El estudio de los efectos de la modalidad lingüística en el léxico mental / The study of the effects of linguistic modality on the mental lexicon

Resumen El estudio se cuestiona sobre un abordaje fructífero en el estudio de los efectos de la modalidad lingüística (de señas versus oral) en la organización de la memoria semántica. Para responder la pregunta de investigación, un aspecto central es definir criterios y procedimientos capaces de distinguir entre los factores transportados por la modalidad lingüística de los que le son propios. Entre los primeros, se encuentran la edad de exposición a la lengua natural y su distribución funcional, etaria o geográfica. Entre los aspectos propios de la modalidad se incluyen la iconicidad y el grado de concreción/abstracción de las piezas léxicas. Se sugiere centrarse en el uso de dicho gradiente para evocar dominios conceptuales. Si lo concreto/abstracto es un continuo, entonces hay que preguntarse qué forma de organización es predominante en el léxico mental de las poblaciones señantes u oyentes y qué factores modulan el perfil de esa organización.

Abstract The efforts to understand the relationship of the meaning of a lexical piece to the object to which it refers, the relationship between the lexical pieces and the concepts, and the understanding of the meanings shared between two speakers who use the same lexical pieces have all constituted major problems for the semantic memory models. According to contemporary literature, perceptual-motor, linguistic, and social information have different weights in the formation of concepts, whether concrete or abstract, stored in the aforementioned memory. Regardless of the models developed so far, it is interesting to note that semantic knowledge is represented by various ways of relating the concepts and the types of relationships between them. In this context, studies in sign languages and comparative studies between spoken and sign languages are scarce. Thus, little is known about the effect of linguistic modality on the semantic networks. After all, the theory on semantic networks and norms for the production of features has been grounded on theories of language and its processing adjusted to spoken languages. As the incorporation of the sign language and the Deaf population has shown in other psycholinguistic and linguistic topics, the importance of including these languages and populations, and comparatives with spoken languages, might increase the explanatory power of the theory to account for the universal and contextual aspects of language and its processing. In this effort, there is a latent risk: the linguistic modality can be only a vehicle for more well-known or studied cross-modal variables (e. g., age of acquisition, functional distribution of language, size of the available lexicon, etc.). If it is considered that languages are not stored together, but similar processes can occur in them, it is essential to find out what may be a singular feature of each modality (spoken versus sign) that might ground differentiated processes. Considering the high iconicity of the sign languages and the possibility of a high concreteness of the lexical pieces in the sign language as distinctive features -not collapsible into well-known variables such as the aforementioned-, this article suggests a careful approach to avoid the aforementioned risk in the study of the effects of the linguistic modality (sign versus oral) in the organization of semantic memory. Since perceptual-motor and social information are the main sources of iconicity, a balanced instrument is necessary in the evocation of perceptual-motor, social, and linguistic information. Repeated free word association tasks seem like an appropriate paradigm for a suggested approach. The reasons for this are that, by not censoring the types of response, then free association tasks allow capturing all kinds of concepts (concrete or abstract), all kinds of semantic relationships/organization (paradigmatic versus thematic) and all kinds of processes (comparison versus interaction). This type of task therefore makes it possible to collect meanings related to linguistic information and non-linguistic experience because affective and experiential information is accessible by doing the task in different repetitions. The approach and the tool are exemplified by an ongoing comparative study between Deaf signing and hearing populations. The partial findings of this study also serve to focus on the expected effects of the difference in iconicity and the level of concreteness/abstractness of the lexical pieces of each linguistic modality; namely, the differences between an abstract and a concrete conceptualization of the conceptual domains. Taxonomic and introspective labels might appear as indicative of paradigmatic relationships, of a taxonomic organization, and of underlying comparison processes. On the other hand, the situational and entity labels, indicative of syntagmatic relationships, of a thematic organization and of underlying interaction processes, might suggest a predominantly concrete organization.

Evaluación neuropsicológica de la memoria semántica en demencia presenil y declive cognitivo atípico: ¿estamos preparados? / Neuropsychological assessment of semantic memory in presenile dementia and atypical cognitive decline: ¿are we prepared?

El envejecimiento de la población es un fenómeno demográfico de preocupación mundial. Junto al aumento de la población mayor, aumenta también el número de enfermedades neurodegenerativas. La enfermedad de Alzheimer y la demencia frontotemporal, son las principales causas del envejecimiento cognitivo patológico, diferenciando dentro de su progresión al Deterioro Cognitivo Leve (DCL) y la demencia. La memoria semántica permite el procesamiento, almacenamiento y representación de información que subyace la comprensión y uso del significado de todo lo que nos rodea, permitiendo la autonomía en el desempeño de actividades de la vida diaria, por lo tanto, su compromiso conlleva a un estado de demencia. Uno de los principales objetivos de estudio clínico y de impacto en salud pública es la detección precoz de la demencia, dirigido hacia un tratamiento farmacológico, no-farmacológico y manejo psicosocial oportuno. Actualmente, los casos de demencias preseniles y las presentaciones iniciales con perfiles atípicos han aumentado, siendo la memoria semántica una de estas manifestaciones. En Chile existen efectivas herramientas para la detección de un envejecimiento cognitivo patológico, sin embargo, no se cuenta con herramientas evaluativas para un diagnóstico efectivo en casos atípicos.

Population ageing is a demographic phenomenon of global concern. As the elderly population increases, so does the number of neurodegenerative diseases. Alzheimer's disease and frontotemporal dementia are the main causes of pathological cognitive aging, differentiating between Mild Cognitive Impairment (MCI) and dementia. Semantic memory allows the processing, storage and representation of information that underlies the understanding and use of the meaning of everything that surrounds us, allowing autonomy in the performance of activities of daily life, therefore, it's commitment leads to a state of dementia. One of the main objectives of clinical studies and public health impact is the early detection of dementia, aimed at a pharmacological treatment, non-pharmacological, and timely psychosocial management. Currently, cases of presenile dementias and initial presentations with atypical profiles have increased, with semantic memory being one of these manifestations. In Chile, there are effective tools for detection of a pathological cognitive aging, however, there are no evaluative tools for an effective diagnosis in atypical cases.

PAPDI: Prueba Argentina Psicolingüística de Denominación de Imágenes.: Segunda parte: Estudio de sus propiedades psicométricas / PAPDI: Argentinean Psycholinguistic Image Naming Test.: Second part: Study of psychometric properties

En el presente trabajo se detallan los análisis realizados con el fin de estudiar las propiedades psicométricas la Prueba Argentina Psicolingüística de Denominación de Imágenes (PAPDI). La misma cuenta con dos cualidades que representan un valor agregado frente a las pruebas actualmente disponibles en nuestro país: a) los estímulos fueron seleccionados controlando las variables que afectan las etapas de análisis visual y de representación conceptual de la imagen del objeto y se manipularon las variables que afectan la selección y recuperación de la etiqueta léxica, en base a valores normativos de población argentina; y b) las claves semánticas se elaboraron de acuerdo con normas de producción de atributos semánticos también recolectadas en nuestro país. En este trabajo se analizaron las propiedades psicométricas mediante el estudio de pacientes con demencia tipo Alzheimer, con lesiones cerebrales focales y participantes sin patología neurológica. Se buscaron evidencias de validez de criterio mediante el análisis de grupos contrastados y la correlación con el test de Boston. A su vez, se estudió la confiabilidad de las puntuaciones por dos métodos: consistencia interna y test-retest. También se analizó la capacidad de discriminación entre pacientes con y sin anomia mediante curvas ROC. Se estudiaron además los efectos de las variables manipuladas, se realizó un análisis cualitativo de los errores y se examinó el desempeño en función del uso de las claves. Los resultados de los análisis aportan evidencia de que presenta cualidades psicométricas sumamente aceptables para su uso en nuestra población.

