Meyer Martin, Elmer Stefan, Baumann Simon, Jancke Lutz
Institute of Neuroradiology, University Hospital of Zurich, Switzerland.
Restor Neurol Neurosci. 2007;25(3-4):411-31.
In this EEG study we sought to examine the neuronal underpinnings of short-term plasticity as a top-down guided auditory learning process. We hypothesized, that (i) auditory imagery should elicit proper auditory evoked effects (N1/P2 complex) and a late positive component (LPC). Generally, based on recent human brain mapping studies we expected (ii) to observe the involvement of different temporal and parietal lobe areas in imagery and in perception of acoustic stimuli. Furthermore we predicted (iii) that temporal regions show an asymmetric trend due to the different specialization of the temporal lobes in processing speech and non-speech sounds. Finally we sought evidence supporting the notion that short-term training is sufficient to drive top-down activity in brain regions that are not normally recruited by sensory induced bottom up processing.
18 non-musicians partook in a 30 channels based EEG session that investigated spatio-temporal dynamics of auditory imagery of "consonant-vowel" (CV) syllables and piano triads. To control for conditioning effects, we split the volunteers in two matched groups comprising the same conditions (visual, auditory or bimodal stimulation) presented in a slightly different serial order. Furthermore the study presents electromagnetic source localization (LORETA) of perception and imagery of CV- and piano stimuli.
Our results imply that auditory imagery elicited similar electrophysiological effects at an early stage (N1/P2) as auditory stimulation. However, we found an additional LPC following the N1/P2 for auditory imagery only. Source estimation evinced bilateral engagement of anterior temporal cortex, which was generally stronger for imagery of music relative to imagery of speech. While we did not observe lateralized activity for the imagery of syllables we noted significantly increased rightward activation over the anterior supratemporal plane for musical imagery.
Thus, we conclude that short-term top-down training based auditory imagery of music and speech prompts involvement of distinct neural circuits residing in the perisylvian cortex.
在这项脑电图研究中,我们试图探究作为自上而下引导的听觉学习过程的短期可塑性的神经基础。我们假设,(i)听觉意象应引发适当的听觉诱发效应(N1/P2复合体)和晚期正成分(LPC)。一般来说,基于最近的人类脑图谱研究,我们预期(ii)观察到不同的颞叶和顶叶区域参与意象以及声学刺激的感知。此外,我们预测(iii)由于颞叶在处理语音和非语音声音方面的不同特化,颞区会呈现不对称趋势。最后,我们寻找证据支持这样一种观点,即短期训练足以驱动在正常情况下不由感觉诱导的自下而上处理所募集的脑区中的自上而下活动。
18名非音乐家参与了一项基于30通道的脑电图实验,该实验研究了“辅音 - 元音”(CV)音节和钢琴和弦的听觉意象的时空动态。为了控制条件作用效应,我们将志愿者分成两个匹配的组,两组包含以略有不同的顺序呈现的相同条件(视觉、听觉或双峰刺激)。此外,该研究还展示了CV刺激和钢琴刺激的感知与意象的电磁源定位(LORETA)。
我们的结果表明,听觉意象在早期阶段(N1/P2)引发了与听觉刺激相似的电生理效应。然而,我们发现仅在听觉意象的N1/P2之后出现了额外的LPC。源估计显示双侧颞前皮质参与,相对于语音意象,音乐意象的这种参与通常更强。虽然我们没有观察到音节意象的偏侧化活动,但我们注意到音乐意象在前颞上平面的右侧激活显著增加。
因此,我们得出结论,基于音乐和语音的短期自上而下训练的听觉意象促使位于外侧裂周皮质的不同神经回路参与其中。