Diagnostic accuracy of anthropometric indices for metabolically healthy obesity in child and adolescent population.

BACKGROUND: A variable percentage of children and adolescents with obesity do not have cardiometabolic comorbidities. A phenotype called metabolically healthy obese (MHO) has emerged to describe this population subgroup. Early identification of this condition may prevent the progression to metabolically unhealthy obesity (MUO). MATERIAL AND METHODS: A cross-sectional descriptive study of 265 children and adolescents from Cordoba (Spain) conducted in 2018. The outcome variables were MHO, established based on three criteria: International Criterion, HOMA-IR, and a combination of the previous two. RESULTS: The prevalence of MHO ranged from 9.4% to 12.8% of the study population, between 41% and 55.7% of the sample with obesity. The highest agreement was reached between the HOMA-IR definitions and the combined criteria. The waist-to-height ratio (WHtR) was the indicator with the highest discriminant capacity for MHO in 2 of the three criteria, with its best cut-off point at 0.47 for both. CONCLUSION: The prevalence of MHO in children and adolescents differed according to the criteria used for diagnosis. The anthropometric variable with the most remarkable discriminating capacity for MHO was WHtR, with the same cut-off point in the three criteria analysed. IMPACT STATEMENT: This research work defines the existence of metabolically healthy obesity through anthropometric indicators in children and adolescents. Definitions that combine cardiometabolic criteria and insulin resistance are used to identify metabolically healthy obesity, as well as the prediction of this phenomenon through anthropometric variables. The present investigation helps to identify metabolically healthy obesity before metabolic abnormalities begin.

Relationship between overweight and obesity and cardiac dimensions and function in a paediatric population.

Obesity in adults is associated with left ventricular hypertrophy, dilatation, and myocardial fibrosis, as well as heart failure and coronary heart disease. These associations have been studied to a lesser extent in the paediatric population. This study aims to investigate the relationship between obesity and cardiac structure and function in the paediatric population. In a southern Spanish village, we selected all inhabitants aged 6-17 years stratifying by age, gender, and educational centres. We performed a complete transthoracic echocardiogram evaluating all the cardiac morphological and functional parameters commonly measured in an echocardiographic study. There were 212 children and adolescents included. Of them, 48.1% were males. The mean age was 10.9 ± 3.0 years. A total of 106 (50%) were normal weight, 57 (26.9%) overweight, and 49 (23.1%) obese. Sex and age were similar in all three groups. Overweight and obesity were associated with larger left ventricular end-diastolic and end-systolic volumes (p < 0.0005), greater left ventricular mass (p < 0.0005), and smaller ejection fraction (p < 0.0005). They were also associated with larger atrial, aortic, and right ventricular size. Lateral and mean E/e' ratios were higher (p = 0.007 and p = 0.01 respectively). Body mass index was independently associated with all cavity size variables as well as left ventricular ejection fraction. CONCLUSION: Childhood obesity is independently associated with larger heart chambers, greater left ventricle mass, and smaller left ventricle ejection fraction. WHAT IS KNOWN: • Childhood obesity is related to the development of cardiovascular risk factors and is considered an epidemic of the twenty-first century; its prevalence is rising. WHAT IS NEW: • Childhood overweight and obesity lead to changes in cardiac structure and function which, although not considered clinically pathological, are significant and a result of obesity, and which behave as unfavourable incipient alterations at an early age.

[Study of obesity in a rural children population and its relationship with anthropometric variables]. / Estudio de la obesidad en una población infantil rural y su relación con variables antropométricas.

