Between Thought and Expression, a Magnetoencephalography Study of the "Tip-of-the-Tongue" Phenomenon

“Tip-of-the-tongue” (TOT) is the phenomenon associated with the inaccessibility of a known word from memory. It is universally experienced, increases in frequency with age, and is most common for proper nouns. It is a good model for the symptom of anomia experienced much more frequently by some aphasic patients following brain injury. Here, we induced the TOT state in older participants while they underwent brain scanning with magnetoencephalography to investigate the changes in oscillatory brain activity associated with failed retrieval of known words. Using confrontation naming of pictures of celebrities, we successfully induced the TOT state in 29% of trials and contrasted it with two other states: “Know” where the participants both correctly recognized the celebrity's face and retrieved their name and “Don't Know” when the participants did not recognize the celebrity. We wished to test Levelt's influential model of speech output by carrying out two analyses, one epoching the data to the point in time when the picture was displayed and the other looking back in time from when the participants first articulated their responses. Our main findings supported the components of Levelt's model, but not their serial activation over time as both semantic and motor areas were identified in both analyses. We also found enduring decreases in the alpha frequency band in the left ventral temporal region during the TOT state, suggesting ongoing semantic search. Finally, we identified reduced beta power in classical peri-sylvian language areas for the TOT condition, suggesting that brain regions that encode linguistic memories are also involved in their attempted retrieval

Neural changes associated with semantic processing in healthy aging despite intact behavioral performance

Semantic memory recruits an extensive neural network including the left inferior prefrontal cortex (IPC) and the left temporoparietal region, which are involved in semantic control processes, as well as the anterior temporal lobe region (ATL) which is considered to be involved in processing semantic information at a central level. However, little is known about the underlying neuronal integrity of the semantic network in normal aging. Young and older healthy adults carried out a semantic judgment task while their cortical activity was recorded using magnetoencephalography (MEG). Despite equivalent behavioral performance, young adults activated the left IPC to a greater extent than older adults, while the latter group recruited the temporoparietal region bilaterally and the left ATL to a greater extent than younger adults. Results indicate that significant neuronal changes occur in normal aging, mainly in regions underlying semantic control processes, despite an apparent stability in performance at the behavioral level

Language Development across the Life Span: A Neuropsychological/Neuroimaging Perspective

Language development has been correlated with specific changes in brain development. The aim of this paper is to analyze the linguistic-brain associations that occur from birth through senescence. Findings from the neuropsychological and neuroimaging literature are reviewed, and the relationship of language changes observable in human development and the corresponding brain maturation processes across age groups are examined. Two major dimensions of language development are highlighted: naming (considered amajormeasure of lexical knowledge) and verbal fluency (regarded as amajormeasure of language production ability). Developmental changes in the brain lateralization of language are discussed, emphasizing that in early life there is an increase in functional brain asymmetry for language, but that this asymmetry changes over time, and that changes in the volume of gray and white matter are age-sensitive. The effects of certain specific variables, such as gender, level of education, and bilingualism are also analyzed. General conclusions are presented and directions for future research are suggested

