Elevating understanding: Linking high-altitude hypoxia to brain aging through EEG functional connectivity and spectral analyses.

High-altitude hypoxia triggers brain function changes reminiscent of those in healthy aging and Alzheimer's disease, compromising cognition and executive functions. Our study sought to validate high-altitude hypoxia as a model for assessing brain activity disruptions akin to aging. We collected EEG data from 16 healthy volunteers during acute high-altitude hypoxia (at 4,000 masl) and at sea level, focusing on relative changes in power and aperiodic slope of the EEG spectrum due to hypoxia. Additionally, we examined functional connectivity using wPLI, and functional segregation and integration using graph theory tools. High altitude led to slower brain oscillations, that is, increased δ and reduced α power, and flattened the 1/f aperiodic slope, indicating higher electrophysiological noise, akin to healthy aging. Notably, functional integration strengthened in the θ band, exhibiting unique topographical patterns at the subnetwork level, including increased frontocentral and reduced occipitoparietal integration. Moreover, we discovered significant correlations between subjects' age, 1/f slope, θ band integration, and observed robust effects of hypoxia after adjusting for age. Our findings shed light on how reduced oxygen levels at high altitudes influence brain activity patterns resembling those in neurodegenerative disorders and aging, making high-altitude hypoxia a promising model for comprehending the brain in health and disease.

Exposure to high-altitude hypoxia, with reduced oxygen levels, can replicate brain function changes akin to aging and Alzheimer's disease. In our work, we propose high-altitude hypoxia as a possible reversible model of human brain aging. We gathered EEG data at high altitude and sea level, investigating the impact of hypoxia on brainwave patterns and connectivity. Our findings revealed that high-altitude exposure led to slower and noisier brain oscillations and produced altered brain connectivity, resembling some remarkable changes seen in the aging process. Intriguingly, these changes were linked to age, even when hypoxia's effects were considered. Our research unveils how high-altitude conditions emulate brain patterns associated with aging and neurodegenerative conditions, providing valuable insights into the understanding of both normal and impaired brain function.

The effect of a cognitive training therapy based on stimulation of brain oscillations in patients with mild cognitive impairment in a Chilean sample: study protocol for a phase IIb, 2 × 3 mixed factorial, double-blind randomised controlled trial.

BACKGROUND: The ageing population has increased the prevalence of disabling and high-cost diseases, such as dementia and mild cognitive impairment (MCI). The latter can be considered a prodromal phase of some dementias and a critical stage for interventions to postpone the impairment of functionality. Working memory (WM) is a pivotal cognitive function, representing the fundamental element of executive functions. This project proposes an intervention protocol to enhance WM in these users, combining cognitive training with transcranial electrical stimulation of alternating current (tACS). This technique has been suggested to enhance the neuronal plasticity needed for cognitive processes involving oscillatory patterns. WM stands to benefit significantly from this approach, given its well-defined electrophysiological oscillations. Therefore, tACS could potentially boost WM in patients with neurodegenerative diseases. METHODS: This study is a phase IIb randomised, double-blind clinical trial with a 3-month follow-up period. The study participants will be 62 participants diagnosed with MCI, aged over 60, from Valparaíso, Chile. Participants will receive an intervention combining twelve cognitive training sessions with tACS. Participants will receive either tACS or placebo stimulation in eight out of twelve training sessions. Sessions will occur twice weekly over 6 weeks. The primary outcomes will be electroencephalographic measurements through the prefrontal theta oscillatory activity, while the secondary effects will be cognitive assessments of WM. The participants will be evaluated before, immediately after, and 3 months after the end of the intervention. DISCUSSION: The outcomes of this trial will add empirical evidence about the benefits and feasibility of an intervention that combines cognitive training with non-invasive brain stimulation. The objective is to contribute tools for optimal cognitive treatment in patients with MCI. To enhance WM capacity, postpone the impairment of functionality, and obtain a better quality of life. TRIAL REGISTRATION: ClinicalTrials.gov NCT05291208. Registered on 28 February 2022. ISRCTN87597719 retrospectively registered on 15 September 2023.

Harmonized multi-metric and multi-centric assessment of EEG source space connectivity for dementia characterization.

