Preservation of memory for people in semantic memory disorder: Further category-specific semantic dissociation

ML, a 70-year-old right-handed woman, presented with a history of semantic memory difficulties and a profound anomia affecting both proper nouns and common nouns following a left-hemisphere CVA some years earlier. She was found to show a striking contrast between her ability to make fine-grained semantic distinctions between objects and animals, on the one hand, and famous faces and names, on the other. Although she was impaired on a series of picture and word semantic comprehension tests when the stimuli consisted of exemplars of object and animal categories, her performance was intact when the materials comprised famous faces and names, suggesting a dissociation between the representation of person-specific knowledge and other categories of semantic information. A number of cases have been reported in which person-specific knowledge has been selectively impaired, but we would suggest that our case provides the clearest evidence so far of the reverse dissociation, in which person-specific knowledge is selectively preserved. We speculate on possible differences in the ways in which person-specific knowledge may be represented, relative to information about objects and animals.     

Generating proper names: A case of selective inability

This paper reports the study of a brain-injured patient with a selective inability to generate various types of proper names. Auditory and reading comprehension for the same category were both fairly intact. As in other similar cases the deficit is believed to be at the level of the output lexicon, which would therefore be presumed to be categorically organised. The question considered is why certain lexical categories are selectively impaired or preserved. A single answer is difficult to find and may be impossible to obtain since there appears to be nothing in common among these categories. As far as proper names are concerned a distinction between them and common names that may justify independent processing is to be found in the thoughts of some modern philosophers. According to them the function of proper names, unlike common names, is simply to refer to the object so named and not to describe them by any property.     

SELECTIVE DEFICIT FOR PEOPLE’S NAMES FOLLOWING LEFT TEMPORAL DAMAGE: AN IMPAIRMENT OF DOMAIN-SPECIFIC CONCEPTUAL KNOWLEDGE

As a consequence of a head trauma, APA presented with selective anomia for the names of familiar people, in the absence of comparable disorders for common names and other proper names. Face recognition was normal; and naming performance was unaffected by stimulus and response types. Selective proper name anomia was not due to effects of frequency of usage or of age of acquisition, or to selective memory/learning deficits for the names of people. Even though APA was able to provide at least some information on many celebrities whom she failed to name, she was clearly impaired in all tasks that required full conceptual information on the same people (but she performed flawlessly in similar tasks that involved common names). This pattern of performance indicates that in our subject the inability to name familiar persons results from damage to conceptual information. It is argued that detailed analyses of conceptual knowledge are necessary before it is concluded that a subject with proper name anomia suffers from a purely output disorder, as opposed to a conceptual disorder. The behaviour observed in APA is consistent with the domain-specific hypothesis of conceptual organisation (Caramazza & Shelton, 1998), and in this framework can be explained by assuming selective damage to knowledge of conspecifics. The anatomo-clinical correlates of our subject's disorder are discussed with reference to recent hypotheses on the neural structures representing knowledge of familiar people.     

Reduced resources and specific impairments in normal and aphasic sentence comprehension

Abstract

Our recent article (Miyake, Carpenter,&Just, 1994) posits that comprehension breakdown in aphasic patients arises, in part, from reduced working memory resources for language. One issue that we consider in this article concerns the nature of the deficits postulated in the theory, in contrast to two alternative views of the deficit: (1) a proposal cast in terms of a partial loss of knowledge rather than reduced resources, and (2) a proposal that there is a separate resource pool for syntactic processing, rather than a more general pool for language comprehension. A second issue that we address here concerns patterns of selective sparing and impairment among some patients that have often been interpreted as indicating specific impairments in sentence processing operations. We argue that such micro-level dissociations at a fine-grain level of analysis can arise for many reasons other than selective impairments and, more specifically, that the occurrence of analogous patterns in normal adults challenges the common interpretations of double dissociations regarding sentence comprehension deficits.     

