Carlos López Escolano

EEG-based upper alpha neurofeedback training improves working memory performance

Neurofeedback (NF) training has revealed its therapeutical effects to treat a variety of neurological and psychological disorders, and has demonstrated its feasibility to improve certain cognitive aptitudes in healthy users. Although promising results of NF training exist in recent literature, the reliability of its effects remains questioned due to a lack of deep studies examining its impact on the human electrophysiology. This paper presents a NF training aimed at improving working memory performance in healthy users by the enhancement of upper alpha band. A user-specific training was used (upper alpha was determined for each user using the individual alpha frequency) to reduce the unspecific factors of training the entire classical alpha band as traditional NF usually does. EEG assessments in active and passive open-eyes state were conducted pre/post the NF training. The EEG analyses reveal the UA enhancement during the active tasks which is independent of other frequency bands. UA was also enhanced in the passive state but independence could not be obtained in lower alpha band. Finally, significant improvement in working memory was obtained with regard to a control group.

Human brain-teleoperated robot between remote places

This paper describes an EEG-based human brain-actuated robotic system, which allows performing navigation and visual exploration tasks between remote places via internet, using only brain activity. In operation, two teleoperation modes can be combined: robot navigation and camera exploration. In both modes, the user faces a real-time video captured by the robot camera merged with augmented reality items. In this representation, the user concentrates on a target area to navigate to or visually explore; then, a visual stimulation process elicits the neurological phenomenon that enables the brain-computer system to decode the intentions of the user. In the navigation mode, the target destination is transferred to the autonomous navigation system, which drives the robot to the desired place while avoiding collisions with the obstacles detected by the laser scanner. In the camera mode, the camera is aligned with the target area to perform an active visual exploration of the remote scenario. In June 2008, within the framework of the experimental methodology, five healthy subjects performed pre-established navigation and visual exploration tasks for one week between two cities separated by 260km. On the basis of the results, a technical evaluation of the device and its main functionalities is reported. The overall result is that all the subjects were able to successfully solve all the tasks reporting no failures, showing a high robustness of the system.

A telepresence robotic system operated with a P300-based brain-computer interface: Initial tests with ALS patients

Brain-computer interfaces (BCIs) open a new valuable communication channel for people with severe neurological or motor degenerative diseases, such as ALS patients. On the other hand, the ability to teleoperate robots in a remote scenario provides a physical entity embodied in a real environment ready to perceive, explore, and interact. The combination of both functionalities provides a system with benefits for ALS patients in the context of neurorehabilitation or maintainment of the neural activity. This paper reports a BCI telepresence system which offers navigation, exploration and bidirectional communication, only controlled by brain activity; and an initial study of applicability with ALS patients. The results show the feasibility of this technology in real patients.

A controlled study on the cognitive effect of alpha neurofeedback training in patients with major depressive disorder

Cognitive deficits are core symptoms of depression. This study aims to investigate whether neurofeedback (NF) training can improve working memory (WM) performance in patients with major depressive disorder (MDD). The NF group (n = 40) underwent eight NF sessions and was compared to a non-interventional control group (n = 20). The NF protocol aimed to increase the individual upper alpha power in the parieto-occipital area of the scalp. Main cognitive variable was WM, which was measured pre- and post- training along with other variables such as attention and executive functions. EEG was recorded in both eyes closed resting state and eyes open task-related activity, pre- and post- NF training, and pre- and post- the NF trials within each session. A power EEG analysis and an alpha asymmetry analysis were conducted at the sensor level. Frequency domain standardized low resolution tomography (sLORETA) was used to assess the effect at brain source level. Correlation analysis between the clinical/cognitive and EEG measurements was conducted at both the sensor and brain source level. The NF group showed increased performance as well as improved processing speed in a WM test after the training. The NF group showed pre-post enhancement in the upper alpha power after the training, better visible in task-related activity as compared to resting state. A current density increase appeared in the alpha band (8–12 Hz) for the NF group, localized in the subgenual anterior cingulate cortex (sgACC, BA 25). A positive correlation was found for the NF group between the improvement in processing speed and the increase of beta power at both the sensor and brain source level. These results show the effectiveness of this NF protocol in improving WM performance in patients with MDD.

Double-blind single-session neurofeedback training in upper-alpha for cognitive enhancement of healthy subjects

This paper reports on a single-session neurofeedback (NF) training procedure on the user-specific upper alpha band for cognitive enhancement in healthy users. A double-blind study was designed using a NF group and an active control group. Control group performed as the NF group but received sham feedback, minimizing the non-specific factors of training. This design aimed to (i) investigate upper alpha as a NF parameter, (ii) evaluate the NF effects on upper alpha during the execution of a cognitive task, and (iii) evaluate the effects on cognitive performance by means of a cognitive task and a battery of psychological tests. Results of EEG analysis show the key role of the feedback: only the NF group enhanced upper alpha during the training, and it led to a desynchronization increase during the execution of the cognitive task. Regarding the behavioral results, a strong learning effect was observed, with the NF group performing better in almost all measurements but many of them without statistical significance.

