Investigations of attentional processing in parietal and occipital human cortical regions with magnetoencephalography

Attention defines our mental ability to select and respond to stimuli, internal or external, on the basis of behavioural goals in the presence of competing, behaviourally irrelevant, stimuli. The frontal and parietal cortices are generally agreed to be involved with attentional processing, in what is termed the 'fronto-parietal' network. The left parietal cortex has been seen as the site for temporal attentional processing, whereas the right parietal cortex has been seen as the site for spatial attentional processing. There is much debate about when the modulation of the primary visual cortex occurs, whether it is modulated in the feedforward sweep of processing or modulated by feedback projections from extrastriate and higher cortical areas. MEG and psychophysical measurements were used to look at spatially selective covert attention. Dual-task and cue-based paradigms were used. It was found that the posterior parietal cortex (PPC), in particular the SPL and IPL, was the main site of activation during these experiments, and that the left parietal lobe was activated more strongly than the right parietal lobe throughout. The levels of activation in both parietal and occipital areas were modulated in accordance with attentional demands. It is likely that spatially selective covert attention is dominated by the left parietal lobe, and that this takes the form of the proposed sensory-perceptual lateralization within the parietal lobes. Another form of lateralization is proposed, termed the motor-processing lateralization, the side of dominance being determined by handedness, being reversed in left- relative to right-handers. In terms of the modulation of the primary visual cortex, it was found that it is unlikely that V1 is modulated initially; rather the modulation takes the form of feedback from higher extrastriate and parietal areas. This fits with the idea of preattentive visual processing, a commonly accepted idea which, in itself, prevents the concept of initial modulation of V1.

Modulation of long-range neural synchrony reflects temporal limitations of visual attention in humans

Because of attentional limitations, the human visual system can process for awareness and response only a fraction of the input received. Lesion and functional imaging studies have identified frontal, temporal, and parietal areas as playing a major role in the attentional control of visual processing, but very little is known about how these areas interact to form a dynamic attentional network. We hypothesized that the network communicates by means of neural phase synchronization, and we used magnetoencephalography to study transient long-range interarea phase coupling in a well studied attentionally taxing dual-target task (attentional blink). Our results reveal that communication within the fronto-parieto-temporal attentional network proceeds via transient long-range phase synchronization in the beta band. Changes in synchronization reflect changes in the attentional demands of the task and are directly related to behavioral performance. Thus, we show how attentional limitations arise from the way in which the subsystems of the attentional network interact. The human brain faces an inestimable task of reducing a potentially overloading amount of input into a manageable flow of information that reflects both the current needs of the organism and the external demands placed on it. This task is accomplished via a ubiquitous construct known as “attention,” whose mechanism, although well characterized behaviorally, is far from understood at the neurophysiological level. Whereas attempts to identify particular neural structures involved in the operation of attention have met with considerable success (1-5) and have resulted in the identification of frontal, parietal, and temporal regions, far less is known about the interaction among these structures in a way that can account for the task-dependent successes and failures of attention. The goal of the present research was, thus, to unravel the means by which the subsystems making up the human attentional network communicate and to relate the temporal dynamics of their communication to observed attentional limitations in humans. A prime candidate for communication among distributed systems in the human brain is neural synchronization (for review, see ref. 6). Indeed, a number of studies provide converging evidence that long-range interarea communication is related to synchronized oscillatory activity (refs. 7-14; for review, see ref. 15). To determine whether neural synchronization plays a role in attentional control, we placed humans in an attentionally demanding task and used magnetoencephalography (MEG) to track interarea communication by means of neural synchronization. In particular, we presented 10 healthy subjects with two visual target letters embedded in streams of 13 distractor letters, appearing at a rate of seven per second. The targets were separated in time by a single distractor. This condition leads to the “attentional blink” (AB), a well studied dual-task phenomenon showing the reduced ability to report the second of two targets when an interval <500 ms separates them (16-18). Importantly, the AB does not prevent perceptual processing of missed target stimuli but only their conscious report (19), demonstrating the attentional nature of this effect and making it a good candidate for the purpose of our investigation. Although numerous studies have investigated factors, e.g., stimulus and timing parameters, that manipulate the magnitude of a particular AB outcome, few have sought to characterize the neural state under which “standard” AB parameters produce an inability to report the second target on some trials but not others. We hypothesized that the different attentional states leading to different behavioral outcomes (second target reported correctly or not) are characterized by specific patterns of transient long-range synchronization between brain areas involved in target processing. Showing the hypothesized correspondence between states of neural synchronization and human behavior in an attentional task entails two demonstrations. First, it needs to be demonstrated that cortical areas that are suspected to be involved in visual-attention tasks, and the AB in particular, interact by means of neural synchronization. This demonstration is particularly important because previous brain-imaging studies (e.g., ref. 5) only showed that the respective areas are active within a rather large time window in the same task and not that they are concurrently active and actually create an interactive network. Second, it needs to be demonstrated that the pattern of neural synchronization is sensitive to the behavioral outcome; specifically, the ability to correctly identify the second of two rapidly succeeding visual targets