In the current paper we present the psychometric analysis of the Argentinean Psycholinguistic Image Naming Test (PAPDI). This test has two characteristics that makes it different from those currently available in our country: a) the stimuli has been chosen and ordered controlling certain psycholinguistic variables proven to have influence on this task, such as Visual Complexity, Image Agreement, Image Variability, Familiarity, Name Agreement, Age of Acquisition and Frequency of Use, following Argentinean normative data base; and b) semantic cues were elaborated according to semantic feature production norms also from Argentina. We present here the psychometric analysis of its properties. There were analyzed through the study of patients with Alzheimer Disease (n = 25) and focal brain lesions (n = 27) and healthy partici-pants (n = 125). On the first place, in order to study criteria validity a group comparison analysis was carried out. On the one hand Alzheimer Disease patients were compared with healthy participants. On the other hand, two focal brain damaged patients were compared: with and without aphasia. Convergent validity was also studied through the correlation with Boston naming test. In the third place, scores reliability was studied through two methods: internal consistency analysis, for Alzheimer, focal and healthy groups, and test-retest for focal brain damage group. Forth, it was analyzed the capacity to discriminate between patient with and without aphasia through ROC curves analysis. The respective sensitivity and specificity values to detect anomia were established. Fifth, the demographic variables´ influence was analyzed through a regression analysis. Moreover, there were analyzed the effects of two psycholinguistic variables that were taken into account to order the images but were not normalized: Lexical Frequency and Age of Acquisition. Finally, type of errors and response to cues were studied for focal brain damaged patients. The results indicated that the PAPDI presents acceptable psychometric properties to be used as a tool in neuropsychological assessment. It showed evidence of internal and external validity and it was observed scores reliability through internal consistency and test-retest. A suggested cutting point was established to detect anomia. Furthermore a main influence of educational level was reported. There were also detected effects of Lexical Frequency and Age of Acquisition which were observed for Alzheimer and aphasic patients groups. Moreover it was illustrated the response profile analysis for aphasic and nonaphasic focal brain damaged patients regarding a proposed taxonomy of error types. It was also studied the response to semantic and phonological cues and it was observed that both contributed to improve patients´ performance.

Memória semântica como fator de resiliência cognitiva em idosos / Semantic memory as a factor of cognitive resilience in the elderly

O processo de envelhecimento é marcado por múltiplos fatores de risco e proteção. A escolaridade em anos reportados tem sido a principal medida que reflete uma resiliência cognitiva durante esse processo, beneficiando o idoso ao lidar com os impactos do envelhecimento. No entanto, ainda são poucos os estudos realizados com amostras socioculturais diversas que possuem fatores específicos que influenciam esse processo. Faz-se necessário verificar se o uso de fatores de resiliência identificados em estudos internacionais é aplicado ao cenário brasileiro. Considerando as particularidades nacionais que permeiam os fatores de resiliência tradicionais, buscou-se verificar se a memória semântica, uma habilidade cristalizada construída ao longo da vida através de exposições culturais, acadêmicas e ocupacionais, é capaz de agir como uma melhor medida de resiliência cognitiva em nosso contexto. Foram realizados quatro estudos que buscaram analisar o objetivo da presente tese. No primeiro estudo uma nova medida de memória semântica desenvolvida, levando em conta a importância dos aspectos culturais e acadêmicos nacionais, demonstrou suas características psicométricas. No segundo estudo a memória semântica atuou como um moderador significativo entre idade e cognição geral, enquanto as medidas tradicionais não foram significativas. No terceiro estudo a estrutura de rede semântica foi avaliada e indicou que a organização e ativação da rede é um moderador sugestivo da relação idade-cognição geral. Por fim, no quarto estudo grupos educacionais diferentes foram submetidos a um mesmo modelo de resiliência multifatorial e indicou que idosos com diferentes níveis educacionais não se beneficiam dos mesmos fatores de resiliência. Em conjunto, os quatro estudos permitem concluir que é possível que outros fatores de resiliência cognitiva sejam mais impactantes em virtude dos fatores ambientais, que a memória semântica é um possível fator de resiliência a ser considerado em nossos estudos futuros, e que idosos com diferentes alcances educacionais podem se beneficiar de modelos mais específicos de resiliência ao invés do uso de um modelo único. Estudos com amostras maiores e longitudinais são necessários para que as limitações dos estudos desenvolvidos sejam superadas.

Multiple risk and protection factors mark the aging process. Formal education, reported in years, has been the primary cognitive resilience measure, aiding older adults to withstand the impacts of aging. However, there are still few studies carried out with diverse sociocultural samples that have specific factors that can influence this process. It is necessary to verify whether the use of resilience factors identified in international studies is applied to the Brazilian scenario. Considering the national peculiarities that permeate the traditional resilience factors, this dissertation tried to verify if the semantic memory, a crystallized ability built in life through cultural, academic and occupational expositions, is capable of acting as a better measure of cognitive resilience in our context. Four studies were carried out that sought to analyze the objective of the present dissertation. In the first study, a new measure of semantic memory was developed taking into account the importance of national, cultural, and academic aspects and demonstrated its psychometric characteristics. In the second study, semantic memory acted as a significant moderator between age and general cognition, while the traditional resilience measures were not significant. In the third study, the semantic network structure was evaluated, and it indicated that the organization and activation of that system is a suggestive moderator of the age-general cognition relationship. Finally, in the fourth study different educational groups were submitted to the same multifactorial resilience model and the results indicated that the older adults with distinct educational levels do not benefit from the same resilience factors. Together, the four studies allow us to conclude that it is possible that other factors of cognitive resilience are more impacting due to environmental factors. Additionally, semantic memory may be a possible resilience factor to be considered in our future studies, and older adults of different educational strata can benefit from more accurate models of resilience rather than the use of a unique model. Studies with larger and longitudinal samples are necessary to overcome the limitations of the present research.

Demencia semántica y demencia tipo Alzheimer ¿Igual rendimiento en tareas semánticas? / Semantic dementia and Alzheimer´s disease: similar performance in semantic tasks?

Introducción: La Demencia Semántica (DS) y la Demencia de tipo Alzheimer (DTA) presentan deterioro semántico; sin embargo, existen pocos estudios comparativos que investiguen las características de éstos déficits en estas patologías. Objetivos: Comparar perfiles de desempeño en tareas semánticas en pacientes con DS y con DTA. Metodología: Se evaluaron 24 pacientes diagnosticados con DS (N=11) o DTA (N= 13) mediante tareas de denominación de dibujos, asociaciones semánticas y fluidez semántica. Resultados: Se hallaron diferencias significativas de rendimiento en las tres tareas semánticas respecto de los controles en ambos grupos de pacientes. Conclusiones: La DS y DTA poseen perfiles de deterioro semántico diferente. El grupo de pacientes con DS presentó mayor compromiso de la memoria semántica especialmente en la tarea de asociaciones semánticas.

