Similarity of fMRI Activity Patterns in Left Perirhinal Cortex Reflects Semantic Similarity between Words

Bruffaerts, Rose; Dupont, Patrick; Peeters, Ronald; Deyne, Simon De; Storms, Gerrit; Vandenberghe, Rik

doi:10.1523/jneurosci.1548-13.2013

Cited by 115 publications

(139 citation statements)

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“…Although we found clear evidence for a semantic code within the left TP, other neighboring regions have also been found to contain semantic-like representations, particularly the anterior ventral temporal cortex (23,25). We suggest that these differing locations are likely a result of the level of semantic abstraction, as the set of studies with results located in anterior ventral temporal cortex all used highly concrete stimuli (either concrete words, or direct use of pictures).…”

Section: Discussionmentioning

confidence: 46%

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Semantic representations in the temporal pole predict false memories

Chadwick

Anjum

Kumaran

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Recent advances in neuroscience have given us unprecedented insight into the neural mechanisms of false memory, showing that artificial memories can be inserted into the memory cells of the hippocampus in a way that is indistinguishable from true memories. However, this alone is not enough to explain how false memories can arise naturally in the course of our daily lives. Cognitive psychology has demonstrated that many instances of false memory, both in the laboratory and the real world, can be attributed to semantic interference. Whereas previous studies have found that a diverse set of regions show some involvement in semantic false memory, none have revealed the nature of the semantic representations underpinning the phenomenon. Here we use fMRI with representational similarity analysis to search for a neural code consistent with semantic false memory. We find clear evidence that false memories emerge from a similarity-based neural code in the temporal pole, a region that has been called the "semantic hub" of the brain. We further show that each individual has a partially unique semantic code within the temporal pole, and this unique code can predict idiosyncratic patterns of memory errors. Finally, we show that the same neural code can also predict variation in true-memory performance, consistent with an adaptive perspective on false memory. Taken together, our findings reveal the underlying structure of neural representations of semantic knowledge, and how this semantic structure can both enhance and distort our memories.false memory | semantic | temporal pole | fMRI | pattern similarity E ach of us has a vast store of semantic knowledge that we apply to incoming sensory data to extract meaning from the world around us. Semantic representations are capable of capturing important structural features of the world at many different levels of abstraction, which allows for rapid and flexible responses to a diverse array of environmental challenges. This preexisting knowledge structure guides ongoing cognition, which usually aids performance, but under some circumstances can lead us into error (1-3). A striking example is the widely studied DRM (Deese, Roediger, and McDermott) false-memory illusion (4, 5). In a typical DRM task, subjects are asked to memorize a set of words such as "snow," "winter," "ice," and "warm." After a delay, subjects will typically falsely remember having seen the semantically related word "cold." It is widely agreed that this memory illusion is driven by the semantic relatedness between words contained in the encoding list (e.g., "snow") and falsely remembered words that were not actually presented (e.g., "cold"). As such, it is thought that each list item automatically, but weakly, activates the semantically related concept (Fig. 1A). This activation leads to memory confusion, either through a cumulative priming of the related lure (5, 6) or the encoding of the semantic overlap as a "gist" memory (3), resulting in a false memory unless the error is detected by some internal monitoring p...

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Section: Discussionmentioning

confidence: 46%

“…This method is therefore wellsuited for assessing neural overlap between semantic representations (23)(24)(25), as the degree of overlap should be directly reflected in the representational similarity. We used this approach to measure the degree of neural overlap between each set of DRM words and their related lure word (Fig.…”

Section: Resultsmentioning

confidence: 99%

Semantic representations in the temporal pole predict false memories

Chadwick

Anjum

Kumaran

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…For written words, semantic similarity between concrete animate entities is reflected by the cosine similarity between fMRI response patterns in perirhinal cortex (Bruffaerts et al, 2013b). The semantic similarity effect in perirhinal cortex was subsequently confirmed by Clarke and Tyler (2014) during overt naming of pictures of animate and inanimate items.…”

Section: Introductionmentioning

confidence: 91%

“…An ever increasing number of studies have succeeded in detecting patterns of brain activity that reflect the identity or the semantic category of pictures (Haxby et al, 2001;Hanson et al, 2004;Shinkareva et al, 2008;Connolly et al, 2012;Mur et al, 2012;Bruffaerts et al, 2013a), written words Just et al, 2010), written words and pictures (Shinkareva et al, 2011;Simanova et al, 2012;Bruffaerts et al, 2013b;Devereux et al, 2013;Fairhall and Caramazza, 2013), written and spoken words (Akama et al, 2012;Simanova et al, 2012) as well as natural sounds (Simanova et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…Left perirhinal cortex is one of the regions that has come out of a number of MVPA studies of this kind in a relatively consistent manner (Bruffaerts et al, 2013b;Fairhall and Caramazza, 2013;Clarke and Tyler, 2014;Mur, 2014). For written words, semantic similarity between concrete animate entities is reflected by the cosine similarity between fMRI response patterns in perirhinal cortex (Bruffaerts et al, 2013b).…”