Are stress and mixed urinary incontinence associated with impaired executive control in community-dwelling older women?

Objectives: To assess whether stress or mixed urinary incontinence (UI) is associated with deficits in executive functioning among community-dwelling women. Design: An observational study comparing the performance, using multivariate analyses of variance (MANOVAs) and Bonferroni post hoc test, of continent women and women with stress or mixed UI during executive control tasks. Setting: The research center of the Institut universitaire de gériatrie de Montréal. Participants: One hundred and fifty-five community-dwelling women aged 60 and older participated in the study. Measurements: Based on the Urogenital Distress Inventory (UDI), participants were split into three groups: 35 continent women, 43 women with stress UI, and 78 women with mixed UI. Participants completed a battery of neuropsychological tests and a computerized dual-task test. Results: Women with mixed UI showed poorer performances than continent and stress UI women in executive control functions. Deficits were specific to tests involving switching and sharing/dividing attention between two tasks. Conclusion: Results of this study suggest that mixed UI can be associated with executive control deficits in community-dwelling older women. Future intervention studies in the treatment of UI should take the higher risk of an executive control deficit in women with UI under consideration.

Are stress and mixed urinary incontinence associated with impaired executive control in community-dwelling older women?

Objectives: To assess whether stress or mixed urinary incontinence (UI) is associated with deficits in executive functioning among community-dwelling women. Design: An observational study comparing the performance, using multivariate analyses of variance (MANOVAs) and Bonferroni post hoc test, of continent women and women with stress or mixed UI during executive control tasks. Setting: The research center of the Institut universitaire de gériatrie de Montréal. Participants: One hundred and fifty-five community-dwelling women aged 60 and older participated in the study. Measurements: Based on the Urogenital Distress Inventory (UDI), participants were split into three groups: 35 continent women, 43 women with stress UI, and 78 women with mixed UI. Participants completed a battery of neuropsychological tests and a computerized dual-task test. Results: Women with mixed UI showed poorer performances than continent and stress UI women in executive control functions. Deficits were specific to tests involving switching and sharing/dividing attention between two tasks. Conclusion: Results of this study suggest that mixed UI can be associated with executive control deficits in community-dwelling older women. Future intervention studies in the treatment of UI should take the higher risk of an executive control deficit in women with UI under consideration.

Efeito de dois programas de reabilitação psicomotora (atividade contínua versus atividade intervalada) na capacidade neuromotora de idosos institucionalizados

