Scene segmentation in early visual cortex during suppression of ventral stream regions

Grassi, Palazzo; Zaretskaya, Natalia; Bartels, Andreas

doi:10.1016/j.neuroimage.2016.11.024

Cited by 14 publications

(26 citation statements)

References 67 publications

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“…Moreover, we observed an increase of activity in the remaining visual field in all visual areas. We therefore found evidence for a within-area enhancement-suppression mechanism mediating the perception of figure and ground, as previously established in macaques (Chen et al, 2014; Gilad et al, 2013; Gilad & Slovin, 2015; Lamme, 1995; Poort et al, 2012, 2016) and humans (Grassi et al, 2017; Kok & de Lange, 2014; Likova & Tyler, 2008).…”

Section: Discussionsupporting

confidence: 84%

“…Surprisingly, however, all these findings are at odds with recent evidence showing a decrease of brain activity in the background and stimulus region of another bistable global-local stimulus along with an increase in the center and inferred contour region for global vs local perception (Grassi et al, 2017). Unlike our diamond stimulus, this bistable stimulus triggers a local percept of four individually rotating disk pairs or a global percept of two floating squares circling around the stimulus center.…”

Section: Discussioncontrasting

confidence: 70%

“…When we directly compared the diamond to the no-diamond percept, our search-light analysis indicated a large-scale suppression of activity in V1 along with tendentially less extensive suppressive effects in V2 and V3. This global dampening effect speaks against the idea of a within-area response amplitude mechanism labelling different portions of the diamond display distinctively to mediate global object perception (Chen et al, 2014; Gilad et al, 2013; Gilad & Slovin, 2015; Grassi et al, 2017; Kok & de Lange, 2014; Lamme, 1995; Likova & Tyler, 2008; Poort et al, 2012, 2016). Critically, however, it echoes prior reports of retinotopically-unspecific deactivation during the diamond vs no-diamond percept and an attenuation of these effects in V2/V3 (De-Wit et al, 2012).…”

Section: Discussionmentioning

confidence: 87%

“…Although this hypothesis argues against hierarchical predictive coding models (e.g., Mumford, 1992; Murray et al, 2004; Rao & Ballard, 1999) because there should be no activity modulations in the peripheral background region (Figure 1, E. and F.), it is compatible with the more general idea of a within-area response amplitude mechanism labeling different parts of a visual scene distinctively (e.g., Gilad et al, 2013; Kok & de Lange, 2014; Lamme, 1995). Interestingly, such a response pattern has recently been observed for another dynamic bistable global-local stimulus (Grassi et al, 2017).…”

Section: Introductionmentioning

confidence: 73%

“…This idea is in line with findings of reduced activity in lower visual cortex for coherent vs incoherent motion (Braddick et al, 2001; Costagli et al, 2014; Harrison et al, 2007; McKeefry et al, 1997; Schindler & Bartels, 2017), although no or opposite effects have also occasionally been observed (Braddick et al, 2001; Rees et al, 2000). However, unlike these studies on motion coherence, we did not compare coherent to random motion nor did Grassi et al (2017). Rather, all our stimuli always comprised coherent motion, but were either perceived as ungrouped and moving out-of-phase (local) or grouped and moving in-phase (global).…”

Section: Discussionmentioning

confidence: 99%

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Topographic Signatures of Global Object Perception in Human Visual Cortex

Stoll

Finlayson

Schwarzkopf

2019

Preprint

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Our visual system readily groups dynamic fragmented input into global objects. How the brain represents such perceptual grouping remains however unclear. To address this question, we recorded brain responses using functional magnetic resonance imaging whilst observers perceived a dynamic bistable stimulus that could either be perceived globally (i.e., as a grouped and coherently moving shape) or locally (i.e., as ungrouped and incoherently moving elements). We further estimated population receptive fields and used these to back-project the brain activity during stimulus perception into visual space via a searchlight procedure. Global perception resulted in non-topographic suppression of responses in lower visual cortex accompanied by wide-spread enhancement in higher object-sensitive cortex. However, follow-up experiments indicated that higher object-sensitive cortex is suppressed if global perception lacks shape grouping, and that grouping-related suppression can be diffusely confined to stimulated sites once stimulus size is reduced. These results speak against a rigid between-area response amplitude code acting as a generic grouping mechanism and point to a within-area response amplitude code mediating the perception of figure and ground.

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Section: Discussionsupporting

confidence: 84%

Section: Discussioncontrasting

confidence: 70%

Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

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Topographic Signatures of Global Object Perception in Human Visual Cortex

Stoll

Finlayson

Schwarzkopf

2019

Preprint

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Separated and overlapping neural coding of face and body identity

Foster

Zhao

Bolkart

et al. 2021

Human Brain Mapping

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Recognising a person's identity often relies on face and body information, and is tolerant to changes in low‐level visual input (e.g., viewpoint changes). Previous studies have suggested that face identity is disentangled from low‐level visual input in the anterior face‐responsive regions. It remains unclear which regions disentangle body identity from variations in viewpoint, and whether face and body identity are encoded separately or combined into a coherent person identity representation. We trained participants to recognise three identities, and then recorded their brain activity using fMRI while they viewed face and body images of these three identities from different viewpoints. Participants' task was to respond to either the stimulus identity or viewpoint. We found consistent decoding of body identity across viewpoint in the fusiform body area, right anterior temporal cortex, middle frontal gyrus and right insula. This finding demonstrates a similar function of fusiform and anterior temporal cortex for bodies as has previously been shown for faces, suggesting these regions may play a general role in extracting high‐level identity information. Moreover, we could decode identity across fMRI activity evoked by faces and bodies in the early visual cortex, right inferior occipital cortex, right parahippocampal cortex and right superior parietal cortex, revealing a distributed network that encodes person identity abstractly. Lastly, identity decoding was consistently better when participants attended to identity, indicating that attention to identity enhances its neural representation. These results offer new insights into how the brain develops an abstract neural coding of person identity, shared by faces and bodies.

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Non‐stimulated regions in early visual cortex encode the contents of conscious visual perception

Kemenade

Wilbertz

Müller

et al. 2021

Human Brain Mapping

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Predictions shape our perception. The theory of predictive processing poses that our brains make sense of incoming sensory input by generating predictions, which are sent back from higher to lower levels of the processing hierarchy. These predictions are based on our internal model of the world and enable inferences about the hidden causes of the sensory input data. It has been proposed that conscious perception corresponds to the currently most probable internal model of the world. Accordingly, predictions influencing conscious perception should be fed back from higher to lower levels of the processing hierarchy. Here, we used functional magnetic resonance imaging and multivoxel pattern analysis to show that non-stimulated regions of early visual areas contain information about the conscious perception of an ambiguous visual stimulus. These results indicate that early sensory cortices in the human brain receive predictive feedback signals that reflect the current contents of conscious perception.

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Scene segmentation in early visual cortex during suppression of ventral stream regions

Cited by 14 publications

References 67 publications

Topographic Signatures of Global Object Perception in Human Visual Cortex

Topographic Signatures of Global Object Perception in Human Visual Cortex

Separated and overlapping neural coding of face and body identity

Non‐stimulated regions in early visual cortex encode the contents of conscious visual perception

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