The Categorical Organization of Semantic and Lexical Knowledge in the Brain

In recent years several papers have shown that different verbal and non-verbal semantic categories can be selectively disrupted by brain damage and that consistent anatomical localizations correspond to each category-specific semantic disorder. This paper aims to suggest that the brain regions typically damaged in a given type of category-specific semantic disorder might be critically involved in processing the kind of information which mainly contributes to organizing that semantic category and to distinguishing among its members. This general hypothesis is discussed taking into account: (a) comprehension and production of object names (nouns) and of action names (verbs) in agrammatic and in anomic aphasic patients; (b) verbal and non-verbal identification of body parts; (c) verbal and non-verbal identification of living beings and of man made artefacts

Differential Contribution of Right and Left Temporo-Occipital and Anterior Temporal Lesions to Face Recognition Disorders

In the study of prosopagnosia, several issues (such as the specific or non-specific manifestations of prosopagnosia, the unitary or non-unitary nature of this syndrome and the mechanisms underlying face recognition disorders) are still controversial. Two main sources of variance partially accounting for these controversies could be the qualitative differences between the face recognition disorders observed in patients with prevalent lesions of the right or left hemisphere and in those with lesions encroaching upon the temporo-occipital (TO) or the (right) anterior temporal cortex. Results of our review seem to confirm these suggestions. Indeed, they show that (a) the most specific forms of prosopagnosia are due to lesions of a right posterior network including the occipital face area and the fusiform face area, whereas (b) the face identification defects observed in patients with left TO lesions seem due to a semantic defect impeding access to person-specific semantic information from the visual modality. Furthermore, face recognition defects resulting from right anterior temporal lesions can usually be considered as part of a multimodal people recognition disorder. The implications of our review are, therefore, the following: (1) to consider the components of visual agnosia often observed in prosopagnosic patients with bilateral TO lesions as part of a semantic defect, resulting from left-sided lesions (and not from prosopagnosia proper); (2) to systematically investigate voice recognition disorders in patients with right anterior temporal lesions to determine whether the face recognition defect should be considered a form of “associative prosopagnosia” or a form of the “multimodal people recognition disorder.

The Role of the Right Hemisphere in Emotional and Behavioral Disorders of Patients With Frontotemporal Lobar Degeneration: An Updated Review

Background: Two main models have been advanced to explain the asymmetries observed in the representation and processing of emotions. The first model, labeled “the right hemisphere hypothesis,” assumes a general dominance of the right hemisphere for all emotions, regardless of affective valence. The second model, named “the valence hypothesis,” assumes an opposite dominance of the left hemisphere for positive emotions and the right hemisphere for negative emotions. Patients with frontotemporal lobar degeneration (FTLD) could contribute to clarifying this issue, because disorders of emotional and social behavior are very common in FTLD and because atrophy, which affects the antero-ventral part of the frontal and temporal lobes, can be clearly asymmetric in the early stages of this disease.Objective: The main scope of the present review therefore consists of evaluating if results of investigations conducted on emotional and behavioral disorders of patients with right and left FTLD, support the “right hemisphere” or the “valence” hypothesis.Method: A thorough review of behavioral and emotional disorders in FTLD patients, found that 177 possible studies, but only 32 papers met the requested criteria for inclusion in our review.Results: Almost all (25 out of 26) studies were relevant with respect to the “right hemisphere hypothesis” and supported the assumption of a general dominance of the right hemisphere for emotional functions, whereas only one of the six investigations were relevant with respect to the “valence hypothesis” and were in part consistent with this hypothesis, though these are also open to interpretation in terms of the “right hemisphere” hypothesis.Conclusions: This study, therefore, clearly supports the model of a general dominance of the right hemisphere for all emotions, regardless of affective valence

Why Are the Right and Left Hemisphere Conceptual Representations Different?

The present survey develops a previous position paper, in which I suggested that the multimodal semantic impairment observed in advanced stages of semantic dementia is due to the joint disruption of pictorial and verbal representations, subtended by the right and left anterior temporal lobes, rather than to the loss of a unitary, amodal semantic system. The main goals of the present review are (a) to survey a larger set of data, in order to confirm the differences in conceptual representations at the level of the right and left hemispheres, (b) to examine if language-mediated information plays a greater role in left hemisphere semantic knowledge than sensory-motor information in right hemisphere conceptual knowledge, and (c) to discuss the models that could explain both the differences in conceptual representations at the hemispheric level and the prevalence of the left hemisphere language-mediated semantic knowledge over the right hemisphere perceptually based conceptual representations

Patterns of neuropsychological impairment in MCI patients with small subcortical infarcts or hippocampal atrophy