Introduction: Harmonization protocols that address batch effects and cross-site methodological differences in multi-center studies are critical for strengthening electroencephalography (EEG) signatures of functional connectivity (FC) as potential dementia biomarkers. Methods: We implemented an automatic processing pipeline incorporating electrode layout integrations, patient-control normalizations, and multi-metric EEG source space connectomics analyses. Results: Spline interpolations of EEG signals onto a head mesh model with 6067 virtual electrodes resulted in an effective method for integrating electrode layouts. Z-score transformations of EEG time series resulted in source space connectivity matrices with high bilateral symmetry, reinforced long-range connections, and diminished short-range functional interactions. A composite FC metric allowed for accurate multicentric classifications of Alzheimer's disease and behavioral variant frontotemporal dementia. Discussion: Harmonized multi-metric analysis of EEG source space connectivity can address data heterogeneities in multi-centric studies, representing a powerful tool for accurately characterizing dementia.

DIVA Meets EEG: Model Validation Using Formant-Shift Reflex.

The neurocomputational model 'Directions into Velocities of Articulators' (DIVA) was developed to account for various aspects of normal and disordered speech production and acquisition. The neural substrates of DIVA were established through functional magnetic resonance imaging (fMRI), providing physiological validation of the model. This study introduces DIVA_EEG an extension of DIVA that utilizes electroencephalography (EEG) to leverage the high temporal resolution and broad availability of EEG over fMRI. For the development of DIVA_EEG, EEG-like signals were derived from original equations describing the activity of the different DIVA maps. Synthetic EEG associated with the utterance of syllables was generated when both unperturbed and perturbed auditory feedback (first formant perturbations) were simulated. The cortical activation maps derived from synthetic EEG closely resembled those of the original DIVA model. To validate DIVA_EEG, the EEG of individuals with typical voices (N = 30) was acquired during an altered auditory feedback paradigm. The resulting empirical brain activity maps significantly overlapped with those predicted by DIVA_EEG. In conjunction with other recent model extensions, DIVA_EEG lays the foundations for constructing a complete neurocomputational framework to tackle vocal and speech disorders, which can guide model-driven personalized interventions.

Diferencias temporales y espaciales en el procesamiento de incongruencias léxicas: un estudio de potenciales relacionados a eventos / Temporal and spatial differences in the processing of lexical incongruities: A study of event-related potentials

Resumen Introducción. La comprensión del lenguaje está determinada por diversos procesos, entre los que se encuentra el reconocimiento léxico. Según el modelo conexionista, este reconocimiento se genera por activación mediante el emparejamiento de la información acumulada y por la inhibición de las entradas léxicas que compiten por activación. Objetivo. Determinar las diferencias temporales y espaciales de procesamiento entre las incongruencias léxicas semánticamente relacionadas a un contexto lingüístico oracional y las no relacionadas a través de mediciones electrofisiológicas de potenciales relacionados a eventos (PRE). Materiales y métodos. Se realizó la medición de los PRE en 10 sujetos sanos por medio de un paradigma de 240 oraciones en español agrupadas de la siguiente manera: 80 oraciones congruentes, 80 con incongruencias dentro del campo léxico y 80 con incongruencias fuera del campo léxico. Resultados. Se observó una diferencia estadística en la latencia de aparición del componente N400 entre las dos condiciones. Por su parte, se encontró una mayor activación del precúneo, del giro orbitofrontal, del giro angular y del giro supramarginal en la condición de incongruencia fuera del campo léxico. Conclusión. Se identificaron diferencias temporales y espaciales (activación del precúneo, del giro orbitofrontal, del giro angular y del giro supramarginal) entre el procesamiento de las incongruencias léxicas y no léxicas.

Abstract Introduction: Language understanding depends on several processes, including lexical recognition. According to the connectionist model, this recognition is generated by activation through the matching of accumulated information and by the inhibition of lexical entries that compete for activation. Objective: To determine, through electrophysiological measurements of event-related potentials (ERP), temporal and spatial processing differences between lexical inconsistencies semantically related to a sentence linguistic context and those that are unrelated. Materials and methods: ERPs were measured in 10 healthy subjects by means of a 240 Spanish sentences paradigm grouped as follows: 80 congruent sentences, 80 sentences with lexical incongruities, and 80 with non-lexical incongruities. Results: A statistical difference was found in the latency of appearance of the N400 component between both conditions. On the other hand, a greater activation of the precuneus, the orbitofrontal gyrus, the angular gyrus and the supramarginal gyrus was observed in the non-lexical incongruity condition. Conclusion: There are temporal and spatial (activation of the precuneus, the orbitofrontal gyrus, the angular gyrus and the supramarginal gyrus) differences between the processing of lexical inconsistencies and the processing of non-lexical inconsistencies.