GOALS: To know the prevalence of obesity in primary and secondary school students, and to evaluate the diagnostic accuracy of anthropometric variables for its detection. DESIGN: Cross-sectional study. LOCATION: Rural area of Córdoba. In the year 2014. PARTICIPANTS: Student population. A stratified sampling was performed according to age, gender and educational centers. A total of 323 students from 6 to 16 years were included in the study, all parents had signed informed consent. MAIN MEASUREMENTS: The prevalence of obesity was determined and sociodemographic, anthropometric, physical condition and dietary predictor variables were collected. A binary logistic regression was performed determining crude and adjusted Odds Ratio (OR) values, ROC curves were obtained and cut-off values were determined, calculating the sensitivity, specificity and Youden index. RESULTS: The prevalence of overweight and obesity was 26.2% and 22.3%, respectively. Only 15.2% of school children had an optimal Mediterranean diet. The waist-height ratio (WtHR) was the predictive variable with the highest adjusted OR 7.1 (4.3-11.6) and the largest area under the curve 0.954 (0.928-0.979), from a global cut-off value to discriminate obesity of 0.507. This gave a sensitivity of 90% and specificity of 87.2%. CONCLUSIONS: The high prevalence of obesity, the low-medium adherence to the Mediterranean diet and the low physical fitness make this population a priority target for the prevention of future cardiovascular events. The WtHR has been the best anthropometric predictor of obesity, recommending its use for the diagnosis of obesity in children at the expense of body mass index.

Multimodal description of whole brain connectivity: A comparison of resting state MEG, fMRI, and DWI.

Structural and functional connectivity (SC and FC) have received much attention over the last decade, as they offer unique insight into the coordination of brain functioning. They are often assessed independently with three imaging modalities: SC using diffusion-weighted imaging (DWI), FC using functional magnetic resonance imaging (fMRI), and magnetoencephalography/electroencephalography (MEG/EEG). DWI provides information about white matter organization, allowing the reconstruction of fiber bundles. fMRI uses blood-oxygenation level-dependent (BOLD) contrast to indirectly map neuronal activation. MEG and EEG are direct measures of neuronal activity, as they are sensitive to the synchronous inputs in pyramidal neurons. Seminal studies have targeted either the electrophysiological substrate of BOLD or the anatomical basis of FC. However, multimodal comparisons have been scarcely performed, and the relation between SC, fMRI-FC, and MEG-FC is still unclear. Here we present a systematic comparison of SC, resting state fMRI-FC, and MEG-FC between cortical regions, by evaluating their similarities at three different scales: global network, node, and hub distribution. We obtained strong similarities between the three modalities, especially for the following pairwise combinations: SC and fMRI-FC; SC and MEG-FC at theta, alpha, beta and gamma bands; and fMRI-FC and MEG-FC in alpha and beta. Furthermore, highest node similarity was found for regions of the default mode network and primary motor cortex, which also presented the highest hubness score. Distance was partially responsible for these similarities since it biased all three connectivity estimates, but not the unique contributor, since similarities remained after controlling for distance.

Dynamics of brain networks in the aesthetic appreciation.

Neuroimage experiments have been essential for identifying active brain networks. During cognitive tasks as in, e.g., aesthetic appreciation, such networks include regions that belong to the default mode network (DMN). Theoretically, DMN activity should be interrupted during cognitive tasks demanding attention, as is the case for aesthetic appreciation. Analyzing the functional connectivity dynamics along three temporal windows and two conditions, beautiful and not beautiful stimuli, here we report experimental support for the hypothesis that aesthetic appreciation relies on the activation of two different networks, an initial aesthetic network and a delayed aesthetic network, engaged within distinct time frames. Activation of the DMN might correspond mainly to the delayed aesthetic network. We discuss adaptive and evolutionary explanations for the relationships existing between the DMN and aesthetic networks and offer unique inputs to debates on the mind/brain interaction.

Mechanical behaviour and formation process of silkworm silk gut.

High performance silk fibers were produced directly from the silk glands of silkworms (Bombyx mori) following an alternative route to natural spinning. This route is based on a traditional procedure that consists of soaking the silk glands in a vinegar solution and stretching them by hand leading to the so called silkworm guts. Here we present, to the authors' best knowledge, the first comprehensive study on the formation, properties and microstructure of silkworm gut fibers. Comparison of the tensile properties and microstructural organization of the silkworm guts with those of naturally spun fibers allows gain of a deeper insight into the mechanisms that lead to the formation of the fiber, as well as the relationship between the microstructure and properties of these materials. In this regard, it is proved that an acidic environment and subsequent application of tensile stress in the range of 1000 kPa are sufficient conditions for the formation of a silk fiber.

