Chakalov Ivan, Paraskevopoulos Evangelos, Wollbrink Andreas, Pantev Christo
Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, 48149 Münster, Germany.
Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, 48149 Münster, Germany; School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Neuroimage. 2014 Oct 15;100:337-46. doi: 10.1016/j.neuroimage.2014.06.026. Epub 2014 Jun 16.
In case of binaural presentation of two tones with slightly different frequencies the structures of brainstem can no longer follow the interaural time differences (ITD) resulting in an illusionary perception of beat corresponding to frequency difference between the two prime tones. Hence, the beat-frequency does not exist in the prime tones presented to either ear. This study used binaural beats to explore the nature of acoustic deviance detection in humans by means of magnetoencephalography (MEG). Recent research suggests that the auditory change detection is a multistage process. To test this, we employed 26 Hz-binaural beats in a classical oddball paradigm. However, the prime tones (250 Hz and 276 Hz) were switched between the ears in the case of the deviant-beat. Consequently, when the deviant is presented, the cochleae and auditory nerves receive a "new afferent", although the standards and the deviants are heard identical (26 Hz-beats). This allowed us to explore the contribution of auditory periphery to change detection process, and furthermore, to evaluate its influence on beats-related auditory steady-state responses (ASSRs). LORETA-source current density estimates of the evoked fields in a typical mismatch negativity time-window (MMN) and the subsequent difference-ASSRs were determined and compared. The results revealed an MMN generated by a complex neural network including the right parietal lobe and the left middle frontal gyrus. Furthermore, difference-ASSR was generated in the paracentral gyrus. Additionally, psychophysical measures showed no perceptual difference between the standard- and deviant-beats when isolated by noise. These results suggest that the auditory periphery has an important contribution to novelty detection already at sub-cortical level. Overall, the present findings support the notion of hierarchically organized acoustic novelty detection system.
在呈现两个频率略有不同的音调时，脑干结构不再能追踪双耳时间差（ITD），从而产生与两个原始音调之间的频率差相对应的节拍错觉感知。因此，节拍频率并不存在于呈现给任何一只耳朵的原始音调中。本研究使用双耳节拍，通过脑磁图（MEG）来探索人类听觉偏差检测的本质。最近的研究表明，听觉变化检测是一个多阶段过程。为了验证这一点，我们在经典的oddball范式中采用了26Hz的双耳节拍。然而，在偏差节拍的情况下，原始音调（250Hz和276Hz）在双耳之间切换。因此，当呈现偏差音调时，耳蜗和听神经会接收到“新的传入信号”，尽管标准音调和偏差音调听起来是相同的（26Hz节拍）。这使我们能够探索听觉外周对变化检测过程的贡献，进而评估其对与节拍相关的听觉稳态反应（ASSR）的影响。确定并比较了典型失配负波时间窗（MMN）中诱发场的LORETA源电流密度估计值以及随后的差异ASSR。结果显示，由包括右侧顶叶和左侧额中回在内的复杂神经网络产生了MMN。此外，中央旁回产生了差异ASSR。此外，心理物理学测量表明，当被噪声隔离时，标准节拍和偏差节拍之间没有感知差异。这些结果表明，听觉外周在皮层下水平就已经对新奇性检测有重要贡献。总体而言，目前的研究结果支持了分层组织的听觉新奇性检测系统这一概念。