Introduction: Semantic Dementia (SD) and Dementia of the Alzheimer´s type (DAT) have deficits in semantic memory. However there are few comparative studies to determine their characteristic semantic impairments. Objectives: Compare performance of semantic tasks in patients with SD and DAT. Methodology: We evaluated 24 patients diagnosed with SD (N = 11) and DAT (N =13). We administered semantic tasks of picture naming, semantic associations and semantic fluency. Results: Significant differences in performance in the three semantic tasks compared to controls in both patient groups were found. Conclusions: SD and DAT profiles have different semantic impairment. The group of patients with SD had higher commitment of semantic memory especially in the task of semantic associations.

Graph analysis of semantic word association among children, adults, and the elderly / Análise de grafos de associação semântica de palavras entre crianças, adultos e idosos

This study used graph analysis to investigate how age differences modify the structure of semantic word association networks of children and adults and if the networks present a small-world structure and a scale-free distribution which are typical of natural languages. Three age groups of Brazilian Portuguese speakers (children, adults and elderly people) participated in the experiment. Quantitative and qualitative measures suggested that adults and elderly speakers have similar network structures. Children's network showed fewer nodes, connections and clusters, and longer inter-node distances. All networks presented a small-world structure, but they did not show entirely scale-free distributions. These results suggest that from childhood to adulthood, there is an increase not only in the number of words semantically linked to a target but also an increase in the connectivity of the network.

Este estudo utilizou análise de grafos para investigar como a idade modifica a estrutura das redes de associações semânticas de palavras de crianças e adultos e se estas redes apresentam estrutura small-world e distribuição scale-free típicas de linguagens naturais. Participaram dos experimentos três grupos etários (crianças, adultos e idosos) falantes do Português Brasileiro. Medidas quantitativas e qualitativas sugeriram que adultos e idosos possuem redes semelhantes quanto a número de nós, conexões e agrupamentos. A rede das crianças expressou menor número de nós, conexões e agrupamentos e maiores distancias inter-nós. As redes apresentaram uma estrutura small-world, mas não uma distribuição scale-free completa. Os resultados sugerem que além do número de palavras semanticamente associadas aos alvos aumentar das crianças para os adultos, as redes se tornaram mais conectadas.

Dissociação entre seres vivos e artefatos: investigação de efeito categoria específica no processamento de substantivos na bateria de memória semântica de cambridge / Dissociation between living and nonliving concepts: investigation of category specific effects in semantic processing using the cambridge battery of semantic memory tests

Este trabalho investigou a existência de dissociação entre seres vivos e artefatos em dois estudos: um com adultos típicos e outro com a descrição de dois pacientes que receberam diagnósticos de Demência Semântica (DS) ou de Doença de Alzheimer (DA). Para tanto, foram utilizadas as provas de fluência verbal, nomeação, compreensão e definição da Bateria de Memória Semântica de Cambridge. Entre os adultos típicos, o número de acertos em seres vivos foi maior na nomeação, definição e fluência verbal. Diante do controle das covariáveis sociodemográficas correlacionadas com as tarefas, não se encontraram diferenças significativas. Já a investigação dos dois casos identificou diferentes perfis de distúrbio nas provas. Sugere-se que o paciente com DS teve dupla-dissociação em relação aos controles e à paciente com DA. Os resultados foram discutidos com base em modelos de organização do conhecimento semântico e correlatos neuroanatômicos.

This study investigated dissociations between nouns representing living and nonliving entities in cognitively unimpaired adults and in two patients, one with Semantic Dementia (SD) and another with Alzheimer's disease (AD), using tests from the Cambridge Battery of Semantic Memory Tests. Among controls a higher number of correct responses in naming, definition and verbal fluency was observed in nouns representing living concepts but differences did not reach statistical significance when we controlled for sociodemographic variables correlated to the tasks. The description of the performance of two patients allowed for recognition of different profiles in the tasks. It is suggested that the patient with SD presented a double-dissociation compared to controls and to the patient with AD. Results are discussed in terms of models of semantic memory organization and neuroanatomical correlates.

Estudo comparativo das associações semânticas de palavras entre adultos jovens e idosos / Comparative study of the semantic word associations between young and elderly adults

Associações de palavras vêm sendo investigadas recentemente, porém há pouco consenso acerca das mudanças nestas associações entre faixas etárias. Este estudo comparou associações semânticas de palavras entre 108 adultos jovens universitários (M = 22,17; DP = 6,04) e 57 idosos (M = 70,89; DP = 6,87). Uma tarefa de associação semântica foi utilizada. A força de associação direta entre estímulos e palavras mais fortemente associadas permaneceu constante entre os grupos. O tamanho do conjunto total e o número de respostas diferentes foram maiores para o grupo de adultos. O índice de diversidade de respostas foi maior para os adultos. Estas diferenças podem ser consideradas na construção de tarefas com estímulos verbais para avaliar memória e linguagem em diferentes faixas etárias.

The number of studies on word associations have increased recently. However, little agreement exists about age differences in relation to these associations. The semantic word associations of 108 adult college students (M = 22.17; SD = 6.04), and 57 elderly (M = 70.89; SD = 6.87) were compared using a semantic word association task. The strength between the stimuli and the strongest word associated were similar for both groups. The number of different words and the total amount of associated words were higher for the adults. Finally, the diversity index of responses was higher for the adults. Future research on memory and language can consider these age differences when developing tasks with verbal stimuli.

Violencia: análisis de su conceptualización enjóvenes estudiantes de bachillerato / Violence: analysis of its conceptualization in young high school students

El objetivo de esta investigación fue describir los elementos semánticos delsignificado de la violencia para una muestra de jóvenes estudiantes de bachillerato. Medianteanálisis de redes semánticas naturales encontramos como principal asociación con la violencia:manifestaciones físicas, golpes, agresión, maltrato y abuso, con mayor peso semántico para lasmujeres. Las definidoras fueron agrupadas en ocho categorías de análisis (tipos, manifestaciones,influencia social, coerción, atributos descriptivos, calificativos, y simbólicos); de éstas, las quecuentan con mayor significancia fueron las de influencia social y atributos emocionales para mujeres.Para los hombres las definidoras están más asociadas con factores externos como desencadenantesde conducta violenta, y para las mujeres las relativas a vulnerabilidad y debilidad ante situacionesviolentas.

