Avaliação breve do défice executivo em pessoas idosas com Acidente Vascular Cerebral: Validação da Bateria de Avaliação Frontal

RESUMO Objetivos: O Acidente Vascular Cerebral (AVC) potencia o desenvolvimento de disfunção executiva, conduzindo a défice no desempenho das tarefas do quotidiano. A avaliação neuropsicológica das funções executivas é importante para desenvolver estratégias de reabilitação adequadas. Assim, são objetivos descrever os dados normativos, precisão de diagnóstico, propriedades psicométricas e análise fatorial da Bateria de Avaliação Frontal (FAB), instrumento breve e de rápida administração, numa amostra de idosos com AVC. Métodos: Inserida no projeto Trajetórias do Envelhecimento de Idosos em Resposta Social, esta investigação conta com uma amostra de 112 pessoas idosas com diagnóstico médico de AVC e 157 pessoas idosas de um subgrupo de controlo sem AVC. Os sujeitos apresentam idades compreendidas entre os 60 e os 100 anos (M = 78,20; DP = 7,57) sendo maioritariamente do sexo feminino (n = 194). A avaliação inclui entrevistas e testes neuropsicológicos agrupados em medidas de funcionamento executivo, medidas cognitivas de referência e medidas clínicas de controlo. Resultados: As variáveis idade e escolaridade interferiram nas pontuações obtidas na amostra clínica, não sendo verificado impacto da variável sexo. Para um ponto de corte de 7, a FAB teve uma sensibilidade de 83,4% e especificidade de 66,1 % (AUC = 0,64); revelou um alfa de Cronbach de 0,79 e correlações fortes com os testes executivos (teste de Stroop, Figura Complexa de Rey, fator Atencional-Executivo do Montreal Cognitive Assessment e Alternância nos testes de Fluência verbal). A análise fatorial confirmatória apontou uma estrutura com um fator. Conclusões: A FAB apresenta boa consistência interna, validade convergente e validade de constructo, aparentando ser uma escala útil para avaliar o défice executivo em pessoas idosas com AVC. Dadas algumas limitações do estudo, que poderão explicar a fraca precisão diagnóstica da FAB, são incentivadas investigações futuras pois a FAB revelou-se um instrumento com propriedades psicométricas promissoras. ABSTRACT Goals: Stroke potentiates the development of executive dysfunction, leading to impairment in performance of daily activities. The neuropsychological assessment of executive functions is important to develop adequate rehabilitation strategies. Thus, describing the normative data, diagnostic accuracy, psychometric properties and factor analysis of the Frontal Assessment Battery (FAB), a brief and easy to administer instrument, in a clinical sample with stroke are objectives of this study. Methods: Being part of the Aging Trajectories of Institutionalized Elderly, this research has a sample 112 elderly people with a medical diagnosis of stroke and a control subgroup of 157 elderly people. The subjects have ages between 60 and 100 years old (M = 78.20, SD = 7.57), mostly females (n = 194). The measurements used include interviews and neuropsychological tests grouped in executive functioning measures, cognitive measures of reference and clinical measures of control. Results: The variables age and education affect the scores obtained in the clinical subgroup, having the variable gender no impact on these. Using a cutoff score of 7, the FAB had a sensitivity of 83.4% and a specificity of 66.1% for screening stroke (AUC = 0.64); showed a Cronbach's α of 0.79, and strong correlations with executive tests (Stroop test, Rey Complex Figure, Attentional-Executive factor of Montreal Cognitive Assessment and Switching in the verbal fluency tests). The confirmatory factor analysis supported a one-factor structure. Conclusions: The FAB presents good internal consistency, convergent, and construct when used for elderly with stroke. Due to some limitations of the study, which may explain the weak discriminant validity, further investigations are encouraged because FAB has showed promising psychometric properties.

Síndrome do Lobo Frontal: uma entidade única?

Os autores procedem a uma revisão sobre a Síndrome do Lobo Frontal à luz dos conhecimentos actuais das neurociências e da neuropsicologia, em particular no que refere ao conceito de Teoria da Mente e aos avanços na definição e estudo das Funções Executivas. Reafirmam a perspectiva actual de que a designação de Síndrome do Lobo Frontal não reflecte a complexidade dos sistemas envolvidos na sua etiologia e reduz a uma única entidade quadros clínicos heterogéneos e com níveis distintos de incapacidade funcional e de interacção social.

Responsiveness of the frontal EMG for monitoring the sedation state of critically ill patients.