Asociación entre maloclusiones y trastornos del lenguaje / Association between malocclusions and language disorders

Entre las enfermedades bucodentales de mayor prevalencia se encuentran las maloclusiones, y dentro de los trastornos más comunes del desarrollo del lenguaje está la dislalia que corresponde a problemas de articulación en los sonidos sin base neurológica. Se realizó una revisión bibliográfica sobre el tema con el objetivo de describir la asociación entre problemas de fonación y maloclusión dental, específicamente identificar las alteraciones en la fonación más comunes, en pacientes con problemas de maloclusión dental. Dentro de los artículos revisados se excluyeron aquellos que asociaban trastornos del lenguaje a algún síndrome. Se puede concluir que la mayoría de los autores muestran una relación entre maloclusiones y trastornos de la articulación del habla, siendo la mordida abierta la anomalía más prevalente. Palabras clave: Trastornos de la articulación; Lenguaje; Mordida abierta; Mordida cruzada (fuente: DeCS BIREME).

Malocclusions are listed among the most prevalent oral diseases; whereas dyslalia is considered the most common speech disorder that involves articulation problems while producing sounds, without neurological basis. A literature review was performed on the topic, in order to describe the correlation between phonation problems and dental malocclusions, specifically identifying the most common phonation issues in patients with dental malocclusion problems. Within the articles reviewed, those where language disorders were associated to any syndrome, were excluded. The corollary after the review revealed that most of the authors demonstrated a relation between malocclusions and speech disorders, with open bite being the most prevalent anomaly. Keywords: Articulation disorders; Language; Open bite; Cross bite (source: MeSH NLM).

Structural insight into the binding mechanism of ATP to EGFR and L858R, and T790M and L858R/T790 mutants.

The L858R mutation in EGFR is particularly responsive to small tyrosine kinase inhibitors (TKIs) such as gefitinib and erlotinib. This efficacy decreases due to drug resistance conferred by a second mutation, T790M, which subsequently produces a double mutant, L858R/T790M. Although this resistance was initially attributed to steric blocking by the T790M mutation, experimental studies have demonstrated that differences in the binding affinities of TKIs to T790M and L858R/T790M mutants are more a result of the increased sensitivity of these mutants to ATP than to a decrease in the affinity to TKIs. Regrettably, detailed information at the atomic level on the origins of the increased binding affinity of mutants for ATP is lacking. In this study, we have combined structural data and molecular dynamics simulations with the MMGBSA approach to determine how the L858R, T790M and L858R/T790 mutations impact the binding mechanism of ATP with respect to wild-type EGFR. Structural and energetic analyses provided novel information that helps to explain the increased affinity of ATP to T790M and L858R/T790 mutants with respect to L858R and wild-type systems. In addition, it was observed that dimerization of the wild-type and mutant systems exerts dissimilar effects on the ATP binding affinity characteristic of negative cooperativity. Communicated by Ramaswamy H. Sarma.

Genetic divergence of tomato ringspot virus.

Tomato ringspot virus (ToRSV) has been detected in Chile, causing economically important diseases in a wide range of hosts. A ToRSV isolate was obtained from raspberry cv Heritage (Rasp-CL) showing leaf yellowing and stunting. The complete genome of Rasp-CL was sequenced by deep sequencing. The Rasp-CL RNA1 sequence shared 97.4 % nucleotide sequence identity with divergent RNA1 of isolate Rasp1-2014, while Rasp-CL RNA2 showed high divergence from all four isolates available in the database, sharing only 63.9-72.7 % nucleotide sequence identity. This difference was mainly based on the X4 coding region, which has been reported to be a high-variability region. Moreover, based on differences in the X4 region, three Rasp-CL RNA2 variants of different length were identified in the same host. One putative recombination event was identified between the Rasp-CL and GYV-2014 X4 genes. Phylogenetic analysis suggested that ToRSV isolates with currently available sequences form three distinct groups. Our results suggest that, for an accurate phylogenetic classification of ToRSV, it is necessary to obtain sequences of both RNAs. This is the first report of a complete ToRSV genome sequence from South America.