Adaptación de la batería de Evaluación de la Memoria Semántica en la Demencia de tipo Alzheimer (EMSDA) a la población de la ciudad de Buenos Aires / Evaluation battery for Semantic Memory Deterioration in Dementia of the Alzheimer type (EMSDA): Item's adjustment to the population of Buenos Aires city

Se llevó a cabo la adaptación de la Batería para la Evaluación de la Memoria Semántica en Demencia de tipo Alzheimer (Peraita, González Labra, Sánchez Bernardos & Galeote Moreno, 2000)¹ para su aplicación en la Ciudad de Buenos Aires (República Argentina). Esta batería permite evaluar mediante pruebas de modalidad visual, verbal y auditiva, el deterioro del conocimiento de seis categorías semánticas de seres vivientes y no vivientes. Ha sido desarrollada para población de habla hispana con la finalidad de evaluar el deterioro semántico en la Demencia de tipo Alzheimer. Su valor radica en que complementa la evaluación neuropsicológica, donde los aspectos de la memoria semántica por lo general están poco representados, otorgándole valor predictivo al posibilitar la detección temprana de determinadas patologías en las que se encuentra afectado ese sistema de la memoria. Se administró la batería a 30 sujetos sin deterioro cognitivo que tenían entre 61 y 88 años de edad y un promedio de 12 años de escolaridad. Los participantes fueron cuidadosamente seleccionados y se excluyeron a quienes pudieran presentar indicadores de deterioro cognitivo. La evaluación de los ítemes se realizó en base a la frecuencia de las respuestas correctas. Se tomó este criterio considerando que se trata de variables categóricas y el tamaño de la muestra. Se estimó la proporción de respuestas correctas en las seis categorías y dominios de seres vivientes y seres no vivientes. Los nuevos ítemes fueron seleccionados respetando la estructura de la batería y considerando su correlación entre las distintas pruebas.

In this work some items of the Evaluation Battery for Semantic Memory Deterioration in Alzheimer's Disease, were adapted to be used in the population of Buenos Aires city - República Argentina (EMSDA -in Spanish-, Peraita, González Labra, Sánchez Bernardos, & Galeote Moreno, 2000). The original battery presents a series of tasks, elaborated with the aim of assessing semantic deterioration and/or conceptual memory in patients with Alzheimer's disease. It allows specifically, assessing some features of the semantic visual and verbal knowledge of six categories concerning to living / animated beings and inanimate objects as well as the attributes that organize them. The evaluation of attributes belonging to the categories assessed by the EMSDA is implemented following a conceptual representation model, according to which attributes can be grouped in at least nine common conceptual components for the living things and inanimate objects categories. This conceptual representation model was constructed on the basis of an empirical approximation to the study of formation and representation of natural categories and objects representation (Peraita, Elosúa, & Linares, 1992). The various conceptual components vary in their frequency, according to the level of generality of the categories (superordinate, basic, or subordinate), category type, age, and education level, verifying this tendency in samples of patients with dementia of the Alzheimer´s type (DAT). The purpose of this paper is to present the items adjustment of some tasks of the EMSDA to the population of Buenos Aires city. The battery was administered to 30 healthy elderly between 61 and 88 years and 12 years average of education. The participants were carefully selected to be included in the sample. To rule out cognitive deterioration we did not include participants whose performance in the Mini Mental State Examination and the Wechsler Memory Scale Revised were one standard deviation bellow the expected scoring for age and educational level. To study the items we evaluated the frequency of answers, considering them more suitable when 75% or more participants gave the expected target. This criterion was chosen considering the variables were categorical, and the sample was formed with healthy elderly participants, i.e. without cognitive deterioration. To this preliminary analysis, it was estimated the proportion of correct answers to the six categories belonging to domains of living beings and in animate objects with the original and new items. We observed that some of them did not reach the 75% of agreement, and consistently, we determined to change the following tasks: Picture Naming, Spoken Word / Picture Matching, Sentence Verification, and Semantic Analogies. We selected new items taking into account the structure of the original version of the battery, and their correlations between the tasks. This new items were administered to 28 participants of the original sample. The means of each task were analyzed by Students distribution obtaining higher scorings with the adapted items (p < .0001). It is important to note that the proportion of expected answers to the living / animate and non living / inanimate objects were similar. The same results were observed to the supra ordinate and basic level of the category. However, to study the reliability of these results it would be necessary to explore the items in a larger sample. These preliminary results indicate that the new items can be considered an appropriate adjustment to our social culture context and to determine semantics impairments. This is considered a useful tool for the neuropsychological assessment to investigate the category specific deficits and other cognitive processes.

Neural correlates of lexical-semantic memory: a voxel-based morphometry study in mild AD, aMCI and normal aging / Correlatos neurais da memória lexical-semântica: um estudo de morfometria baseada em voxel na doença de Alzheimer, comprometimento cognitivo leve amnéstico e envelhecimento normal

Neuroanatomical correlations of naming and lexical-semantic memory are not yet fully understood. The most influential approaches share the view that semantic representations reflect the manner in which information has been acquired through perception and action, and that each brain area processes different modalities of semantic representations. Despite these anatomical differences in semantic processing, generalization across different features that have similar semantic significance is one of the main characteristics of human cognition. Methods: We evaluated the brain regions related to naming, and to the semantic generalization, of visually presented drawings of objects from the Boston Naming Test (BNT), which comprises different categories, such as animals, vegetables, tools, food, and furniture. In order to create a model of lesion method, a sample of 48 subjects presenting with a continuous decline both in cognitive functions, including naming skills, and in grey matter density (GMD) was compared to normal young adults with normal aging, amnestic mild cognitive impairment (aMCI) and mild Alzheimers disease (AD). Semantic errors on the BNT, as well as naming performance, were correlated with whole brain GMD as measured by voxel-based morphometry (VBM). Results: The areas most strongly related to naming and to semantic errors were the medial temporal structures, thalami, superior and inferior temporal gyri, especially their anterior parts, as well as prefrontal cortices (inferior and superior frontal gyri). Conclusion: The possible role of each of these areas in the lexical-semantic networks was discussed, along with their contribution to the models of semantic memory organization.

As correlações neuroanatômicas de nomeação e memória lexical-semântica não são totalmente entendidas. As abordagens mais influentes compartilham a idéia de que representações refletem a maneira na qual a informação foi adquirida por meio da percepção e ação e que cada área do cérebro processa diferentes modalidades de representações semânticas. Apesar destas diferenças anatômicas no processamento semântico, a generalização de diferentes aspectos que tem significância semântica análoga é uma das principais características da cognição humana. Métodos: Nós avaliamos as regiões cerebrais relacionadas à nomeação e à generalização semântica de desenhos de objetos visualmente apresentados do Teste de Nomeação de Boston (TNB), que compreende diferentes categorias, como animais, vegetais, utensílios, comida e móveis. Para criar um modelo de método de lesão, nós investigamos uma amostra de 48 pessoas que demonstraram um declínio contínuo em funções cognitivas, incluindo habilidades de nomeação e em densidade de substância cinzenta (DSC) em relação a adultos jovens: envelhecimento normal, comprometimento cognitivo leve amnéstico (CCLa) e doença de Alzheimer (DA). Nós correlacionamos seus erros semânticos no TNB, assim como seus desempenhos de nomeação, com a DSC de todo o cérebro que foi medido por morfometria baseada em vóxel (MBV). Resultados: As áreas que mais se relacionaram à nomeação e aos erros semânticos foram as estruturas mediais temporais, tálamo, giro temporal superior e inferior, especialmente em suas partes anteriores e os córtices pré-frontais (giro frontal inferior e superior). Conclusão: Discutimos o provável papel de cada uma dessas áreas na rede lexical-semântica e sua contribuição para os modelos de organização semântica.

