Okazaki Yuka O, Horschig Jörn M, Luther Lisa, Oostenveld Robert, Murakami Ikuya, Jensen Ole
Department of Life Sciences, University of Tokyo, Tokyo 153-8902, Japan; Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6500HB Nijmegen, the Netherlands.
Donders Institute for Brain, Cognition and Behaviour, Radboud University, 6500HB Nijmegen, the Netherlands.
Neuroimage. 2015 Feb 15;107:323-332. doi: 10.1016/j.neuroimage.2014.12.014. Epub 2014 Dec 13.
It has been demonstrated that alpha activity is lateralized when attention is directed to the left or right visual hemifield. We investigated whether real-time neurofeedback training of the alpha lateralization enhances participants' ability to modulate posterior alpha lateralization and causes subsequent short-term changes in visual detection performance. The experiment consisted of three phases: (i) pre-training assessment, (ii) neurofeedback phase and (iii) post-training assessment. In the pre- and post-training phases we measured the threshold to covertly detect a cued faint Gabor stimulus presented in the left or right hemifield. During magnetoencephalography (MEG) neurofeedback, two face stimuli superimposed with noise were presented bilaterally. Participants were cued to attend to one of the hemifields. The transparency of the superimposed noise and thus the visibility of the stimuli were varied according to the momentary degree of hemispheric alpha lateralization. In a double-blind procedure half of the participants were provided with sham feedback. We found that hemispheric alpha lateralization increased with the neurofeedback training; this was mainly driven by an ipsilateral alpha increase. Surprisingly, comparing pre- to post-training, detection performance decreased for a Gabor stimulus presented in the hemifield that was un-attended during neurofeedback. This effect was not observed in the sham group. Thus, neurofeedback training alters alpha lateralization, which in turn decreases performances in the untrained hemifield. Our findings suggest that alpha oscillations play a causal role for the allocation of attention. Furthermore, our neurofeedback protocol serves to reduce the detection of unattended visual information and could therefore be of potential use for training to reduce distractibility in attention deficit patients, but also highlights that neurofeedback paradigms can have negative impact on behavioral performance and should be applied with caution.
已有研究表明，当注意力指向左侧或右侧视觉半视野时，阿尔法波活动会出现偏侧化。我们研究了阿尔法波偏侧化的实时神经反馈训练是否能增强参与者调节后阿尔法波偏侧化的能力，并导致视觉检测性能的后续短期变化。实验包括三个阶段：（i）训练前评估，（ii）神经反馈阶段和（iii）训练后评估。在训练前和训练后阶段，我们测量了隐蔽检测出现在左半视野或右半视野的提示性微弱伽柏刺激的阈值。在脑磁图（MEG）神经反馈期间，双侧呈现两个叠加有噪声的面部刺激。提示参与者关注其中一个半视野。叠加噪声的透明度以及因此刺激的可见性根据半球阿尔法波偏侧化的瞬时程度而变化。在双盲程序中，一半的参与者接受假反馈。我们发现，半球阿尔法波偏侧化随着神经反馈训练而增加；这主要是由同侧阿尔法波增加驱动的。令人惊讶的是，比较训练前后，在神经反馈期间未被关注的半视野中呈现的伽柏刺激的检测性能下降。在假手术组中未观察到这种效应。因此，神经反馈训练改变了阿尔法波偏侧化，这反过来又降低了未训练半视野的性能。我们的研究结果表明，阿尔法波振荡在注意力分配中起因果作用。此外，我们的神经反馈方案有助于减少对未被关注的视觉信息的检测，因此可能潜在地用于训练以减少注意力缺陷患者的注意力分散，但也强调神经反馈范式可能对行为表现产生负面影响，应谨慎应用。
