Erminio Capitani

WHAT ARE THE FACTS OF SEMANTIC CATEGORY-SPECIFIC DEFICITS? A CRITICAL REVIEW OF THE CLINICAL EVIDENCE

In this study we provide a critical review of the clinical evidence available to date in the field of semantic category-specific deficits. The motivation for undertaking this review is that not all the data reported in the literature are useful for adjudicating among extant theories. This project is an attempt to answer two basic questions: (1) what are the categories of category-specific deficits, and (2) is there an interaction between impairment for a type of knowledge (e.g., visual, functional, etc.) and impairment for a given category of objects (e.g., biological, artefacts, etc.). Of the 79 case studies in which the reported data are sufficiently informative with respect to the aims of our study, 61 presented a disproportionate impairment for biological categories and 18 presented a disproportionate impairment for artefacts. Less than half of the reported cases provide statistically and theoretically interpretable data. Each case is commented upon individually. The facts that emerge from our critical review are that (1) the categories of category-specific semantic deficits are animate objects, inanimate biological objects, and artefacts (the domain of biological objects fractionates into two independent semantic categories: animals, and fruit/vegetables); (2) the types of category-specific deficits are not associated with specific types of conceptual knowledge deficits. Other conclusions that emerge from our review are that the evidence in favour of the existence of cases of reliable category-specific agnosia or anomia is not very strong, and that the visual structural description system functions relatively autonomously from conceptual knowledge about object form.

Progressive language impairment without dementia: a case with isolated category specific semantic defect.

A patient is described with a 5 year progressive defect of naming and auditory verbal comprehension, the pathological nature of which was presumably degenerative. The auditory comprehension defect unevenly affected different semantic categories, and was particularly severe for the names of animals, fruits and vegetables. The patients showed loss of the verbal knowledge of the physical attributes of the concepts corresponding to the words he was unable to understand, and sparing of the verbal knowledge of the functional attributes. His performance was defective also on the colour-figure and sound-picture matching test.

Brain and conscious representation of outside reality

Abstract Right brain-damaged patients with contralateral neglect proved unable to describe accurately the left half of recollected images. Analogical brain processes seem therefore to underlie these representations. It is suggested that the left half of the spatial framework of visual representations is impaired in these patients. The alternative explanation based on the unilateral involvement of a hypothetical scanning of inner images is criticized.

A neuropsychological instrument adding to the description of patients with suspected cortical dementia: the Milan overall dementia assessment.

A new, short, neuropsychologically oriented test for dementia assessment--the Milan Overall Dementia Assessment (MODA)--is described. Age and education adjusted norms based on 217 healthy controls are given. A validation study on 312 outpatients suspected of dementia (121 with probable Alzheimers disease) showed that the MODA differentiated patients with cognitive impairment from normal subjects more effectively than did the DSM III-R. The correlation between the MODA and the mini mental state examination was 0.63 in controls and 0.84 in patients with Alzheimers dementia. The MODA test-retest reliability was 0.83. The test proved to be well suited to longitudinal studies.

Perceptual and Associative Knowledge in Category Specific Impairment of Semantic Memory: A Study of two Cases

We report two head-injured patients whose knowledge of living things was selectively disrupted. Their semantic knowledge was tested with naming and verbal comprehension tasks and a verbal questionnaire. In all of them there was consistent evidence that knowledge of living things was impaired and that of non-living things was relatively preserved. The living things deficit emerged irrespective of whether the question tapped associative or perceptual knowledge or required visual or non visual information. In all tasks the category effect was still significant after the influence on the performance of the following variables was partialled out: word frequency, concept familiarity, prototypicality, name agreement, image agreement and visual complexity. In the verbal questionnaire dissociations were still significant even after adjustment for the difficulty of questions for normals, that had proven greater for living things. Besides diffuse brain damage, both patients presented with a left posterior temporo-parietal lesion.

