The Heterogeneity of Category-Specific Semantic Disorders: Evidence from a New Case

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<ul><li><p>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</p><p>Neurocase: The Neural Basis of CognitionPublication details, including instructions for authors and subscription information:</p><p>The Heterogeneity of Category-Specific SemanticDisorders: Evidence from a New CaseCristina Rosazza , Emilia Imbornone , Marco Zorzi , Elisabetta Farina , Leonora Chiavari &amp;Stefano F. CappaPublished online: 09 Aug 2010.</p><p>To cite this article: Cristina Rosazza , Emilia Imbornone , Marco Zorzi , Elisabetta Farina , Leonora Chiavari &amp; 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</p><p>To link to this article:</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all the information (the Content) containedin the publications on our platform. However, Taylor &amp; Francis, our agents, and our licensors make norepresentations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of theContent. Any opinions and views expressed in this publication are the opinions and views of the authors, andare not the views of or endorsed by Taylor &amp; Francis. The accuracy of the Content should not be relied upon andshould be independently verified with primary sources of information. Taylor and Francis shall not be liable forany losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoeveror howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use ofthe Content.</p><p>This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in anyform to anyone is expressly forbidden. Terms &amp; Conditions of access and use can be found at</p><p></p></li><li><p>The Heterogeneity of Category-Specific SemanticDisorders: Evidence from a New Case</p><p>Cristina Rosazza1, Emilia Imbornone2, Marco Zorzi1, Elisabetta Farina2, Leonora Chiavari2</p><p>and Stefano F. Cappa1</p><p>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</p><p>Abstract</p><p>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.</p><p>Introduction</p><p>Category-specific semantic impairments have attracted con-</p><p>siderable attention in neuropsychology because of their con-</p><p>tribution to the understanding of the organisation, of the</p><p>mechanisms and of the neuroanatomical bases of semantic</p><p>memory. Various patterns of deficit have been pointed out.</p><p>Coltheart et al. (1998) suggested that selective deficits of</p><p>semantic memory can be classified according to three distinctclasses: (i) category-specific semantic impairments, (ii) input-</p><p>modality specific semantic impairments and (iii) attribute-</p><p>specific semantic impairments, with some patients showing</p><p>more than one type of selectivity. Among the examples of the</p><p>first class there are impairments related to the distinction</p><p>between abstract and concrete words (Warrington, 1975),</p><p>as well as the most frequently reported dissociation between</p><p>knowledge of living things and man-made artefacts(Warrington and Shallice, 1984; Laiacona et al., 1997; Cappa</p><p>et al., 1998; Caramazza and Shelton, 1998; Samson et al.,</p><p>1998; Gainotti, 2000). In patients belonging to the second</p><p>class of selective semantic impairment, the ability to perform</p><p>semantic tasks depends on the modality of stimulus input, i.e.</p><p>for example, pictures or words (McCarthy and Warrington,</p><p>1988). Finally, attribute-specific semantic impairments are</p><p>characterised by the patients inability to retrieve specificsemantic attributes in semantic memory (for example, visual</p><p>information about objects), whereas other semantic attributes</p><p>are accessible (Coltheart et al., 1998). Although patients with</p><p>an isolated, selective attribute impairment are rare (Coltheart</p><p>et al., 1998; Lambon Ralph et al., 1998), there are some cases</p><p>of combined attribute-categorical impairments. For example,</p><p>Michelangelo (Sartori and Job, 1988), L.A. (Silveri and</p><p>Gainotti, 1988), Giulietta (Sartori et al., 1993) and Felicia</p><p>(De Renzi and Lucchelli, 1994) represent cases of category-</p><p>specific deficit restricted to living things in association withattribute-specific impairments for visual knowledge.</p><p>As detailed above, data from the literature agree that dif-</p><p>ferent semantic categories can be damaged in isolation, but</p><p>several explanations have been suggested to account for them.</p><p>These explanations can be divided into two broad categories:</p><p>reductionist theories and non-reductionist theories. Among the</p><p>reductionist theories, the first to be proposed was the sensory/</p><p>functional theory (SFT): Warrington and Shallice (1984)suggested that semantic memory is organised by modality</p><p>(visual, olfactory, motor/functional . . . ), i.e. according to thetype of semantic information, rather than category per se.