Disparate connectivity for structural and functional networks is revealed when physical location of the connected nodes is considered.

Macroscopic brain networks have been widely described with the manifold of metrics available using graph theory. However, most analyses do not incorporate information about the physical position of network nodes. Here, we provide a multimodal macroscopic network characterization while considering the physical positions of nodes. To do so, we examined anatomical and functional macroscopic brain networks in a sample of twenty healthy subjects. Anatomical networks are obtained with a graph based tractography algorithm from diffusion-weighted magnetic resonance images (DW-MRI). Anatomical connections identified via DW-MRI provided probabilistic constraints for determining the connectedness of 90 different brain areas. Functional networks are derived from temporal linear correlations between blood-oxygenation level-dependent signals derived from the same brain areas. Rentian Scaling analysis, a technique adapted from very-large-scale integration circuits analyses, shows that functional networks are more random and less optimized than the anatomical networks. We also provide a new metric that allows quantifying the global connectivity arrangements for both structural and functional networks. While the functional networks show a higher contribution of inter-hemispheric connections, the anatomical networks highest connections are identified in a dorsal-ventral arrangement. These results indicate that anatomical and functional networks present different connectivity organizations that can only be identified when the physical locations of the nodes are included in the analysis.

Predictors of schizophrenia spectrum disorders in early-onset first episodes of psychosis: a support vector machine model.

Identifying early-onset schizophrenia spectrum disorders (SSD) at a very early stage remains challenging. To assess the diagnostic predictive value of multiple types of data at the emergence of early-onset first-episode psychosis (FEP), various support vector machine (SVM) classifiers were developed. The data were from a 2-year, prospective, longitudinal study of 81 patients (age 9-17 years) with early-onset FEP and a stable diagnosis during follow-up and 42 age- and sex-matched healthy controls (HC). The input was different combinations of baseline clinical, neuropsychological, magnetic resonance imaging brain volumetric and biochemical data, and the output was the diagnosis at follow-up (SSD vs. non-SSD, SSD vs. HC, and non-SSD vs. HC). Enhanced recursive feature elimination was performed for the SSD vs. non-SSD classifier to select and rank the input variables with the highest predictive value for a diagnostic outcome of SSD. After validation with a test set and considering all baseline variables together, the SSD vs. non-SSD, SSD vs. HC and non-SSD vs. HC classifiers achieved an accuracy of 0.81, 0.99 and 0.99, respectively. Regarding the SSD vs. non-SSD classifier, a combination of baseline clinical variables (severity of negative, disorganized symptoms and hallucinations or poor insight) and neuropsychological variables (impaired attention, motor coordination, and global cognition) showed the highest predictive value for a diagnostic outcome of SSD. Neuroimaging and biochemical variables at baseline did not add to the predictive value. Thus, comprehensive clinical/cognitive assessment remains the most reliable approach for differential diagnosis during early-onset FEP. SVMs may constitute promising multivariate tools in the search for predictors of diagnostic outcome in FEP.

Limb-Shaking TIA Presenting as Hemichorea-Hemiballismus: TIA Chameleons Diagnostic Challenge in the Emergency Department.