Un caso de demencia frontotemporal en su variante lingüística fluente / A case of frontotemporal dementia in fluent linguistic variant

La dificultad para encontrar las palabras en una conversación y expresar lo que se piensa, así como la pérdida del conocimiento en la escritura de las palabras y su significado en presencia de un habla fluida; se evidencia en este estudio de caso; en una mujer de 62 años, con estudios en comercio y secretariado bilingüe, quien previamente a sus dificultades, se desempeñó como secretaria de alta gerencia con sobresalientes habilidades lingüísticas y en su escritura tipo palmer. Ha presentado una progresión gradual de sus déficits, evolucionando hacia un perfil de deterioro global cognoscitivo, específicamente de sus habilidades del lenguaje, déficit de memoria explicita verbal y semántica, alteración en el cálculo, disortografía, agrafia y disfunción ejecutiva, con parcial limitación para desempeñarse funcionalmente en las actividades de la vida diaria. Con la presentación de este caso, se encuentra un cuadro clínico inicial de afectación del sistema semántico y de la representación mental de las palabras, siendo congruente con una demencia semántica. Se presenta el papel fundamental de la evaluación neuropsicológica y la elaboración de la historia clínica, para efectuar un diagnóstico clínico diferencial entre las demencias degenerativas primarias como la enfermedad de Alzheimer y las variantes de las demencias frontotemporales.

The difficulty of finding words in a conversation and express what we think, and unconsciousness in the writing of words and their meaning in the presence of fluent speech, is evident in this study case, a woman of 62 years, with studies in business and bilingual secretary, who prior to his difficulties, she served as secretary of senior management with outstanding language skills and writing Palm OS. He has presented a gradual progression of their deficits, evolving towards a profile of global cognitive impairment, specifically their language skills, verbal explicit memory deficit and semantic change in the calculation, dysorthography, agraphia and executive dysfunction, with partial limitation to perform functionally in activities of daily living. By presenting this case, is a clinical initial involvement of the semantic system and the mental representation of words, being consistent with a semantic dementia. We report the role of neuropsychological assessment and the development of clinical history, to conduct a clinical differential diagnosis between primary degenerative dementia's such as Alzheimer's disease and variants of frontotemporal dementia.

Herramientas informáticas para la representación del conocimiento / Software tools for knowledge representation

La Psicología Cognitiva plantea en el modelo general de la memoria tres tipos de almacenamiento de la información: Memoria Sensorial (MS), Memoria de Corto Plazo (MCP), y Memoria de Largo Plazo (MLP). En la MLP se almacena información de modo permanente, su capacidad es extremadamente grande y conserva la información de modo indefinido. Uno de los subsistemas de la MLP es la Memoria declarativa o conceptual que está compuesta a su vez, por una memoria semántica y una memoria episódica. La organización del conocimiento en la memoria semántica humana tiene una estructura reticular, es decir los conocimiento se representan mediante redes semánticas, a través de representaciones proposicionales. Estas son unidades semánticas que articulan un concepto (nodo 1) con otro concepto (nodo 2) unidos por medio de una relación significativa. El modo en que la información se aprende (fase de adquisición) es importante, tanto para la organización del conocimiento en la memoria como para la fase de recuperación. El mejor modo de aprender es integrar la nueva información en el formato en que la memoria opera para recuperarla/recordarla, es decir en el formato de redes semánticas y mapas conceptuales. En el presente artículo se presenta un software cognitivo: Knowledge Master que emula la forma de la representación del conocimiento en la memoria semántica por medio de la creación de mapas conceptuales y redes semánticas. Se ilustra su aplicación mediante la visualización de redes semánticas sobre conceptos desarrollados en el propio artículo.

Cognitive Psychology proposes three types of information storage for the general pattern of memory: Sensory Memory (SM), Short Term Memory (STM), and Long Term Memory (LTM). In the LTM, information is stored on a permanent basis, its capacity isextremely large and it keeps information indefinitely. One of the sub-systems of LTM is the declarative or conceptual memory which is composed in turn by a semantic memory as well as by an episodic one. The organization of knowledge in the semantic human memory has a reticular structure,which means that knowledge is represented by semantic nets, through propositional representations. These are semantic units which articulate a concept (node 1) with another concept (node 2) joined by means of a significant relation. The way in which information is learned (acquisition phase) is important, for theorganization of knowledge in the memory as much as for the retrieval phase. The best way to learn is to integrate the new information in the format in which memory operatesto retrieve/recall, that is to say in the format of semantic nets and conceptual maps. In the present article a specimen of cognitive software is presented: Knowledge Master, which follows the outline of representation of knowledge in the semantic memory by meansof the generation of conceptual maps and semantic nets. Its application is exemplified by visualization of semantic nets regarding concepts developed in this same article.

¿Pirámides y palmeras o pirámides y faraones?: Adaptación y validación de un test de asociación semántica al español rioplatense / Pyramids and palm trees or pyramids and pharaohs?: Adaptation and valifation of semantic association test to the spanish

La memoria semántica es definida como el sistema que permite almacenar el significado de las palabras, objetos, conceptos y el significado del mundo en general. El test más utilizado para evaluar los déficit semánticos adquiridos es el Test de Pirámides y Palmeras (Howard & Patterson, 1992). Es una prueba de asociación semántica que se administra desde diferentes modalidades (pictórica y verbal) y se encuentra muy condicionada por el medio sociocultural. Los objetivos de este trabajo son: presentar la adaptación y validación del Test de Pirámides y Palmeras al español rioplatense, comparar una versión original del test con una nueva versión abreviada y modificada, denominada Test de Pirámides y Faraones, comparar el rendimiento entre sujetos normales y pacientes y obtener puntajes de corte para el diagnóstico de dificultades semánticas en ambas versiones. El test se administró en forma computarizada a 50 voluntarios (40 controles y 10 pacientes con demencia semántica). De las 66 tríadas adaptadas y construidas se seleccionaron las 20 que mejor discriminaron entre pacientes y controles. La fiabilidad del test original fue de alpha igual a .857 para la modalidad pictórica y alpha igual a .910 para la modalidad verbal. La del nuevo test fue de alpha igual a .917 para la modalidad pictórica y alpha igual a .918 para la modalidad verbal. Se obtuvo así la adaptación y validación del Test de Pirámides y Palmeras, como así también una versión abreviada, el Test de Pirámides y Faraones, que evalúa adecuadamente la memoria semántica en nuestro medio sociolingüístico y se adecua a los requerimientos clínicos actuales.