Sparing of country and nationality names in a case of modality-specific oral output impairment: Implications for theories of speech production

This paper describes a patient (BF) with Pick's disease who presented with a modality-specific category preservation. In the oral output modality (oral naming and reading aloud) she presented with a selective sparing of country and nationality names in the context of severe impairment affecting a wide variety of common and proper nouns. In the written output modality (written naming and writing to dictation) her deficits were restricted only to proper nouns (except country names). Her written production of common nouns is virtually intact. Semantic errors were present only in the oral output modality. It is argued that this evidence is seriously problematic for the dual-stage models of lexical production and for the hypothesis of obligatory phonological mediation. It is concluded that: (1) access to words' modality-specific lexical information need not to be mediated by the selection of a modality-neutral level of lexical representation (lemma); (2) orthographical lexical forms can indeed be independently accessed for production without the mediating role of phonology. The possible distinct neuronal structures underpinning country and nationality names categories are discussed.     

Converging functional magnetic resonance imaging evidence for a role of the left inferior frontal lobe in semantic retention during language comprehension

Increasing evidence supports dissociable short-term memory (STM) capacities for semantic and phonological representations. Cognitive neuropsychological data suggest that damage to the left inferior and middle frontal gyri are associated with deficits of semantic STM, while damage to inferior parietal areas is associated with deficits of phonological STM. Patients identified as having semantic STM deficits are also impaired on a number of language comprehension and production paradigms. We used one such comprehension task derived from cognitive neuropsychological data to test predictions with functional magnetic resonance imaging (fMRI) using healthy participants. Using a task that required participants to make semantic anomaly judgements, we found significantly greater activation in areas of the left inferior frontal and middle frontal gyri for phrases that required maintenance of multiple words for eventual integration with a subsequent noun or verb. These data are consistent with our previous patient studies (Hanten & Martin, 2000; R. C. Martin & He, 2004; R. C. Martin & Romani, 1994 Martin, R. C. and Romani, C. 1994. Verbal working memory and sentence comprehension: A multiple-components view. Neuropsychology, 8: 506–523. [Crossref] , [Google Scholar]) that suggest that semantic STM is associated with the left inferior and middle frontal gyri and that deficits of semantic STM have particular consequences for comprehension tasks that require maintenance of several word meanings in unintegrated form.     

Sparing of country and nationality names in a case of modality-specific oral output impairment: Implications for theories of speech production

This paper describes a patient (BF) with Pick's disease who presented with a modality-specific category preservation. In the oral output modality (oral naming and reading aloud) she presented with a selective sparing of country and nationality names in the context of severe impairment affecting a wide variety of common and proper nouns. In the written output modality (written naming and writing to dictation) her deficits were restricted only to proper nouns (except country names). Her written production of common nouns is virtually intact. Semantic errors were present only in the oral output modality. It is argued that this evidence is seriously problematic for the dual-stage models of lexical production and for the hypothesis of obligatory phonological mediation. It is concluded that: (1) access to words' modality-specific lexical information need not to be mediated by the selection of a modality-neutral level of lexical representation (lemma); (2) orthographical lexical forms can indeed be independently accessed for production without the mediating role of phonology. The possible distinct neuronal structures underpinning country and nationality names categories are discussed.     

An exaggerated effect for proper nouns in a case of superior written over spoken word production

We describe a brain-damaged subject, RR, who manifests superior written over spoken naming of concrete entities from a wide range of conceptual domains. His spoken naming difficulties are due primarily to an impairment of lexical-phonological processing, which implies that his successful written naming does not depend on prior access to the sound structures of words. His performance therefore provides further support for the "orthographic autonomy hypothesis," which maintains that written word production is not obligatorily mediated by phonological knowledge. The case of RR is especially interesting, however, because for him the dissociation between impaired spoken naming and relatively preserved written naming is significantly greater for two categories of unique concrete entities that are lexicalised as proper nouns-specifically, famous faces and famous landmarks-than for five categories of nonunique (i.e., basic level) concrete entities that are lexicalised as common nouns-specifically, animals, fruits/vegetables, tools/utensils, musical instruments, and vehicles. Furthermore, RR's predominant error types in the oral modality are different for the two types of stimuli: omissions for unique entities vs. semantic errors for nonunique entities. We consider two alternative explanations for RR's extreme difficulty in producing the spoken forms of proper nouns: (1) a disconnection between the meanings of proper nouns and the corresponding word nodes in the phonological output lexicon; or (2) damage to the word nodes themselves. We argue that RR's combined behavioural and lesion data do not clearly adjudicate between the two explanations, but that they favour the first explanation over the second.     

