Revealing the neural networks that extract conceptual gestalts from continuously evolving or changing semantic contexts

Branzi, Francesca M.; Humphreys, Gina F.; Hoffman, Paul; Ralph, Matthew A. Lambon

doi:10.1101/666370

Cited by 12 publications

(41 citation statements)

References 98 publications

(169 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, in our experiment, integration unfolded over time, with semantic decisions occurring roughly 2 s after the presentation of the cue. A recent study by Branzi and others (2019) suggests that ventral AG supports the integration of meanings during time-extended narratives (see also Bonnici et al., 2016 ; Ramanan et al., 2017 ). Future research should establish whether semantic integration that emerges over time leads to a different pattern of activation along the principal gradient compared with the integration of simultaneously-presented information.…”

Section: Discussionmentioning

confidence: 98%

The role of default mode network in semantic cue integration

et al. 2020

View full text Add to dashboard Cite

Recent accounts of large-scale cortical organisation suggest that the default mode network (DMN) is positioned at the top of a principal gradient, reflecting the separation between heteromodal and unimodal sensory-motor regions in patterns of connectivity and in geodesic distance along the cortical surface (Margulies et al., 2016). This isolation of DMN from external inputs might allow the integration of disparate sources of information that can constrain subsequent cognition. We tested this hypothesis by manipulating the degree to which semantic decisions for ambiguous words (e.g. jam ) were constrained by preceding visual cues depicting relevant spatial contexts (e.g. supermarket or road ) and/or facial emotions (e.g. happy vs. frustrated ). We contrasted (i) the effects of a single preceding cue with a no-cue condition employing scrambled images, and (ii) convergent spatial and emotion cues with single cues. Single cues elicited stronger activation in the multiple demand network relative to no cues, consistent with the requirement to maintain information in working memory. The availability of two convergent cues elicited stronger activation within DMN regions (bilateral angular gyrus, middle temporal gyrus, medial prefrontal cortex, and posterior cingulate), even though behavioural performance was unchanged by cueing – consequently task difficulty is unlikely to account for the observed differences in brain activation. A regions-of-interest analysis along the unimodal-to-heteromodal principal gradient revealed maximal activation for the convergent cue condition at the heteromodal end, corresponding to the DMN. Our findings are consistent with the view that regions of DMN support states of information integration that constrain ongoing cognition and provide a framework for understanding the location of these effects at the heteromodal end of the principal gradient.

show abstract

Section: Discussionmentioning

confidence: 98%

The role of default mode network in semantic cue integration

et al. 2020

View full text Add to dashboard Cite

show abstract

“…In contrast the anterior vLPC (PGa) showed structural connectivity with temporal lobe language processing areas (5,30,31). Indeed, the same region has been shown to be positively engaged by tasks that involve sentence-level processing (1,35,36). Whereas, the posterior vLPC (posterior PGp) connected with the occipital lobe and medial parietal areas associated with visual attention (2,34), and this same region has been shown to be positively engaged by a picture-sequence task (35).…”

Section: Summary Of Main Resultsmentioning

confidence: 99%

The convergence and divergence of episodic and semantic functions across lateral parietal cortex

Humphreys

Jung

Ralph

2020

Preprint

Self Cite

View full text Add to dashboard Cite

Several decades of neuropsychological and neuroimaging research have highlighted the importance of lateral parietal cortex (LPC) across a myriad of cognitive domains. Yet, despite the prominence of this region the underlying function of LPC remains unclear. Two domains that have placed particular emphasis on LPC involvement are semantic memory and episodic memory retrieval. From each domain, sophisticated models have been proposed as to the underlying function, as well as the more domain-general that LPC is engaged by any form of internally-directed cognition (episodic and semantic retrieval both being examples if this process). Here we directly address these alternatives using a combination of fMRI and DTI white-matter connectivity data. The results show that ventral LPC (angular gyrus) was positively engaged during episodic retrieval but disengaged during semantic memory retrieval. In addition, the level of activity negatively varied with task difficulty in the semantic task whereas episodic activation was independent of difficulty. In contrast, dorsal LPC (intraparietal sulcus) showed domain general activation that was positively correlated with task difficulty. In terms of structural connectivity, a dorsal-ventral and anterior-posterior gradient of connectivity was found to different processing networks (e.g., mid-angular gyrus (AG) connected with episodic retrieval). We propose a unifying model in which LPC as a whole might share a common underlying function (e.g., multimodal buffering) and variations across subregions arise due to differences in the underlying white matter connectivity.

show abstract

“…pMTG shows increased engagement for processing verbs relative to nouns and is also involved in the neural representation of tools and actions (Bedny et al, 2008;Caspers et al, 2010;Peelen et al, 2012;Ishibashi et al, 2016). AG, in addition, has been implicated in the processing of meaningful stimuli that are extended in time, such as sentences, narratives and action sequences (Humphries et al, 2006;Lerner et al, 2011;Humphreys and Lambon Ralph, 2017;Branzi et al, 2020). This has led to claims that this region is essential for combinatorial semantic processes, in which individual word meanings are integrated into a coherent global representation (Humphries et al, 2006;Bemis and Pylkkänen, 2012;Price et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Stimulus-independent neural coding of event semantics: Evidence from cross-sentence fMRI decoding

Asyraff

Lemarchand

Tamm

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Multivariate neuroimaging studies indicate that the brain represents word and object concepts in a format that readily generalises across stimuli. Here we investigated whether this was true for neural representations of events described using sentences. Participants viewed sentences describing four events in different ways. Multivariate classifiers were trained to discriminate the four events using a subset of sentences, allowing us to test generalisation to novel sentences. We found that neural patterns in a left-lateralised network of frontal, temporal and parietal regions discriminated events in a way that generalised successfully over changes in the syntactic and lexical properties of the sentences used to describe them. In contrast, decoding in visual areas was sentence-specific and failed to generalise to novel sentences. In the reverse analysis, we tested for decoding of syntactic and lexical form, independent of the event being described. Regions displaying this coding were limited and largely fell outside the canonical semantic network. Our results indicate that a distributed neural network represents the meaning of event sentences in a way that is robust to changes in their structure and form. They suggest that the semantic system disregards the surface properties of stimuli in order to represent their underlying conceptual significance.

show abstract

Revealing the neural networks that extract conceptual gestalts from continuously evolving or changing semantic contexts

Cited by 12 publications

References 98 publications

The role of default mode network in semantic cue integration

The role of default mode network in semantic cue integration

The convergence and divergence of episodic and semantic functions across lateral parietal cortex

Stimulus-independent neural coding of event semantics: Evidence from cross-sentence fMRI decoding

Contact Info

Product

Resources

About