BACKGROUND: demonstrate the importance of considering limb-shaking syndrome in the differential diagnosis of patients who present to the emergency department (ED) with hyperkinetic movements. METHODS: In this article, we describe a diagnostic challenge in the ED in which a patient presents with hyperkinetic movements that are initially diagnosed as hemichorea-hemiballismus (HCHB) but are subsequently found to be limb-shaking syndrome with important therapeutic opportunities. RESULTS: Following a diagnosis of left carotid obstruction, the patient underwent left carotid endarterectomy 5 days after admission. Six months after surgery, the patient had no further symptoms, and an ultrasound scan and magnetic resonance angiography have confirmed no restenosis. CONCLUSION: Limb shaking is an uncommon form of transient ischemic attack that should be recognized and differentiated from conditions such as focal motor seizures. Recognition will almost invariably indicate carotid artery occlusion, and timely treatment may not only abolish the attacks in patients but also reduce their risk of stroke. HCHB represents a spectrum of hyperkinetic movement disorders varying in the severity of choreic and/or ballistic movements. The presented case includes limb-shaking syndrome in the differential diagnosis and prompts for further investigations to complete the assessment.

A Fuzzy Inference System for Closed-Loop Deep Brain Stimulation in Parkinson's Disease.

Parkinsons disease is a complex neurodegenerative disorder for which patients present many symptoms, tremor being the main one. In advanced stages of the disease, Deep Brain Stimulation is a generalized therapy which can significantly improve the motor symptoms. However despite its beneficial effects on treating the symptomatology, the technique can be improved. One of its main limitations is that the parameters are fixed, and the stimulation is provided uninterruptedly, not taking into account any fluctuation in the patients state. A closed-loop system which provides stimulation by demand would adjust the stimulation to the variations in the state of the patient, stimulating only when it is necessary. It would not only perform a more intelligent stimulation, capable of adapting to the changes in real time, but also extending the devices battery life, thereby avoiding surgical interventions. In this work we design a tool that learns to recognize the principal symptom of Parkinsons disease and particularly the tremor. The goal of the designed system is to detect the moments the patient is suffering from a tremor episode and consequently to decide whether stimulation is needed or not. For that, local field potentials were recorded in the subthalamic nucleus of ten Parkinsonian patients, who were diagnosed with tremor-dominant Parkinsons disease and who underwent surgery for the implantation of a neurostimulator. Electromyographic activity in the forearm was simultaneously recorded, and the relation between both signals was evaluated using two different synchronization measures. The results of evaluating the synchronization indexes on each moment represent the inputs to the designed system. Finally, a fuzzy inference system was applied with the goal of identifying tremor episodes. Results are favourable, reaching accuracies of higher 98.7% in 70% of the patients.

Differential contribution of hippocampal circuits to appetitive and consummatory behaviors during operant conditioning of behaving mice.

Operant conditioning is a type of associative learning involving different and complex sensorimotor and cognitive processes. Because the hippocampus has been related to some motor and cognitive functions involved in this type of learning (such as object recognition, spatial orientation, and associative learning tasks), we decided to study in behaving mice the putative changes in strength taking place at the hippocampal CA3-CA1 synapses during the acquisition and performance of an operant conditioning task. Mice were chronically implanted with stimulating electrodes in the Schaffer collaterals and with recording electrodes in the hippocampal CA1 area and trained to an operant task using a fixed-ratio (1:1) schedule. We recorded the field EPSPs (fEPSPs) evoked at the CA3-CA1 synapse during the performance of appetitive (going to the lever, lever press) and consummatory (going to the feeder, eating) behaviors. In addition, we recorded the local field potential activity of the CA1 area during similar behavioral displays. fEPSPs evoked at the CA3-CA1 synapse presented larger amplitudes for appetitive than for consummatory behaviors. This differential change in synaptic strength took place in relation to the learning process, depending mainly on the moment in which mice reached the selected criterion. Thus, selective changes in CA3-CA1 synaptic strength were dependent on both the behavior display and the learning stage. In addition, significant changes in theta band power peaks and their corresponding discrete frequencies were noticed during these behaviors across the sequence of events characterizing this type of associative learning but not during the acquisition process.

Early prefrontal activation as a mechanism to prevent forgetting in the context of interference.

