Neuroanatomical dissociation for taxonomic and thematic knowledge in the human brain

Abstract

It is thought that semantic memory represents taxonomic information differently from thematic information. This study investigated the neural basis for the taxonomic-thematic distinction in a unique way. We gathered picture-naming errors from 86 individuals with poststroke language impairment (aphasia). Error rates were determined separately for taxonomic errors ("pear" in response to apple) and thematic errors ("worm" in response to apple), and their shared variance was regressed out of each measure. With the segmented lesions normalized to a common template, we carried out voxel-based lesion-symptom mapping on each error type separately. We found that taxonomic errors localized to the left anterior temporal lobe and thematic errors localized to the left temporoparietal junction. This is an indication that the contribution of these regions to semantic memory cleaves along taxonomicthematic lines. Our findings show that a distinction long recognized in the psychological sciences is grounded in the structure and function of the human brain.A fundamental question in cognitive neuroscience is how semantic knowledge is represented in the brain. We pursued this question by analyzing picture-naming errors generated by individuals with acquired language impairment (aphasia), focusing on errors that reflect the structure of semantic memory. When one views object A with the intention to name it, semantically related concepts B, C, and D come to mind along with A. These related concepts compete for access to the mental lexicon and occasionally stimulate the production of an error. Insight into the organization of semantic memory comes from analyzing the relations that link the target-error pairs.All types of speakers produce semantic errors when tasked with naming objects from pictures. In neurologically intact speakers, error rates are quite low unless special techniques are used to exaggerate the retrieval competition or force a speeded response (e.g., refs. 1 and 2). Across all types of speakers and all manner of testing, semantic naming errors overwhelmingly reflect taxonomic relations; that is, the predominant error is a category coordinate (apple named as "pear" or "grape"), superordinate (apple → "fruit"), or subordinate (apple → "Granny Smith"). A small subset are thematic errors, such as apple → "worm" or bone → "dog," in which the target and error are from different taxonomic categories but frequently play complementary roles in the same actions or events (1, 3).The distinction between taxonomic and thematic relations has been extensively researched in the psychology of concepts and conceptual relations (4, 5). Moreover, the distinction echoes the long-standing interest among philosophers in how similarity and contiguity organize the associative structure of the mind (e.g., ref. 6). Evidence from naming errors affords a rare opportunity to study how the taxonomic-thematic distinction manifests in language production. Most empirical research on this topic uses matching and sorting tasks that invoke explicit strat...

When the zebra loses its stripes but is still in the savannah: Results from a semantic priming paradigm in semantic dementia

“…Taxonomic relationships appear to activate neural bases that are commonly reported when perceptual processing is engaged (i.e., visual associated areas, bilaterally), whereas thematic relationships recruit a bilateral temporoparietal network (Kalénine et al, 2009). It is worth noting that the involvement of the temporoparietal junction -known to be involved in motion, action and spatial processing -has been consistently revealed across several studies (de Zubicaray et al, 2013;Mirman and Grazanio, 2012b;Schwartz et al, 2011). Concerning the neural correlates of semantic priming for taxonomic and thematic relationships in lexical-decision tasks, several fMRI studies (Kotz et al, 2002;Sachs et al, 2008b;Sass et al, 2009) revealed that taxonomic relationships require the recruitment of additional areas in the right hemisphere, interpreted as reflecting a more effortful semantic processing than for thematic one.…”

The representation of concrete and abstract concepts: Categorical versus associative relationships.

“…Most research has focused on concrete concepts, showing that semantic category and association both play a key role in representing concrete concepts (e.g., Kalénine et al, 2009;Sachs, Weis, Krings, Huber, & Kircher, 2008;Sachs, et al, 2011;Schwartz, et al, 2011; for reviews, see Hutchison, 2003;Mahon & Caramazza, 2009;Martin, 2007), but the representations of abstract concepts are less explored. The recent different representational frameworks theory proposes that category and association are important for representing both concrete and abstract words but concrete words rely more on category whereas abstract words rely more on association (Crutch & Warrington, 2005.…”

Thematic relatedness production norms for 100 object concepts

“…The general consensus is that taxonomic and thematic relations rely on two functionally distinct, but complementary, modes of conceptual organization in semantic memory. The dissociation of taxonomic versus thematic processing has been documented in behavioral (Borghi & Caramelli, 2003;Lin & Murphy, 2001;Masuda & Nisbett, 2001;Mirman & Graziano, 2012), neuroimaging (Kalénine, Mirman, & Buxbaum, 2012;Sachs, Weis, Krings, Huber, & Kircher, 2008;Schwartz et al, 2011), and patient (Davidoff & Roberson, 2004) studies. Furthermore, thematic processing has been shown to be as crucial in language comprehension, analogy making, similarity judgment, and memory processes as is taxonomic knowledge (for a review, see Estes et al, 2011).…”