Objetivo: Investigar o efeito de dois programas de reabilitação psicomotora (atividade contínua versus atividade intervalada) na capacidade neuromotora de idosos institucionalizados. Metodologia: A amostra integrou 17 participantes (85,81±6,26 anos) que, numa fase inicial, mantiveram as atividades durante 6 semanas (período de controlo) e, posteriormente, 9 integraram um programa com intervenção intervalada (GI) e 8 um programa com intervenção contínua (GC). Ambos os programas tiveram a duração de 12 semanas, com uma periodicidade de 2 sessões por semana e duração de 60 minutos. Foram avaliadas as variáveis atenção (Trail Making Test), capacidade de planeamento (Torre de Londres), o desempenho em situação de dupla tarefa (Timed Up and Go modificado) e equilíbrio (Timed Up and Go e Índice de Tinetti). Resultados: O GI evidenciou melhorias significativas nas variáveis da atenção, da capacidade de planeamento, dupla tarefa e equilíbrio (p<0,05), enquanto que o GC apenas o evidenciou na variável capacidade de planeamento (p<0,05). Conclusão: Os resultados sugerem que o programa de reabilitação psicomotora com atividade intervalada será mais benéfico para os idosos institucionalizados que programa com atividade contínua, particularmente na atenção, no desempenho em situação de dupla tarefa e no equilíbrio; ABSTRACT: Objective: To research the effect of two psychomotor rehabilitation programs (continuous activity against intervealed activity) in the neuromotor ability of institutionalized elderly people. Metodology: The sample had 17 participants (85.81 ± 6.26 years), that in an initial phase retained activity for 6 weeks (control period) and then, 9 integrated a program with intervealed intervention (GI) and 8 a program with continuous intervention (GC). ). Both of the programs had 12 weeks, 2 sessions per week and 60 minutes per session. Was evaluated the variables attention (Trail Making Test); planning capacity (London Tower); dual task capacity (modified Timed Up and Go) and balance (Timed Up and Go and Tinetti Index). Results: The GI showed significant improvements in the variables attention, performance in dual task ability and balance (p<0,05), while GC revealed significant improvements in planning capacity (p<0,05). Conclusion: The results suggest that the psychomotor rehabilitation program with intervealed activity will be more beneficial for the institutionalized elderly than the program with continuous activity, particularly in the attention, planning capacity, performance in dual task ability and balance.

Correlates of Vitamin D Status in Healthy Older Adults Living in Miami-Dade and its Association with Non-Skeletal Outcomes: A Cross-Sectional Study

Examining factors that affect vitamin D status in the fast-growing elderly population of Miami-Dade, Florida, is needed. Vitamin D deficiency in older adults has been linked to correlates of disability, including falls and fractures, and cardiovascular disease. The purpose of this study was to determine the proportion of vitamin D insufficient individuals and their relationship with vitamin D insufficiency in older adults (n=97) living in Miami-Dade. We evaluated the association between vitamin D status and 1) dual task physical performance to understand the link between vitamin D and cognition in the context of mobility; and 2) cardiometabolic risk, measured by galvanic skin response, pulse oximetry, and blood pressure to create a composite score based on autonomic nervous system and endothelial function. Participants completed baseline assessments that included serum levels of vitamin D, anthropometrics, body composition, dual task physical performance and cardiometabolic risk. Surveys to evaluate vitamin D intake, sun exposure, physical activity, and depressive symptoms were completed. Spearman’s correlations, independent t-tests, paired t-tests, repeated measures ANOVAs, and multiple logistic and linear regressions were used to examine the relationship of vitamin D insufficiency (25(OH)D /ml) and sufficiency (25(OH)D ≥30 ng/ml) with determinants of vitamin D status, dual task physical performance variables and cardiometabolic risk scores. Although the proportion of vitamin D insufficient individuals was lower when compared to the prevalance of the general United States elderly population, it was still common in healthy community-dwelling older adults living in Miami-Dade County, especially among Hispanics. Factors that affected skin synthesis (ethnicity, and sun exposure), and bioavailability/metabolism (obesity) were significant predictors of vitamin D status. Vitamin D insufficiency was not significantly correlated with worse dual task physical performance; however, cognitive performance was worse in the vitamin D insufficient group. Our results suggest a relationship of vitamin D insufficiency with executive dysfunction, and support an association with cardiometabolic risk using an innovative electro-sensor complex, possibly by modulating autonomic nervous system activity and vascular function, thus affecting cardiac performance.

