the heterogeneity of category-specific semantic disorders: evidence from a new case

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  • This article was downloaded by: [The University of Manchester Library]On: 09 December 2014, At: 17:30Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

    Neurocase: The Neural Basis of CognitionPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/nncs20

    The Heterogeneity of Category-Specific SemanticDisorders: Evidence from a New CaseCristina Rosazza , Emilia Imbornone , Marco Zorzi , Elisabetta Farina , Leonora Chiavari &Stefano F. CappaPublished online: 09 Aug 2010.

    To cite this article: Cristina Rosazza , Emilia Imbornone , Marco Zorzi , Elisabetta Farina , Leonora Chiavari & Stefano F.Cappa (2003) The Heterogeneity of Category-Specific Semantic Disorders: Evidence from a New Case, Neurocase: The NeuralBasis of Cognition, 9:3, 189-202

    To link to this article: http://dx.doi.org/10.1076/neur.9.3.189.15557

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  • The Heterogeneity of Category-Specific SemanticDisorders: Evidence from a New Case

    Cristina Rosazza1, Emilia Imbornone2, Marco Zorzi1, Elisabetta Farina2, Leonora Chiavari2

    and Stefano F. Cappa1

    1Department of Psychology, Universita Vita Salute San Raffaele, Milan, Italy and 2Unita di Neurologia Riabilitativa, IRCCS SantaMaria Nascente, Fondazione Don Carlo Gnocchi Onlus, Milan, Italy

    Abstract

    We report a new case of category-specific semantic impairment, affecting living entities, in a patient with traumatic braindamage. In the present investigation we attempted to replicate as closely as possible the testing procedures whichhave been developed by Caramazza and Shelton (1998) to evaluate EW, a patient with a selective semantic disorder forthe animal category. The results in our patient indicated a different performance profile, characterised by a moreextensive semantic disorder for living entities, and by a more severe loss of specific visual rather than functionalknowledge. These findings concur with other evidence indicating that category-specific semantic disorders areheterogeneous, reflecting different mechanisms of impairment, most likely associated with different neurobiologicalunderpinnings.

    Introduction

    Category-specific semantic impairments have attracted con-

    siderable attention in neuropsychology because of their con-

    tribution to the understanding of the organisation, of the

    mechanisms and of the neuroanatomical bases of semantic

    memory. Various patterns of deficit have been pointed out.

    Coltheart et al. (1998) suggested that selective deficits of

    semantic memory can be classified according to three distinctclasses: (i) category-specific semantic impairments, (ii) input-

    modality specific semantic impairments and (iii) attribute-

    specific semantic impairments, with some patients showing

    more than one type of selectivity. Among the examples of the

    first class there are impairments related to the distinction

    between abstract and concrete words (Warrington, 1975),

    as well as the most frequently reported dissociation between

    knowledge of living things and man-made artefacts(Warrington and Shallice, 1984; Laiacona et al., 1997; Cappa

    et al., 1998; Caramazza and Shelton, 1998; Samson et al.,

    1998; Gainotti, 2000). In patients belonging to the second

    class of selective semantic impairment, the ability to perform

    semantic tasks depends on the modality of stimulus input, i.e.

    for example, pictures or words (McCarthy and Warrington,

    1988). Finally, attribute-specific semantic impairments are

    characterised by the patients inability to retrieve specificsemantic attributes in semantic memory (for example, visual

    information about objects), whereas other semantic attributes

    are accessible (Coltheart et al., 1998). Although patients with

    an isolated, selective attribute impairment are rare (Coltheart

    et al., 1998; Lambon Ralph et al., 1998), there are some cases

    of combined attribute-categorical impairments. For example,

    Michelangelo (Sartori and Job, 1988), L.A. (Silveri and

    Gainotti, 1988), Giulietta (Sartori et al., 1993) and Felicia

    (De Renzi and Lucchelli, 1994) represent cases of category-

    specific deficit restricted to living things in association withattribute-specific impairments for visual knowledge.

    As detailed above, data from the literature agree that dif-

    ferent semantic categories can be damaged in isolation, but

    several explanations have been suggested to account for them.

    These explanations can be divided into two broad categories:

    reductionist theories and non-reductionist theories. Among the

    reductionist theories, the first to be proposed was the sensory/

    functional theory (SFT): Warrington and Shallice (1984)suggested that semantic memory is organised by modality

    (visual, olfactory, motor/functional . . . ), i.e. according to thetype of semantic information, rather than category per se.

    According to this account, visual (sensory) and functional

    features have different weights in the identification of mem-

    bers of living and non-living categories, respectively: as a

    consequence, damage to visual semantic subsystem results in

    impairment of living things, whereas damage to the functionalsubsystem results in impairment of non-living things.

    Recently, Moss, Tyler and colleagues proposed another reduc-

    tionist model (Durrant-Peatfield et al., 1997; Moss and Tyler,

    Neurocase 1355-4794/03/0903189$16.002003, Vol. 9, No. 3, pp. 189202 # Swets & Zeitlinger

    Correspondence to: Stefano F. Cappa, M.D., Vita Salute San Raffaele S. Raffaele University, DIBIT Via Olgettina 58, 20132 Milan, Italy.Tel: 39 0226434887 (secr 4784); Fax: 39 0226434892; e-mail: cappa.stefano@hsr.it

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  • 2000). They emphasise the concept of intercorrelation between

    perceptual and functional features, and the different role of

    shared semantic properties versus distinct semantic properties.

    A similar proposal had been already put forward by De Renzi

    and Lucchelli (1994). Their patient had a deficit in the retrieval

    of perceptual attributes. Her performance with artefacts was

    better, according to the authors, because non-living items can

    access their structural representation, since shape and functionare in a close correspondence. Similarly, Laiacona et al. (1997)

    claimed that living entities are more vulnerable than non-living

    ones because perceptual and functional properties show a

    lesser degree of correlation. Moss and Tylers proposal is more

    articulated. They suggest that for living things the shared

    functional (biological) properties (e.g. can see, can run, can

    hear, etc.) and the shared perceptual properties (e.g. has eyes,

    has legs, has ears) are highly intercorrelated. On the other hand,the distinctive properties (e.g. has a mane, is pink, chases mice)

    tend to be weakly correlated and therefore very vulnerable to

    damage. For artefacts, the pattern is reversed: non-living items

    have strong correlations between pairs of individual, distinc-

    tive form and function properties (e.g. has a serrated edge can

    cut), whereas the shared properties are fewer and less

    correlated than those of living things. When the corresponding

    neural network model is lesioned by a random removal ofconnections, category-specific impairments can arise: with

    mild degrees of damage, non-living entities are less affected,

    because of the presence of the strong form-function intercor-

    relations among the distinctive features of these items. With

    more severe levels of lesioning, artefacts are more affected

    because the model can only operate on shared properties and

    living items are more resistant because they are supported by a

    greater degree of shared, intercorrelated properties.An influential, non-reductionist theory is the domain-specific

    kn

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