Semantic memory is a long term memory system proposed by Tulving (2000) that stores objects, words, and general world knowledge's meanings without connection with any particular time or place. Conceptual knowledge is mostly shared across individuals in a given culture, although its precise scope depends on the individual's experience (Hodges & Patterson,1997; Patterson & Hodges, 1995). Semantic memory may be impaired in many neurological disorders. This disruption may be attributed to pathology in the infer-lateral temporal lobes. Patients with semantic dementia have difficulties with objects and words meanings (Budson & Price, 2005). Pyramids and Palm Trees Test is one of the most used measures to assess acquired semantic impairments (Howard & Patterson, 1992). It's a semantic association test and has six different administration modalities: pictorial, verbal, and combined. This test contains 52 triads. The English normative data from the original Pyramids and Palm Trees Test Manual (Howard & Patterson, 1992) was only obtained in13 young adults, and no participant made morethan three errors. This is a socio-cultural influenced test. The aims of this article are to present the Pyramids and Palm Trees Test adaptation and validation to our language (Spanish) and cultural context, to compare the 52 triads from the original version with a new and shorter 20 triads version, to assess differences in performance between controls and patients in both tests, and to get cutoff scores on both versions. A computerized version of the original test (52 triads) plus 14 new triads (66 triads in total) were administered to 50 volunteers (40 controls and 10 semantic dementia patients). Presentation program was used to present the stimulus. Non frequent cultural associations were omitted: (a) windmill, tulip-daffodil, (b) carrot, lamb-donkey, (c) acorns, donkey-pig, and (d) Eskimo-rowing, boat-kayak. Also, others triads were slightly modified: (a) caterpillar, butterfly-dragonfly by caterpillar, butterfly-ant, (b) Eskimo, igloo-house by Indian, carp-house, (c) crook, sheep-mice by dog, rabbit-mice, (d) padlock, bicycle-car by pump, bicycle- car, (e) blackboard, table-desk by blackboard, pen-chalk, (f) eggs, hen-swan by flock, hen-duck, and (g) soldier, church-castle by knight, church-castle. Triads with composed words in Spanish were changed: (a) safety pin (alfiler de gancho), girl-baby by pacifier, girl-baby, (b) safe (caja fuerte),necklace-tie by jacket (chaleco), necklace-tie, and (c) bath, owl-woodpecker (pájaro carpintero) by bath, owl-canary. Of the 66 adapted triads, the 20 that allowed better discrimination between patients and controls were selected. The new and shorter version is called Pyramids and Pharaohs, because the Pyramids and Palm Trees Test triad had low specificity and moderate sensitivity in our sample and wasn´t selected. In the adapted Pyramids and Palm Trees Test the reliability index of the pictorial version was moderately high (α = .857), and high for the verbal modality (α = .910). In the Pyramids and Pharaohs Test the reliability index was high for both versions (pictorial: α = .917; verbal: α = .918). The cutoff score for the original version was 44 for the pictorial modality and 43 for the verbal modality. In the Pyramids and Pharaohs Test the cutoff score was 17 for the pictorial modality and 18 for the verbal one. Regarding the specificity, the adapted Pyramids and Palm Trees Test was high (98.8%) same as the new shorter test. In relation to the sensitivity, the original test was moderate (70%), lower than the Pyramids and Pharaohs Test (85%). Results indicate that the Pyramids and Palm Trees Test can be considered an appropriate adaptation to our social culture. Moreover a new test was designed, Pyramids and Pharaohs, with only 20 triads, adequate for semantics acquired impairments assessment, useful for the research on cognitive processes and current clinical requirements.

Reabilitação na demência semântica: estudo da eficácia da reaquisição lexical em três pacientes / Rehabilitation in semantic dementia: study of the effectiveness of lexicalreacquisition in three patients

Although language rehabilitation in patients with primary progressive aphasia (PPA) is recommended, rehabilitation studies in this clinical syndrome are scarce. Specifically, in relation to semantic dementia (SD), few studies have shown the possibility of lexical relearning. Objective: To analyze the effectiveness of rehabilitation for lexical reacquisition in SD. Methods: Three SD patients were submitted to training for lexical reacquisition based on principles of errorless learning. Comparisons between naming performance of treated items (pre and post-training) and non-treated items of the Boston Naming Test (BNT) were made. Results: All patients improved their performance in naming treated words after intervention. However, decline in performance in naming of non-treated items was observed. Case 1 named zero items at baseline while her performance post-training was 29.4% correct responses without cueing, and 90.7% correct with and without cueing. Case 2 named 6.9% of items correctly at baseline and his performance in post-training was 52.9% without cueing and 87.3%, with and without cueing. Case 3 named zero items at baseline and his performance in post-training was 100% correct responses without cueing. Considering the performance in naming the non-treated items of the BNT, the percentages of correct responses in the first evaluation and in the re-evaluation, respectively were: 16.7% and 8.3% (case 1; 14 month-interval); 26.7% and 11.6% (case 2; 18 month-interval) and 11.6% and 8.3% (case 3; 6 month-interval). Conclusions: The reacquisition of lost vocabulary may be possible in SD despite progressive semantic deterioration.

Apesar de recomendada reabilitação da linguagem na afasia progressiva primária (APP), há poucos estudos sobre reabilitação nesta síndrome. Especificamente, quanto à demência semântica (DS), os poucos estudos têm mostrado possibilidade de reaprendizado lexical. Objetivo: Analisar a eficácia da reabilitação para reaquisição lexical na DS. Métodos: Três pacientes com DS foram submetidos à reabilitação para reaquisição lexical baseada nos princípios do aprendizado sem erro. Comparações entre desempenhos na nomeação de itens treinados (pré e pós-tratamento) e de itens não-treinados do Teste de Nomeação de Boston (TNB) foram realizadas. Resultados: Os pacientes obtiveram melhor desempenho na nomeação das palavras treinadas após intervenção. Por outro lado, houve declínio no desempenho dos itens não-treinados. O caso 1 não nomeou nenhum item na linha de base (pré-tratamento) e seu desempenho após o tratamento foi de 29,4% de acertos sem pistas e 90,7% com e sem pistas. O caso 2 nomeou corretamente 6,9% na linha de base e sua performance, pós-treinamento, foi de 52,9% sem pistas e 87,3%, com e sem pistas. O caso 3 não nomeou nenhum item na linha de base e após o treinamento nomeou 100% dos itens sem pista. Considerando a nomeação dos itens lexicais não-treinados do TNB, as porcentagens de acertos na primeira e segunda avaliações foram respectivamente: 16,7% e 8,3% (caso 1; 14 meses de intervalo); 26,7% e 11,6% (caso 2; 18 meses de intervalo) e 11,6% e 8,3% (caso 3; 6 meses de intervalo). Conclusões: A reaquisição do vocabulário perdido pode ser possível na DS apesar da progressiva deterioração semântica.

Generación de agrupamientos semánticos en una tarea de fluidez verbal en pacientes víctimas de un accidente cerebro vascular y controles sin patología cerebral / Generation of semantic clustering in a verbal fluency task in stroke patients and patients without cerebral pathology

Este artículo se propone comparar el desempeño de tres grupos de personas en una tarea de fluidez verbal semántica: pacientes que sufrieron un Accidente Cerebro Vascular (ACV), adultos mayores sanos y adultos jóvenes sanos. La tarea consiste en solicitarle a lo participantes que emitan la mayor cantidad de ejemplares que conozcan de una categoría semántica en un lapso de tiempo de un minuto. En este caso se escogió la categoría animales. En primer lugar, el análisis de varianza permitió detectar diferencias de medias significativas (p<0.05) en la cantidad de palabras emitidas por grupo, siendo los pacientes los que produjeron menor cantidad de ejemplares. Luego, se realizó un escalamiento multidimensional por grupo para analizar los agrupamientos de los ejemplares de acuerdo al orden en que fueron emitidos. Se observó que los pacientes son los que generaron menor cantidad de agrupamientos y los adultos jóvenes mayor cantidad de agrupamientos. De este modo, cabe suponer que existe una asociación entre la escasa conformación de agrupamientos y la dificultad en la recuperación de ejemplares de la memoria semántica. Así, tanto en el grupo de pacientes como en las personas adultas mayores (en menor grado) habría un funcionamiento deficiente los mecanismos de recuperación de la información semántica que disminuiría la capacidad de generar ejemplares de una categoría semántica.

