Sigalovsky Irina S, Melcher Jennifer R
Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
Hear Res. 2006 May;215(1-2):67-76. doi: 10.1016/j.heares.2006.03.002. Epub 2006 Apr 27.
The dependence of fMRI activation on sound level was examined throughout the auditory pathway of normal human listeners using continuous broadband noise, a stimulus widely used in neuroscientific investigations of auditory processing, but largely neglected in neuro-imaging. Several specialized techniques were combined here for the first time to enhance detection of brainstem activation, mitigate scanner noise, and recover temporal resolution lost by the mitigation technique. The main finding was increased activation with increasing level in cochlear nucleus, superior olive, inferior colliculus, medial geniculate body and auditory cortical areas. We suggest that these increases reflect monotonically increasing activity in a preponderance of individual auditory neurons responsive to broadband noise. While the time-course of activation changed with level, the change was subtle and only significant in a part of the cortex. To our knowledge, these are the first fMRI data showing the effects of sound level in subcortical centers or for a non-tonal, non-speech stimulus at any stage of the pathway. The present results add to the body of parametric data in normal human listeners and are fundamental to the design of any fMRI experiment employing continuous noise.
利用连续宽带噪声，在正常人类听众的整个听觉通路中研究了功能磁共振成像（fMRI）激活对声音水平的依赖性。连续宽带噪声是一种在听觉处理的神经科学研究中广泛使用的刺激，但在神经成像中很大程度上被忽视。这里首次结合了几种专门技术，以增强对脑干激活的检测、减轻扫描仪噪声，并恢复因减轻技术而损失的时间分辨率。主要发现是，随着声音水平的增加，耳蜗核、上橄榄核、下丘、内侧膝状体和听觉皮层区域的激活增加。我们认为，这些增加反映了对宽带噪声有反应的大多数单个听觉神经元的活动单调增加。虽然激活的时间进程随声音水平而变化，但这种变化很细微，仅在部分皮层中显著。据我们所知，这些是首批显示声音水平对皮层下中枢的影响或在通路任何阶段对非音调、非语音刺激的fMRI数据。目前的结果增加了正常人类听众的参数数据，并对于任何使用连续噪声的fMRI实验设计至关重要。
