Relative category-specific preservation in semantic dementia? Evidence from 35 cases Catherine Merck a,⇑,1 , Pierre-Yves Jonin a,1 , Hélène Vichard a , Sandrine Le Moal Boursiquot a , Virginie Leblay a , Serge Belliard a,b a CHU Pontchaillou, Service de neurologie, CMRR, Rennes, France b Inserm, Unité U1077, Caen, France article info Article history: Accepted 10 January 2013 Available online 11 February 2013 Keywords: Semantic dementia Alzheimer’s disease Category-specificity Fruit and vegetables Fusiform gyrus abstract Category-specific deficits have rarely been reported in semantic dementia (SD). To our knowledge, only four previous studies have documented category-specific deficits, and these have focused on the living versus non-living things contrast rather than on more fine-grained semantic categories. This study aimed to determine whether a category-specific effect could be highlighted by a semantic sorting task admin- istered to 35 SD patients once at baseline and again after 2 years and to 10 Alzheimer’s disease patients (AD). We found a relative preservation of fruit and vegetables only in SD. This relative preservation of fruit and vegetables could be considered with regard to the importance of color knowledge in their discrimination. Indeed, color knowledge retrieval is known to depend on the left posterior fusiform gyrus which is relatively spared in SD. Finally, according to predictions of semantic memory models, our findings best fitted the Devlin and Gonnerman’s computational account. Ó 2013 Elsevier Inc. All rights reserved. 1. Introduction Semantic memory is currently defined as a system where general knowledge (or ‘‘conceptual knowledge’’) about words, living and nonliving entities, people, public events and places, is stored in the form of symbolic representations (Tulving, 1972). The notion of semantic memory first appeared in the 1960s (Quillian, 1966), in influential cognitive psychology works on artificial intelligence, with an emphasis on language abilities. Evidence from neuropsy- chological studies with brain-injured patients subsequently raised questions as to whether semantic memory consists of a unitary sys- tem, or whether multiple systems are required. Should it be re- garded as an amodal system accessible via every input modality (Caramazza, Hillis, Rapp, & Romani, 1990; Fodor, 1983) or, on the contrary, as a multimodal system with separate verbal and visual semantic stores (Beauvois, 1982; McCarthy & Warrington, 1988)? Although the jury is still out on this last point (Gainotti, 2011, 2012), semantic storage deterioration is usually characterized by crossmodal disorders, that is, it manifests itself across different for- mats of stimulus presentation and response modalities (Warrington & Shallice, 1979). Considerable progress has been made in our understanding of semantic memory, through observations of pa- tients presenting with category-specific semantic deficits (see case review by Capitani, Laiacona, Mahon, and Caramazza (2003)). These case studies have inspired new cognitive neuropsychological ac- counts of semantic system organization, which can be divided into two sets. The first set considers that semantic memory is composed of multiple subsystems that are either partially or totally indepen- dent at the functional and anatomical levels. For example, according to sensory/functional theory (SFT) and its variants (Warrington & McCarthy, 1987; Warrington & Shallice, 1984), semantic knowledge about concepts is topographically organized according to the prop- erties that are mostly distinctive for a given category or more rele- vant during their acquisition. Similarly, according to the domain- specific knowledge (DSK) systems hypothesis (Caramazza & Mahon, 2003; Caramazza & Shelton, 1998), the semantic system is divided into topographically organized domains of knowledge: animals, fruit/vegetables, conspecifics and, possibly, tools. The second set of accounts regards this semantic system as a unitary one, without any explicit functional or anatomical organization. Here, all the fea- tures of the different domains of knowledge are brought together within the same distributed network. The internal structure of knowledge is governed by the frequency of co-occurrence between features and the distinctiveness of those features for a given entity. In these models (computational account; Devlin, Gonnerman, Andersen, & Seidenberg, 1998; Gonnerman, Andersen, Devlin, Kempler, & Seidenberg, 1997; conceptual structure account; Tyler & Moss, 2001), concepts are therefore represented by shared or 0093-934X/$ - see front matter Ó 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.bandl.2013.01.003 ⇑ Corresponding author. Address: Service de neurologie, CMRR du CHU Pontc- haillou, Rennes, 2 rue Henri Le Guilloux, 35 033 Rennes Cedex, France. Fax: +33 (0)2 99 28 41 32. E-mail address: catherine.merck@chu-rennes.fr (C. Merck). 1 These authors contributed equally to this work. Brain & Language 124 (2013) 257–267 Contents lists available at SciVerse ScienceDirect Brain & Language journal homepage: www.elsevier.com/locate/b&l