Section: Introductionmentioning

confidence: 99%

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Left perirhinal cortex codes for similarity in meaning between written words: Comparison with auditory word input

et al. 2015

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This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Neuropsychologia following peer review. The definitive publisher-authenticated version (Liuzzi A.G., Bruffaerts R., Dupont P., Adamczuk K., Peeters R., De Deyne S., Storms G., Vandenberghe R. AbstractLeft perirhinal cortex has been previously implicated in associative coding. According to a recent experiment, the similarity of perirhinal fMRI response patterns to written concrete words is higher for words which are more similar in their meaning. If left perirhinal cortex functions as an amodal semantic hub, one would predict that this semantic similarity effect would extend to the spoken modality. We conducted an event-related fMRI experiment and evaluated whether a same semantic similarity effect could be obtained for spoken as for written words. Twenty healthy subjects performed a property verification task in either the written or the spoken modality. Words corresponded to concrete animate entities for which extensive feature generation was available from more than 1000 subjects. From these feature generation data, a concept-feature matrix was derived which formed the basis of a cosine similarity matrix between the entities reflecting their similarity in meaning (called the "semantic cossimilarity matrix"). Independently, we calculated a cosine similarity matrix between the left perirhinal fMRI activity patterns evoked by the words (called the "fMRI cossimilarity matrix"). Next, the similarity was determined between the semantic cossimilarity matrix and the fMRI cossimilarity matrix. This was done for written and spoken words pooled, for written words only, for spoken words only, as well as for crossmodal pairs. Only for written words did the fMRI cossimilarity matrix correlate with the semantic cossimilarity matrix. Contrary to our prediction, we did not find any such effect for auditory word input nor did we find cross-modal effects in perirhinal cortex between written and auditory words. Our findings situate the contribution of left perirhinal cortex to word processing at the top of the visual processing pathway, rather than at an amodal stage where visual and auditory word processing pathways have already converged.

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Perilesional and homotopic area activation during proverb comprehension after stroke

Kim

Shim

et al. 2018

Brain and Behavior

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IntroductionThe mechanism of functional recovery in right hemisphere (RH) stroke patients when attempting to comprehend a proverb has not been identified. We previously reported that there is bilateral hemisphere involvement during proverb comprehension in the normal population. However, the underlying mechanisms of proverb comprehension following a right middle cerebral artery (MCA) infarction have not yet been fully elucidated.MethodsWe here compared the brain regions activated by literal sentences and by opaque or transparent proverbs in right MCA infarction patients using functional magnetic resonance imaging (fMRI). Experimental stimuli included 18 opaque proverbs, 18 transparent proverbs, and 18 literal sentences that were presented pseudorandomly in 1 of 3 predesigned sequences.ResultsFifteen normal adults and 17 right MCA infarction patients participated in this study. The areas of the brain in the stroke patients involved in understanding a proverb compared with a literal sentence included the right middle frontal gyrus (MFG) and frontal pole, right anterior cingulate gyrus/paracingulate gyrus and left inferior frontal gyrus (IFG), middle temporal gyrus (MTG), precuneus, and supramarginal gyrus (SMG). When the proverbs were presented to these stroke patients in the comprehension tests, the left supramarginal, postcentral gyrus, and right paracingulate gyrus were activated for the opaque proverbs compared to the transparent proverbs.ConclusionsThese findings suggest that the functional recovery of language in stroke patients can be explained by perilesional activation, which is thought to arise from the regulation of the excitatory and inhibitory neurotransmitter system, and by homotopic area activation which has been characterized by decreased transcallosal inhibition and astrocyte involvement.

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Similarity of fMRI Activity Patterns in Left Perirhinal Cortex Reflects Semantic Similarity between Words

Cited by 115 publications

References 50 publications

Semantic representations in the temporal pole predict false memories

Semantic representations in the temporal pole predict false memories

Left perirhinal cortex codes for similarity in meaning between written words: Comparison with auditory word input

Perilesional and homotopic area activation during proverb comprehension after stroke

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