How modality-specific is morphology?

Writing has long been considered to be dependent on speaking. However, modality-specific dissociations between written and spoken word production imply that word production is supported by distinct neural mechanisms in writing, which can be impaired or spared regardless of the intactness of spoken word production. Rapp et al. (2015). Modality and morphology: What we write may not be what we say. Psychological Science, 26, 892–902 documented a double dissociation where problems with regular inflections were selectively restricted to writing or speaking. We report on two English-speaking aphasic individuals who exhibit this same modality-specific dissociation of inflectional processing, replicating the original findings. We expand on Rapp et al.’s study by examining whether the dissociations observed with regular inflections extend to other morphological forms, such as derivation and irregular inflection. Results showed that the dissociation holds for derivation; however, both participants were impaired with irregular inflections in both output modalities. Implications of these findings for morphological processing and the independence of the orthographic system are discussed.     

Phonological short-term store,phonological processing and sentence comprehension: A neuropsychological case study

Abstract

Phonological processing and speech comprehension were investigated in a patient with left hemisphere damage and a grossly reduced auditory verbal span, attributed to a selective impairment of a phonological short-term store (Vallar & Baddeley, in press). Her phonological processing perfomance was well within the normal range as measured by phonological discrimination, the assignment of stress to words, and rhyme judgement. Comprehension of individual words and of short sentences was unaffected. However, the patient's comprehension of long sentences was defective, whether presented visually or auditorily, when preservation of the specific wording was essential for understanding. These results suggest a dissociation between the processes that perform phonological analysis of verbal information and a phonological short-term store, the latter being selectively impaired in the present case. The pattern of deficit observed in this case suggests that such a system may be useful for comprehending sentences, whenever the verbatim content has to be retained in order to extract meaning     

Aphasia in a user of British Sign Language: Dissociation between sign and gesture

This paper reports a single case investigation of “Charles”, a Deaf man with sign language aphasia following a left CVA. Anomia, or a deficit in sign retrieval, was a prominent feature of his aphasia, and this showed many of the well‐documented characteristics of speech anomia. For example, sign retrieval was sensitive to familiarity, it could be cued, and there were both semantic and phonological errors. Like a previous case in the literature (Corina, Poizner, Bellugi, Feinberg, Dowd, & O'Grady‐Batch, 1992), Charles demonstrated a striking dissociation between sign and gesture, since his gesture production was relatively intact. This dissociation was impervious to the iconicity of signs. So, Charles' sign production showed no effect of iconicity, and gesture production was superior to sign production even when the forms of the signs and gestures were similar. The implications of these findings for models of sign and gesture production are discussed.     

Regions of neural dysfunction associated with impaired naming of actions and objects in acute stroke

The proposal that there are distinct neural regions devoted to the representation or processing of names of objects versus actions has received support from a variety of sources. However, there have been conflicting results regarding the localisation of the postulated mechanisms that are more crucial for one category or the other. There is also controversy as to whether the separation of mechanisms devoted to object versus action naming arises at the level of lexical-semantics or at the level of accessing lexical representations for output. We addressed these issues by testing oral naming and word comprehension of object and action names in 33 right-handed patients with acute left-hemisphere stroke, and by obtaining magnetic resonance (MR) perfusion-weighted and diffusion-weighted imaging of each patient at the same time. We identified regions of abnormal blood flow or infarction associated with impaired naming (with and without impaired word comprehension) of objects, of actions, or of both, using Fisher Exact tests. We found both neural regions shared by networks underlying naming of actions and networks underlying naming of objects, and other neural regions that were crucial to only one network or the other. One of the shared components (in the left superior temporal gyrus) was also essential to comprehension of action and object names (as tested by word/picture verification). These results converge with evidence from chronic lesion studies and functional imaging studies, indicating that some components of the neural networks for accessing lexical representations for output are more important for object names (e.g., left temporal cortex) and others more important for action names (e.g., left posterior frontal cortex).     