We investigated whether MCI patients with hippocampal atrophy or multiple subcortical infarcts demonstrate neuropsychological patterns and markers considered typical of Alzheimer's disease (AD) and of vascular dementia (VD), respectively. An extensive neuropsychological battery, including tests of memory, visual-spatial and executive functions, language, attention, praxis and psychomotor speed, was administered to 36 mild cognitive impairment (MCI) patients with hippocampal atrophy and 41 MCI patients with multiple subcortical infarcts. Both groups of MCI patients were very mildly impaired and well matched in terms of MMSE scores. A clear, disproportionately severe, episodic memory disorder was observed in MCI patients with hippocampal atrophy. A less specific neuropsychological profile, consisting of impairment on an Action Naming task that is sensitive to frontal lobe lesions, was observed in MCI patients with multiple subcortical infarcts. In MCI patients, a disproportionately severe episodic memory impairment strongly points to an Alzheimer's type brain pathology, whereas the prevalence of executive deficits and other frontal lobe symptoms are a much weaker diagnostic marker of small vessel subcortical disease. (JINS, 2008, 14, 611–619.

«Fatta l’Europa bisogna fare gli europei». Considerazioni su una educazione e una formazione all’Europa

This essay faces an important argument: the building of European citizenship. The Author makes a historical reconstruction on this argument and then she writes about the immagine of Europe on scholastic books. What do childreen know about European Union and on their role of European citizens

Different Apathy Profile in Behavioral Variant of Frontotemporal Dementia and Alzheimer's Disease: A Preliminary Investigation

Apathy is one of the most common behavioral symptoms of dementia; it is one of the salient features of behavioral variant of frontotemporal dementia (bvFTD) but is also very frequent in Alzheimer's disease. This preliminary investigation was aimed at assessing the type of apathy-related symptoms in a population of bvFTD and AD subjects showing comparable apathy severity. Each patient underwent a comprehensive neuropsychological assessment; behavioral changes were investigated by the neuropsychiatric inventory (NPI), using the NPI-apathy subscale to detect apathetic symptoms. At univariate analysis, bvFTD subjects showed lack of initiation (χ2 = 4.602, p = 0.032), reduced emotional output (χ2 = 6.493, p = 0.008), and reduced interest toward friends and family members (χ2 = 4.898, p = 0.027), more frequently than AD subjects. BvFTD displayed higher scores than AD on NPI total score (p = 0.005) and on subscales assessing agitation (p = 0.004), disinhibition (p = 0.007) and sleep disturbances (p = 0.025); conversely, AD subjects were more impaired on memory, constructional abilities, and attention. On multivariate logistic regression, reduced emotional output was highly predictive of bvFTD (OR = 18.266; p = 0.008). Our preliminary findings support the hypothesis that apathy is a complex phenomenon, whose clinical expression is conditioned by the site of anatomical damage. Furthermore, apathy profile may help in differentiating bvFTD from AD

Role of the anterior temporal lobes in semantic representations: paradoxical results of a cTBS study

According to the 'Semantic Hub' model, which was developed from data gathered in the moderate to advanced stages of semantic dementia (SD), a unitary amodal mechanism, located in the anterior parts of both temporal lobes (ATLs), should support the interactive activation of semantic representations in all modalities and for all semantic categories. This model has been challenged by clinical findings, which show that in the early stages of SD, when important asymmetries can be observed at the level of the right and left ATLs, the semantic impairment can be modality-specific, mainly affecting lexical-semantic knowledge when the left temporal lobe is more atrophic and pictorial representations when atrophy prevails on the right side. On the other hand, findings of experiments conducted in normal subjects with repetitive transcranial magnetic stimulations (rTMS), support the unitary model. In the most compelling of these studies, rTMS was used to investigate the role of right and left ATLs directly, by comparing semantic processing of the same concepts, presented as written words or pictures. The efficiency of semantic processing for words and pictures was reduced to the same degree by rTMS applied to the left and right ATLs. However, to consider more in depth some methodological inconsistencies of these studies and with the aim of discussing the effects of rTMS on high-level cognitive functions, we decided to repeat that experimental paradigm, using the continuous theta burst stimulation (cTBS) protocol over the right ATL, left ATL and vertex (as control site). A significant interaction was found between side of cTBS application and type of stimulus, but, contrary to our predictions, we observed significantly faster (rather than slower) responses to pictures after application of cTBS to the right ATL and no difference between responses to written words after application of cTBS to the left ATL in comparison with the vertex. These unexpected results are discussed with respect to the nature of the semantic representations supported by the right and left ATLs and to re-appraisal of the 'virtual lesion' account to explain results obtained with rTMS experiments on high-level cognitive functions