Descriptive analysis of the test of everyday attention for children in a Spanish normative sample

Introduction. Test of Everyday Attention for Children (TEA-Ch) has been validated in different countries demonstrating that it is an instrument with a correct balance between reliability and duration. Given the shortage of trustworthy instruments of evaluation in our language for infantile population we decide to explore the Spanish version of the TEA-Ch. Methods. We administered TEA-Ch (version A) to a sample control of 133 Spanish children from 6 to 11 years enrolled in school in the Community of Madrid. Four children were selected at random by course of Primary Education, distributing the sex of equivalent form. Descriptive analysis and comparison by ages and sex in each of the TEA-Ch's subtests were conducted to establish a profile of the sample. In order to analyze the effect of the age, subjects were grouped in six sub-samples: 6, 7, 8, 9, 10 and 11 years-old. Results. This first descriptive analysis demonstrates age exerted a significant effect on each measure, due to an important "jump" in children's performance between 6 and 7 years-old. The effect of sex was significant only in two visual attention measures (Sky Search & Map) and interaction age and sex exerted a significant effect only in the dual task (Score DT). Conclusions. The results suggest that the Spanish version of the TEA-Ch (A) might be a useful instrument to evaluate attentional processes in Spanish child population.

Efeitos de um programa de exercício multimodal em pessoas idosas institucionalizadas

Objetivo: Investigar os efeitos de um programa de exercício multimodal sobre o funcionamento cognitivo e aptidão física funcional em pessoas idosas institucionalizadas. Método: Os participantes foram selecionados por conveniência entre os utentes de duas instituições de apoio a pessoas idosas. O grupo inicial foi constituído por um total de 21 pessoas de ambos os sexos (77-92 anos). Inicialmente, foi garantido um “período de controlo” de 4 semanas, em que os participantes mantiveram as suas atividades de vida quotidianas normais. Posteriormente, todos os idosos integraram um programa de exercício multimodal durante 8 semanas. Para estudar os efeitos da intervenção foram recolhidos dados em 3 momentos distintos: previamente ao período de controlo, após o período de controlo e no final do programa de intervenção. Foram efetuados testes físicos/motores, cognitivos e de dupla-tarefa (motor-cognitivo). Durante as sessões de exercício, alternaram-se períodos constituídos por tarefas motoras com períodos em que as tarefas motoras implicavam uma mobilização simultânea de recursos cognitivos. Resultados: A análise estatística dos dados recolhidos nos três momentos de avaliação, revelou efeitos positivos da intervenção ao nível da atenção, tempo de reação, força muscular, agilidade e capacidade cardiorrespiratória. Nos testes realizados em dupla-tarefa, foram encontradas melhorias no teste timed up and go, mas não se verificaram melhorias no teste de tempo de reação. A análise estatística dos dados recolhidos nos três momentos de avaliação, revelou efeitos positivos (p<0.05). da intervenção ao nível da atenção, tempo de reação, força muscular, agilidade e capacidade cardiorrespiratória. Nos testes realizados em dupla-tarefa, foram encontradas melhorias no teste timed up and go (p<0.05), mas não se verificaram melhorias no teste de tempo de reação. Conclusões: Um programa de exercícios multimodal induz melhorias no funcionamento cognitivo e motor de pessoas idosas institucionalizadas. É aconselhada a divulgação deste tipo de intervenção para pessoas idosas institucionalizadas; Effects of a Multimodal Exercise Program for Elderly Institutionalized Abstract: Objective: To investigate wthe effects of a multimodal exercise program on cognitive functioning and physical fitness of institutionalized elderly. Method: Participants were selected by convenience among two nursing home residents. Twenty-one people (77-92 years old) of both genders participated. During the first 4 weeks (control period), participants were not engaged in the exercise program and continue with their normal daily life activities. After the control period, the group was engaged in a multimodal exercise program for 8 weeks (2 times per week). To study the effects of a multimodal exercise program, data were collected at three different times: prior to the control period, after the control period, and at the end of the intervention. Several motor tests (physical fitness), cognitive tests and dual-tasks (motor-cognitive) were performed. The exercise sessions alternated between periods of motor taks and periods with motor plus cognitive tasks performed simultaneously. Results: The analysis of the data collected in the three moments of evaluation, show positive effects of the exercise program in cognitive dimensions (information processing speed and attention) and functional physical fitness components (muscle resistance, cardiorespiratory fitness and dynamic balance). In tests carried out in dual-task conditions, the exercise program promoted improvements in the timed up and go test (with mental calculations). Statistical analysis of the data collected at the three evaluation moments revealed positive effects (p <0.05). Of attention intervention, reaction time, muscle strength, agility and cardiorespiratory capacity. In the double-task tests, improvements were found in the timed up and go test (p <0.05), but there were no improvements in the reaction time test. Conclusions: The results of this study indicate that a multimodal exercise program can improve cognitive functioning and physical fitness in institutionalized older people. Thus, this type of intervention should be promoted among nursing home residents.