OBJECTIVE: Recent research has focused on interference resolution deficits as the main cause of short-term memory decreases in aging. To determine whether activation of brain compensatory mechanisms occur during the encoding process in older people. Moreover, two different levels of interference (distraction and interruption) were presented during the maintenance period to examine how they modulate brain activity profiles. DESIGN: A delayed match-to-sample task with two experimental conditions: distraction and interruption. PARTICIPANTS: Twenty-seven young adults from Complutense University of Madrid and 20 healthy older adults from Complutense Elderly University of Madrid. MEASUREMENTS: Magnetoencephalography scans were recorded during the execution of a working memory interference task. Brain activity sources from younger and older adults during the encoding stage were compared in each condition using minimum norm estimation analyses. RESULTS: The elderly showed enhancement of prefrontal activity during early latencies of the encoding process in both conditions. In the distraction condition, enhanced activity was located in left ventrolateral prefrontal regions, whereas in the interruption condition, enhanced activity was observed in the right ventral prefrontal areas and anterior cingulate cortex. CONCLUSION: Increased recruitment of prefrontal regions in the elderly might be related to the processing depth of information, encoding of new information and semantic associations that are successfully recalled, and with interference resolution and preparatory control when the level of interference becomes higher. These prefrontal modulations during early latencies might reflect a higher top-down control of the encoding process in normal aging to prevent forgetting.

Remote effects of hippocampal sclerosis on effective connectivity during working memory encoding: a case of connectional diaschisis?

Accumulating evidence suggests a role for the medial temporal lobe (MTL) in working memory (WM). However, little is known concerning its functional interactions with other cortical regions in the distributed neural network subserving WM. To reveal these, we availed of subjects with MTL damage and characterized changes in effective connectivity while subjects engaged in WM task. Specifically, we compared dynamic causal models, extracted from magnetoencephalographic recordings during verbal WM encoding, in temporal lobe epilepsy patients (with left hippocampal sclerosis) and controls. Bayesian model comparison indicated that the best model (across subjects) evidenced bilateral, forward, and backward connections, coupling inferior temporal cortex (ITC), inferior frontal cortex (IFC), and MTL. MTL damage weakened backward connections from left MTL to left ITC, a decrease accompanied by strengthening of (bidirectional) connections between IFC and MTL in the contralesional hemisphere. These findings provide novel evidence concerning functional interactions between nodes of this fundamental cognitive network and sheds light on how these interactions are modified as a result of focal damage to MTL. The findings highlight that a reduced (top-down) influence of the MTL on ipsilateral language regions is accompanied by enhanced reciprocal coupling in the undamaged hemisphere providing a first demonstration of "connectional diaschisis."

The effects of obesity on longitudinal ventricular and atrial strain in a rural population of Spanish children and adolescents, evaluated by a new strain software.

BACKGROUND AND OBJECTIVES: Research on the relationship between body mass index (BMI) and strain values in children and adolescents is limited. Our aim was to analyse the relationship between BMI and strain values of both ventricles and left atrium in children and adolescents. METHODS: Both ventricles and left atrial strain values were compared among different BMI categories in children and adolescents from a town in the South of Spain. RESULTS: Of the 198 subjects, aged 6-17 years, 53% were of normal weight, 26% were overweight and 21% had obesity. Lower absolute values of left ventricular global longitudinal strain (25.9 ± 2.0% vs. 26.9 ± 2.2%, p = 0.002) and right ventricular free wall longitudinal strain (29.5 ± 4.2% vs. 30.8 ± 4.5%, p = 0.04) were found in subjects with obesity and overweight versus subjects with normal weight. A lower right ventricular four-chamber longitudinal strain was also observed in males with obesity and overweight (24.8 ± 3.3% vs. 26.4 ± 3.6%, p = 0.03). Statistically significant negative correlations of BMI were found for all ventricular, but not atrial, strain values in univariate analysis. This association turned non-significant for right ventricular four-chamber longitudinal strain in multivariate analysis. CONCLUSIONS: Utilizing this new strain software, children and adolescents with high BMI were associated with significantly lower values for left and right ventricular free wall longitudinal strain, without impact in left atrial strain.

