Sex differences in <i>RSP</i> (example left frontal channel).

<p><b>(A)</b> Mean <i>RSP</i> curves for males and females during Solo2-concentrate condition. <b>(B)</b> Sex effect across all guided conditions. Top: mean participant scores with error bars representing 95% CI. Bottom: associated frequency pattern, represented with bootstrap ratios across conditions. Reliable positive bootstrap indicated by red (blue) circles identify frequencies (35–45 Hz) where females have more power compared to males. Weak trend by which males exhibit more power alpha range (blue bootstrap ratios) is not consistently reliable across conditions.</p

My Virtual Dream: the ‘dreamery’ and the stage.

<p>In front of an audience, twenty participants at a time experienced a two-part interaction within the dome. Based on the collective neurofeedback of all 20 participants, the ‘dreamers’, artistic video animations were projected on the 360° surface of the semi-transparent dome and soundscapes were generated based on a pre-recorded sound library and improvisations from live musicians.</p

Game screenshots.

<p><b>(A)</b> EEG data observation and welcome messages. Players are ordered from left to right. <b>(B)</b> Solo relax. Number of particles indicates cumulative relaxation result (e.g., players 4 and 5 accumulated large particle cloud). Ovals on the top of the screen represent additional feedback such that light shading of the oval signifies <i>a+</i> state (e.g. player 4). <b>(C)</b> Solo concentrate. Brightness of particles indicates cumulative concentration result (e.g., players 1, 2 and 4 have good result). Dot inside an oval indicates that player is in <i>b+</i> state (e.g., players 1 and 4). <b>(D)</b> Group game, guided and freestyle.</p

Neurofeedback performance measures.

<p><b>(A)</b> Group mean alpha performance <i>aP</i> and beta performance <i>bP</i> for all participants taken together (yellow bullets), with 95% CI’s shown as error bars, beta learners (gray bullets) and non-learners (white bullets). Conditions where neurofeedback did not depend on the respective band of interest are shown in desaturated color. Black asterisks indicate conditions which expressed reliable PLS difference between learners and non-learners. <b>(B)</b> Analysis of differences in baseline <i>RSP</i> between beta learners and non-learners. Top: mean participant scores with error bars representing 95% CI. Bottom: associated frequency pattern for the left frontal channel with reliable positive (negative) bootstrap ratios indicated by red (blue) circles. High power in delta range and low power in beta/gamma range during baseline predicted subsequent beta learning.</p

Training effects on brain states (example left frontal channel).

<p><b>(A)</b> Relaxation training effect. Left: mean participant scores with respect to the relaxation training effect, with error bars representing 95% CI. Right: associated frequency pattern with reliable positive (negative) bootstrap ratios indicated by red (blue) circles. Overall effect of relaxation training is a decrease in 17–18 Hz and 35–45 Hz frequency range. <b>(B)</b> Concentration training effect. Left: mean participant scores with error bars representing 95% CI. Right: associated frequency pattern with reliable positive (negative) bootstrap ratios indicated by red (blue) circles. Overall effect of concentration training is an increase in beta power (20–40 Hz frequency range) and a decrease in delta power (<3 Hz). <b>(C)</b> Reliability of concentration training effect across a series of analyses with varying number of participants, N. For each N we plotted mean estimate of the reliability measure <i>maxp</i>. Reliable results (<i>maxp</i> < 0.05, i.e., below the red dotted line) are consistently obtained when the number of participants is >>200.</p

‘My Virtual Dream’: Collective Neurofeedback in an Immersive Art Environment

<div><p>While human brains are specialized for complex and variable real world tasks, most neuroscience studies reduce environmental complexity, which limits the range of behaviours that can be explored. Motivated to overcome this limitation, we conducted a large-scale experiment with electroencephalography (EEG) based brain-computer interface (BCI) technology as part of an immersive multi-media science-art installation. Data from 523 participants were collected in a single night. The exploratory experiment was designed as a collective computer game where players manipulated mental states of relaxation and concentration with neurofeedback targeting modulation of relative spectral power in alpha and beta frequency ranges. Besides validating robust time-of-night effects, gender differences and distinct spectral power patterns for the two mental states, our results also show differences in neurofeedback learning outcome. The unusually large sample size allowed us to detect unprecedented speed of learning changes in the power spectrum (~ 1 min). Moreover, we found that participants' baseline brain activity predicted subsequent neurofeedback beta training, indicating state-dependent learning. Besides revealing these training effects, which are relevant for BCI applications, our results validate a novel platform engaging art and science and fostering the understanding of brains under natural conditions.</p></div

Results of the automated artifact rejection procedure.

<p>EEG traces from the left frontal channel of 5 randomly selected participants are shown during the first 20 s of the Solo 1-concentrate condition. Shaded areas indicate rejected intervals.</p

Game timeline.

<p>Each phase of the game ended with fireworks display, size and brightness of which were determined by the performance of the participants. Total duration of the game was 6.5 min. In the Tutorial individual thresholds for alpha and beta were estimated based on guided ‘relax’ and ‘concentrate’ conditions. Participants obtained individual visual feedback on their performance to either increase alpha or beta. Solo 1 and 2 games were qualitatively identical with the tutorial, however individual thresholds were used. During the ‘group-guided’ game each ‘pod’ obtained feedback about the collective performance in addition to the individual feedback. In the ‘Group—freestyle’ period, participants did not obtain specific instructions other than to attempt to synchronize as a group by targeting the same brain state.</p

Time-of-night effect (example left frontal channel).

<p><b>(A)</b> Mean <i>RSP</i> curves from 29 sessions during Tutorial-relax condition. <b>(B)</b> Top: omnibus correlation between <i>RSP</i> values and time-of-night across all guided conditions. Error bar indicates 95% CI based on bootstrap resampling. Bottom: associated frequency pattern, represented with bootstrap ratios across conditions. Reliable positive (negative) bootstrap ratios are positively (negatively) correlated with time-of-night and are indicated by red (blue) circles. As the night progressed, there was as a gradual shift towards more power in high frequencies and less in low frequencies.</p