Background. Excessive sedation is associated with adverse patient outcomes during critical illness, and a validated monitoring technology could improve care. We developed a novel method, the responsiveness index (RI) of the frontal EMG. We compared RI data with Ramsay clinical sedation assessments in general and cardiac intensive care unit (ICU) patients. Methods. We developed the algorithm by iterative analysis of detailed observational data in 30 medical–surgical ICU patients and described its performance in this cohort and 15 patients recovering from scheduled cardiac surgery. Continuous EMG data were collected via frontal electrodes and RI data compared with modified Ramsay sedation state assessments recorded regularly by a blinded trained observer. RI performance was compared with EntropyTM across Ramsay categories to assess validity. Results. RI correlated well with the Ramsay category, especially for the cardiac surgery cohort (general ICU patients r¼0.55; cardiac surgery patients r¼0.85, both P,0.0001). Discrimination across all Ramsay categories was reasonable in the general ICU patient cohort [PK¼0.74 (SEM 0.02)] and excellent in the cardiac surgery cohort [PK¼0.92 (0.02)]. Discrimination between ‘lighter’ vs ‘deeper’ (Ramsay 1–3 vs 4–6) was good for general ICU patients [PK¼0.80 (0.02)] and excellent for cardiac surgery patients [PK¼0.96 (0.02)]. Performance was significantly better than EntropyTM. Examination of individual cases suggested good face validity. Conclusions. RI of the frontal EMG has promise as a continuous sedation state monitor in critically ill patients. Further investigation to determine its utility in ICU decision-making is warranted.

Verbal emotional memory in children and adolescents with temporal lobe epilepsy: A first study

International audience

Proyecto de diseño y cálculo de retroexcavadora de pala frontal

El objetivo del presente proyecto es el diseño y cálculo de la pala frontal para una retroexcavadora de minería. Para el desarrollo del proyecto se han realizado una serie de estudios con sus respectivas iteraciones hasta lograr un equilibrio entre todos los elementos a estudio. Partiendo de la función objetivo a cumplir por el diseño, el primer paso consiste en definir el tipo de mecanismo más adecuado a las necesidades planteadas mediante un proceso de síntesis estructural. De esta forma se obtiene el tipo y número de elementos y pares a utilizar, así como su secuencia de unión (diagrama estructural). A continuación, a partir de las especificaciones dimensionales dadas por la empresa minera se obtienen las dimensiones principales del mecanismo, es decir, las longitudes, las posiciones y orientaciones relativas entre pares. Una vez obtenidas las dimensiones principales, se aplica cinemática inversa, para obtener la trayectoria de las posiciones a estudio y a continuación se realiza el análisis cinemático para los valores calculados para dichas posiciones. Por tanto, es necesario hacer una estimación inicial de las secciones de los elementos, pudiendo tomar como referencia aquellas que en otros diseños similares hayan resultado adecuadas. Con la distribución másica que implican estas dimensiones secundarias, y suministrando como dato el movimiento requerido para el mecanismo, así como todas las acciones resistentes a las que está sometido, se resuelve el problema dinámico. Este da como resultado las reacciones en los pares y las acciones motoras necesarias para que el sistema se mueva como previamente se ha especificado. Si los esfuerzos en los elementos generan un fallo (estático) en cualquiera de los elementos de la máquina, se modifican los materiales y dimensiones de las secciones en cuestión, y se realiza de nuevo un análisis cinetostático hasta que las dimensiones secundarias de los elementos sean tales que resistan las reacciones que aparecerán. A partir de aquí, si la diferencia entre lo requerido y los resultados obtenidos son aceptables, puede darse como válido el diseño. En caso contrario habría que modificar las características inerciales de los elementos y proseguir con el ciclo del diseño.

Lower limb and associated injuries in frontal-impact road traffic collisions.

Objectives: To study the relationship between severity of injury of the lower limb and severity of injury of the head, thoracic, and abdominal regions in frontal-impact road traffic collisions. Methods: Consecutive hospitalised trauma patients who were involved in a frontal road traffic collision were prospectively studied over 18 months. Patients with at least one Abbreviated Injury Scale (AIS) ≥3 or AIS 2 injuries within two AIS body regions were included. Patients were divided into two groups depending on the severity of injury to the head, chest or abdomen. Low severity group had an AIS < 2 and high severity group had an AIS ≥ 2. Backward likelihood logistic regression models were used to define significant factors affecting the severity of head, chest or abdominal injuries. Results: Eighty-five patients were studied. The backward likelihood logistic regression model defining independent factors affecting severity of head injuries was highly significant (p=0.01, nagelkerke r square = 0.1) severity of lower limb injuries was the only significant factor (p=0.013) having a negative correlation with head injury (Odds ratio of 0.64 (95% CI: 0.45-0.91). Conclusion: Occupants who sustain a greater severity of injury to the lower limb in a frontal-impact collision are likely to be spared from a greater severity of head injury.