The eye contact effect on naming famous faces

Tese de mestrado, Neurociências, Faculdade de Medicina, Universidade de Lisboa, 2012A perceção de contacto ocular tem um efeito modulador em vários aspetos do processamento cognitivo, podendo facilitar o reconhecimento facial ou o acesso à memória semântica. Nesse sentido, realizaram-se duas experiências para analisar o efeito do contacto ocular na capacidade de nomeação de faces famosas e a sua variação dependentemente do tipo de tarefa. Na primeira experiência foi apresentado um conjunto de faces famosas masculinas a um grupo de participantes, com mais de 50 anos de idade, sem doença neurológica conhecida.. As faces foram apresentadas aleatoriamente em contacto ocular ou em olhar desviado e foi pedido aos participantes para realizarem uma tarefa de nomeação das faces. Numa segunda tarefa de controlo foi solicitado aos participantes para indicarem a presença ou ausência de contacto ocular, nos estímulos apresentados. Na segunda experiência, repetiram-se as tarefas de nomeação e identificação da direção do olhar, tendo sido acrescentadas um igual número de faces femininas aos estímulos e adicionada uma tarefa de descriminação de género. Em ambas as experiências foi encontrado um efeito facilitador do contacto ocular na nomeação das faces que pertenciam ao mesmo género do participante. Pelo contrário, na tarefa de direção do olhar (na segunda experiência) verificou-se um efeito facilitador do contacto ocular, mas apenas para faces do género oposto ao participante. Na tarefa de género, o contacto ocular conduziu a uma redução no número de acertos para faces do género oposto. Estes resultados mostram um efeito facilitador do contacto ocular na nomeação, e a sua dependência de fatores como o género. A existência de um efeito facilitador do contacto ocular está então, dependente do tipo de tarefa (nomeação, género e descriminação da direção do olhar) e da interação entre a tarefa e o género observador/estímulo. Assim o efeito modulador do contacto ocular, nas diferentes atividades cognitivas é complexo, podendo facilitar ou interferir dependendo da tarefa e da sua interação com outras variáveis. O efeito facilitador, a confirmar em situações patológicas, poderá ser utilizado na reabilitação das dificuldades de nomeação.Awareness of eye contact has a modulatory effect on several cognitive tasks, enhancing facial recognition and encoding, as well as the access to semantic memory related to these faces. To analyse the effect of eye contact on proper name retrieval, and how it may depend upon type of task, two experiments using famous faces as stimuli were designed. In the first experiment a set of well-known public male faces was presented randomly in eye contact or averted gaze. Participants were asked to perform two tasks, one in which they had to name the presented faces and a control task in which they had to discriminate gaze direction. Since in this experiment all stimuli were male, a second experiment added an equal number of female and male faces. In this experiment a gender decision task was added. Participants were adult volunteers with fifty or more years, without known mental or neurological disease. Results from both experiments showed a facilitator effect of eye contact in naming faces of the same sex as the participant. In the gaze direction task of the second experiment, eye contact was easier to discriminate compared to averted gaze but only when the presented face was of the opposite sex than the participant’s. In the gender task, eye contact diminished accuracy but only with opposite-sex faces. These results show that eye contact facilitates proper name retrieval, but that this effect depends upon the sex of the perceiver and the perceived face. The existence of a facilitation effect due to eye contact was shown to be dependent both of task and of the interaction of sex of the stimuli and the participant. The modulator effect of eye contact in different cognitive tasks seems to be complex, either being a facilitator or causing interference depending on type of task and its interaction with other variables. Its facilitator effect, if confirmed in cases of pathology, may be used in rehabilitation settings of proper name retrieval

Systematic Influence of Perceived Grasp Shape on Speech Production

Previous research has shown that precision and power grip performance is consistently influenced by simultaneous articulation. For example, power grip responses are performed relatively fast with the open-back vowel [a], whereas precision grip responses are performed relatively fast with the close-front vowel [i]. In the present study, the participants were presented with a picture of a hand shaped to the precision or power grip. They were required to pronounce speech sounds according to the front/above perspective of the hand. The results showed that not only the grip performance is affected by simultaneously pronouncing the speech sound but also the production of speech sound can be affected by viewing an image of a grip. The precision grip stimulus triggered relatively rapid production of the front-close vowel [i]. In contrast, the effect related to the power grip stimulus was mostly linked to the vertical dimension of the pronounced vowel since this stimulus triggered relatively rapid production of the back-open vowel [a] and back-mid-open vowel [o] while production of the back-close vowel [u] was not influenced by it. The fact that production of the dorsal consonant [k] or coronal consonant [t] were not influenced by these stimuli suggests that the effect was not associated with a relative front-back tongue shape of the articulation in the absence of changes in any vertical articulatory components. These findings provide evidence for an intimate interaction between certain articulatory gestures and grip types, suggesting that an overlapping visuomotor network operates for planning articulatory gestures and grasp actions.Peer reviewe

Die Verarbeitung von Eigennamen im Mandarin-Chinesischen : eine Verhaltens- und Neuroimaging-Studie

