Reflections on the concept of the central executive

Notes that the central executive lies at the heart of A. D. Baddeley's theory of working memory, but that what it does has been characterized in several different ways. This chapter reviews and brings together various interpretations of central executive functioning. The authors describe an experiment involving a novel cognitive task to point out the restrictive nature of the term 'executive capacity.' The chapter concludes by commenting briefly on the implications of a working memory model in which the executive does not play a major part.

Empirical impact of cache effects for vision system design

Computer vision applications generally split their problem into multiple simpler tasks. Likewise research often combines algorithms into systems for evaluation purposes. Frameworks for modular vision provide interfaces and mechanisms for algorithm combination and network transparency. However, these don’t provide interfaces efficiently utilising the slow memory in modern PCs. We investigate quantitatively how system performance varies with different patterns of memory usage by the framework for an example vision system.

Planning rigid body motions using elastic curves

This paper tackles the problem of computing smooth, optimal trajectories on the Euclidean group of motions SE(3). The problem is formulated as an optimal control problem where the cost function to be minimized is equal to the integral of the classical curvature squared. This problem is analogous to the elastic problem from differential geometry and thus the resulting rigid body motions will trace elastic curves. An application of the Maximum Principle to this optimal control problem shifts the emphasis to the language of symplectic geometry and to the associated Hamiltonian formalism. This results in a system of first order differential equations that yield coordinate free necessary conditions for optimality for these curves. From these necessary conditions we identify an integrable case and these particular set of curves are solved analytically. These analytic solutions provide interpolating curves between an initial given position and orientation and a desired position and orientation that would be useful in motion planning for systems such as robotic manipulators and autonomous-oriented vehicles.

The hanging man: death, indeterminacy and the event

This article discusses approaches to the interpretation and analysis an event that is poised between reality and performance. It focuses upon a real event witnessed by the author while driving out of Los Angeles, USA. A body hanging on a rope from a bridge some 25/30 feet above the freeway held up the traffic. The status of the body was unclear. Was it the corpse of a dead human being or a stuffed dummy, a simulation of a death? Was it is tragic accident or suicide or was it a stunt, a protest or a performance? Whether a real body or not, it was an event: it drew an audience, it took place in a defined public space bound by time and it disrupted everyday normality and the familiar. The article debates how approaches to performance can engage with a shocking event, such as the Hanging Man, and the frameworks of interpretation that can be brought to bear on it. The analysis takes account of the function of memory in reconstructing the event, and the paradigms of cultural knowledge that offered themselves as parallels, comparators or distinctions against which the experience could be measured, such as the incidents of self-immolation related to demonstrations against the Vietnam War, the protest by the Irish Hunger Strikers and the visual impact of Anthony Gormley’s 2007 work, 'Event Horizon'. Theoretical frameworks deriving from analytical approaches to performance, media representation and ethical dilemmas are evaluated as means to assimilate an indeterminate and challenging event, and the notion of what an ‘event’ may be is itself addressed.

'The Elements' and Hobbesian moral thinking

It is easy to read Hobbes's moral thinking as a deviant contribution to 'modern' natural law, especially if Leviathan (1651) is read through a lens provided by De Cive (1642). But The Elements of Law (1640) encourages the view that Hobbes's argument is 'physicalist', that is, that it requires no premises beyond those required by his physics of matter in motion. The Elements included a draft De Homine and its argument is intimately connected with De Cive's; it shows how such concepts as 'reason', 'right', 'natural law' and 'obligation' can be understood in physicalist terms. But Hobbes's decision to print the latter work in isolation has led to serious misunderstandings

Potential health effects of Champagne wine consumption

Epidemiological studies have suggested an inverse correlation between red wine consumption and the incidence of cardiovascular and neurodegenerative disorders. Although white wines are generally low in polyphenol content as compared to red wines, champagne has been shown to contain relatively high amounts of phenolic acids that may exert protective cellular actions in vivo. In this study, we have investigated the potential cardioprotective and neuroprotective effects of champagne. Our data suggest that a daily moderate consumption of champagne may improve vascular performance via the delivery of phenolic constituents capable of improving NO bioavailability and the modulation of metalloproteinase. Moreover, champagne intervention significantly increased spatial working memory in aged animals, whilst no improvement was observed in the presence of alcohol. Together, these data indicate that polyphenols present in champagne may induce cardioprotective and neuroprotective effects, delaying the onset of degenerative disorders.