Parte frontal de la Escuela Francisco Julian Olaya

Parte frontal de la Escuela Francisco Julian Olaya. Trujillo. C. 1990

THE INFLUENCE OF MOTIVATION ON EMOTION REGULATION AND MOTOR PERFORMANCE: EXAMINATION OF A NEURO-AFFECTIVE MODEL

Mental stress is known to disrupt the execution of motor performance and can lead to decrements in the quality of performance, however, individuals have shown significant differences regarding how fast and well they can perform a skilled task according to how well they can manage stress and emotion. The purpose of this study was to advance our understanding of how the brain modulates emotional reactivity under different motivational states to achieve differential performance in a target shooting task that requires precision visuomotor coordination. In order to study the interactions in emotion regulatory brain areas (i.e. the ventral striatum, amygdala, prefrontal cortex) and the autonomic nervous system, reward and punishment interventions were employed and the resulting behavioral and physiological responses contrasted to observe the changes in shooting performance (i.e. shooting accuracy and stability of aim) and neuro-cognitive processes (i.e. cognitive load and reserve) during the shooting task. Thirty-five participants, aged 18 to 38 years, from the Reserve Officers’ Training Corp (ROTC) at the University of Maryland were recruited to take 30 shots at a bullseye target in three different experimental conditions. In the reward condition, $1 was added to their total balance for every 10-point shot. In the punishment condition, $1 was deducted from their total balance if they did not hit the 10-point area. In the neutral condition, no money was added or deducted from their total balance. When in the reward condition, which was reportedly most enjoyable and least stressful of the conditions, heart rate variability was found to be positively related to shooting scores, inversely related to variability in shooting performance and positively related to alpha power (i.e. less activation) in the left temporal region. In the punishment (and most stressful) condition, an increase in sympathetic response (i.e. increased LF/HF ratio) was positively related to jerking movements as well as variability of placement (on the target) in the shots taken. This, coupled with error monitoring activity in the anterior cingulate cortex, suggests evaluation of self-efficacy might be driving arousal regulation, thus affecting shooting performance. Better performers showed variable, increasing high-alpha power in the temporal region during the aiming period towards taking the shot which could indicate an adaptive strategy of engagement. They also showed lower coherence during hit shots than missed shots which was coupled with reduced jerking movements and better precision and accuracy. Frontal asymmetry measures revealed possible influence of the prefrontal lobe in driving this effect in reward and neutral conditions. The possible interactions, reasons behind these findings and implications are discussed.

Current knowledge on the role of the inferior frontal gyrus in Theory of Mind - a commentary on Schurz and Tholen (2016)

Schurz and Tholen (2016) argue that common approaches to studying the neural basis of “theory of mind” (ToM) obscure a potentially important role for inferior frontal gyrus (IFG) in managing conflict between perspectives, and urge new work to address this question: “to gain a full understanding of the IFG's role in ToM, we encourage future imaging studies to use a wider range of control conditions.” (p332). We wholeheartedly agree, but note that this observation has been made before, and has already led to a programme of work that provides evidence from fMRI, EEG, and TMS on the role of IFG in managing conflict between self and other perspectives in ToM. We highlight these works, and in particular we demonstrate how careful manipulation within ToM tasks has been used to act as an internal control condition, wherein conflict has been manipulated within-subject. We further add to the discussion by framing key questions that remain regarding IFG in the context of these. Using limitations in the existing research, we outline how best researchers can proceed with the challenge set by Schurz and Tholen (2016).