Yen H-L. Processing of proper names in Mandarin Chinese : a behavioral and neuroimaging study. Bielefeld (Germany): Bielefeld University; 2006.Proper names have been considered as a universal language class (Bright, 2003; Müller 2004). The distinction between proper names and common nouns has been postulated since several thousand years in ancient Greek and in Chinese philosophy of language (e.g., Kripke, 1972; Wu, 1997). Furthermore, this dissociation has been supported by experimental data (e.g., Müller & Kutas, 1996) and case studies (e.g., Lyons, 2002). This dissertation explores the processing of proper names in Mandarin Chinese in which the morphology of proper names and the tradition of name giving differ greatly from Indo-European languages such as German and English. It aims to figure out whether the theoretically based dissociation has a neurocognitive reality. Besides a behavior study (category decision task), we carried out an auditory and a visual functional magnetic resonance imaging (fMRI) experiment. Forty native speakers of Mandarin Chinese took part in the behavior study whereas twelve different participants participated the fMRI study. For both modalities, forty personal names, forty geographical names and forty common nouns were used as experimental stimuli. Different words were applied in the auditory and the visual experiment. The behavior study tested 20 brand names in addition. In general, Mandarin Chinese speakers of the present study were able to recognize proper names as type (here: personal names and geographical names) significantly faster than common nouns in both auditory and visual modality. In contrast, brand names did not exhibit the faster reaction time than common nouns. The reaction time of brand names was significantly longer than personal names and geographical names. In our fMRI study, processing of proper names and processing of common nouns revealed partially different brain activation patterns. Contrasts between personal names and common nouns as well as contrasts between geographical names and common nouns revealed significant activation. In auditory modality, proper names revealed more activation in bilateral anterior temporal cortices, premotor area and anterior precuneus. In visual modality, proper names evoked significant activation in the frontal lobe including frontal eye fields and premotor area. Despite of modality, common nouns yielded significant activation in the left posterior temporal cortex. Further characteristic of processing of common nouns was activation in occipital area and temporo-parietal junction. Our fMRI findings support the view that processing of proper names and common nouns involve different brain areas. This may due to the difference between general semantic processing and identity-specific semantic processing. Moreover, the corresponding cognitive mechanism of proper name processing may differ from common nouns. The present finding in Mandarin Chinese is also supported by previous research of Indo-European languages. Corresponding to the hypothesis which has been discussed in the philosophy of language over two thousand years, the special status of proper names can be supported by our neurocognitive evidence

Substrats neuronaux du traitement visuel et sémantique des mots dans le vieillissement normal : apports de la MEG