The Assessment of Myocardial Longitudinal Strain in a Paediatric Spanish Population Using a New Software Analysis.

BACKGROUND: Two-dimensional speckle-tracking echocardiography (2DSTE) has been present for years. However, it is underutilized due to the expertise and time requirements for its analysis. Our aims were to provide strain values in a paediatric Spanish population and to assess the feasibility and reproducibility of a new strain software analysis in our environment. METHODS: A cross-sectional study of 156 healthy children aged 6 to 17 years. Longitudinal strain (LS) analysis of the left ventricle, right ventricle, and left atrium was performed. Feasibility and reproducibility were assessed. The associations of clinical and echocardiographic variables with strain values were investigated by multivariate analysis. RESULTS: Mean age was 11 ± 3 years (50% female). Feasibility of LS measurement ranged from 94.2% for left ventricle global LS (LVGLS) to 98.1% for other chamber strain parameters. Strain values were 26.7 ± 2.3% for LVGLS; 30.5 ± 4.4% and 26.9 ± 4% for right ventricle free wall LS (RVFWLS) and four chambers view LS (RV4CLS) respectively; and 57.8 ± 10.5%, 44.9 ± 9.5%, and 12.9 ± 5.5% for left atrium LS reservoir phase (LALSr), conduct phase (LALScd) and contraction phase (LALSct), also respectively. Body surface area (BSA) and age presented a negative correlation with strain values. Higher values were found in females than in males, except for LALScd. Excellent intra- and inter-observer reproducibility were found for right and left ventricular strain measurement, with intraclass correlation coefficients (ICC) ranging from 0.88 to 0.98, respectively. In conclusion, we described strain values in a healthy Spanish paediatric population. LS assessment by this new strain analysis software by semi-automatic manner was highly feasible and reproducible.

Principles of recovery from traumatic brain injury: reorganization of functional networks.

Recovery after brain injury is an excellent platform to study the mechanism underlying brain plasticity, the reorganization of networks. Do complex network measures capture the physiological and cognitive alterations that occurred after a traumatic brain injury and its recovery? Patients as well as control subjects underwent resting-state MEG recording following injury and after neurorehabilitation. Next, network measures such as network strength, path length, efficiency, clustering and energetic cost were calculated. We show that these parameters restore, in many cases, to control ones after recovery, specifically in delta and alpha bands, and we design a model that gives some hints about how the functional networks modify their weights in the recovery process. Positive correlations between complex network measures and some of the general index of the WAIS-III test were found: changes in delta-based path-length and those in Performance IQ score, and alpha-based normalized global efficiency and Perceptual Organization Index. These results indicate that: 1) the principle of recovery depends on the spectral band, 2) the structure of the functional networks evolves in parallel to brain recovery with correlations with neuropsychological scales, and 3) energetic cost reveals an optimal principle of recovery.

Reorganization of functional connectivity as a correlate of cognitive recovery in acquired brain injury.

Cognitive processes require a functional interaction between specialized multiple, local and remote brain regions. Although these interactions can be strongly altered by an acquired brain injury, brain plasticity allows network reorganization to be principally responsible for recovery. The present work evaluates the impact of brain injury on functional connectivity patterns. Networks were calculated from resting-state magnetoencephalographic recordings from 15 brain injured patients and 14 healthy controls by means of wavelet coherence in standard frequency bands. We compared the parameters defining the network, such as number and strength of interactions as well as their topology, in controls and patients for two conditions: following a traumatic brain injury and after a rehabilitation treatment. A loss of delta- and theta-based connectivity and conversely an increase in alpha- and beta-band-based connectivity were found. Furthermore, connectivity parameters approached controls in all frequency bands, especially in slow-wave bands. A correlation between network reorganization and cognitive recovery was found: the reduction of delta-band-based connections and the increment of those based on alpha band correlated with Verbal Fluency scores, as well as Perceptual Organization and Working Memory Indexes, respectively. Additionally, changes in connectivity values based on theta and beta bands correlated with the Patient Competency Rating Scale. The current study provides new evidence of the neurophysiological mechanisms underlying neuronal plasticity processes after brain injury, and suggests that these changes are related with observed changes at the behavioural level.

