Talavage T M, Ledden P J, Benson R R, Rosen B R, Melcher J R
Speech and Hearing Sciences Program, MIT-Harvard Division of Health Sciences and Technology, Cambridge, MA, USA.
Hear Res. 2000 Dec;150(1-2):225-44. doi: 10.1016/s0378-5955(00)00203-3.
Recordings in experimental animals have detailed the tonotopic organization of auditory cortex, including the presence of multiple tonotopic maps. In contrast, relatively little is known about tonotopy within human auditory cortex, for which even the number and location of tonotopic maps remains unclear. The present study begins to develop a more complete picture of cortical tonotopic organization in humans using functional magnetic resonance imaging, a technique that enables the non-invasive localization of neural activity in the brain. Subjects were imaged while listening to lower- (below 660 Hz) and higher- (above 2490 Hz) frequency stimuli presented alternately and at moderate intensity. Multiple regions on the superior temporal lobe exhibited responses that depended upon stimulus spectral content. Eight of these 'frequency-dependent response regions' (FDRRs) were identified repeatedly across subjects. Four of the FDRRs exhibited a greater response to higher frequencies, and four exhibited a greater response to lower frequencies. Based upon the location of the eight FDRRs, a correspondence is proposed between FDRRs and anatomically defined cortical areas on the human superior temporal lobe. Our findings suggest that a larger number of tonotopically organized areas exist (i.e., four or more) in the human auditory cortex than was previously recognized.
对实验动物的记录已经详细描述了听觉皮层的音频拓扑组织，包括多个音频拓扑图的存在。相比之下，对于人类听觉皮层内的音频拓扑学，人们了解得相对较少，甚至音频拓扑图的数量和位置仍不清楚。本研究开始使用功能磁共振成像技术，对人类皮层音频拓扑组织形成更完整的认识，该技术能够对大脑中的神经活动进行非侵入性定位。在受试者聆听交替呈现的低频（低于660赫兹）和高频（高于2490赫兹）刺激且强度适中时对其进行成像。颞上叶的多个区域表现出依赖于刺激频谱内容的反应。在受试者中反复识别出八个这样的“频率依赖性反应区域”（FDRR）。其中四个FDRR对高频表现出更大的反应，四个对低频表现出更大的反应。基于八个FDRR的位置，提出了FDRR与人类颞上叶解剖学定义的皮层区域之间的对应关系。我们的研究结果表明，人类听觉皮层中存在比之前认识到的更多的音频拓扑组织区域（即四个或更多）。
