Test-Retest Reliability of Resting-State Magnetoencephalography Power in Sensor and Source Space

Several studies have reported changes in spontaneous brain rhythms that could be used asclinical biomarkers or in the evaluation of neuropsychological and drug treatments in longitudinal studies using magnetoencephalography (MEG). There is an increasing necessity to use these measures in early diagnosis and pathology progression; however, there is a lack of studies addressing how reliable they are. Here, we provide the first test-retest reliability estimate of MEG power in resting-state at sensor and source space. In this study, we recorded 3 sessions of resting-state MEG activity from 24 healthy subjects with an interval of a week between each session. Power values were estimated at sensor and source space with beamforming for classical frequency bands: delta (2–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), low beta (13–20 Hz), high beta (20–30 Hz), and gamma (30–45 Hz). Then, test-retest reliability was evaluated using the intraclass correlation coefficient (ICC). We also evaluated the relation between source power and the within-subject variability. In general, ICC of theta, alpha, and low beta power was fairly high (ICC > 0.6) while in delta and gamma power was lower. In source space, fronto-posterior alpha, frontal beta, and medial temporal theta showed the most reliable profiles. Signal-to-noise ratio could be partially responsible for reliability as low signal intensity resulted inhigh within-subject variability, but also the inherent nature of some brain rhythms in resting-state might be driving these reliability patterns. In conclusion, our results described the reliability of MEG power estimates in each frequency band, which could be considered in disease characterization or clinical trials

Choice of Magnetometers and Gradiometers after Signal Space Separation

Background: Modern Elekta Neuromag MEG devices include 102 sensor triplets containing one magnetometer and two planar gradiometers. The first processing step is often a signal space separation (SSS), which provides a powerful noise reduction. A question commonly raised by researchers and reviewers relates to which data should be employed in analyses: (1) magnetometers only, (2) gradiometers only, (3) magnetometers and gradiometers together. The MEG community is currently divided with regard to the proper answer. Methods: First, we provide theoretical evidence that both gradiometers and magnetometers result from the backprojection of the same SSS components. Then, we compare resting state and task-related sensor and source estimations from magnetometers and gradiometers in real MEG recordings before and after SSS. Results: SSS introduced a strong increase in the similarity between source time series derived from magnetometers and gradiometers (r2 = 0.3–0.8 before SSS and r2 > 0.80 after SSS). After SSS, resting state power spectrum and functional connectivity, as well as visual evoked responses, derived from both magnetometers and gradiometers were highly similar (Intraclass Correlation Coefficient > 0.8, r 2 > 0.8). Conclusions: After SSS, magnetometer and gradiometer data are estimated from a single set of SSS components (usually ≤ 80). Equivalent results can be obtained with both sensor types in typical MEG experiments

Neuronas Espejo y Teoría de la Mente en la explicación de la empatía

La empatía es la capacidad de una persona para vivenciar los pensamientos y sentimientos de los otros, reaccionando adecuadamente. Diferenciamos en la empatía dos componentes: cognitivo y emocional. El componente cognitivo comprende los pensamientos y sentimientos del otro. El componente afectivo comparte el estado emocional de otra persona. Comentamos dos teorías para explicar la empatía: las neuronas espejo y la Teoría de la Mente. Las neuronas espejo son un tipo particular de neuronas que se activan cuando un individuo realiza una acción, pero también cuando él observa una acción similar realizada por otro individuo Para la teoría de la mente atribuir mente a otro es una actividad teórica ya que no podemos observar su mente, pero generamos hipótesis sobre lo que está pensando o sintiendo, e interpretamos así su comportamiento. Argumentamos una continuidad genética entre ambas teorías, que se sitúan a nivel explicativo distinto: las neuronas espejo a nivel neuronal (neurociencia básica) y la teoría de la mente en el nivel cognitivo. Mostramos implicaciones de ambas teorías en la comprensión del autismo. [ABSTRACT]Empathy is a person’s ability to experiment other people’s thoughts and feelings and to react to them in an adequate manner. There are two different components within the concept of empathy: cognitive and emotional. The former implies the ability to understand thoughts and feelings of another person; the latter allows the individual to share the mental state of another person responding to his/her demands. We comment here on two theories that explain empathy: the mirror neurons and the Theory of Mind. Mirror neurons are a particular type of neurons which are activated when an individual performs an action, but also when he/she observes a similar action performed by someone else. For theory of mind, to attribute mind to another person is a theoretical activity because we cannot observe his mind, but we generate hypotheses about what he/she is thinking about or feeling, and, in this way, we interpret his/her behaviour. We deduce a genetic continuity between both theories in a different explanatory level: mirror neurons at a neuronal level (basic neuroscience) and theory of mind at a cognitive level. Implications of both theories in the explanation of autism are discussed