The Effects of Individual Upper Alpha Neurofeedback in ADHD: An Open-Label Pilot Study

Standardized neurofeedback (NF) protocols have been extensively evaluated in attention-deficit/hyperactivity disorder (ADHD). However, such protocols do not account for the large EEG heterogeneity in ADHD. Thus, individualized approaches have been suggested to improve the clinical outcome. In this direction, an open-label pilot study was designed to evaluate a NF protocol of relative upper alpha power enhancement in fronto-central sites. Upper alpha band was individually determined using the alpha peak frequency as an anchor point. 20 ADHD children underwent 18 training sessions. Clinical and neurophysiological variables were measured pre- and post-training. EEG was recorded pre- and post-training, and pre- and post-training trials within each session, in both eyes closed resting state and eyes open task-related activity. A power EEG analysis assessed long-term and within-session effects, in the trained parameter and in all the sensors in the (1–30) Hz spectral range. Learning curves over sessions were assessed as well. Parents rated a clinical improvement in children regarding inattention and hyperactivity/impulsivity. Neurophysiological tests showed an improvement in working memory, concentration and impulsivity (decreased number of commission errors in a continuous performance test). Relative and absolute upper alpha power showed long-term enhancement in task-related activity, and a positive learning curve over sessions. The analysis of within-session effects showed a power decrease (“rebound” effect) in task-related activity, with no significant effects during training trials. We conclude that the enhancement of the individual upper alpha power is effective in improving several measures of clinical outcome and cognitive performance in ADHD. This is the first NF study evaluating such a protocol in ADHD. A controlled evaluation seems warranted due to the positive results obtained in the current study.

EEG-based upper-alpha neurofeedback for cognitive enhancement in major depressive disorder: A preliminary, uncontrolled study

Conditioning of the upper-alpha rhythm to improve cognitive performance in healthy users by means of neurofeedback (NF) has been evaluated by several studies, however its effectiveness in people with severe cognitive deficits, such as depressive subjects, remains underexplored. This paper reports on a preliminary uncontrolled study to assess the effects of an upper-alpha NF intervention on patients with major depressive disorder (MDD). The NF effects on the EEG and cognitive performance were assessed. The EEG results showed that patients were able to modulate the upper-alpha rhythm in task-related EEG and during training, in both cases across the executions of the NF sessions, and pre and post within each session. The behavioral results showed the effectiveness of this intervention in a variety of cognitive functions such as working memory, attention, and executive functions.

Single-trial classification of feedback potentials within neurofeedback training with an EEG brain-computer interface

Neurofeedback therapies are an emerging technique used to treat neuropsychological disorders and to enhance cognitive performance. The feedback stimuli presented during the therapy are a key factor, serving as guidance throughout the entire learning process of the brain rhythms. Online decoding of these stimuli could be of great value to measure the compliance and adherence of the subject to the training. This paper describes the modeling and classification of performance feedback potentials with a Brain-Computer Interface (BCI), under a real neurofeedback training with five subjects. LDA and SVM classification techniques are compared and are both able to provide an average performance of approximately 80%.

Sistema de Teleoperación Multi-Robot Basado en Interfaz Cerebro-Computador

This paper reports multi-robot teleoperation system based on a brain-computer interface, which allows the user to control simultaneously a non-predefined number of robots via internet, only by brain activity. These devices are oriented to people with severe neuromuscular disabilities, providing them telepresence with a interaction mode based on their thoughts. This work is an extension of a teleoperation system which has been improved to support the teleoperation of N robots, and that uses small and portable robots (of two orders of dimension below the original). The brain-computer interface is based on EEG with a P300-based protocol of control, and the robots are able to navigate, interact by sending alarms, and visually perceive the environments. The system has been validated with two healthy users and the main result is that all of them were able to successfully solve the proposed tasks with no failures, which demonstrates the validity and high robustness of the prototype.

Upper-Alpha Neurofeedback Training for Cognitive Enhancement: A Single-Session Study

This paper reports on a single-session neurofeedback (NF) training procedure on the user-specific upper alpha band for cognitive enhancement of healthy users. A double-blind study was designed using a NF group and an active control group. Control group performed as the NF group but received sham feedback, minimizing the non-specific factors of training. Results of EEG analysis show the key role of the feedback: only the NF group enhanced upper alpha during the training, and it led to a desynchronization increase during the execution of a cognitive task. Regarding the behavioral results, a strong learning effect was observed, with the NF group performing better in almost all measurements but many of them without statistical significance.