Frontiers in Psychology (Apr 2014)
"That thing in New York": Impaired naming vs. preserved recognition of unique entities following an anterior temporal lobe lesion
Abstract
Background Anterior temporal lobe (aTL) damage often results in semantic impairment. As such, the contribution of this region to semantic processing has received considerable attention. Two theories exist to explain aTL function based on conflicting neuropsychological investigations. The first proposes bilateral aTLs form a “hub” implicated in multimodal semantics (for review see: Jefferies, 2013). The second assumes distinct functions. The left is thought to function as a repertoire for knowledge of entities with unique lexical-conceptual associations (for review: Ross & Olson, 2012). These items represent an extreme end of a continuum of semantic specificity spanning unique (e.g., Eiffel Tower) over less specific (e.g., tower) to nonspecific (e.g., landmark) – often denoted by famous faces, landmarks and proper names. LaTL function, therefore, is to link semantics to language systems for naming, whilst RaTL is involved in familiarity and recognition (e.g., Eiffel Tower -> a building in Paris; Drane et al., 2013). Evidence for each theory has proceeded in parallel but there has been no attempt to directly test them in a patient (Simmons & Martin, 2009). The novelty of this study, therefore, was to determine whether LaTL lesions disproportionately affect unique entity naming vs. recognition. Method WRP, a 51year old right-handed male, three year post-HSVE has a LaTL lesion with destruction of the temporal pole, extending to medial temporal, amygdala and hippocampus and atypical connectivity particularly involving the uncinate fasciculas. There is no evidence of either cortical or white matter damage in the right hemisphere. Previous work with WRP revealed a mild/moderate category-specific semantic deficit (Roberts et al., 2012). This new study focuses on unique entity picture naming, recognition and word-to-picture matching (WPM). Results & Discussion As predicted, results (Table 1) show that WRP was severely impaired in naming different categories of unique entities. However, he was able to produce semantic information about unnamed items (e.g., Richard Branson -> “He owns Virgin, the rail track, lives in Oxford”; Empire State -> “Tall building in America”) and performed at/near ceiling for WPM. This striking dissociation between the comprehension vs. production of unique entities in WRP support previous research of the differential involvement of left and right temporopolar regions, and suggests the functioning of the left – be it involved in proper names, unique entities or semantic specificity – is more multifaceted than either theory implies.
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