1,720,961 research outputs found
Qualitative features of semantic fluency in mesial and lateral frontal patients
No full textSemantic verbal fluency is widely used in clinical and experimental studies. This task is highly sensitive to the presence of brain pathology and is frequently impaired after frontal lesions. Besides the total number of words generated, a qualitative analysis of their sequence can add valuable information about the impaired cognitive components. Thirty-four frontal patients and a group of matched controls were examined. Besides the number of words and subcategories retrieved by each group, we analysed two distinct aspects of the word sequence: the search strategy through a semantically organized store and the ability to switch from one subcategory to another. We checked whether the pattern of impairment changed according to the lesion site within the frontal lobe. Overall, patients produced fewer words than controls. However, only lateral frontal patients presented a reduced semantic relatedness between contiguously produced words and a specifically increased proportion of switches to different subcategories. The performance of lateral frontal patients was in line with the hypothesis of a search strategy impairment and cannot be attributed to a switching deficit. The performance of mesial frontal patients could be ascribed to a general deficit of activation
Slowly progressive aphasia : a four-year follow-up study
No full textThis paper reports the long-term follow-up of GC, a patient with primary progressive aphasia of the fluent type. GC presented at onset with an anomia characterized by sparing of first letter knowledge, that applied mainly to proper names and living categories. No semantic deficits were observed in the first stage of the disease, and MRI showed a left temporal lobe atrophy with a gradient from the pole to the posterior regions, the latter being less involved. We now report the clinical evolution of GC from the 2nd to the 4th year of disease. As the disease progressed, the anomia became more severe and the phenomenon of first letter sparing was no longer detectable. Also semantic knowledge was gradually affected and, eventually, was dramatically lost. However, no other cognitive deficits were seen at the last examination. By that time, the temporal atrophy shown by MRI was bilateral, although still more evident on the left side
Facts and hypotheses relevant for contrasting animal and plant life semantics. A comment to Gainotti (2010)
No full textWisconsin card sorting test : a new global score, with Italian norms, and its relationship with the Weigl sorting test
No full textThe 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, with 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
Mirror asymmetry of category and letter fluency in traumatic brain injury and Alzheimer's patients
No full textIn this study we contrasted the Category fluency and Letter fluency performance of 198 normal subjects, 57 Alzheimer's patients and 57 patients affected by traumatic brain injury (TBI). The aim was to check whether, besides the prevalence of Category fluency deficit often reported among Alzheimer's patients, the TBI group presented the opposite dissociation. According to some recent claims, in fact, the deficit of TBI would be equally severe for both fluency types. The inquiry followed different approaches for data analysis, including the evaluation of a unique index (Fluency Type Index or FTI), independent of the overall fluency and aimed at expressing at individual subject level the relationship between Category and Letter fluency. The results confirmed that Alzheimer's patients are more defective on Category than Letter fluency, and also clearly indicated that an opposite pattern applies to TBI patients. TBI seems to cause a relatively more severe impairment of Letter than Category fluency, probably due to its impact on the frontal lobe structures. We discuss whether, on the basis of the statistical distribution of our data, it is worth considering as homogeneous populations broadly defined groups as Alzheimer's or TBI patients
The double dissociation between the knowledge of gestures and the actual object use. A study of two patients
No full textConcerning the debate about the relationship between gesture representation related to tools and semantic action knowledge, we focus our attention on the gesture concepts necessary for performing a skilled tool-use and on their possible nature, semantic versus presemantic. We present 14 patients who were examined for praxis abilities with our Apraxia Battery and discuss their performance related to most common cognitive model for praxis. 14 patients with different etiology (6 cortico-basal disease, 1 possible Alzheimer’s disease with atypical onset and 7 left hemispheric strokes) perform an Apraxia Battery composed of 8 tasks (semantic questionnaire, denomination task, verbal recognition tasks, utilization apraxia task, pantomime comprehension , gesture similarity judgment, functional-manipulation similarity judgment, and De Renzi’s imitation test for ideomotor apraxia). All the degenerative patients underwent to a general neuropsychological examination to assess the cognitive profile and the patients with stroke received the Token Test to assess the present of aphasia. Among all patient, we found two patient who present an opposite performance on GSJ task and the manipulation part of the FMSJ one. The patient A (CBD patient) and B (left thalamic stroke patient) performs normal in manipulation similarity judgment part, while shows difficulties in GSJ. On the other hand patient C (CBD patient) shows the opposite pattern (pathological performance in GSJ and preserved abilities in MSJ task. As we suppose, Gesture Similarity Judgment task examine the gesture representations through a semantic route by verbal modality, while the Manipulation Similarity Judgment task explores them though a direct visual modality. We believe that patient A and B present unimpaired gesture representations to a presemantic level, but show a possible deficit at semantic level or a interrupted link between action semantic knowledge and peripheral representations
