functional magnetic resonance imaging (fMRI) was conducted over two separate runs for each participant in one scanning session. Each run consisted of 6 blocks each of Face, place, and object images. Region-of-interest analyses were conducted to locate Face-preferential [fusiform Face Area (FFA), Occipital Face Area (OFA)] and place-preferential [parahippocampal place Area (PPA), transverse Occipital sulcus (TOS)] regions-of-interest. Descriptive statistics are reported. Results. Enucleated adults exhibited reduced functional activation in Face-preferential regions (left FFA, right OFA, left OFA), but similar activation within the Face-preferential right FFA and the place-preferential regions (bilateral PPA and TOS). Conclusions. These results indicate that early monocular enucleation prevents robust development of late-maturing Face processing capabilities and that this disruption is specific to Face networks and not to networks supporting other visual image categories.
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Consecutive TMS-fMRI reveals remote effects of neural noise to the "Occipital Face Area".
Brain research, 2016Co-Authors: Lily M. Solomon-harris, Sara A. Rafique, Jennifer K. E. SteevesAbstract:The human cortical system for Face perception comprises a network of connected regions including the middle fusiform gyrus ("fusiform Face Area" or FFA), the inferior Occipital gyrus ("Occipital Face Area" or OFA), and the posterior superior temporal sulcus (pSTS). Here, we sought to investigate how transcranial magnetic stimulation (TMS) to the OFA affects activity within the Face processing network. We used offline repetitive TMS to temporarily introduce neural noise in the right OFA in healthy subjects. We then immediately performed functional magnetic resonance imaging (fMRI) to measure changes in blood oxygenation level dependent (BOLD) signal across the Face network using an fMR-adaptation (fMR-A) paradigm. We hypothesized that TMS to the right OFA would induce abnormal Face identity coding throughout the Face processing network in regions to which it has direct or indirect connections. Indeed, BOLD signal for Face identity, but not non-Face (butterfly) identity, decreased in the right OFA and FFA following TMS to the right OFA compared to both sham TMS and TMS to a control site, the nearby object-related lateral Occipital Area (LO). Further, TMS to the right OFA decreased Face-related activation in the left FFA, without any effect in the left OFA. Our findings indicate that TMS to the right OFA selectively disrupts Face coding at both the stimulation site and bilateral FFA. TMS to the right OFA also decreased BOLD signal for different identity stimuli in the right pSTS. Together with mounting evidence from patient studies, we demonstrate connectivity of the OFA within the Face network and that its activity modulates Face processing in bilateral FFA as well as the right pSTS. Moreover, this study shows that deep regions within the Face network can be remotely probed by stimulating structures closer to the cortical surFace.
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TMS to the “Occipital Face Area” affects recognition but not categorization of Faces
Brain and cognition, 2013Co-Authors: Lily M. Solomon-harris, Caitlin Mullin, Jennifer K. E. SteevesAbstract:The human cortical system for Face perception is comprised of a network of connected regions including the middle fusiform gyrus ("fusiform Face Area" or FFA), the inferior Occipital cortex ("Occipital Face Area" or OFA), and the superior temporal sulcus. The traditional hierarchical feedforward model of visual processing suggests information flows from early visual cortex to the OFA for initial Face feature analysis to higher order regions including the FFA for identity recognition. However, patient data suggest an alternative model. Patients with acquired prosopagnosia, an inability to visually recognize Faces, have been documented with lesions to the OFA but who nevertheless show Face-selective activation in the FFA. Moreover, their ability to categorize Faces remains intact. This suggests that the FFA is not solely responsible for Face recognition and the network is not strictly hierarchical, but may be organized in a reverse hierarchical fashion. We used transcranial magnetic stimulation (TMS) to temporarily disrupt processing in the OFA in neurologically-intact individuals and found participants' ability to categorize intact versus scrambled Faces was unaffected, however Face identity discrimination was significantly impaired. This suggests that Face categorization but not recognition can occur without the "earlier" OFA being online and indicates that "lower level" Face category processing may be assumed by other intact Face network regions such as the FFA. These results are consistent with the patient data and support a non-hierarchical, global-to-local model with re-entrant connections between the OFA and other Face processing Areas.
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The fusiform Face Area is not sufficient for Face recognition: Evidence from a patient with dense prosopagnosia and no Occipital Face Area
Neuropsychologia, 2005Co-Authors: Jennifer K. E. Steeves, Bradley Duchaine, Jody C. Culham, Cristiana Cavina Pratesi, Kenneth F. Valyear, I. Schindler, G. Keith Humphrey, A. David Milner, Melvyn A GoodaleAbstract:We tested functional activation for Faces in patient D.F., who following acquired brain damage has a profound deficit in object recognition based on form (visual form agnosia) and also prosopagnosia that is undocumented to date. Functional imaging demonstrated that like our control observers, D.F. shows significantly more activation when passively viewing Face compared to scene images in an Area that is consistent with the fusiform Face Area (FFA) (p < 0.01). Control observers also show Occipital Face Area (OFA) activation; however, whereas D.F.'s lesions appear to overlap the OFA bilaterally. We asked, given that D.F. shows FFA activation for Faces, to what extent is she able to recognize Faces? D.F. demonstrated a severe impairment in higher level Face processing--she could not recognize Face identity, gender or emotional expression. In contrast, she performed relatively normally on many Face categorization tasks. D.F. can differentiate Faces from non-Faces given sufficient texture information and processing time, and she can do this is independent of color and illumination information. D.F. can use configural information for categorizing Faces when they are presented in an upright but not a sideways orientation and given that she also cannot discriminate half-Faces she may rely on a spatially symmetric feature arrangement. Faces appear to be a unique category, which she can classify even when she has no advance knowledge that she will be shown Face images. Together, these imaging and behavioral data support the importance of the integrity of a complex network of regions for Face identification, including more than just the FFA--in particular the OFA, a region believed to be associated with low-level processing.
