Differences in evoked potentials during the active processing of sound location and motion
Differences in evoked potentials during the active processing of sound location and motion
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DOI：
10.1016/j.neuropsychologia.2013.03.001
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发表时间：
2013-06
期刊：
影响因子：
2.6
通讯作者：
Nicole Richter;E. Schröger;R. Rübsamen
中科院分区：
文献类型：
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作者：
Nicole Richter;E. Schröger;R. Rübsamen
本文用脑电描记法研究了人大脑皮层对动静声的加工差异。在三种不同的刺激条件下，在向左47°和向右47°之间的声学自由场中呈现声突发：（i）静态，（ii）横向运动，和（iii）横向运动。在主动古怪设计中，受试者被要求检测随机嵌入在频繁发生的非目标事件（即“标准”）和罕见的非目标刺激（即“异常”）流中的目标刺激。相应的声学刺激以块的形式呈现，其中每种刺激类型以三种刺激条件中的任一种呈现：作为目标、作为非目标或作为标准。分析了不同刺激类型在各自标准条件下诱发的事件相关电位。与以前的研究一样，所有三种不同的声刺激都在50- 200 ms的范围内引起了强制性P1/N1/P2复合波。然而，由静态刺激和两种运动刺激引起的ERP的比较早在刺激开始后100 ms就产生了差异，即在外源性N1和P2成分的水平上。在300- 400 ms的时间窗内也发现了信号幅度的差异（“运动-静态”差异波中的“d300 - 400 ms”分量）。对于运动刺激，N1振幅较大的半球对侧的运动的起源，而静态刺激N1振幅在两个半球是在相同的范围内。与N1成分相反，在'd300- 400 ms'的时间段内的ERP表现出更强的反应，在半球对侧的运动终止，与静态刺激再次产生相等的双边幅度。对于P2分量的运动特定的效果与更大的信号幅度在左半球被发现相比，静态刺激。目前记录的N1成分符合以往的研究结果的听觉空间处理，并建议对侧优势的过程中，皮层整合的空间声学信息。此外，“d300- 400 ms”时间段中的皮层活动表明，除了运动原点（如N1所反映的）之外，运动的方向（顺/逆运动）或运动终止也被皮层编码。这些电生理结果是根据“快照”假设，假设听觉运动处理是不是基于一个真正的运动敏感系统，而是在一个比较过程中的运动原点（发病）和运动终止（偏移）的空间位置。尽管如此，本P2分量的特异性提供了可能与运动特异性属性（即在左半球占优势的运动方向和/或速度）的评估相关的额外运动特异性过程的证据。
Difference in the processing of motion and static sounds in the human cortex was studied by electroencephalography with subjects performing an active discrimination task. Sound bursts were presented in the acoustic free-field between 47° to the left and 47° to the right under three different stimulus conditions: (i) static, (ii) leftward motion, and (iii) rightward motion. In an active oddball design, subject was asked to detect target stimuli which were randomly embedded within a stream of frequently occurring non-target events (i.e. ‘standards’) and rare non-target stimuli (i.e. ‘deviants’). The respective acoustic stimuli were presented in blocks with each stimulus type presented in either of three stimulus conditions: as target, as non-target, or as standard. The analysis focussed on the event related potentials evoked by the different stimulus types under the respective standard condition. Same as in previous studies, all three different acoustic stimuli elicited the obligatory P1/N1/P2 complex in the range of 50-200ms. However, comparisons of ERPs elicited by static stimuli and both kinds of motion stimuli yielded differences as early as ∼100ms after stimulus-onset, i.e. at the level of the exogenous N1 and P2 components. Differences in signal amplitudes were also found in a time window 300-400ms (‘d300-400ms’ component in ‘motion-minus-static’ difference wave). For motion stimuli, the N1 amplitudes were larger over the hemisphere contralateral to the origin of motion, while for static stimuli N1 amplitudes over both hemispheres were in the same range. Contrary to the N1 component, the ERP in the ‘d300-400ms’ time period showed stronger responses over the hemisphere contralateral to motion termination, with the static stimuli again yielding equal bilateral amplitudes. For the P2 component a motion-specific effect with larger signal amplitudes over the left hemisphere was found compared to static stimuli. The presently documented N1 components comply with the results of previous studies on auditory space processing and suggest a contralateral dominance during the process of cortical integration of spatial acoustic information. Additionally, the cortical activity in the ‘d300-400ms’ time period indicates, that in addition to the motion origin (as reflected by the N1) also the direction of motion (leftward/ rightward motion) or rather motion termination is cortically encoded. These electrophysiological results are in accordance with the ‘snap shot’ hypothesis, assuming that auditory motion processing is not based on a genuine motion-sensitive system, but rather on a comparison process of spatial positions of motion origin (onset) and motion termination (offset). Still, specificities of the present P2 component provides evidence for additional motion-specific processes possibly associated with the evaluation of motion-specific attributes, i.e. motion direction and/or velocity which is preponderant in the left hemisphere.