Draganova Rossitza, Ross Bernhard, Wollbrink Andreas, Pantev Christo
Institute for Biomagnetism and Biosignalanalysis, University of Münster, Malmedyweg 15, D-48149 Münster, Germany.
Cereb Cortex. 2008 May;18(5):1193-200. doi: 10.1093/cercor/bhm153. Epub 2007 Sep 7.
Different types of generation mechanisms of 40-Hz auditory steady-state response (ASSR) were investigated using diotic and dichotic stimulation with 500- and 540-Hz pure tones of 1.0-s duration and 2.0-s stimulus onset asynchrony. When the sum of both tones was presented to both ears simultaneously, they interacted at cochlear level and resulted in perception of a 40-Hz beat termed "peripheral beat." Dichotic presentation of the 500-Hz tone to one ear and the 540-Hz tone to the other one resulted in beat perception as the effect of central interaction, most likely in the superior olivary nuclei and was termed "central beat." ASSR and transient N1m responses were found in the averaged 151-channel whole-head magnetoencephalographic recordings under both stimulus conditions and were modeled with single spatiotemporal equivalent current dipoles in both hemispheres. The ASSR sources in both conditions were more anterior, more inferior, and more medial compared with N1m sources. Right hemispheric lateralization of the magnetic field strength was found for the ASSR in both stimulus conditions. Although the central and peripheral beat interacted at different levels of the auditory system, the initial responses were projected along the afferent auditory pathway and activated common cortical sources.
使用持续时间为1.0秒、刺激起始异步为2.0秒的500赫兹和540赫兹纯音，通过双耳和双听刺激，研究了40赫兹听觉稳态反应（ASSR）的不同类型产生机制。当两个纯音的总和同时呈现给双耳时，它们在耳蜗水平相互作用，产生一种被称为“外周拍”的40赫兹拍的感知。将500赫兹纯音呈现给一只耳朵，540赫兹纯音呈现给另一只耳朵的双听呈现方式，由于中枢相互作用，最有可能是在上橄榄核，产生了拍的感知，被称为“中枢拍”。在两种刺激条件下的平均151通道全头脑磁图记录中均发现了ASSR和瞬态N1m反应，并在两个半球用单个时空等效电流偶极子进行了建模。与N1m源相比，两种条件下的ASSR源更靠前、更低、更靠内侧。在两种刺激条件下，均发现ASSR的磁场强度存在右半球偏侧化。尽管中枢拍和外周拍在听觉系统的不同水平相互作用，但初始反应沿传入听觉通路投射并激活了共同的皮质源。
