The study investigates the effectiveness of two NF approaches within a "school-holiday-camp"-setting. NF is a learning method based on neural plasticity, where specific EEG frequency bands are fed back in real-time. Participants will be randomly assigned to one of two conditions:
- Standard-NF training targeting a reduction of the TBR with fixed reward frequencies for the entire group.
- iAPF-TBR NF training targeting a reduction of the TBR with reward frequencies individually adjusted based on the child's pre-measured iAPF.
The training includes two sessions daily over eight camp days (a total of 16 sessions). While a small effect size (d = .2) would be expected for the comparison of iAPF-TBR NF and standard TBR NF requiring a total sample of N = 620 α= .05, 1-β = .8, G*Power; Faul et al., 2007), the present study is designed as a preliminary proof-of-concept study including an adopted target sample size. Therefore, the target sample size is set at N = 40 participants (n = 20 per arm). This sample size is sufficient to detect a medium to large effect (d = .7) with α= .10 and 1-β = .7 using one-tailed testing. This directional testing is justified by the theoretical advantage of personalized iAPF-TBR over the standard-TBR NF. The results of this pilot study will serve as essential preliminary evidence to justify the scaling of the protocol in a fully powered RCT.
The effects will be evaluated at the EEG, parent-, teacher- and self-report questionnaires, and behavioral (CPT) levels. The main objective is to determine whether the personalized NF protocol leads to superior and more sustainable effects.
Baseline frequency bands: Prior to each neurofeedback session, a one-minute resting-state EEG baseline is recorded to establish individual gain thresholds for theta and beta power. To control for non-cortical influences such as EMG artefacts, Power in frequency band 20-40 Hz is additionally required to be below a baseline threshold.
For NF and QEEG the THERA PRAX® MOBILE 13-channel full-band DC-EEG devices will be used (neuroConn GmbH, Ilmenau, Germany). They include a THERA PRAX® MOBILE MONITOR (PC panel) with INTEL CPU Core i3, 15" TFT color monitor and Windows® 10. The EEG amplifier is the THERA PRAX® DC-EEG Amplifier with 13 unipolar channels with an input impedance of < 10 GΩ, digitized with 24-bit-resolution and a sampling rate of 256/s. For skin preparation alcohol and abrasive gel (Nuprep Gel, D.O. Weaver, Aurora, CO), Ag/AgCl ring electrodes, covered with conductive paste (Ten20, D.O. Weaver) will be used. EEG, EOG and EMG data will be measured and stored by the THERA PRAX® system. The online processing of the measured EEG data during NF sessions uses a short-time Fourier-transformed moving average before the participants receive feedback on the monitor. As feedback, elements of a 15*15 grid picture selected by the participant were uncovered if the dynamic reward condition (with respect to Baseline B: EMGLOW ≤ B - 2.0 μV and Theta ≤ B + 3.0 μV and Beta ≥ B + 3.0 μV activity) is reached for 250 ms , respectively. The length of the time window analyzed in each case is 1 s which is shifted in steps of 40 ms.