The aim of the present article is to compare the performance of three groups of people in a semantic fluency task: stroke patients, older healthy adults and young healthy adults. The task requires the participants to say as many exemplars as possible from a semantic category in one minute. In the current research, the semantic category animal was chosen. First, analysis of variance revealed a significant group differences (p<0.05) in the number of exemplars generated, poorer for stroke patients. Then, it was conducted a multidimensional scaling for each group to analyze the clustering of exemplars according to the order of emission. It was observed that stroke patients generated less clusters than the other groups, while young adults generated a mayor number of clusters. Then, it is possible to assume an association between the scarce clustering and the difficulty in the recovery of exemplars from the semantic memory. To conclude, in both, patients and older adults group (in a minor degree), there would be an impaired performance in the use of organization strategies in semantic recovery that would diminish the capacity to generate exemplars from a semantic category.

Incidencia de las expectativas en la memoria episódico-semántica / The incidence of expectations in the episodic-semantic memory

Se realizó un estudio descriptivo y transversal en el que se evaluó la capacidad de recuperar información episódico-semántica y la incidencia del falso recuerdo en una prueba de memoria encubierta aplicada a estudiantes universitarios bajo tres condiciones: 1) inducción de expectativas positivas (confianza), 2) inducción de expectativas negativas (dificultad) y 3) grupo control (sin inducción). Se evaluaron 104 sujetos mayores de 19 años con carrera universitaria o terciaria en curso. A todos se les informó que la tarea consistía en una prueba de nivel de castellano donde clasificarían palabras según fueran adjetivos, sustantivos o verbos. Antes de la inducción, se evaluaron las expectativas de rendimiento en memoria de cada sujeto. Posteriormente, se evaluó la autopercepción de rendimiento una vez finalizada la tarea de recuperación. Los resultados indican que las personas de mayor edad mostraron una peor performance no sólo en el aspecto cuantitativo de la recuperación (p< 0.004), sino también en la agudeza de la información (p< 0.01). Las expectativas de rendimiento de cada sujeto también resultaron un buen predictor de la capacidad de recuperación de información (p<0.04). No se encontraron efectos principales de la variable inducción de expectativas, aunque sí hubo efectos significativos de interacción entre esta variable y la autovaloración de los sujetos sobre su capacidad mnémica (p< 0.02).

Aplicación de un método para el análisis de las redes semánticas en pacientes que sufrieron un accidente cerebro vascular / Application of a semantic network analysis method in stroke patients

Se presenta la aplicación de un método de estimación de distancias semánticas, denominado DISTSEM, en pacientes que sufrieron un Accidente Cerebro Vascular (ACV). Este método se basa en la Teoría de Propagación de la Activación (Collins & Loftus, 1975) y permite obtener la configuración de una red de conceptos en función de la estimación de distancias semánticas realizada entre pares de palabras. Se informan los resultados de la administración a 30 pacientes con ACV y a un grupo control de 30 sujetos. Se analizaron cuali y cuantitativamente los patrones hallados en los pacientes y se compararon con los del otro grupo. Los resultados ponen de manifiesto que algunos pacientes luego de sufrir un ACV realizan estimaciones de proximidad entre conceptos, distintas a las esperables de acuerdo al desempeño del grupo control. Las respuestas no fueron homogéneas. Se hallaron sujetos que establecieron escasas asociaciones entre los pares de palabras. También se hallaron sujetos que encontraron más vinculaciones que el grupo control, incluso encontrando similitudes en aquellos pares que no tenían vinculación semántica y que utilizaron justificaciones para realizar sus estimaciones, que no se corresponden con categorías semánticas sino que se basan principalmente en la funcionalidad. La lectura de estos resultados a la luz de la Teoría de Propagación de la Activación indica que dichos pacientes tienden a fallar en el proceso de búsqueda dentro de la red, particularmente en la regulación de la propagación de la activación que es necesaria para realizar la tarea.

There are many ways in which semantic organization can be assessed. The methods usually used are useful in many ways but fail to provide the possibility to visualise the configuration of a semantic network corresponding to a certain group of concepts and to make qualitative and quantitative comparisons between different networks. The aim of the current research is to show the application of a semantic distance judgment method to stroke patients. This method is called DISTSEM and it was build on the basis of Spreading Activation Theory (Collins & Loftus, 1975). It allows obtaining the configuration of a semantic network according to the semantic distance judgment realized by the individuals between pairs of concepts of different and equal semantic category given by the examiner. The method has been administered to 30 stroke patients and 30 healthy controls. In the current paper, the response patterns of the patients are analyzed quantitatively and qualitatively and comparisons are made with the production of healthy controls. In the first place, all the matrixes were correlated with an interjudges matrix and the results show that strokepatients obtained significantly lower correlations than controls. In the second place, the matrixes of the stroke patients were correlated with a matrix that represented the mode of the estimations made by the group of healthy subjects. There were found two atypical groups. On the one hand, there was a group of patients that found scarce relations between concepts. On the other hand, there was another group that found a great number of relations between concepts, including relations between concepts that were not from the same semantic category. This data can be interpreted in light of Collins and Loftus theory as a failure of the spreading of the activation. Some patients seem to fail in the searching process within the network, particularly in the control of the spread of the activation necessary to look for the similarities requested in the task. In the first case, there was an inhibition in the activation spreading, which did not allow reaching the intersection node between the presented pair of concepts. In the second case, there was an activation spreading superior than expected for that task, that is to say that it failed the inhibition of the competitors that allow establishing the estimation accurate for the task (Howard, Nickel, Coltheart, & Cole-Virtue, 2006). Furthermore, a Multiple Correspondence Analysis was performed with the justifications used in each election. This analysis showed that there was a group of patients that tended to use atypical justifications in some pairs of concepts. Some of these patients justify their elections using functional justifications (e.g., "They are alike because they are useful for men"), another group used perceptual justifications (e.g., "They are alike because they have legs") and there was a small group that found scarce similarities. This indicates that the justifications used by this group of stroke patients tend to be less precise and less adequate for the context of the task. This inappropriate selection of responses leads to an explanation related to executive functions, which would be responsible for selecting the most accurate response according to the context. To sum up, this paper shows some ways in which data can be visualized and some means to analyse and interpret data resulting from the application of the DISTSEM method.

Lexical semantic memory in amnestic mild cognitive impairment and mild Alzheimer's disease

OBJECTIVE: To study lexical semantic memory in patients with amnestic mild cognitive impairment (aMCI), mild Alzheimer's disease (AD) and normal controls. METHOD: Fifteen mild AD, 15 aMCI, and 15 normal control subjects were included. Diagnosis of AD was based on DSM-IV and NINCDS-ADRDA criteria, and that of aMCI, on the criteria of the International Working Group on Mild Cognitive Impairment, using CDR 0.5 for aMCI and CDR 1 for mild AD. All subjects underwent semantic memory tests (Boston Naming-BNT, CAMCOG Similarities item), Rey Auditory Verbal Learning Test (RAVLT), Mini-Mental Status Examination (MMSE), neuropsychological tests (counterproofs), and Cornell Scale for Depression in Dementia. Data analysis used Mann-Whitney test for intergroup comparisons and Pearson's coefficient for correlations between memory tests and counterproofs (statistical significance level was p<0.05). RESULTS: aMCI patients were similar to controls on BNT and Similarities, but worse on MMSE and RAVLT. Mild AD patients scored significantly worse than aMCI and controls on all tests. CONCLUSION: aMCI impairs episodic memory but tends to spare lexical semantic system, which can be affected in the early phase of AD.