Direct evidence for attention-dependent influences of the frontal eye-fields on feature-responsive visual cortex

Voluntary selective attention can prioritize different features in a visual scene. The frontal eye-fields (FEF) are one potential source of such feature-specific top-down signals, but causal evidence for influences on visual cortex (as was shown for "spatial" attention) has remained elusive. Here, we show that transcranial magnetic stimulation (TMS) applied to right FEF increased the blood oxygen level-dependent (BOLD) signals in visual areas processing "target feature" but not in "distracter feature"-processing regions. TMS-induced BOLD signals increase in motion-responsive visual cortex (MT+) when motion was attended in a display with moving dots superimposed on face stimuli, but in face-responsive fusiform area (FFA) when faces were attended to. These TMS effects on BOLD signal in both regions were negatively related to performance (on the motion task), supporting the behavioral relevance of this pathway. Our findings provide new causal evidence for the human FEF in the control of nonspatial "feature"-based attention, mediated by dynamic influences on feature-specific visual cortex that vary with the currently attended property.

Curcumin protects organotypic hippocampal slice cultures 4 from Ab1–42 -induced synaptic toxicity

Increasing evidence demonstrates that beta-amyloid (Ab) is toxic to synapses, resulting in the progressive dismantling of neuronal circuits. Counteract the synaptotoxic effects of Ab could be particularly relevant for providing effective treatments for Alzheimer’s disease (AD). Curcumin was recently reported to improve learning and memory in animal models of AD. Little is currently known about the specific mechanisms by which Ab affects neuronal excitability and curcumin ameliorates synaptic transmission in the hippocampus. Organotypic hippocampal slice cultures exposed to Ab1–42 were used to study the neuroprotective effects of curcumin through a spectral analysis of multi-electrode array (MEA) recordings of spontaneous neuronal activity. Curcumin counteracted both deleterious effects of Ab; the initial synaptic dysfunction and the later neuronal death. The analysis of MEA recordings of spontaneous neuronal activity showed an attenuation of signal propagation induced by Ab before cell death and curcumin-induced alterations to local field potential (LFP) phase coherence. Curcumin-mediated attenuation of Ab-induced synaptic dysfunction involved regulation of synaptic proteins, namely phospho-CaMKII and phosphosynapsin I. Taken together, our results expand the neuroprotective role of curcumin to a synaptic level. The identification of these mechanisms underlying the effects of curcumin may lead to new targets for future therapies for AD.

Evidence for a second meal cognitive effect: glycaemic responses to high and low glycaemic index evening meals are associated with cognition the following morning

Low glycaemic index (GI) foods consumed at breakfast can enhance memory in comparison to high-GI foods; however, the impact of evening meal GI manipulations on cognition the following morning remains unexplored. Fourteen healthy males consumed a high-GI evening meal or a low-GI evening meal in a counterbalanced order on two separate evenings. Memory and attention were assessed before and after a high-GI breakfast the following morning. The high-GI evening meal elicited significantly higher evening glycaemic responses than the low-GI evening meal. Verbal recall was better the morning following the high-GI evening meal compared to after the low-GI evening meal. In summary, the GI of the evening meal was associated with memory performance the next day, suggesting a second meal cognitive effect. The present findings imply that an overnight fast may not be sufficient to control for previous nutritional consumption.

En undersökning om typografins betydelse för läsbarhet av ord i rörelse

The purpose of this work was to determine how important a word’s setting was for the readability of typography in motion. Facts regarding how reading works and the importance of the words formation for the readability were used to form a computer test. This test was performed by 15 test persons and the results were analyzed. The results show that the serif was easier to read than the sanserif. The words of the serif which were easiest to read were the words with positive tracking and the words with capital letters. Also for the sanserif, these words were the easiest to read.

”När man kollar på bilden tänker man så här” : en receptionsstudie av gymnasieelevers uppfattning om bilder som kunskapskällor i historieundervisningen