Study of behavioural and neural bases of visuo-spatial working memory with an fMRI paradigm based on an n-back task

The goal of this study was to propose a new functional magnetic resonance imaging (fMRI) paradigm using a language-free adaptation of a 2-back working memory task to avoid cultural and educational bias. We additionally provide an index of the validity of the proposed paradigm and test whether the experimental task discriminates the behavioural performances of healthy participants from those of individuals with working memory deficits. Ten healthy participants and nine patients presenting working memory (WM) deficits due to acquired brain injury (ABI) performed the developed task. To inspect whether the paradigm activates brain areas typically involved in visual working memory (VWM), brain activation of the healthy participants was assessed with fMRIs. To examine the task's capacity to discriminate behavioural data, performances of the healthy participants in the task were compared with those of ABI patients. Data were analysed with GLM-based random effects procedures and t-tests. We found an increase of the BOLD signal in the specialized areas of VWM. Concerning behavioural performances, healthy participants showed the predicted pattern of more hits, less omissions and a tendency for fewer false alarms, more self-corrected responses, and faster reaction times, when compared with subjects presenting WM impairments. The results suggest that this task activates brain areas involved in VWM and discriminates behavioural performances of clinical and non-clinical groups. It can thus be used as a research methodology for behavioural and neuroimaging studies of VWM in block-design paradigms.

Conductivity in the gravity dual to massive ABJM and the membrane paradigm

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A theoretical analysis of eyewitness identification: Dual -process theory, signal detection theory and eyewitness confidence

Given the growing number of wrongful convictions involving faulty eyewitness evidence and the strong reliance by jurors on eyewitness testimony, researchers have sought to develop safeguards to decrease erroneous identifications. While decades of eyewitness research have led to numerous recommendations for the collection of eyewitness evidence, less is known regarding the psychological processes that govern identification responses. The purpose of the current research was to expand the theoretical knowledge of eyewitness identification decisions by exploring two separate memory theories: signal detection theory and dual-process theory. This was accomplished by examining both system and estimator variables in the context of a novel lineup recognition paradigm. Both theories were also examined in conjunction with confidence to determine whether it might add significantly to the understanding of eyewitness memory. ^ In two separate experiments, both an encoding and a retrieval-based manipulation were chosen to examine the application of theory to eyewitness identification decisions. Dual-process estimates were measured through the use of remember-know judgments (Gardiner & Richardson-Klavehn, 2000). In Experiment 1, the effects of divided attention and lineup presentation format (simultaneous vs. sequential) were examined. In Experiment 2, perceptual distance and lineup response deadline were examined. Overall, the results indicated that discrimination and remember judgments (recollection) were generally affected by variations in encoding quality and response criterion and know judgments (familiarity) were generally affected by variations in retrieval options. Specifically, as encoding quality improved, discrimination ability and judgments of recollection increased; and as the retrieval task became more difficult there was a shift toward lenient choosing and more reliance on familiarity. ^ The application of signal detection theory and dual-process theory in the current experiments produced predictable results on both system and estimator variables. These theories were also compared to measures of general confidence, calibration, and diagnosticity. The application of the additional confidence measures in conjunction with signal detection theory and dual-process theory gave a more in-depth explanation than either theory alone. Therefore, the general conclusion is that eyewitness identifications can be understood in a more complete manor by applying theory and examining confidence. Future directions and policy implications are discussed. ^

Separating deviant and non-deviant sexual preferences with a dual-target rapid serial visual presentation task