OBJETIVO: Estudar a memória léxico-semântica no comprometimento cognitivo leve amnéstico (aCCL), doença de Alzheimer (DA) leve e controles normais. MÉTODO: Incluímos 15 pacientes com DA leve, 15 com aCCL e 15 controles normais, usando os critérios DSM-IV, NINCDS-ADRDA e CDR 1 para DA, e os do International Working Group on Mild Cognitive Impairment, e CDR 0,5 para aCCL. Todos os sujeitos passaram por testes de memória semântica (Teste de nomeação de Boston - TNB, item de Similaridades do CAMCOG), teste de aprendizado auditivo-verbal de Rey (TAAVR), Mini-Exame do Estado Mental (MEEM), testes neuropsicológicos (contraprovas) e Escala Cornell para Depressão em Demência. A análise dos dados usou o teste de Mann-Whitney para comparações entre os grupos e o coeficiente de Pearson para correlação entre testes e contraprovas (nível de significância p<0,05). RESULTADOS: Os pacientes com aCCL foram semelhantes aos controles no TNB e Similaridades, mas inferiores no MEEM e TAAVR. Pacientes com DA leve tiveram performance inferior à de sujeitos com aCCL e controles em todos os testes. CONCLUSÃO: O aCCL prejudica a memória episódica, mas tende a poupar o sistema léxico-semântico, que pode estar afetado na fase inicial da DA.

Procesamiento léxico-semántico en un grupo de sujetos sanos: estudio con potenciales relacionados a eventos

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Abstract: Introduction: An insight into the meaning of words is one of the central processes of semantic memory. To evalúate the access to the cognitive representation of the meaning of words, in the present study we used the lexical decision paradigm developed by Marcos. In this situation, the subject has to recognize if the presented stimulus corresponds to a word or a pseudo-word with the purpose of building a model of normal processing. Once such a model of normal processing is obtained, the findings can be contrasted with pathologies in which semantic memory is altered. Method: The sample consisted of 32 healthy subjects (7 men, 25 women), right-handed and with no personal or familial history of neurological or psychiatric conditions. The average age of the subjects was 34.4 (+ 9.56) years and they had an average educational level of 16.2 (+ 4.4) years. The lexical decision paradigm employed in this study is constituted by 408 stimuli, 240 words and 168 pseudo-words. The criteria for word selection were: frequency, length, grammatical category and morphology. Electroencephalogram (EEG) monopolar recording was obtained from 19 derivations (F3, F4, C3, C4, P3, P4, O1, O2, F7, F8, T3, T4, T5, T6, Fz, Cz and Pz), as well as event-related potentials (ERPs) for the word and pseudo-word sub-states. Results: In the first place, a chi-squared analysis was performed to establish whether significative differences existed between the rates of correct and incorrect answers for both sub-states. The value of chi-squared was 65.7 (gl=1) and significant for p<0.0001. A correlation value of 0.43 (p< 0.02) was found when the educational level and the percentage of correct answers in the sub-sate word were compared. On the other hand, for the pseudo-word sub-state, the value 0.24 was encountered for the same correlation, being statistically non-significant. Pearson's correlation coefficient was also calculated for the educational level variable compared to the mistakes committed when subjects were presented with frequent and infrequent words. In the case of infrequent words, a value of r = - 0.43 (p<0.02) was obtained when the educational level and the number of mistakes were correlated. No correlation was found when the educational level and the number of mistakes commited for frequent words were compared (r = - 0.06). A multivariate variance analysis for repeated measures was performed to determine significant differences between the reaction times when recognizing words or pseudo-words. The outcome showed that all effects were significant in the following cases: reaction times for words and pseudo-words, notwithstanding whether they were correct or incorrect; comparison between correct and incorrect answers, independently of their being words or pseudo-words, as well as the interactions between both effects. To determine differences between average ERPs for both sub-states, Student's T-test was applied with Bonferroni's correction and p<0.0002 as the significance level. Significant differences were encountered between the two sub-states, independently of the age or gender. In the 375-495 ms latency interval, a negative component was appreciated in the pseudo-words case, showing significant differences (p<0.0002) in the following derivations: F3, F4, C3, C4, P3, P4, O1, O2, T3, T5, T6, Fz, Cz and Pz. Amplitude differences between the two sub-states were more evident in Pz and P3 derivations followed by Cz. In addition, a positive component in the 700-795 ms latency interval was detected (mainly in 795 ms) when pseudo-words were presented. Here, the significant differences (p<0.0002) were manifest in the following derivations: F3, C3, P3, F7, T3, T5 and Pz. Amplitude differences between the two sub-states were mainly patent in Pz and P3 followed by C3. Discussion: When analyzing behavioral aspects, subjects made more mistakes when presented with words. However, individuals with less education were the ones committing more mistakes. From this we can infer that this variable may be associated with the range of lexical repertoire. A relation was encountered between educational level and word recognition. With regard to reaction times, significant differences were detected between both sub-states, since the recognition of both words and correct answers was achieved in shorter reaction times. Average reaction times for words and pseudo-words were 819.73 ms and 999.35 ms, respectively. Similarly, the latest potential component appeared in an interval of significant differences between 600 and 940 ms, though with a significance p<0.0005 between 690 and 805 ms. This means that positiveness occurred much sooner than the response, implying that the activity underlying ERPs is related to a cognitive processing of information due to the paradigm used. The analysis of ERPs primary components for both sub-states shows that significant differences arise until 270 ms. The negative component in this study was present between 270 and 580 ms, rendering it similar to N400 given its latency (around 400 ms). Although well-defined in centro-parietal regions, its distribution was generalized, which corresponds to the results of studies using the semantic incongruence paradigm. According to the data from previous research on ERPs, N400 has been associated with the integration process. If this were the case, this association would be equivalent to the semantic incongruence within a lexical integration process described in conventional literature as a "semantic facilitator", only that this time it would be limited to the process of access to the lexicon, which can be interpreted as a discrimination of the answer by assigning a meaning to a word, that is, to process information in the semantic module. This negative component may be related to the generalized response to brain activity when given a meaningless stimulus, i.e., a pseudo-word. Similarly, the wave amplitude may be related to the amount of activation necessary to gain access to the semantic representation of the stimulus in the memory. With regard to the positive component in this study, it is present between 600 and 940 ms and is interpreted as a late P300 (P3b), which has a latency in the 500-1400 ms interval. It is distributed over the centro-parietal region, making it a liable participant in the task categorization process, in which it is necessary to discriminate between the target from the non-target stimulus, and also reflects focalized attentional processes (voluntary) involved in the execution of the task. From the former, it is believed that this component may be related to attentional resources necessary to process the presentation of pseudo-words. Research dealing with the P600 component locate it within the context of statements and associate it with an anomaly in statement syntax. Therefore, even though the positive component lies within the P600 latency domain, this particular component was not considered as being present in this study, because a syntax incongruence paradigm was not used. Finally, the contribution of the present study lies in the finding of N400 and "P600" components, which have been reported when the "semantic facilitator" and the syntax incongruence paradigm were respectively used, but had not been observed when a lexical decision paradigm based on word recognition per se was utilized. Similarly, given that our results stem from a sample of healthy subjects, a comparison can be made with a patient population with semantic memory alterations.