Images are used in history education for a variety of reasons, not least to generate interest through a better understanding of historical events and people. The aim of this study was to investigate how historical pictures, either illustrated or documentary/photographic, can be used as a resource for activating and improving pupils' historical empathy, in the way described by Stéphane Lévasque. I conducted a reception study on five different focus groups consisting of pupils from different upper secondary schools in Sweden. The pupils varied with regard to number of credits for admission to upper secondary school. A sixth group of pupils was interviewed as a contrasting control group in order to add perspective to the results. The discussions were based on the pupils' interpretations of 34 selected pictures, all of which were taken from the most common history textbooks. Each pupil was asked to choose the picture he/she felt was the most representative historical image. On the basis of the strategies used by the pupils when interpreting the pictures and discussing them, the material was analysed in accordance with Lévesque's categories: imagination, historical contextualisation and morals. The last category, morals, was further divided into three sub-categories: sense of justice, sympathy and progression. The reflections of the pupils and the degree of contextualisation varied. It appeared that the pupils were less inclined to discuss assumptions about the persons in the pictures; instead they chose to discuss the historical context in question. The pictures in this study did not seem to trigger the pupils to fabricate anachronistic reasoning about history; when they did produce lengthy reasoning, it was contextual, structural and metahistorical. In this context, the pupils who belonged to the group with the highest average of credits showed some signs of reflection on the basis of historical context and some criticism about the historical sources. On no occasion did any of the pupils choose a picture as a concrete expression of injustice. One of the questions this study aimed to explore was whether a lack of historical context affects how pictures trigger emotions and reasoning on the basis of moral aspects. Some of the pupils displayed moral standpoints, primarily the degree of morals concerning injustice. One possible interpretation could be that the feeling of being unfairly treated and subjected to insulting behaviour and social injustice was something the pupils could relate to. The group of pupils who had not yet studied history at upper secondary school, the control group, generally made reflections using this sort of reasoning when they discussed the historical aspects of the pictures.

Influência do tratamento crônico com cafeína em modelos animais de esquizofrenia : parâmetros cognitivos e comportamentais

A esquizofrenia envolve um conjunto de sintomas de sensopercepção, cognição e afeto que compromete significativamente a vida do sujeito. O mais aceito modelo para se entender essa doença é o modelo de hiperatividade dopaminérgica, pois drogas como anfetamina e cocaína, que aumentam a atividade dopaminérgica, mimetizam alguns sintomas dessa patologia, e os fármacos usados para o tratamento são os que bloqueiam os receptores de dopamina. Além da dopamina, o sistema glutamatérgico também tem sido relacionado à esquizofrenia, pelo fato de antagonistas de receptores glutamatérgicos do tipo NMDA, tais como PCP, MK-801 e cetamina, provocarem alguns sintomas dessa doença, como desorganização cognitiva e delírios em pessoas saudáveis. adenosina, por sua vez, desempenha um papel neuromodulatório tanto da atividade dopaminérgica quanto da atividade glutamatérgica, inibindo o tônus de ambos neurotransmissores por diferentes vias. Assim, sugerimos que antagonistas de receptores adenosinérgicos, como a cafeína, também seriam um modelo farmacológico para a doença. Com base nisso, demonstramos previamente que camundongos tratados cronicamente com cafeína desenvolvem tolerância cruzada ao efeito do antagonista NMDA MK-801 em provocar hiperlocomoção, mas não em seu déficit cognitivo na esquiva inibitória. Buscando ampliar e melhor caracterizar essa interação, os seguintes parâmetros foram avaliados em camundongos: atividade locomotora realizando-se as curvas de dose e de tempo; memória de trabalho, avaliada na tarefa de alternação tardia; memória de longa duração, avaliada na tarefa de esquiva inibitória e a avaliação de ataxia. Os resultados nos mostraram que camundongos subcronicamente tratados com cafeína na bebida (1 mg/mL, por 1, 3, ou 7 dias) apresentaram habituação semelhante entre os grupos e que MK-801 (0,25 mg/kg, i.p.) produziu hiperlocomoção nos animais tratados com água e 1 dia de cafeína, com efeito diminuído depois de 3 dias e praticamente abolido depois de 7 dias. Depois de 7 dias, o efeito também foi dose-dependente, sem tolerância cruzada na dose de 0,1 mg/mL, intermediária na dose de 0,3 mg/mL e total a 1,0 mg/mL. Os escores de ataxia induzidos por 0,5 mg/kg de MK-801 não foram afetados pelo tratamento com cafeína por 7 dias a 1 mg/mL, mas uma hiperlocomoção transitória foi observada. O tratamento com cafeína por 7 dias a 1 mg/mL preveniu os déficits induzidos por 0,01 mg/kg de MK-801 na tarefa de esquiva inibitória e os atenuou, a 0,4 mg/kg de MK-801, na tarefa de alternação tardia, no labirinto em T. Conclui-se, então, que a hiperlocomoção e os déficits cognitivos – mas não a ataxia – induzidos por MK-801 podem estar influenciados pela atividade reduzida da adenosina. Assim, os estudos sobre a ação da adenosina podem se fazer relevantes para a melhor compreensão da neurobiologia da esquizofrenia. Estes resultados são concordantes com o novo modelo proposto, que é o de hipofunção adenosinérgica na esquizofrenia.

