The Role of the Occipital Cortex in Resolving Perceptual Ambiguity

Grassi, Palazzo; Schauer, Georg; Dwarakanath, A

doi:10.1523/jneurosci.2402-16.2016

Cited by 4 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As anticipated, increasing ambiguity was related to a network of brain regions typically associated with salience processing and the explicit resolution of ambiguity: bilateral anterior insula, sensory-motor/dorsal anterior cingulate cortex, and inferior frontal regions [49,50] (table 1 and figure 2). Furthermore, increasing ambiguity was associated with greater activity in the occipital cortex, a region that is also implicated in the resolution of perceptual ambiguity [51], and greater activity in the right fusiform gyrus, which is typically associated with configural face encoding [52][53][54]. No regions showed significant associations with increasing Black prototypicality at our whole-brain thresholds (see electronic supplementary material, table S1 for neural activity in response to decreasing ambiguity and increasing White prototypicality).…”

Section: (B) Conservatism Tracked Neural Sensitivity To Ambiguitymentioning

confidence: 85%

The neural basis of ideological differences in race categorization

Krosch

Jost

Bavel

2021

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

Multiracial individuals are often categorized as members of their ‘socially subordinate’ racial group—a form of social discrimination termed hypodescent—with political conservatives more likely than liberals to show this bias. Although hypodescent has been linked to racial hierarchy preservation motives, it remains unclear how political ideology influences categorization: Do conservatives and liberals see, feel or think about mixed-race faces differently? Do they differ in sensitivity to Black prototypicality (i.e. skin tone darkness and Afrocentric features) or racial ambiguity (i.e. categorization difficulty) of Black/White mixed-race faces? To help answer these questions, we collected a politically diverse sample of White participants and had them categorize mixed-race faces as Black or White during functional neuroimaging. We found that conservatism was related to greater anterior insula activity to racially ambiguous faces, and this pattern of brain activation mediated conservatives' use of hypodescent. This demonstrates that conservatives' greater sensitivity to racial ambiguity (rather than Black prototypicality) gives rise to greater categorization of mixed-race individuals into the socially subordinate group and tentatively suggests that conservatives may differ from liberals in their affective reactions to mixed-race faces. Implications for the study of race categorization and political psychology are discussed. This article is part of the theme issue ‘The political brain: neurocognitive and computational mechanisms'.

show abstract

Section: (B) Conservatism Tracked Neural Sensitivity To Ambiguitymentioning

confidence: 85%

The neural basis of ideological differences in race categorization

Krosch

Jost

Bavel

2021

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

show abstract

“…As our results cast doubt on prior cTBS studies, also the functional fractionation between IPS and pSPL (from Kanai et al 2010 and will have to be reexamined, as it is based on relatively weak cTBS evidence from small samples. Also, a single pulse TMS-EEG study revealed no systematic difference between IPS and SPL stimulation in neither behaviour nor evoked EEG signal (Schauer et al, 2016), and our prior online 2-Hz TMS study did not reveal any effect during SPL stimulation, while revealing a lengthening of percept durations when disrupting IPS (Zaretskaya et al, 2010). As shown in Table 1, the key inconsistency among non-cTBS studies remains between the lowest-powered study that did not include a vertex control and Zaretskaya et al (2010).…”

Section: Synthesis and Conclusionmentioning

confidence: 76%

“…Electrophysiological measurements on frontal areas of macaques reveal robust responses that correlate with and precede perceptual switches, even independent of behavioural responses (Panagiotaropoulos et al, 2012;Kapoor et al, 2022;Dwarakanath et al, 2023). And, although similar transient responses exist in posterior sensory cortices (de Jong et al, 2016), new evidence suggests that these could be the results from feedback from anterior higher-level non-sensory areas (Grassi et al, 2016;de Jong et al, 2020).…”

Section: Evidence For a Causal Parietal Involvement In Multistabilitymentioning

confidence: 93%

Parietal theta burst TMS does not modulate bistable perception

Schauer,

Grassi,

Gharabaghi

et al. 2023

Preprint

View full text Add to dashboard Cite

The role of the parietal cortex in perceptual awareness and in resolving perceptual ambiguity is unsettled. Early influential TMS studies have revealed differences in conscious perception following parietal stimulation, fuelling the notion that parietal cortex causally contributes to resolving perceptual ambiguity. However, central to this conclusion is the reliability of the method employed. Several prior studies have revealed opposing effects, such as shortening, lengthening, or no effect on multistable perceptual transitions following parietal stimulation. Here we addressed the reliability of continuous theta-burst stimulation (cTBS) on parietal cortex on the perception of bistable stimuli. We conducted three cTBS experiments that were matched to prior experiments in terms of stimuli, stimulation protocol, and target site, and used a higher number of participants. None of our cTBS experiments replicated prior cTBS results. The only experiment using individual functional localizers led to weak effects, while the two others led to null results. Individual variability of motor cortex cTBS did not predict parietal cTBS effects. In view of recent reports of highly variable cTBS effects over motor cortex, our results suggest that cTBS is particularly unreliable in modulating bistable perception when applied over parietal cortex.

show abstract

“…And, although similar transient responses exist in posterior sensory cortices ( de Jong et al. 2016 ), new evidence suggests that these could be the results from feedback from anterior higher-level non-sensory areas ( Grassi et al. 2016a , de Jong et al.…”

Section: Discussionmentioning

confidence: 98%

Parietal theta burst TMS does not modulate bistable perception

Schauer,

Grassi,

Gharabaghi

et al. 2024

Neuroscience of Consciousness

Self Cite

View full text Add to dashboard Cite

The role of the parietal cortex in perceptual awareness and in resolving perceptual ambiguity is unsettled. Early influential transcranial magnetic stimulation studies have revealed differences in conscious perception following parietal stimulation, fuelling the notion that parietal cortex causally contributes to resolving perceptual ambiguity. However, central to this conclusion is the reliability of the method employed. Several prior studies have revealed opposing effects, such as shortening, lengthening, or no effect on multistable perceptual transitions following parietal stimulation. Here we addressed the reliability of continuous theta-burst stimulation (cTBS) on parietal cortex on the perception of bistable stimuli. We conducted three cTBS experiments that were matched to prior experiments in terms of stimuli, stimulation protocol, and target site, and used a higher number of participants. None of our cTBS experiments replicated prior cTBS results. The only experiment using individual functional localizers led to weak effects, while the two others led to null results. Individual variability of motor cortex cTBS did not predict parietal cTBS effects. In view of recent reports of highly variable cTBS effects over motor cortex, our results suggest that cTBS is particularly unreliable in modulating bistable perception when applied over parietal cortex.

show abstract

The Role of the Occipital Cortex in Resolving Perceptual Ambiguity

Cited by 4 publications

References 12 publications

The neural basis of ideological differences in race categorization

The neural basis of ideological differences in race categorization

Parietal theta burst TMS does not modulate bistable perception

Parietal theta burst TMS does not modulate bistable perception

Contact Info

Product

Resources

About