Regions of neural dysfunction associated with impaired naming of actions and objects in acute stroke

The proposal that there are distinct neural regions devoted to the representation or processing of names of objects versus actions has received support from a variety of sources. However, there have been conflicting results regarding the localisation of the postulated mechanisms that are more crucial for one category or the other. There is also controversy as to whether the separation of mechanisms devoted to object versus action naming arises at the level of lexical-semantics or at the level of accessing lexical representations for output. We addressed these issues by testing oral naming and word comprehension of object and action names in 33 right-handed patients with acute left-hemisphere stroke, and by obtaining magnetic resonance (MR) perfusion-weighted and diffusion-weighted imaging of each patient at the same time. We identified regions of abnormal blood flow or infarction associated with impaired naming (with and without impaired word comprehension) of objects, of actions, or of both, using Fisher Exact tests. We found both neural regions shared by networks underlying naming of actions and networks underlying naming of objects, and other neural regions that were crucial to only one network or the other. One of the shared components (in the left superior temporal gyrus) was also essential to comprehension of action and object names (as tested by word/picture verification). These results converge with evidence from chronic lesion studies and functional imaging studies, indicating that some components of the neural networks for accessing lexical representations for output are more important for object names (e.g., left temporal cortex) and others more important for action names (e.g., left posterior frontal cortex).     

Identifying Neisseria Species by Use of the 50S Ribosomal Protein L6 (rplF) Gene

The comparison of 16S rRNA gene sequences is widely used to differentiate bacteria; however, this gene can lack resolution among closely related but distinct members of the same genus. This is a problem in clinical situations in those genera, such as Neisseria, where some species are associated with disease while others are not. Here, we identified and validated an alternative genetic target common to all Neisseria species which can be readily sequenced to provide an assay that rapidly and accurately discriminates among members of the genus. Ribosomal multilocus sequence typing (rMLST) using ribosomal protein genes has been shown to unambiguously identify these bacteria. The PubMLST Neisseria database (http://pubmlst.org/neisseria/) was queried to extract the 53 ribosomal protein gene sequences from 44 genomes from diverse species. Phylogenies reconstructed from these genes were examined, and a single 413-bp fragment of the 50S ribosomal protein L6 (rplF) gene was identified which produced a phylogeny that was congruent with the phylogeny reconstructed from concatenated ribosomal protein genes. Primers that enabled the amplification and direct sequencing of the rplF gene fragment were designed to validate the assay in vitro and in silico. Allele sequences were defined for the gene fragment, associated with particular species names, and stored on the PubMLST Neisseria database, providing a curated electronic resource. This approach provides an alternative to 16S rRNA gene sequencing, which can be readily replicated for other organisms for which more resolution is required, and it has potential applications in high-resolution metagenomic studies.     

Selective deficit for people's names following left temporal damage: an impairment of domain-specific conceptual knowledge

As a consequence of a head trauma, APA presented with selective anomia for the names of familiar people, in the absence of comparable disorders for common names and other proper names. Face recognition was normal; and naming performance was unaffected by stimulus and response types. Selective proper name anomia was not due to effects of frequency of usage or of age of acquisition, or to selective memory/learning deficits for the names of people. Even though APA was able to provide at least some information on many celebrities whom she failed to name, she was clearly impaired in all tasks that required full conceptual information on the same people (but she performed flawlessly in similar tasks that involved common names). This pattern of performance indicates that in our subject the inability to name familiar persons results from damage to conceptual information. It is argued that detailed analyses of conceptual knowledge are necessary before it is concluded that a subject with proper name anomia suffers from a purely output disorder, as opposed to a conceptual disorder. The behaviour observed in APA is consistent with the domain-specific hypothesis of conceptual organisation (Caramazza & Shelton, 1998), and in this framework can be explained by assuming selective damage to knowledge of conspecifics. The anatomo-clinical correlates of our subject's disorder are discussed with reference to recent hypotheses on the neural structures representing knowledge of familiar people.     