ROLE OF THE FRONTAL EYE FIELD, SUPERIOR COLLICULUS, AND BASAL GANGLIA IN FLEXIBLE SACCADE BEHAVIOR

A distributed network of cortical and subcortical brain regions mediates the control of voluntary behavior, but it is unclear how this complex system may flexibly shift between different behavioral events. This thesis describes the neurophysiological changes in several key nuclei across the brain during flexible behavior, using saccadic eye movements in rhesus macaque monkeys. We examined five nuclei critical for saccade initiation and modulation: the frontal eye field (FEF) in the cerebral cortex, the subthalamic nucleus (STN), caudate nucleus (CD), and substantia nigra pars reticulata (SNr) in the basal ganglia (BG), and the superior colliculus (SC) in the midbrain. The first study tested whether a ‘threshold’ theory of how neuronal activity cues saccade initiation is consistent with the flexible control of behavior. The theory suggests there is a fixed level of FEF and SC neuronal activation at which saccades are initiated. Our results provide strong evidence against a fixed saccade threshold in either structure during flexible behavior, and indicate that threshold variability might depend on the level of inhibitory signals applied to the FEF or SC. The next two studies investigated the BG network as a likely candidate to modulate a saccade initiation mechanism, based on strong inhibitory output signals from the BG to the FEF and SC. We investigated the STN and CD (BG input), and the SNr (BG oculomotor output) to examine changes across the BG network. This revealed robust task-contingent shifts in BG signaling (Chapter 3), which uniquely impacted saccade initiation according to behavioral condition (Chapters 3 and 4). The thesis concludes with a published short review of the mechanistic effects of BG deep brain stimulation (Chapter 5), and a general discussion including proof of concept saccade behavioral changes in an MPTP-induced Parkinsonian model (Chapter 6). The studies presented here demonstrate that the conditions for saccade initiation by the FEF and SC vary according to behavioral condition, while simultaneously, large-scale task dependent shifts occur in BG signaling consistent with the observed modulation of FEF and SC activity. Taken together, these describe a mechanistic framework by which the cortico-BG loop may contribute to the flexible control of behavior.

Altered oscillatory dynamics of CA1 parvalbumin-basket cells during theta-gamma rhythmopathies of temporal lobe epilepsy

Recent reports in human demonstrate a role of theta– gamma coupling in memory for spatial episodes and a lack of coupling in people experiencing temporal lobe epilepsy, but the mechanisms are unknown. Using multisite silicon probe recordings of epileptic rats engaged in episodic-like object recognition tasks, we sought to evaluate the role of theta– gamma coupling in the absence of epileptiform activities. Our data reveal a specific association between theta– gamma (30 – 60 Hz) coupling at the proximal stratum radiatum of CA1 and spatial memory deficits. We targeted the microcircuit mechanisms with a novel approach to identify putative interneuronal types in tetrode recordings (parvalbumin basket cells in particular) and validated classification criteria in the epileptic context with neurochemical identification of intracellularly recorded cells. In epileptic rats, putative parvalbumin basket cells fired poorly modulated at the falling theta phase, consistent with weaker inputs from Schaffer collaterals and attenuated gamma oscillations, as evaluated by theta-phase decomposition of current–source density signals. We propose that theta– gamma interneuronal rhythmopathies of the temporal lobe are intimately related to episodic memory dysfunction in this condition.

Deficit of quantal release of GABA in experimental models of temporal lobe epilepsy

Because GABA (gamma-aminobutyric acid) receptor-mediated inhibition controls the excitability of principal neurons in the brain, deficits in GABAergic inhibition have long been favored to explain seizures. In an experimental model of temporal lobe epilepsy, we have identified a deficit of inhibition in presynaptic GABAergic terminals characterized by decreased GABA quantal activity associated with reduced synaptic vesicle density. This decrease in vesicle number primarily seems to affect the reserve pool, rather than the docked or the readily releasable pool.

Relación entre atrofia cortical difusa y desempeño cognitivo : estudio en población mayor de 60 años en un hospital universitario en la ciudad de Bogotá

El presente trabajo tuvo como objetivo evaluar la existencia de la relación entre la atrofia cortical difusa objetivada por neuroimagenes cerebrales y desempeños cognitivos determinados mediante la aplicación de pruebas neuropsicológicas que evalúan memoria de trabajo, razonamiento simbólico verbal y memoria anterógrada declarativa. Participaron 114 sujetos reclutados en el Hospital Universitario Mayor Méderi de la ciudad de Bogotá mediante muestreo de conveniencia. Los resultados arrojaron diferencias significativas entre los dos grupos (pacientes con diagnóstico de atrofia cortical difusa y pacientes con neuroimagenes interpretadas como dentro de los límites normales) en todas las pruebas neuropsicológicas aplicadas. Respecto a las variables demográficas se pudo observar que el grado de escolaridad contribuye como factor neuroprotector de un posible deterioro cognitivo. Tales hallazgos son importantes para determinar protocoles tempranos de detección de posible instalación de enfermedades neurodegenerativas primarias.