Bien que l’on ait longtemps considéré que les substrats cérébraux de la mémoire sémantique (MS) demeuraient intacts au cours du vieillissement normal (VN), en raison d’une préservation de la performance des personnes âgées à des épreuves sémantiques, plusieurs études récentes suggèrent que des modifications cérébrales sous-tendant le traitement sémantique opèrent au cours du vieillissement. Celles-ci toucheraient principalement les régions responsables des aspects exécutifs du traitement sémantique, impliqués dans les processus de recherche, de sélection et de manipulation stratégique de l’information sémantique. Cependant, les mécanismes spécifiques régissant la réorganisation cérébrale du traitement sémantique au cours du VN demeurent méconnus, notamment en raison de divergences méthodologiques entre les études. De plus, des données de la littérature suggèrent que des modifications cérébrales associées au vieillissement pourraient également avoir lieu en relation avec les aspects perceptifs visuels du traitement des mots. Puisque le processus de lecture des mots représente un processus interactif et dynamique entre les fonctions perceptuelles de bas niveau et les fonctions de plus haut niveau tel que la MS, il pourrait exister des modifications liées à l’âge au plan des interactions cérébrales entre les aspects perceptifs et sémantiques du traitement des mots. Dans son ensemble, l’objectif de la présente thèse était de caractériser les modifications cérébrales ainsi que le décours temporel du signal cérébral qui sont associés au traitement sémantique ainsi qu’au traitement perceptif des mots en lien avec le VN, ainsi que les relations et les modulations entre les processus sémantiques et perceptifs au cours du VN, en utilisant la magnétoencéphalographie (MEG) comme technique d’investigation. Dans un premier temps (chapitre 2), les patrons d’activation cérébrale d’un groupe de participants jeunes et d’un groupe de participants âgés sains ont été comparés alors qu’ils effectuaient une tâche de jugement sémantique sur des mots en MEG, en se concentrant sur le signal autour de la N400, une composante associée au traitement sémantique. Les résultats démontrent que des modifications cérébrales liées à l’âge touchent principalement les structures impliquées dans les aspects exécutifs du traitement sémantique. Une activation plus importante du cortex préfrontal inférieur (IPC) a été observée chez les participants jeunes que chez les participants âgés, alors que ces derniers activaient davantage les régions temporo-pariétales que les jeunes adultes. Par ailleurs, le lobe temporal antérieur (ATL) gauche, considéré comme une région centrale et amodale du traitement sémantique, était également davantage activé par les participants âgés que par les jeunes adultes. Dans un deuxième temps (chapitre 3), les patrons d’activation cérébrale d’un groupe de participants jeunes et d’un groupe de participants âgés sains ont été comparés en se concentrant sur le signal associé au traitement perceptif visuel, soit dans les 200 premières millisecondes du traitement des mots. Les résultats montrent que des modifications cérébrales liées à l’âge touchent le gyrus fusiforme mais aussi le réseau sémantique, avec une plus grande activation pour le groupe de participants âgés, malgré une absence de différence d’activation dans le cortex visuel extrastrié entre les deux groupes. Les implications théoriques des résultats de ces deux études sont ensuite discutées, et les limites et perspectives futures sont finalement adressées (chapitre 4).While it has long been assumed that the organization of the brain network underlying semantic processing remains intact in normal aging, mainly due to older adults’ intact behavioral performance on semantic tasks, several recent studies suggest that brain changes underlying semantic processing operate during aging. These changes appear to affect mainly the brain regions responsible for the executive aspects of semantic memory (SM), involved in semantic search and selection processes, as well as the strategic manipulation of semantic knowledge. However, the specific mechanisms underlying cerebral reorganization of semantic processing in normal aging are not well understood, partly because of methodological differences among studies. Recent literature also suggests that brain changes may be observed in relation to visual perceptual aspects of word processing in older adults. Since reading words is a dynamic interactive process between low-level perceptual functions and higher-order processes such as semantic processing, there may be age-related changes in terms of brain interactions between perceptual and semantic aspects of word processing. The general aim of this thesis was to characterize the cortical changes and the time course of brain signal associated with semantic and perceptual processing of words, as well as the modulations between semantic and perceptual processes in normal aging, using magnetoencephalography (MEG) as the investigative method. Firstly (Chapter 2), the patterns of brain activation of two groups of healthy younger and older adults were compared relative to a semantic task participants carried out during MEG acquisition, by focusing on the signal around the N400, a component associated with semantic processing. The results indicate that brain changes associated with normal aging mainly affect structures involved in the executive aspects of semantic processing. Greater activation was observed in prefrontal cortex for younger relative to older adults, while the latter group of participants activated the temporoparietal region to a greater extent than young adults. Moreover, the left anterior temporal lobe (ATL), considered to be a central and amodal region of semantic processing, was also more activated by older than younger participants. Secondly (Chapter 3), specific patterns of brain activation of younger and healthy older adults were compared in relation to visual perceptual processing, by focusing on the 200 first milliseconds of cortical signal during word processing. The results show that the age-related brain changes affect the fusiform gyrus, as well as the semantic network, with greater activation found in these regions in the group of older participants relative to younger participants, while no difference in activation of the visual extrastriate cortex was found between groups. The theoretical implications of the results of these two studies are discussed. Finally, limitations of this thesis and future perspectives are addressed (Chapter 4)

Language Development across the Life Span: A Neuropsychological/Neuroimaging Perspective

Language development has been correlated with specific changes in brain development. The aim of this paper is to analyze the linguistic-brain associations that occur from birth through senescence. Findings from the neuropsychological and neuroimaging literature are reviewed, and the relationship of language changes observable in human development and the corresponding brain maturation processes across age groups are examined. Two major dimensions of language development are highlighted: naming (considered a major measure of lexical knowledge) and verbal fluency (regarded as a major measure of language production ability). Developmental changes in the brain lateralization of language are discussed, emphasizing that in early life there is an increase in functional brain asymmetry for language, but that this asymmetry changes over time, and that changes in the volume of gray and white matter are age-sensitive. The effects of certain specific variables, such as gender, level of education, and bilingualism are also analyzed. General conclusions are presented and directions for future research are suggested

Neuropsychological model of the realization of information need

The main goal of information retrieval (IR) is to satisfy information need (IN). IN refers to a complex concept: at the very initial state of the phenomenon (that is, at a visceral level), even the searcher may not be aware of its existence. Thus, despite advances in the past few decades in both the IR and relevant scientific communities, we do not fully understand how an IN emerges and how it is physically manifested. In this article we aim to inform a holistic view of the realization of IN using functional magnetic resonance imaging. We collected new data of brain activity of 24 participants while they formulated and stated a realization of IN in a Question Answering task, focusing on a distributed set of brain regions associated with activities related to IN, found in our previous study. Results of a functional connectivity analysis led us to propose a neuropsychological model of the realization of IN. Our model consists of three components: (a) a successful memory retrieval component, (b) an information flow regulation component, and (c) a high-level perception component. We believe this study constitutes an important step in unraveling the nature of IN and how to better satisfy IN