Associated impairment of the categories of conspecifics and biological entities. Cognitive and neuroanatomical aspects of a new case
No full textCase A.C.A. presented an associated impairment of visual recognition and semantic knowledge for celebrities and biological objects. This case was relevant for (a) the neuroanatomical correlations, and (b) the relationship between visual recognition and semantics within the biological domain and the conspecifics domain. A.C.A. was not affected by anterior temporal damage. Her bilateral vascular lesions were localized on the medial and inferior temporal gyrus on the right and on the intermediate fusiform gyrus on the left, without concomitant lesions of the parahippocampal gyrus or posterior fusiform. Data analysis was based on a novel methodology developed to estimate the rate of stored items in the visual structural description system (SDS) or in the face recognition unit. For each biological object, no particular correlation was found between the visual information accessed through the semantic system and that tapped by the picture reality judgement. Findings are discussed with reference to whether a putative resource commonality is likely between biological objects and conspecifics, and whether or not either category may depend on an exclusive neural substrate
Different variables predict anomia in different subjects: A longitudinal study of two Alzheimer's patients
No full textTwo Alzheimer's patients participated in a longitudinal study of picture naming aimed at analysing the effect of lexical frequency, age of acquisition, stimulus familiarity, word length, name imageability, visual complexity and semantic category membership on naming success. The results were analysed with a new method [Capitani, E., & Laiacona, M. (2004). A method for studying the evolution of naming error types in the recovery of acute aphasia: A single-patient and single-stimulus approach. Neuropsychologia, 42, 613-623] that allows us to consider the consistency of responses to stimuli over repeated testing within clinical stages. The experiment was carried out as a longitudinal study of single cases, and the effect of each variable was estimated after removing the overlap with the other predictors. The semantic category of stimuli was not an influential factor for either patient. Other findings sharply distinguished between the two patients. In one case, disease-related decline consistently affected mainly late acquired names, whereas in the other case the decline affected names corresponding to low-familiarity items. To interpret this contrast, we further analysed the quality of the errors produced by each patient. This study shows that the psycholinguistic characteristics of a stimulus may exert varying influence in different patients, warranting further development of this line of inquiry. (C) 2007 Elsevier Ltd. All rights reserved
Posterior cerebral artery infarcts and semantic categgory dissociations
No full textIn this study we analysed the relationship between damage in the territory of the posterior cerebral artery and semantic knowledge, with special reference to category dissociations. Twenty-eight posterior cerebral artery stroke patients (18 left, 8 right and 2 bilateral posterior cerebral artery infarctions) completed a neuropsychological battery aimed at assessing semantic knowledge. The battery included picture naming, word-picture matching, a verbal semantic questionnaire and a picture-reality decision task. For each participant, the lesion was reconstructed on the basis of MRI images, and was classified according to the involvement of the areas supplied by posterior cerebral artery. Defective naming scores were observed in 12 of 18 left posterior cerebral artery cases (67%), four of eight posterior cerebral artery cases (50%), and one of two bilateral posterior cerebral artery cases (50%). Only in the bilateral posterior cerebral artery lesion case did we observe the pattern expected in pure visual agnosia, i.e. poor picture naming, poor picture reality decision, and normal verbal semantic questionnaire. Nine left posterior cerebral artery cases and two right posterior cerebral artery cases presented with poor performance on both the picture naming task and the verbal semantic questionnaire, thus suggesting semantic impairment. For 5 of the 12 left posterior cerebral artery patients who fared poorly on the naming task, biological stimuli (overall) were significantly more impaired than artifacts. In three of these five subjects, performance on plant-life stimuli was significantly less accurate than that on animals. A further left posterior cerebral artery patients presented a disproportionate impairment on plant-life stimuli only on the word-picture matching and on the questionnaire. The pattern of performance in these subjects suggest that the observed dissociations originated at the semantic level. Among left posterior cerebral artery patients, a naming deficit only occurred when damage to the fusiform gyrus extended anterior to Talairach’s y-coordinate -50, and a disproportionate impairment of biological categories only when the lesion extended anterior to y= -32.5. Results show that the semantic deficit for the category of plant life is a genuine cognitive pattern, and does not depend on loss of colour knowledge. The contrast of left posterior cerebral artery strokes and herpes simplex encephalitis cases shows that the neural substrates for the semantic representation of plant life and animals are, at least in part, distinct. Middle and posterior portions of the left fusiform are crucial for the representation of plant-life knowledge, whereas left anterior temporal areas are more crucial than left posterior and basal temporal areas for the representation of knowledge about animals
- …