Slowly progressive semantic impairment with category specificity

Abstract We describe the case of an architect, MF, who in his fifties presented a 10-year progressive cognitive deterioration similar to that recently classified as semantic dementia. For a long period general intelligence, non-lexical aspects of language, memory and pre-semantic stages of visual perception were spared. MF showed a lexical-semantic deficit that was more severe for living things, famous people and architectural knowledge and concerned both visual and encyclopaedic information. Visual and encyclopaedic knowledge about tools, vehicles and furniture was completely spared for a long time. On MRI, our patient presented severe atrophy of the temporal lobes, that most severely affected the right side and also involved basal neocortex, hippocampus and parahippocampal gyri.

Wisconsin card sorting test: a new global score, with Italian norms, and its relationship with the Weigl sorting test.

Abstract The Wisconsin card sorting test and the Weigl test are two neuropsychological tools widely used in clinical practice to assess frontal lobe functions. In this study we present norms useful for Italian subjects aged from 15 to 85 years, within 5–17 years of education. Concerning the Wisconsin card sorting test, a new measure of global efficiency (global score) is proposed as well as norms for some well known, qualitative aspects of the performance, i. e. perseverative responses, failure to maintain the set and non-perseverative errors. In setting normative values, we followed a statistical methodology (equivalent scores) employed in Italy for other neuropsychological tests, in order to favour the possibility of comparison among these tests. A correlation study between the global score of the Wisconsin card sorting test and the score on the Weigl test was carried out and it emerges that some cognitive aspects are not overlapping in these two measures.

Gender affects word retrieval of certain categories in semantic fluency tasks.

Recent studies suggest that gender influences phonetically-cued fluency and some semantic memory tasks. In this study we analysed the effect of demographic variables on semantic fluency tasks. The semantic categories considered were: animals, fruits, tools and vehicles. The influence of age and education was common to all the categories considered and seems a general characteristic of the semantic fluency task. Gender had a significant effect only with fruits and tools, but a diverging role: females fared better with fruits and males with tools. We discuss whether the source of the gender effect should be located at the level of the semantic representation of each category or at the level of item recall in the short time (one minute) granted for the task.

Recency, primacy and memory: Reappraising and standardising the serial position curve

In this paper we consider the serial position curve in immediate verbal free recall. A large literature has argued that two components of the serial position curve, recency and primacy, reflect the functioning respectively of short-term and of long-term memory. However, there are a number of difficulties in interpreting the recency effect as a phenomenon uniquely associated with short-term memory. Moreover, the serial position curve has been used widely for clinical investigations in patients with memory deficits. This is despite the lack of norms for the measures derived from the curve. We present a set of standardised norms based on 321 Italian normal subjects. These norms are shown to be applicable both to an English speaking population, and to three groups of brain damaged-patients, namely Alzheimers, amnesics, and frontals. The standardised norms offer a clinical and experimental tool which, coupled with a multiple single case approach, allows us to show dissociations and double dissociations among the performance patterns obtained from all three pathological groups. The paper concludes with a discussion of a possible interpretation of the recency effect as a emergent property of all types of memory system, including verbal short-term memory. Taking into account previous literature as well as our own data, the recency effect in immediate verbal free recall is here interpreted in terms of a two-component view of verbal short-term memory.

Guillain-Barré syndrome associated with high titers of anti-GM1 antibodies

We found high titers of anti-GM1 antibodies (1/1280 or more) in 3 of 14 consecutive patients (21%) with Guillain-Barré syndrome (GBS) and in 2 additional patients who developed GBS, 10-11 days after starting parenteral treatment with gangliosides. Antibodies were IgG in 4 patients and IgM in one, and they all bound to asialo-GM1, and, in 3, to GD1b as well. Although the clinical features in all the patients with high anti-GM1 titers fulfilled the criteria for the diagnosis of GBS and in 4 of them, proteins but not cells were elevated in cerebrospinal fluid, electrodiagnostic studies in 3 patients showed prominent signs of axonal degeneration, that in one case were confirmed by morphological studies on sural nerve biopsy. No recent antecedent infection was reported by these patients, but in 3, including patients treated with gangliosides, anti-Campylobacter jejuni antibodies were elevated. In 3 patients a consistent decrease in anti-GM1 levels was observed after the acute phase of the disease suggesting that the frequent occurrence of these antibodies in patients with GBS and their frequent association with a prominent axonal impairment may have pathogenetic relevance.