</p><p>According to this account, visual (sensory) and functional</p><p>features have different weights in the identification of mem-</p><p>bers of living and non-living categories, respectively: as a</p><p>consequence, damage to visual semantic subsystem results in</p><p>impairment of living things, whereas damage to the functionalsubsystem results in impairment of non-living things.</p><p>Recently, Moss, Tyler and colleagues proposed another reduc-</p><p>tionist model (Durrant-Peatfield et al., 1997; Moss and Tyler,</p><p>Neurocase 1355-4794/03/0903189$16.002003, Vol. 9, No. 3, pp. 189202 # Swets &amp; Zeitlinger</p><p>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:</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>The</p><p> Uni</p><p>vers</p><p>ity o</p><p>f M</p><p>anch</p><p>este</p><p>r L</p><p>ibra</p><p>ry] </p><p>at 1</p><p>7:30</p><p> 09 </p><p>Dec</p><p>embe</p><p>r 20</p><p>14 </p></li><li><p>2000). They emphasise the concept of intercorrelation between</p><p>perceptual and functional features, and the different role of</p><p>shared semantic properties versus distinct semantic properties.</p><p>A similar proposal had been already put forward by De Renzi</p><p>and Lucchelli (1994). Their patient had a deficit in the retrieval</p><p>of perceptual attributes. Her performance with artefacts was</p><p>better, according to the authors, because non-living items can</p><p>access their structural representation, since shape and functionare in a close correspondence. Similarly, Laiacona et al. (1997)</p><p>claimed that living entities are more vulnerable than non-living</p><p>ones because perceptual and functional properties show a</p><p>lesser degree of correlation. Moss and Tylers proposal is more</p><p>articulated. They suggest that for living things the shared</p><p>functional (biological) properties (e.g. can see, can run, can</p><p>hear, etc.) and the shared perceptual properties (e.g. has eyes,</p><p>has legs, has ears) are highly intercorrelated. On the other hand,the distinctive properties (e.g. has a mane, is pink, chases mice)</p><p>tend to be weakly correlated and therefore very vulnerable to</p><p>damage. For artefacts, the pattern is reversed: non-living items</p><p>have strong correlations between pairs of individual, distinc-</p><p>tive form and function properties (e.g. has a serrated edge can</p><p>cut), whereas the shared properties are fewer and less</p><p>correlated than those of living things. When the corresponding</p><p>neural network model is lesioned by a random removal ofconnections, category-specific impairments can arise: with</p><p>mild degrees of damage, non-living entities are less affected,</p><p>because of the presence of the strong form-function intercor-</p><p>relations among the distinctive features of these items. With</p><p>more severe levels of lesioning, artefacts are more affected</p><p>because the model can only operate on shared properties and</p><p>living items are more resistant because they are supported by a</p><p>greater degree of shared, intercorrelated properties.An influential, non-reductionist theory is the domain-specific</p><p>knowledge hypothesis proposed by Caramazza and Shelton</p><p>(1998). According to these authors, semantic memory is orga-</p><p>nised categorically in the brain and separate neural systems may</p><p>have become specialised, under evolutionary pressures, for the</p><p>recognition of animals (that are potential predators and a source</p><p>of food) and plants (that are a source of food and medicine). On</p><p>this view the only true category-specific deficits will be thosethat involve the category of animals, plant life and by contrast</p><p>artefacts. These, and only these, three categories form the basis</p><p>for the organisation of conceptual knowledge.</p><p>Problematic findings exist for each of these theories. The</p><p>reductionist theories have clear limitations. As for the sen-</p><p>sory-functional theory (SFT), patient EW reported by</p><p>Caramazza and Shelton (1998) showed a deficit restricted</p><p>to the category of animals, whereas she was equally impairedon functional and perceptual notions about animate entities.</p><p>There was no evidence that the two patients studied by</p><p>Laiacona et al. (1997) with a deficit for living entities showed</p><p>a greater loss of visual than functional information. Further,</p><p>there is some evidence of cases with defective visual knowl-</p><p>edge that do not display a category-specific effect (Coltheart</p><p>et al., 1998; Lambon Ralph et al., 1998). These cases run</p><p>against the SFT.