Polyakov A, Pratt H
Evoked Potentials Laboratory, Technion, Israel Institute of Technology, Haifa, Israel.
Ear Hear. 1998 Jun;19(3):232-9. doi: 10.1097/00003446-199806000-00006.
The purpose of this study was to compare the effects of monaural and binaural broadband masking noise on binaural interaction components (BICs) of the human auditory brain stem evoked potentials (ABEPs).
The BICs of the human ABEPs were studied by subtracting the potentials to binaural clicks from the algebraic sum of monaurally evoked potentials to clicks alone or to clicks with ipsilateral monaural or binaural broadband masking noise. Alternating polarity, 11/sec clicks were presented at 65 dB nHL, and noise was presented at 45 dB nHL. Analysis included peak-to-prestimulus baseline amplitudes and latencies of BICs' peaks and troughs from the vertex-mastoid (A) and vertex-neck (Z) channels. In addition, 3-channel Lissajous' trajectory (3-CLT) analysis, estimating the single, centrally located dipole equivalent of surface activity, was performed on data recorded from three orthogonally positioned electrode pairs. 3-CLT measures included apex latency, amplitude, and orientation, as well as planar segment duration, size, shape, and orientation.
All BICs 3-CLTs included five main components (labeled BdI, BdII, BdIII, BeI, and BeII). In general, apex latencies were longer with masking noise. However, BdII and BeI apex latencies were shorter with binaural than with ipsilateral monaural masking noise. Apex amplitude and planar segment size of component BeI, as well as P1 peak amplitude in BICs of the Z-channel records, were larger with binaural than with monaural noise. No significant difference between the monaural and binaural noise conditions was found in durations, shapes, and orientations of planar segments of BICs 3-CLT, nor in peak latency of BICs in the A- and Z-channel records.
We suggest that these effects on the latency and amplitude of BICs reflect binaural processing in the human brain stem. In particular, the larger amplitudes and shorter latencies of P1 and BeI with binaural than with ipsilateral monaural masking may be associated with the psychophysical effect of binaural masking level difference.
本研究旨在比较单耳和双耳宽带掩蔽噪声对人类听觉脑干诱发电位（ABEP）双耳相互作用成分（BIC）的影响。
通过从单耳诱发的点击电位或与同侧单耳或双耳宽带掩蔽噪声一起的点击电位的代数和中减去双耳点击电位，来研究人类ABEP的BIC。以65 dB nHL呈现交替极性、11次/秒的点击，以45 dB nHL呈现噪声。分析包括顶点-乳突（A）和顶点-颈部（Z）通道中BIC峰谷的峰到刺激前基线振幅和潜伏期。此外，对从三个正交放置的电极对记录的数据进行了三通道李萨如轨迹（3-CLT）分析，估计表面活动的单个、位于中心的偶极等效物。3-CLT测量包括顶点潜伏期、振幅和方向，以及平面段持续时间、大小、形状和方向。
所有BIC的3-CLT包括五个主要成分（标记为BdI、BdII、BdIII、BeI和BeII）。一般来说，有掩蔽噪声时顶点潜伏期更长。然而，双耳掩蔽噪声时BdII和BeI的顶点潜伏期比同侧单耳掩蔽噪声时短。BeI成分的顶点振幅和平面段大小，以及Z通道记录的BIC中P1峰振幅，双耳掩蔽噪声时比单耳掩蔽噪声时更大。在BIC的3-CLT平面段的持续时间、形状和方向上，以及在A和Z通道记录的BIC的峰潜伏期上，单耳和双耳噪声条件之间没有显著差异。
我们认为这些对BIC潜伏期和振幅的影响反映了人类脑干中的双耳处理。特别是，与同侧单耳掩蔽相比，双耳掩蔽时P1和BeI的振幅更大、潜伏期更短，这可能与双耳掩蔽级差的心理物理效应有关。