Laparoscopic video analysis for training and image-guided surgery.

Automatic analysis of Minimally Invasive Surgical video has the potential to drive new solutions for alleviating needs of safe and reproducible training programs, objective and transparent evaluation systems and navigation tools to assist surgeons and improve patient safety. Surgical video is an always available source of information, which can be used without any additional intrusive hardware in the operating room. This paper is focused on surgical video analysis methods and techniques. It describes authors' contributions in two key aspects, the 3D reconstruction of the surgical field and the segmentation and tracking of tools and organs based on laparoscopic video images. Results are given to illustrate the potential of this field of research, like the calculi of the 3D position and orientation of a tool from its 2D image, or the translation of a preoperative resection plan into a hepatectomy surgical procedure using the shading information of the image. Research efforts are required to further develop these technologies in order to harness all the valuable information available in any video-based surgery.

Ongoing Oscillatory Electrophysiological Alterations in Frail Older Adults: A MEG Study.

Objective: The role of the central nervous system in the pathophysiology of frailty is controversial. We used magnetoencephalography (MEG) to search for abnormalities in the ongoing oscillatory neural activity of frail individuals without global cognitive impairment. Methods: Fifty four older (≥70 years) and cognitively healthy (Mini-Mental State Examination ≥24) participants were classified as robust (0 criterion, n = 34) or frail (≥ 3 criteria, n = 20) following Fried's phenotype. Memory, language, attention, and executive function were assessed through well-validated neuropsychological tests. Every participant underwent a resting-state MEG and a T1-weighted magnetic resonance imaging scan. We performed MEG power spectral analyses to compare the electrophysiological profiles of frail and robust individuals. We used an ensemble learner to investigate the ability of MEG spectral power to discriminate frail from robust participants. Results: We identified increased relative power in the frail group in the mu (p < 0.05) and sensorimotor (p < 0.05) frequencies across right sensorimotor, posterior parietal, and frontal regions. The ensemble learner discriminated frail from robust participants [area under the curve = 0.73 (95% CI = 0.49-0.98)]. Frail individuals performed significantly worse in the Trail Making Test, Digit Span Test (forward), Rey-Osterrieth Complex Figure, and Semantic Fluency Test. Interpretation: Frail individuals without global cognitive impairment showed ongoing oscillatory alterations within brain regions associated with aspects of motor control, jointly to failures in executive function. Our results suggest that some physical manifestations of frailty might partly arise from failures in central structures relevant to sensorimotor and executive processing.

Oscillatory activity in prefrontal and posterior regions during implicit letter-location binding.

Many cognitive abilities involve the integration of information from different modalities, a process referred to as "binding." It remains less clear, however, whether the creation of bound representations occurs in an involuntary manner, and whether the links between the constituent features of an object are symmetrical. We used magnetoencephalography to investigate whether oscillatory brain activity related to binding processes would be observed in conditions in which participants maintain one feature only (involuntary binding); and whether this activity varies as a function of the feature attended to by participants (binding asymmetry). Participants performed two probe recognition tasks that were identical in terms of their perceptual characteristics and only differed with respect to the instructions given (to memorize either consonants or locations). MEG data were reconstructed using a current source distribution estimation in the classical frequency bands. We observed implicit verbal-spatial binding only when participants successfully maintained the identity of consonants, which was associated with a selective increase in oscillatory activity over prefrontal regions in all frequency bands during the first half of the retention period and accompanied by increased activity in posterior brain regions. The increase in oscillatory activity in prefrontal areas was only observed during the verbal task, which suggests that this activity might be signaling neural processes specifically involved in cross-code binding. Current results are in agreement with proposals suggesting that the prefrontal cortex function as a "pointer" which indexes the features that belong together within an object.