Análisis Psicométrico del Diagnóstico de Efectividad Gerencial de Reddin / Psychometric Analysis of the Reddin Managerial Effectiveness Diagnosis

Resumen: El liderazgo ha sido tema de interés debido a su importancia para las organizaciones, por el impacto que las acciones de una persona tienen para influir en lo equipos y resultados. Así, la teoría tridimensional de Reddin (1983) propone que el comportamiento de los gerentes se relaciona con estilos comportamentales vinculados a la orientación a la tarea y a las relaciones. El propósito de esta investigación fue identificar si la configuración factorial, confiabilidad y validez del Diagnóstico de Efectividad Gerencial (DEG) (Reddin, 1983), para ello se empleó una muestra histórica aleatoria y no probalística de evaluados del 2010 al 2014 de 94'819 gerentes activos de empresas en América Latina para identificar si el test mantenía sus índices psicométricos a lo largo del tiempo; además de una muestra de 726 participantes para replicar los estudios realizados originalmente por el autor. Todos eran gerentes con al menos un año en la posición y una persona a su cargo. La investigación demuestra que este test sigue siendo una herramienta útil y sin sesgo cultural que puede ser empleada en las organizaciones para obtener información acerca del comportamiento que indiquen su estilo básico, estilo gerencial y grado efectividad en el desempeño de sus tareas.

Abstract: Leadership it's a topic of interest in organizational research because the impact of the leaders and manager's behavior in their teams and the results. Thus, the 3D theory of Reddin (1983) suggests that the behavior of managers is related to behavioral styles related to task orientation and relationships. The purpose of this research was to identify whether the factorial configuration, reliability and validity of the Managerial Effectiveness Diagnosis (MED) (Reddin, 1983). For the we use a non-probabilistic random sample of 94'819 participants, all active managers' companies in Latin America from 2010 to 2014; to identify if the test kept their psychometric values over time. Also we use a non-probabilistic sample of 726 participants to replicate the studies originally conducted by the author. All they were managers with at least one year in the position and one person in charge. Research shows that this remains a useful test without cultural bias that can be used in organizations for information about the behavior to indicate their basic style, management style and degree effectiveness in performing their chores.

Anchos mesiodistales de dentición temporal en niños de la ciudad de Concepción, Chile y su correlación con el tamaño de coronas metálicas preformadas de stock / Mesiodistal width in temporary molars of Chilean children of Concepción and his correlation with standard preformed steel crowns

Las coronas metálicas preformadas son el tratamiento de elección al restaurar extensas caries en molares temporales. Para lograr un óptimo tratamiento es necesario conocer los anchos mesiodistales de las piezas involucradas en la terapia restauradora. En nuestro medio se utilizan los anchos mesiodistales de otras poblaciones, al conocer que pueden existir diferencias significativas con nuestra población en particular decidimos estudiar el ancho mesiodistal en nuestros pacientes. El propósito de esta investigación fue determinar anchos mesiodistales de molares temporales sanos en niños chilenos, analizando dimorfismo sexual, simetría intraarcada y con la pieza contralateral, así como la concordancia con los tamaños estandarizados de las coronas metálicas preformadas. Se realizó un estudio descriptivo odontométrico, seleccionando 34 niños (17 hombres y 17 mujeres) que asistían a la Clínica de Odontopediatría. Se procedió a medir anchos mesiodistales con un calibre ortodóncico en modelos de yeso obtenidos de cada paciente. Simultáneamente se midieron anchos mesiodistales de coronas metálicas preformadas. No se observan diferencias estadísticamente significativas entre los diámetros de piezas derechas e izquierdas ni entre géneros. Molares inferiores presentaron mayor ancho mesiodistal que los superiores. El promedio de ancho mesiodistal de molares temporales se corresponde de manera significativa con un solo tamaño de corona metálica preformada, salvo en las piezas 5.5 y 8.5 donde la correlación es con 2 tamaños de coronas metálicas.

Metallic preformed steel crowns are the best treatment choice to restaurate extense cavities in temporary molars. To achieve optimal results it is necessary to know the mesiodistal width of the temporary teeth involved. We currently use other population’s data regarding mesiodistal width, and since we believe there could be significant variations in between populations we decided to study mesiodistal width in our patients. The purpose of this investigation was to determine mesiodistal widths of healthy temporary molars in Chilean children.Sexual dimorphism, interarch symmetry and with the contralateral tooth, and comparison with the standard preformed steel crown were analyzed. This is a descriptive odonthometric study. 34 children (17 male, 17 female) assisting to the Pediatric Clinic were selected. Mesiodistal widths were assessed with an orthodontic caliper on a plaster model obtained from each patient. Simultaneously, preformed steel crown mesiodistal widths were measured. Results and conclusions: There were no statistically significant differences between right and left teeth’s mesiodistal width, nor between genders. The mean mesiodistal width of temporary molars corresponds with only one size of preformed steel crown, except on 5.5 and 8.5. In these teeth the width corresponds with two sizes of the preformed steel crown.