Training for voluntarily increasing individual upper α power as a method for cognitive enhancement

Abstract

40Neurofeedback or EEG biofeedback training is a technology for developing the skills of voluntary mod ification of the EEG frequency and/or amplitude. The purpose of neurofeedback is to teach the subject to perceive and reproduce a specific cerebral activity. Therefore, EEG biofeedback training is a uniquely useful tool for finding the correspondence between a given state of cerebral activity and cognitive functions. For example, a distinct correspondence has been found between the power of the upper (high fre quency) α rhythm (10-12 Hz) and the performance of tasks requiring inner control of information process ing, such as mental rotation performance [1-3] and musical performance [4]. These results served as the basis for the development of α stimulating biofeed back training for the enhancement of mental functions and the demonstration of the key role of α activity in the control of cognitive functions [3, 5-9].However, as data on the effect of α stimulating bio feedback training on cognitive functions accumulated, a number of methodological limitations of its use became evident. For example, a conclusion on EEG biofeedback training efficiency cannot be considered valid unless it is based on the comparison of the results of biofeedback training with the results of training where the subjects fulfilled the same instructions as in the true biofeedback variant, but there was no feed back [10][11]. Many authors [7-9, 12] compare the results of feedback training with data on the control group where the subjects received neither biofeedback nor instructions on other self regulation techniques that were included in the biofeedback training ses sions. Therefore, evaluation of the results of biofeed back training require an adequate control group where the instructions, recommendations, methods of influ ence, and the duration of the contact between the sub jects and the trainer should be the same as in the experimental group, with the absence of biofeedback being the only difference. This "ideal control" is gen erally referred to as sham biofeedback [11,13]. Since this adequate method of identification of the biofeed back training effect has not been used thus far, the spe cific role of feedback in the training for increasing the α activity remains unknown; i.e., it is unclear where the increase in the α power and cognitive enhance Abstract-In order to estimate the effect of simultaneous α EEG stimulating and electromyogram (EMG) decreasing biofeedback training on the α activity and cognitive functions, fluency, accuracy, and flexibility during cognitive tasks, as well as α activity characteristics before, during, and after ten training sessions of voluntarily increasing α power in an individual upper α range with the eyes closed were studied in 27 healthy men aged 18-34 years. To isolate the biofeedback effect in training for the α power increase, data on two groups of subjects were compared: an experimental group (14 subjects) with true biofeedback and a control group (13 subjects) with sham biofeedback. Follow up t...

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

“…A NF intervention in the upper-alpha band and parietooccipital area of the scalp has already demonstrated to improve performance in healthy users [4]- [7]. To the authors' knowledge, the current study is one of the first research studies assessing the effectiveness of such an intervention to improve the cognitive performance in patients with major depressive disorder (MDD).…”

“…An Independent Component Analysis (ICA) filter was computed on the pre-NF task-related EEG screening, where the blinking component was automatically detected (the component with the most number of samples higher than 75µV in prefrontal sensors) and removed. The UA frequency band was defined as the frequency interval [IAF, IAF+2] Hz, where the Individual Alpha Frequency (IAF) was the frequency bin with the maximum power value in the alpha range ( [7,13] Hz) [8]. The IAF was computed per sensor on the power spectra of the pre-NF task-related EEG screening, and when no clear alpha peak was found the power spectra of the basal EEG screening was used instead.…”

“…An alternative NF intervention for depression could be to perform an intervention for cognitive enhancement, which has been extensively explored in healthy users [4]- [7]. This NF intervention could alleviate the severe cognitive impairment caused by depression.…”

“…Alpha is the dominant rhythm in the human EEG, which is characterized by a 'peak' in the power spectra in the frequency range [7,13] Hz (denoted alpha band), and is related to cognitive factors, such as working memory [9]. Regarding the alpha rhythm electrophysiology in depressive patients, a prefrontal alpha asymmetry has been commonly reported (see [10] for a review).…”

“…of cognitive abilities in healthy users [4]- [7]. The latter studies targeted the enhancement of the upper section of the alpha band, referred to as upper-alpha band, which has been traditionally linked to performance [8].…”