El papel de la neuropsicología en la formación del psicólogo

The impulse that neurosciences are receiving in the world of the investigation, has its reflection in the advances, as to experimental level as clinical, in psychology, in the specialty in neuropsychology. Neuropsychology means nowadays in the psychology, the approach to the world of the neurosciences and with it the adaptation of this ancient and long-lived discipline to the methodology of the century XXI. This fact justifies the importance to form in an adequate way the future psychologists in this discipline, or at least to offer them the basic knowledge so that themselves do not they remain stragglers of the advance in the investigation of the cognitive processes, base and object of study in psychology.El impulso que las neurociencias están recibiendo en el mundo de la investigación, tiene su reflejo en los avances, tanto a nivel experimental como clínico, en la psicología, en forma de la especialidad en neuropsicología. La neuropsicología significa hoy en día en la psicología, el acercamiento al mundo de las neurociencias y con ello la adaptación de esta ancestral y longeva disciplina a la metodología del siglo XXI. De aquí la importancia de formar de manera adecuada a los futuros psicólogos en neuropsicología, al menos ofrecerles los conocimientos básicos para que no se queden rezagados del avance en la investigación de los procesos cognitivos, desde luego, base y objeto de estudio en psicología

La ansiedad estado en personas sanas puede aumentar su vulnerabilidad a la distracción neutra pero no a la desagradable en la memoria de trabajo

Se sabe que los hechos desagradables irrelevantes influyen negativamente en nuestra capacidad para mantener en la memoria de trabajo información no emocional aunque importante para la tarea. Paralelamente, la ansiedad sesga nuestras respuestas atencionales a aquellos estímulos potencialmente amenazadores para, de este modo, mejorar adaptativamente su detección y valoración. En este trabajo hemos investigado las diferencias entre voluntarios sanos y ansiosos mientras realizaban una tarea de memoria de trabajo en la que se presentaban como distractores imágenes neutras y desagradables. Los resultados muestran que la ansiedad estado puede aumentar el efecto de interferencia de los distractores neutros pero no de los desagradables. Se comentan dichos resultados en relación a estudios anteriores que concluyen que la ansiedad y el estrés agudo pueden disminuir el nivel de especificidad en el mecanismo de vigilancia que sirve para optimizar la detección y evaluación de las amenazas

Early detection and late cognitive control of emotional distraction by the prefrontal cortex

Unpleasant emotional distraction can impair the retention of non-emotional information in working memory (WM). Research links the prefrontal cortex with the successful control of such biologically relevant distractors, although the temporal changes in this brain mechanism remain unexplored. We use magnetoencephalography to investigate the temporal dynamics of the cognitive control of both unpleasant and pleasant distraction, in the millisecond (ms) scale. Behavioral results demonstrate that pleasant events do not affect WM maintenance more than neutral ones. Neuroimaging results show that prefrontal cortices are recruited for the rapid detection of emotional distraction, at early latencies of the processing (70-130 ms). Later in the processing (360-450 ms), the dorsolateral, the medial and the orbital sections of the prefrontal cortex mediate the effective control of emotional distraction. In accordance with the behavioral performance, pleasant distractors do not require higher prefrontal activity than neutral ones. These findings extend our knowledge about the brain mechanisms of coping with emotional distraction in WM. In particular, they show for the first time that overriding the attentional capture triggered by emotional distractors, while maintaining taskrelevant elements in mind, is based on the early detection of such linked-to-survival information and on its later cognitive control by the prefrontal cortex

