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Marcella Laiacona

Publications and source records attributed to Marcella Laiacona.

10 recordsLinked to original sources
PubMed2006

A case of impaired naming and knowledge of body parts. Are limbs a separate sub-category?

A left hemisphere stroke patient presented a disproportionate difficulty for body parts knowledge without autotopagnosia. The deficit concerned the lexical-semantic representation of body parts and was most severe for limbs. The ability to gesture was spared and action naming was not more impaired than object naming. On the basis of normal naming latencies, we conclude that limbs are the most vulnerable component of the overall category of body parts. This vulnerability is not explained by unbalanced nuisance variables. More cognitive effort is probably required for the appropriate differentiation of limbs during semantic processing and lexical access.

Adult↗
PubMed2005

Qualitative features of semantic fluency performance in mesial and lateral frontal patients.

Semantic 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 organised 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.

Adult↗
PubMed2005

Objective versus estimated age of word acquisition: a study of 202 Italian children.

We provide objective data concerning the age of acquisition (AoA) of words from 202 Italian children 34-69 months of age. We investigated picture naming with 80 concrete words belonging to eight semantic categories that are included in a widely used battery for the study of naming and semantic memory. For each word, we calculated three different indices: two directly expressing the age at which a picture was given the correct name by at least 75% of the subjects, and one expressing the overall percentage of our children who were correct in the task. (For the latter index, we provide separate values for boys and girls.). The correlation between objective indices of AoA and adult estimates culled from the literature was not very high. Moreover, objective indices showed low correlations with frequency and familiarity, in contrast to adult ratings. We conclude that adult estimates of AoA present validity problems and should be used with caution. The full set of stimuli is available at www.psychonomic.org/archive.

Age Factors↗
PubMed2004

A method for studying the evolution of naming error types in the recovery of acute aphasia: a single-patient and single-stimulus approach.

In this study, we present a method for analysing the evolution of picture naming errors in the follow-up of single patients affected by acute aphasia. In particular, we have based our analysis on the presence of response type inconsistency, as patients often fail to give the same type of response to the same stimulus at a task repetition attempted after a short time. Due to the uncertain definition of the type of response associated to a given stimulus for each stage of the clinical course, the investigation of the factors underlying the transition between different types of response is a serious methodological challenge. The solution presented here is based on a multiple presentation of the same naming battery at different stages of the clinical course, on the estimation of the probability associated with each response type at each stage, and on the estimation of the transition probability between different response types from one clinical stage to another. The basic idea was to use the set of probabilities referred to above as single stimuli weights in the study of linear models; these permit to compare different types of responses and different types of transitions. We present the application of this method to the study of a single case, a woman affected by fluent aphasia examined twice in the first 2 weeks following stroke. Besides discussing empirical findings, we comment on the usefulness of this method for wider fields of inquiry.

Aged↗
PubMed2003

Multiple patterns of writing disorders in dementia of the Alzheimer type and their evolution.

This paper reports the results obtained from a writing task given to 23 Italian patients suffering from mild to moderate dementia of the Alzheimer's type (DAT). Spelling performance was tested with a task that taps the sub-word-level (spelling of regular words and nonwords), and the lexical route (spelling of regular and irregular words), in line with contemporary models of writing. Each patient's performance was classified according to the emergence of dissociated patterns of damage between regular words and nonwords and between regular and irregular words. The 23 DAT patients span the whole spectrum of dysgraphic taxonomy; five showed the characteristic pattern of impairment of surface dysgraphia, two showed the characteristics of phonological dysgraphia, while a mixed pattern (i.e. better performance on regular words compared to irregular words and regular nonwords) emerged in seven cases. Three patients presented undifferentiated writing disorders, two were completely agraphic, while four patients showed only minimal or no writing defects. The rate of dissociated impairments in the lexical and the sub-word-level routine is very similar to that observed after acute focal brain damage, which contradicts the hypothesis that degenerative brain damage selectively impairs writing performance along the lexical-semantic route. To test the hypothesis that surface sub-word-level processing abilities are affected only during the evolution of the disease, nine patients were tested longitudinally after an interval of 6-12 months. Once again, the data showed high variability across subjects, and do not seem to support involvement of the sub-word-level spelling routine only at a late stage in the development of the disease.

Aged↗
PubMed2003

Apraxia is not associated to a disproportionate naming impairment for manipulable objects.

The relevance of gesture knowledge for the semantic representation of manipulable objects was investigated in a series of 15 patients with a focal left-hemisphere lesion. The patients were classified according to the presence/absence of ideomotor and ideational apraxia. We investigated picture naming and word-picture matching (pointing to a picture on verbal command) with stimuli including items from three categories: manipulable objects, non-manipulable objects, and animals. The analysis was performed at group level and at single-patient level. Nine patients were affected by ideational apraxia and nine by ideomotor apraxia: two cases presented ideomotor but not ideational apraxia, and two cases presented the opposite dissociation. Patients affected by ideational apraxia were more severely impaired in all tasks, but did not show a disproportionate impairment with the category of manipulable objects in contrast to the other categories. The presence of ideomotor apraxia did not cause a greater impairment in any task or category. Finally, we observed a patient with ideational apraxia who performed flawlessly in naming and word-picture matching for all the stimuli, including manipulable objects. In conclusion, we did not find a relationship between ideational apraxia and a disproportionate impairment of the semantic knowledge of manipulable objects.

Aged↗
PubMed2003

Category-specific semantic deficits do not reflect the sensory/functional organization of the brain: a test of the "sensory quality" hypothesis.

We report the performance of a herpes simplex encephalitis patient, EA, who shows a dissociation between poor performance for living things and spared performance for sensory quality categories, when appropriate measures are taken to control for baseline differences among categories in task difficulty and when we eliminate the contribution of visual processing deficits in the recognition of objects. This pattern of performance is problematic for theories of category-specific deficits that are based on the assumption that these deficits reflect selective damage to modality-specific semantic subsystems but is consistent with domain-specific accounts and theories based on the assumption that the structure of conceptual knowledge reflects the correlational structure among object properties.

Brain↗
PubMed2002

Picture reality decision, semantic categories and gender. A new set of pictures, with norms and an experimental study.

We present a new corpus of 80 pictures of unreal objects, useful for a controlled assessment of object reality decision. The new pictures were assembled from parts of the Snodgrass and Vanderwart [J. Exp. Psychol., Hum. Learning Memory 6; 1980: 174] set and were devised for the purpose of contrasting natural categories (animals, fruits and vegetables), artefacts (tools, vehicles and furniture), body parts and musical instruments. We examined 140 normal subjects in a free-choice and a multiple-choice object decision task, assembled with 80 pictures of real objects and above 80 new pictures of unreal objects in order to obtain a difficulty index for each picture. We found that the tasks were more difficult with pictures representing natural entities than with pictures of artefacts. We found a gender by category interaction, with a female superiority with some natural categories (fruits and vegetables, but not animals), and a male advantage with artefacts. On this basis, the difficulty index we calculated for each picture is separately reported for males and females. We discuss the possible origin of the gender effect, which has been found with the same categories in other tasks and has a counterpart in the different familiarity of the stimuli for males and females. In particular, we contrast explanations based on socially determined gender differences with accounts based on evolutionary pressures. We further comment on the relationship between data from normal subjects and the domain-specific account of semantic category dissociations observed in brain-damaged patients.

Adult↗