Donders Institute for Brain, Cognition and Behaviour, Centre for Cognition, Radboud University, Montessorilaan 3, 6525 HE Nijmegen, The Netherlands.
Clin Neurophysiol. 2011 Aug;122(8):1526-32. doi: 10.1016/j.clinph.2011.01.042. Epub 2011 Feb 25.
An auditory rhythm can be perceived as a sequence of accented (loud) and non-accented (soft) beats or it can be imagined. Subjective rhythmization refers to the induction of accenting patterns during the presentation of identical auditory pulses at an isochronous rate. It can be an automatic process, but it can also be voluntarily controlled. We investigated whether imagined accents can be decoded from brain signals on a single-trial basis, and if there is information shared between perception and imagery in the contrast of accents and non-accents.
Ten subjects perceived and imagined three different metric patterns (two-, three-, and four-beat) superimposed on a steady metronome while electroencephalography (EEG) measurements were made. Shared information between perception and imagery EEG is investigated by means of principal component analysis and by means of single-trial classification.
Classification of accented from non-accented beats was possible with an average accuracy of 70% for perception and 61% for imagery data. Cross-condition classification yielded significant performance above chance level for a classifier trained on perception and tested on imagery data (up to 66%), and vice versa (up to 60%).
Results show that detection of imagined accents is possible and reveal similarity in brain signatures relevant to distinction of accents from non-accents in perception and imagery.
Our results support the idea of shared mechanisms in perception and imagery for auditory processing. This is relevant for a number of clinical settings, most notably by elucidating the basic mechanisms of rhythmic auditory cuing paradigms, e.g. as used in motor rehabilitation or therapy for Parkinson's disease. As a novel Brain-Computer Interface (BCI) paradigm, our results imply a reduction of the necessary BCI training in healthy subjects and in patients.
听觉节奏可以被感知为一系列重音（响亮）和非重音（柔和）的节拍，也可以被想象出来。主观节奏化是指在等时率呈现相同的听觉脉冲时，引入重音模式。它可以是一个自动的过程，但也可以被自愿控制。我们研究了在单次试验的基础上，是否可以从大脑信号中解码出想象中的重音，以及在重音和非重音的对比中，感知和想象之间是否存在信息共享。
10 名受试者在脑电图（EEG）测量的同时感知和想象三种不同的度量模式（两拍、三拍和四拍）叠加在稳定的节拍器上。通过主成分分析和单次试验分类来研究感知和想象 EEG 之间的共享信息。
对重音和非重音节拍的分类准确率在感知时为 70%，在想象时为 61%。在条件交叉分类中，对于在感知上训练并在想象数据上测试的分类器，表现显著高于机会水平（最高可达 66%），反之亦然（最高可达 60%）。
结果表明，想象中的重音是可以被检测到的，并揭示了在感知和想象中，与区分重音和非重音相关的大脑特征的相似性。
我们的结果支持了听觉处理中感知和想象之间存在共享机制的观点。这在许多临床环境中都具有重要意义，特别是通过阐明节律性听觉提示范式的基本机制，例如在运动康复或帕金森病治疗中使用的范式。作为一种新的脑机接口（BCI）范式，我们的结果意味着可以减少健康受试者和患者进行必要的 BCI 训练。