Forskning visar att avvikande sexuell preferens (ASP) är en av de mest centrala prediktorerna för återfall i sexualbrott. Eftersom det är viktigt att det i juridiskt beslutsfattande och behandling av sexualförbrytare finns valida och standardiserade verktyg att tillgå för bedömning av ASP, har forskningen under de senaste åren fokuserats på uppmärksamhetsbaserade metoder. Syftet med avhandlingen var att förbättra uppmärksamhetsbaserade metoder genom utvecklingen av en s.k. Rapid Serial Visual Presentation (dtRSVP) metod för att identifiera ASP. Innan vi testade sampel med sexualbrottslingar så genomförde vi tre studier för att kalibrera förfarandena. I dessa studier undersökte vi möjligheten att differentiera mellan homosexuella och heterosexuella män och hur enkelt deltagarna kunde fuska. Dessutom skapade vi en ny uppsättning standardiserade stimuli för bedömningen av pedofilt sexuellt intresse (Virtual People Set, VPS). I skapandet av stimuli togs de etiska och juridiska problemen i beaktande så långt som möjligt. När vi använde dtRSVP som mätningsförfarande för att skilja åt sexuellläggning i ett sampel av homosexuella och heterosexuella män fann vi att sexuellt relevanta stimuli påverkade informationsbehandlingen på ett förutsägbart sätt. Förfarandet hade en god förmåga att skilja sexuella preferenser mellan grupperna och förfarandet var svårt att påverka genom att fuska. När vi använde dtRSVP som mätningsförfarande för att identifiera avvikande sexuell läggning bland dömda sexbrottslingar fann vi att de visade en annorlunda bearbetning av sexuella stimuli jämfört med andra deltagare och att dessa skillnader var i de förväntade riktningarna. Det var däremot svårt att dra några slutsatser angående denna mätmetods förmåga att skilja mellan grupperna pedofiler och icke-pedofiler. Slutligen fann vi att VPS verkar vara ett användbart stimuluspaket för experimentell forskning om pedofilt sexuellt intresse. ---------------------------------------------------- Tutkimuksien mukaan poikkeava seksuaalinen mieltymys (PSM) on yksi seksuaalirikoksen uusimisen keskeisimmistä ennustajista. Oikeudellisessa päätöksenteossa ja seksuaalirikollisten hoidossa on tärkeää, että on käytettävissä kelvollisia ja standardisoituja välineitä PSM:n arvioinnissa. Sen vuoksi on tutkimuksissa viime vuosina keskitytty huomaavaisuuteen perustuviin menetelmiin. Tämän tutkielman tarkoitus oli parantaa huomaavaisuuteen perustuvia menetelmiä kehittämällä nk. Rapid Serial Visual Presentation (dtRSVP) menetelmän. Kalibroidakseen menettelytapoja suoritettiin kolme tutkimusta ennen kuin tutkittiin koeryhmää, johon kuuluvat seksuaalirikollisia. Näissä tutkimuksissa tutkittiin mahdollisuutta erotella homoseksuaalisia ja heteroseksuaalisia miehiä ja tutkittiin missä määrin osallistujien oli helppo huiputtaa. Sen lisäksi, pedofiilisen seksuaalisen mieltymyksen arviointia varten kehitettiin uutta sarjaa standardisoituja virikkeitä (Virtual People Set, VPS). Kehitettäessä virikkeitä otettiin mahdollisimman pitkälti huomioon eettisiä ja oikeudellisia ongelmia. Käytettäessä dtRSVP mittausmenetelmää erotellakseen homo- ja heteroseksuaalista suuntautumista havaitsimme, että seksuaaliset virikkeet vaikuttivat tietojenkäsittelyyn ennustettavalla tavalla. Menettelytavan avulla pystyttiin erotella koeryhmässä olevia seksuaalisia mieltymyksiä ja menettelytapaan oli vaikeaa vaikuttaa huijaamalla. Käytettäessä dtRSVP mittausmenetelmää tunnistaakseen poikkeavaa seksuaalista mieltymystä tuomittujen seksuaalirikollisten keskenään havaitsimme, että he osoittivat erilaista käsittelyä seksuaalisista virikkeistä toisiin osallistujiin verrattuna ja tulokset olivat ennustettavia. Silti oli vaikeaa tehdä johtopäätöksiä mittausmenetelmän kyvystä erotella ryhmiä pedofiilisiä ja ei-pedofiilisiä miehiä. Lopuksi havaitsimme, että VPS näyttää olevan käyttökelpoinen stimulussarja pedofiilisen seksuaalisen mieltymyksen kokeellisissa tutkimuksissa.