Exploratory analysis of power spectrum and functional connectivity during resting state in young binge drinkers: A MEG study

© Electronic version of an article published as International Journal of Neural Systems, Volume 25, Issue 03, May 2015, 13 Pages (https://doi.org/10.1142/S0129065715500082)Binge Drinking (BD) is a pattern of intermittent intensive alcohol intake which has spread among young adults over the last decades. Adolescence constitutes a critical neuromaturation period in which the brain is particularly sensitive to the effects of alcohol. However, little is known about how BD affects the brain activity. This study aimed to characterize the brain's functional organization in BD and non-BD young population by means of analyzing functional connectivity (FC) and relative power spectra (PS) profiles measured with magnetoencephalography (MEG) during eyes-closed resting state. Our sample composed 73 first-year university students (35 BDs and 38 controls). Results showed that the BD subjects displayed a decreased alpha FC in frontal-parietal regions, and conversely, an enhanced FC in the delta, theta and beta bands in fronto-temporal networks. Besides the FC differences, the BD group showed a decreased PS within alpha range and an increased PS within theta range in the brain's occipital region. These differences in FC and PS measurements provide new evidence of the neurophysiological alterations related to the alcohol neurotoxicity and could represent an initial sign of an anomalous neural activity caused by a BD pattern of alcohol consumption during youthThis study was supported by the project SPI/2010/134 and SPI/2010/051, from the Spanish Ministry of Health and Social Politics (National Plan on Drugs), and two predoctoral fellowships from the Ministry of Education (FPI, BES-2010-036469 and FPU, AP2008-03433)S

Binge drinking affects brain oscillations linked to motor inhibition and execution

Introduction: Neurofunctional studies have shown that binge drinking (BD) patterns of alcohol consumption during adolescence and youth are associated with anomalies in brain functioning. Recent evidence suggests that event-related oscillations (EROs) may be an appropriate index of neurofunctional damage associated with alcoholism. However, there is no study to date that has evaluated the effects of BD on oscillatory brain responses related to task performance. The purpose of the present study was to examine brain oscillations linked to motor inhibition and execution in young binge drinkers (BDs) compared to age-matched controls. Methods: Electroencephalographic activity was recorded from 64 electrodes while 72 university students (36 controls and 36 BDs) performed a visual Go/NoGo task. EROs along with the Go-P3 and NoGo-P3 event-related potential (ERP) components were analysed. Results: While no significant differences between groups were observed regarding ERPs, ERO analysis showed that BDs displayed a lower oscillatory response than controls in delta and theta frequency ranges during Go and NoGo conditions. Conclusions: Findings are congruent with ERO studies showing reduced delta and/or theta oscillations in alcoholics during Go/NoGo tasks. Thus, BDs appear to show disruptions in neural oscillations linked to motor inhibition and execution similar to those observed in alcohol-dependent subjects. Finally, these results are the first to evidence that oscillatory brain activity may be a sensitive indicator of underlying brain anomalies in young BDs, which could complement standard ERP measures.This study was supported by the projects SPI/2010/134 and SPI/2010/051 from the Spanish Ministry of Health and Social Politics (National Plan on Drugs). Eduardo López-Caneda was supported by the SFRH/BPD/109750/2015 Postdoctoral Fellowship of the Portuguese Foundation for Science and Technology as well as by the Psychology Research Centre (UID/PSI/01662/2013), co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653). Carina Carbia was supported through the FPU program (FPU2013-04569) of the Spanish Ministry of Education, Culture and Sports.S