Modelando a volatilidade dos retornos de Petrobrás usando dados de alta frequência

O objetivo do presente trabalho é analisar as características empíricas de uma série de retornos de dados em alta freqüência para um dos ativos mais negociados na Bolsa de Valores de São Paulo. Estamos interessados em modelar a volatilidade condicional destes retornos, testando em particular a presença de memória longa, entre outros fenômenos que caracterizam este tipo de dados. Nossa investigação revela que além da memória longa, existe forte sazonalidade intradiária, mas não encontramos evidências de um fato estilizado de retornos de ações, o efeito alavancagem. Utilizamos modelos capazes de captar a memória longa na variância condicional dos retornos dessazonalizados, com resultados superiores a modelos tradicionais de memória curta, com implicações importantes para precificação de opções e de risco de mercado

Caminhos do lembrar: a construção e os usos políticos da memória no morro do Borel

O objetivo do presente trabalho é elaborar uma reflexão sobre os processos de construção e os usos políticos da memória na favela do Borel. Para o alcance dessa finalidade, serão analisados o livro “As lutas do povo do Borel”, de autoria de Manoel Gomes, ex-morador local e ex-militante comunista, já falecido, e o projeto Condutores de Memória, realizado por moradoras das favelas do Borel e da Casa Branca em parceria com a Agenda Social Rio. Desse modo, pretende-se pensar as características da articulação de diferentes atores na elaboração de suportes de memória de moradores de favelas, a partir do caso do Borel, bem como a forma como diferentes contextos históricos podem interferir na instrumentalização da memória como forma de reivindicação política.

Os determinantes morfogenéticos da linguagem expressiva

O presente trabalho parte de uma reinterpretação dos determinantes e da organização da linguagem expressiva em indivíduos portadores de deficiência da audição. Neste sentido, submete a uma análise crítica as condições de estruturação e aquisição de um sistema de comunicação simbólica de natureza essencialmente verbal por parte de tais indivíduos. Avalia, em particular modo, a perspectiva de uma organização fonológica do discurso em portadores de surdez profunda “pré-linguagem~, como um processo que ultrapassa as possibilidades d e uma mera aprendizagem. A linguagem vista então como um processo semiótico de natureza percepto-expressiva, que se estabelece ao longo do desenvolvimento filogenético e ontogenético é assim interpretada, a luz de um novo modelo teórico sobre a Cognição Humana . Tal modelo, pautado em contribuições da Cibernética, da Lógica, da Linguística e da Epistemologia Genética, estabelece plataformas morfogenéticas, a partir das quais o psiquismo se organizaria. Desta maneira, 2 (dois) objetivos essenciais pretendem ser atingidos no presente e s tudo. 1º ) oferecer uma base teórica à dinâmica e processual cognitivo em que o surdo se vê envolvido ao longo da aprendizagem de um sistema verbal-simbólico - à luz de uma hipótese pré-formista, de base morfogenética. 2º) avaliar, a partir da linguagem expressiva escrita apresentada por deficientes auditivos com perda profunda ~pré-linguagem", a hipótese formulada por F. Lo P. Seminério (1980) "de uma memória morfogenética na espécie humana", a partir do que, toda a atividade cognitiva se organizaria, passando a operar segundo estruturas-código, pré-fixadas. A fim de confirmar as proposições estabelecidas, apresenta - se uma Verificação Empírica através de estudos exploratórios realizados com 6 (seis) sujeitos. Os resultados obtidos confirmam a existência de um marco seletivo e organizador de natureza audio-fonética, também entre indivíduos surdos. Constata-se que a informação veiculada é capaz de ser tratada, programada e recuperada linguisticamente, ainda que sem a possibilidade de um mecanismo de retroalimentação ao sistema que se desenvolve. O que equivale a dizer, que o indivíduo surdo apesar de não ouvir, programa à nível áudio-fonético, programação essa que vem a ser recuperada ou atualizada graças aos recursos e técnicas pedagógicas especializadas. Tais resultados sugerem uma reavaliação dos métodos psicopedagógicos usuais nesta área, podendo-se retomar sob nova orientação o debate de temas atuais, nas diretrizes das técnicas e do instrumental utilizado.