Case-Control Studies
Research Papers
Reliability of Electroencephalogram-Based Individual Markers - Case Study
The aim of this study was to evaluate individual level of natural variability of electroencephalogram (EEG) based markers. Three linear: alpha power variability, spectral asymmetry index, relative gamma power and three nonlinear methods: Higuchi's fractal dimension, detrended fluctuation analysis, and Lempel-Ziv complexity were selected. The markers were evaluated over 15 sessions acquired in 14 months. The results indicate that individual natural variability for five of the selected markers is lower compared to differences between healthy and depressed groups of subjects in our previous studies. The results of the current study suggest that EEG based markers can be applied for evaluation of disturbances in brain activity at individual level.Clinical Relevance-The indicated stability in the current study of widely used EEG-based markers at individual level suggests a promising opportunity to apply EEG as a novel method in diagnoses of brain mental disorders in clinical practice.
View Full Paper →Neurofeedback training with a low-priced EEG device leads to faster alpha enhancement but shows no effect on cognitive performance: A single-blind, sham-feedback study
INTRODUCTION: Findings of recent studies indicate that it is possible to enhance cognitive capacities of healthy individuals by means of individual upper alpha neurofeedback training (NFT). Although these results are promising, most of this research was conducted based on high-priced EEG systems developed for clinical and research purposes. This study addresses the question whether such effects can also be shown with an easy to use and comparably low-priced Emotiv Epoc EEG headset available for the average consumer. In addition, critical voices were raised regarding the control group designs of studies addressing the link between neurofeedback training and cognitive performance. Based on an extensive literature review revealing considerable methodological issues in an important part of the existing research, the present study addressed the question whether individual upper alpha neurofeedback has a positive effect on alpha amplitudes (i.e. increases alpha amplitudes) and short-term memory performance focussing on a methodologically sound, single-blinded, sham controlled design. METHOD: Participants (N = 33) took part in four test sessions over four consecutive days of either neurofeedback training (NFT group) or sham feedback (SF group). In the NFT group, five three-minute periods of visual neurofeedback training were administered each day whereas in the SF group (control group), the same amount of sham feedback was presented. Performance on eight digit-span tests as well as participants' affective states were assessed before and after each of the daily training sessions. RESULTS: NFT did not show an effect on individual upper alpha and cognitive performance. While performance increased in both groups over the course of time, this effect could not be explained by changes in individual upper alpha. Additional analyses however revealed that participants in the NFT group showed faster and larger increase in alpha compared to the SF group. Surprisingly, exploratory analyses showed a significant correlation between the initial alpha level and the alpha improvement during the course of the study. This finding suggests that participants with high initial alpha levels benefit more from alpha NFT interventions. In the discussion, the appearance of the alpha enhancement in the SF group and possible reasons for the absence of a connection between NFT and short-term memory are addressed.
View Full Paper →Bereitschaftspotential augmentation by neuro-feedback training in Parkinson's disease
OBJECTIVE: Decreased early Bereitschaftspotential (BP) is one of the electrophysiological characteristics in patients with Parkinson's disease (PD). We examined whether PD patients could increase BP amplitude by means of neuro-feedback (NFB) training for their slow cortical potentials (SCPs). METHODS: We worked with 10 PD patients and 11 age-matched controls. BP was measured for self-paced button pressing by their right thumb. The subjects were instructed to make the introspective efforts to produce negative SCPs (negativation). The one-day session consisted of three trials, that is, the first BP, NFB training and the second BP, and each patient performed this routine for 2-4 days. Amplitudes of the first and second BPs were compared between the two groups that were divided depending on NFB performance. RESULTS: Good NFB performance had the tendency of larger early BP in the second BP recording than in the first one, whereas in the poor NFB performance the early BP was smaller in the second BP recording than in the first one in both patient and normal groups (p < 0.001). CONCLUSIONS: Good NFB performance of negativation could increase excitatory field potentials of pyramidal cells for the generation of early BP. SIGNIFICANCE: Voluntary regulation of SCPs could enhance BP in PD patients and in aged controls.
View Full Paper →Real-time self-regulation of emotion networks in patients with depression
Many patients show no or incomplete responses to current pharmacological or psychological therapies for depression. Here we explored the feasibility of a new brain self-regulation technique that integrates psychological and neurobiological approaches through neurofeedback with functional magnetic resonance imaging (fMRI). In a proof-of-concept study, eight patients with depression learned to upregulate brain areas involved in the generation of positive emotions (such as the ventrolateral prefrontal cortex (VLPFC) and insula) during four neurofeedback sessions. Their clinical symptoms, as assessed with the 17-item Hamilton Rating Scale for Depression (HDRS), improved significantly. A control group that underwent a training procedure with the same cognitive strategies but without neurofeedback did not improve clinically. Randomised blinded clinical trials are now needed to exclude possible placebo effects and to determine whether fMRI-based neurofeedback might become a useful adjunct to current therapies for depression.
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