Class Information Predicts Activation by Object Fragments in Human Object Areas

Lerner, Yulia; Epshtein, Boris; Ullman, Shimon; Malach, Rafael

doi:10.1162/jocn.2008.20082

Cited by 41 publications

(43 citation statements)

References 44 publications

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“…the basic representational elements are entire faces or at least large and complex object fragments. However, certainly at various stages of these representations, local image elements, such as informative “fragments”, also play an important role (Lerner et al, 2008). Similarly, recent evidence from single unit recordings in monkeys point to important contributions of certain face feature parameters such as iris size to the neuronal activation (Freiwald et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Perceptual shape sensitivity to upright and inverted faces is reflected in neuronal adaptation

2010

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Using an fMR-adaptation paradigm for different face morphing levels we have recently demonstrated a narrow neuronal tuning to faces even at the sub-exemplar level which was tightly related to perceptual discrimination (Gilaie-Dotan and Malach, 2007). However, it is unclear whether this relationship is unique to faces or is a general property of object representations including unfamiliar objects, and whether the adaptation tuning is due to physical changes in the stimulus or to changes in perceptual discrimination. Here we compared the same face-morph paradigm for upright and inverted faces, thus modulating familiarity and perceptual discrimination effects while equating all low-level features. We found, as expected, a perceptual “inversion effect”, i.e. a significant reduction in inverted face discrimination. Importantly, the fMR-adaptation tuning in the fusiform face area (FFA) changed in accordance with the different perceptual sensitivity both for upright and inverted faces. Additional object selective regions displayed differential tuning widths to the two categories. Our results are compatible with a model by which the ability of human observers to discriminate objects depends on the shape tuning properties of individual neurons.

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Section: Discussionmentioning

confidence: 99%

Perceptual shape sensitivity to upright and inverted faces is reflected in neuronal adaptation

2010

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“…The optimal solution would enable representation of both object category (largest component of variance) and object identity. Such a solution might be implemented by feature selectivity at the columnar level (Tanaka, 1996) which is tuned to those object features that are most informative for discriminating categories as well as exemplars (Sigala and Logothetis, 2002;Ullman et al, 2002;Lerner et al, 2008), while untangling category and exemplar distinctions from accidental properties in multivariate space (DiCarlo and Cox, 2007).…”

Section: In What Sense Is the Representation Categorical? And In Whatmentioning

confidence: 99%

Categorical, Yet Graded - Single-Image Activation Profiles of Human Category-Selective Cortical Regions

Mur

Ruff²,

Bodurka³

et al. 2012

Journal of Neuroscience

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Human inferior temporal cortex contains category-selective visual regions, including the fusiform face area (FFA) and the parahippocampal place area (PPA). These regions are defined by their greater category-average activation to the preferred category (faces and places, respectively) relative to nonpreferred categories. The approach of investigating category-average activation has left unclear to what extent category selectivity holds for individual object images. Here we investigate single-image activation profiles to address (1) whether each image from the preferred category elicits greater activation than any image outside the preferred category (categorical ranking), (2) whether there are activation differences within and outside the preferred category (gradedness), and (3) whether the activation profile falls off continuously across the category boundary or exhibits a discontinuity at the boundary (category step). We used functional magnetic resonance imaging to measure the activation elicited in the FFA and PPA by each of 96 object images from a wide range of categories, including faces and places, but also humans and animals, and natural and manmade objects. Results suggest that responses in FFA and PPA exhibit almost perfect categorical ranking, are graded within and outside the preferred category, and exhibit a category step. The gradedness within the preferred category was more pronounced in FFA; the category step was more pronounced in PPA. These findings support the idea that these regions have category-specific functions, but are also consistent with a distributed object representation emphasizing categories while still distinguishing individual images.

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“…Although some studies have implied that the involvement of OFA in face representation is limited to processing of facial features (Liu et al, 2009), or their spatial configuration (Rotshtein et al, 2007; Rhodes et al, 2009), others have suggested the involvement of OFA in higher levels of facial processing (Chen et al, 2007) including its necessity for facial recognition, as patients with a lesion overlap in the right OFA exhibit face recognition deficits (Rossion et al, 2003; Steeves et al, 2006, 2009). Thus, the face-related activation in the OFA region may arise from the processing of low-level face or shape features that face images contain (Lerner et al, 2008; Dakin and Watt, 2009; Liu et al, 2009), or alternatively, this region may contain neuronal representations that encode face identity (independently of low-level features).…”

Section: Introductionmentioning

confidence: 99%

“…The LO region (Malach et al, 1995; Grill-Spector et al, 1998a; Lerner et al, 2001) served as a control site since it is non-selectively activated by objects and faces (Avidan et al, 2002b; Fang et al, 2007; Gilaie-Dotan et al, 2008, 2010; Lerner et al, 2008). Furthermore it is in the vicinity of OFA yet functionally separable from OFA as has been previously shown in TMS studies (Pitcher et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Investigating representations of facial identity in human ventral visual cortex with transcranial magnetic stimulation

Gilaie-Dotan

Silvanto

Schwarzkopf

et al. 2010

Front. Hum. Neurosci.

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The occipital face area (OFA) is face-selective. This enhanced activation to faces could reflect either generic face and shape-related processing or high-level conceptual processing of identity. Here we examined these two possibilities using a state-dependent transcranial magnetic stimulation (TMS) paradigm. The lateral occipital (LO) cortex which is activated non-selectively by various types of objects served as a control site. We localized OFA and LO on a per-participant basis using functional MRI. We then examined whether TMS applied to either of these regions affected the ability of participants to decide whether two successively presented and physically different face images were of the same famous person or different famous people. TMS was applied during the delay between first and second face presentations to investigate whether neuronal populations in these regions played a causal role in mediating the behavioral effects of identity repetition. Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different. Surprisingly, TMS applied over LO (but not OFA) modulated overall RTs, compared to the No-TMS condition. But critically, we found no effects of TMS to either area that were modulated by identity repetition. Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing. Instead, these brain regions may be involved in the processing of more generic features of their preferred stimulus categories.

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Class Information Predicts Activation by Object Fragments in Human Object Areas

Cited by 41 publications

References 44 publications

Perceptual shape sensitivity to upright and inverted faces is reflected in neuronal adaptation

Perceptual shape sensitivity to upright and inverted faces is reflected in neuronal adaptation

Categorical, Yet Graded - Single-Image Activation Profiles of Human Category-Selective Cortical Regions

Investigating representations of facial identity in human ventral visual cortex with transcranial magnetic stimulation

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