Specific order impairment in arabic number writing: A case‐study

The present study examines the transitory deficit in transcoding verbal to Arabic numbers in an aphasic patient, TM. She showed a mild syntactic impairment in syntactic comprehension of verbal numbers, with preserved performance in comprehension of Arabic numbers, in access to semantic representation, as well as in reading of Arabic numbers, but she committed 75% of errors when required to write numbers in the Arabic format to dictation. In conformity to the previous literature on transcoding deficits, the majority of her errors were syntactic (60%). However, most of them were unusual “order errors” (50%) in which lexical digits (e.g., 1 to 9) were written on the left and zeros on the right of the number, which contained in the majority of the cases the correct number of digits. A similar type of errors has been reported in only one previous case study (Delazer & Denes, 1998), but not specifically studied. We discuss hypotheses concerning its origins as stemming from a syntactic disorder within existing models of transcoding (McCloskey, Caramazza, & Basili, 1985; Power & Dal Martello, 1990). We also report kinematic assessment of the patient's handwriting before and after recovery. At time of the second examination, results show that her pattern of movement fluency parallels that of healthy subjects and supports a distinction between two types of zeros within Arabic numbers, in relation to the verbal code and the rules required to produce them. This paper thus also highlights the potential usefulness of using a digitising tablet in the study of transcoding deficits.     

Dissociations of lexical function: Semantics,syntax, and morphology

Abstract

Aphasic patients who exhibit “asyntactic comprehension” show poor performance on a sentence-picture matching task with semantically unconstrained sentences, such as “The cow bit the horse,” but good performance, when the sentences are semantically constrained, such as “The boy threw the ball.” The assumption has been that such patients are able to interpret these latter sentences by relying solely on the meanings of the individual words, and that their intact lexical semantics can support some amount of sentence processing. We test this claim by investigating, in detail, the lexical semantics of an aphasic patient (JG), whose speech production is severely agrammatic and whose sentence-picture matching in asyntactic. We explore the semantics of JG's lexicon for both morphologically simple and complex words. We find that word meanings are represented normally in his mental lexicon, and he is able to use this information to integrate words into phrases. In contrast, lexical syntactic and morphological processes are severely impaired. This pattern confirms that lexical semantics can support some limited amount of sentence processing in patients with asyntactic comprehension, and that different lexically based processes can be impaired differentially following brain damage.     

Effect of SK&F 86002 on cytokine production by human monocytes

Human monocytes respond to a variety of stimuliin vitro by producing a number of physiologically important macromolecules including the cytokines. SK&F 86002, a dual inhibitor of the arachidonate metabolism, has been shown to inhibit LPS induced IL-1 production in human monocytes. We examined its effect on the production of other cytokines which are coordinately expressed as a result of LPS stimulation such as tumor necrosis factor alpha (TNF), alpha interferon (IFN-A), interferon beta-2 (IL-6) and granulocyte colony stimulating factor (g-CSF). The IC₅₀ of SK&F 86002 for the TNF production was 5–8 M, and >20M for the other three cytokines. These IC₅₀s were significantly higher than that previously reported for IL-1 production (1–2M). Taken together these data indicate that the inhibitory effect of SK&F 86002 on IL-1 production is selective and the production of cytokines in drug treated monocytes can be differentially affected.     

Impaired naming of unique landmarks is associated with left temporal polar damage

Previous studies have shown that the left temporal polar (TP) region is important for the retrieval of proper names for persons. It has been proposed that the key specialization of left TP is for proper nouns (rather than names for persons, per se), which predicts that left TP should support other categories whose members are denoted by proper names (e.g., landmarks). A lesion study tested the hypothesis that impaired naming of famous unique landmarks would be associated with damage to left TP. A Landmark Recognition and Naming Test was administered to participants with lesions to left TP, right TP, or regions outside TP. The results provided strong support for the hypothesis: Landmark naming was significantly inferior in the left group, supporting the hypothesis. The findings converge with previous lesion and functional imaging data to support the idea that the left TP region is important for the retrieval of names for unique entities. This fits the proposal that left TP contains convergence regions that operate as intermediaries between conceptual knowledge retrieval and lexical retrieval for classes of unique stimuli (H. Damasio, D. Tranel, T. J. Grabowski, R. Adolphs, & A. R. Damasio, 2004).