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Abstract: Word-association tasks are considered useful tools to assess the normal functioning of the lexico-semantic system in healthy people and patients suffering from neurological disorders. Parkinson's Disease (PD) patients usually present some language dysfunction related to the functioning of the semantic system as a consequence of dopamine depletion. The aim of this study was to check if there were differences in the strength of association of the words generated by a group of non-demented PD patients on and off dopamine medication using a word-association task. In the study, 20 PD patients and 20 healthy-matched controls performed a word association task consisting of 10 nouns and 10 verbs matched by psycholinguistic variables. The participants were asked to generate the first word that came to mind given a specific single target. The results revealed that PD patients off medication said words less associated with the target compared with when they were on medication. Interestingly, comparisons between PD off patients and healthy controls revealed statistical differences only in response to verbs, while differences between PD on and controls were not found. Regarding nouns, we did not find any difference between PD off or PD on and healthy controls. This experiment adds more evidence to the assumption that the lexico-semantic system is disrupted in the absence of dopamine, resulting in poor spreading activation among associative words. [Copyright &y& Elsevier]

Abstract: The aim of this study was to determine the brain areas responsible for the semantic impairment observed in Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI) patients. Thirteen AD, 14 MCI patients, and 13 matched healthy older adults were assessed with a test battery aimed to study their semantic competence. Different subtasks were designed to study their semantic knowledge related to objects and faces in the context of semantic retrieval- and semantic association-dependent tasks. Aggregate scores obtained in the different tests were entered into voxel-based regression analyses with grey matter volume values obtained from three-dimensional brain MRI scans. Areas of significant correlation between volume loss and poor semantic scores were restricted to the temporal lobe in the AD group, while in the MCI and control groups significant associations were found with lower grey matter volume values in a widely distributed network of bilateral fronto-temporo-parietal regions. Our results suggest that degradation of partially overlapping and widely distributed neural networks, mainly including temporal regions, subserve semantic deficits related to objects and faces in AD and MCI patients. [Copyright &y& Elsevier]

Abstract: Previous studies involving lexical access in anomic patients had employed regression analyses to separate the lexical variables. But it is now known that when the relevant variables are as closely related as frequency, age of acquisition (AoA), and familiarity, regression analysis loses efficacy. The aim of the present paper was to investigate which of these variables determines lexical access in anomic patients. In order to disentangle the effects of frequency from those of AoA, we conducted two picture-naming studies. In the first study, we used a semifactorial design in which we manipulated one variable and matched the other. In the second, we used an orthogonal factorial design in which the two variables were crossed to detect any interaction between them. The participants were pure anomic patients whose disorders affected lexical access exclusively; they had neither semantic nor phonological deficits. The statistical analyses show a clear effect of AoA, no effect of frequency, and no interaction between the two variables. The results of this study indicate that AoA is the main determinant of lexical access in anomic patients, and this must be taken into account in constructing materials for the assessment and rehabilitation of these patients. [Copyright &y& Elsevier]

Abstract Alzheimer's disease (AD) patients are known to present semantic memory impairments, and semantic processing plays a crucial role in the formation of false memories. We assessed 40 early stage AD patients and 35 matched healthy volunteers with an emotional version of the Deese-Roediger-McDermott paradigm, which allows the study of false memory formation. Participants were presented with three negative, three neutral and three positive lists of words, each semantically associated to a critical unpresented word. After the presentation of the lists the volunteers were asked to respond to a recognition questionnaire stating whether these critical lures, as well as other presented and unpresented words, had been previously shown or not. We replicate the pattern of decreased discriminability between list-related and -unrelated items for AD patients compared to healthy seniors observed in previous studies. Moreover, like control participants, AD patients displayed enhanced true recognition for emotional materials, both positive and negative. With regards to false recognition, our data show decreased discriminability between related and unrelated lures for positive material. These results point out differential involvement of semantic-based information during memory formation in AD patients compared to healthy seniors. Nevertheless, our data indicate that emotional content effects over semantic-based false memory formation persist in this population, at least at early stages of disease development. Highlights • Alzheimer's disease patients present semantic memory impairments. • Valence affects false memory formation in healthy adults. • Early-stage AD patients and matched controls were presented with valenced DRM lists. • AD patients presented reduced discriminability for true and false recognition. • Valence still affects semantic-based false memories in early-stage AD patients. [ABSTRACT FROM AUTHOR]

The human motor cortex is involved in the planning and execution of movements as well as in the processing of action language, and it is impaired in Parkinson's disease (PD) as a consequence of dopamine degeneration. The aim of this study is to understand the role of dopamine in the processing of action words by looking at PD patients with and without medication. A group of 23 healthy controls and 34 non-demented PD patients participated in an action verbal fluency task on and off dopamine medication. A repeated measures 2 × 2 ANOVA was conducted with dopamine (on/off) and type of verb (high and low specificity motor verbs) as independent variables and the number of words generated as a dependent variable. Our results showed that patients on dopamine medication produced a significantly greater number of high specificity motor verbs than low ones. In contrast, patients off dopamine medication generated a similar number of verbs with high and low motor specificity. MANOVA analyses showed a significantly lower production of verbs with high motor specificity on PD patients off medication compared to healthy controls. However, performance of PD patients in the on condition was similar to that found in healthy controls. In conclusion, the dopamine network from basal ganglia to brain motor areas might play a role in retrieving action verbs with specific semantic representations. [ABSTRACT FROM AUTHOR]

Abstract: We investigated picture naming in Spanish-speaking patients with probable Alzheimer''s disease using coloured line drawings of actions and objects matched on several key psycholinguistic variables. The patients were less accurate than healthy controls but we found no significant evidence for an effect of grammatical class. Generalized linear mixed-effects analyses indicated that patient naming accuracy was affected by lexical frequency and age of acquisition, and by the name agreement of the pictures. These observations support the view that, while the effect of grammatical class is not an important influence, accurate picture naming in dementia is determined by the impact of lesions on a lexico-semantic mapping structured by experience. [Copyright &y& Elsevier]