</p><p>Moreover, the model of Moss, Tyler and colleagues</p><p>(Durrant-Peatfield et al., 1997; Moss and Tyler, 2000), in</p><p>which an initial advantage for non-living entities is replaced</p><p>by an advantage for living ones, has not been empirically</p><p>supported (Garrard et al., 2001).</p><p>On the other hand, the domain-specific knowledge hypoth-</p><p>esis does not account for a number of cases of category</p><p>specific impairments restricted to living things in whichperceptual information was specifically lost (Sartori and</p><p>Job, 1988; Silveri and Gainotti, 1988; Sartori et al., 1993;</p><p>De Renzi and Lucchelli, 1994), as well as for the impairment</p><p>of categories which do not have evolutionary significance,</p><p>such as musical instruments, body parts or gems (but see</p><p>Caramazza and Shelton, 1998, for a criticism of the evidence).</p><p>Different hypotheses have been proposed in order to account</p><p>for category-specific disorders, but only a few efforts havebeen made to capture the heterogeneity of the cases described</p><p>in the literature (Humphreys and Forde, 2001). Each hypoth-</p><p>esis tends to focus on selected cases, without taking into</p><p>account the differences among patients at the psycholinguistic</p><p>(categories impaired, task effects) and neural level (aetiology,</p><p>localisation of the brain lesion).</p><p>At this stage an important question is still open: does a</p><p>unique interpretative hypothesis apply to each patient withcategory-specific semantic impairment? It is critically impor-</p><p>tant to understand if variability gives us clues to the different</p><p>mechanisms of impairment or if it is only the effect of</p><p>nuisance variables, which obscure an underlying unique</p><p>mechanism. Another important factor to take into account</p><p>from this point of view is the way in which the patient is</p><p>tested. It is possible that different methodologies affect the</p><p>results, because of differences in processing requirements,insufficiently detailed assessment or inadequate control of</p><p>nuisance variables.</p><p>With this problem in mind, we decided to submit a brain-</p><p>damaged patient, MA, with a deficit for living things, to the</p><p>same testing procedures employed by Caramazza and Shelton</p><p>(1998). The reasons for this choice were twofold. In the first</p><p>place, the procedures employed in this case study are excep-</p><p>tionally detailed and well-controlled. Second, the results ofthe investigation, which showed a selective disorder for</p><p>animals, without any differential impairment in perceptual/</p><p>functional knowledge, led the authors to reject reductionist</p><p>approaches, in favour of the domain-specific account.</p><p>The aim of this study is to replicate the methodology used by</p><p>Caramazza and Shelton (1998) to another case of category-</p><p>specific semantic impairment in order to assess, first, whether</p><p>their results could be generalised to our case and second,whether there is theory, either reductionist or non-reductionist,</p><p>that could explain the different patterns of category-specific</p><p>deficits shown in the literature, included ours.</p><p>Case report</p><p>In July 1999 MA, a 28-year-old, left-handed student, who was</p><p>about to take the final examination for his engineering degree,</p><p>190 C. Rosazza et al.</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>The</p><p> Uni</p><p>vers</p><p>ity o</p><p>f M</p><p>anch</p><p>este</p><p>r L</p><p>ibra</p><p>ry] </p><p>at 1</p><p>7:30</p><p> 09 </p><p>Dec</p><p>embe</p><p>r 20</p><p>14 </p></li><li><p>had a serious motorbike accident and suffered severe facial</p><p>and head trauma. A CT scan immediately after admission to</p><p>hospital showed multiple facial and right orbital fractures and</p><p>a large right frontal haematoma.</p><p>He was given to emergency surgery to reconstruct the facial</p><p>and orbital fractures; he remained in a coma for eight days andthis was followed by gradual neurological improvement. One</p><p>month later he had another operation to further reconstruct the</p><p>facial fractures, which had severely affected the right orbital</p><p>cavity, and to evacuate a small left frontal hygroma. A follow-</p><p>up CT showed a small right frontal hygroma.</p><p>At the end of August MA was discharged to a rehabilitation</p><p>hospital; there he started to communicate verbally, even if</p><p>spontaneous speech was reported to be limited; he did notshow motor deficits.</p><p>In November 1999 MA was given to an initial neuropsy-</p><p>chological examination at the Neuropsychology Laboratory</p><p>of the University of Brescia. He was disoriented in time and</p><p>place, and was severely amnesiac for past as well as recent</p><p>memories concerning personal and public events. He could</p><p>read words and sentences, but not numbers and he made</p><p>several m...</p></li></ul>