Department of Psychology, University of Graz, Austria; BioTechMed-Graz, Austria.
Department of Psychology, University of Graz, Austria.
Int J Psychophysiol. 2017 Oct;120:1-13. doi: 10.1016/j.ijpsycho.2017.06.005. Epub 2017 Jun 24.
Neurofeedback (NF) is often criticized because of the lack of empirical evidence of its specificity. Our present study thus focused on the specificity of NF on three levels: band specificity, cognitive specificity, and baseline specificity. Ten healthy middle-aged individuals performed ten sessions of SMR (sensorimotor rhythm, 12-15Hz) NF training. A second group (N=10) received feedback of a narrow gamma band (40-43Hz). Effects of NF on EEG resting measurements (tonic EEG) and cognitive functions (memory, intelligence) were evaluated using a pre-post design. Both training groups were able to linearly increase the target training frequencies (either SMR or gamma), indicating the trainability of these EEG frequencies. Both NF training protocols led to nonspecific changes in other frequency bands during NF training. While SMR NF only led to concomitant changes in slower frequencies, gamma training affected nearly the whole power spectrum. SMR NF specifically improved memory functions. Gamma training showed only marginal effects on cognitive functions. SMR power assessed during resting measurements significantly increased after SMR NF training compared to a pre-assessment, indicating specific effects of SMR NF on baseline/tonic EEG. The gamma group did not show any pre-post changes in their EEG resting activity. In conclusion, SMR NF specifically affects cognitive functions (cognitive specificity) and tonic EEG (baseline specificity), while increasing SMR during NF training nonspecifically affects slower EEG frequencies as well (band non-specificity). Gamma NF was associated with nonspecific effects on the EEG power spectrum during training, which did not lead to considerable changes in cognitive functions or baseline EEG activity.
神经反馈（NF）经常因其特异性缺乏经验证据而受到批评。因此，我们目前的研究侧重于 NF 在三个层面上的特异性：频带特异性、认知特异性和基线特异性。十名健康的中年个体进行了十次 SMR（感觉运动节律，12-15Hz）NF 训练。第二组（N=10）接受了窄伽马频带（40-43Hz）的反馈。使用预-后设计评估 NF 对 EEG 静息测量（紧张 EEG）和认知功能（记忆、智力）的影响。两个训练组都能够线性地增加目标训练频率（SMR 或伽马），表明这些 EEG 频率具有可训练性。两种 NF 训练方案在 NF 训练期间导致其他频带的非特异性变化。虽然 SMR NF 仅导致较慢频率的伴随变化，但伽马训练几乎影响整个功率谱。SMR NF 特异性地改善了记忆功能。伽马训练对认知功能仅显示出轻微的影响。与 SMR NF 训练前评估相比，SMR 静息测量期间的 SMR 功率在 SMR NF 训练后显著增加，表明 SMR NF 对基线/紧张 EEG 具有特异性影响。伽马组在其 EEG 静息活动中没有显示出任何前后变化。总之，SMR NF 特异性地影响认知功能（认知特异性）和紧张 EEG（基线特异性），而 NF 训练期间增加 SMR 则非特异性地影响较慢的 EEG 频率（频带非特异性）。伽马 NF 与训练期间 EEG 功率谱的非特异性影响相关，但不会导致认知功能或基线 EEG 活动的显著变化。
