Human Cognitive Neurophysiology Laboratory, VANCHCS Martinez, CA, USA.
Front Syst Neurosci. 2010 Dec 3;4:155. doi: 10.3389/fnsys.2010.00155. eCollection 2010.
While auditory cortex in non-human primates has been subdivided into multiple functionally specialized auditory cortical fields (ACFs), the boundaries and functional specialization of human ACFs have not been defined. In the current study, we evaluated whether a widely accepted primate model of auditory cortex could explain regional tuning properties of fMRI activations on the cortical surface to attended and non-attended tones of different frequency, location, and intensity. The limits of auditory cortex were defined by voxels that showed significant activations to non-attended sounds. Three centrally located fields with mirror-symmetric tonotopic organization were identified and assigned to the three core fields of the primate model while surrounding activations were assigned to belt fields following procedures similar to those used in macaque fMRI studies. The functional properties of core, medial belt, and lateral belt field groups were then analyzed. Field groups were distinguished by tonotopic organization, frequency selectivity, intensity sensitivity, contralaterality, binaural enhancement, attentional modulation, and hemispheric asymmetry. In general, core fields showed greater sensitivity to sound properties than did belt fields, while belt fields showed greater attentional modulation than core fields. Significant distinctions in intensity sensitivity and contralaterality were seen between adjacent core fields A1 and R, while multiple differences in tuning properties were evident at boundaries between adjacent core and belt fields. The reliable differences in functional properties between fields and field groups suggest that the basic primate pattern of auditory cortex organization is preserved in humans. A comparison of the sizes of functionally defined ACFs in humans and macaques reveals a significant relative expansion in human lateral belt fields implicated in the processing of speech.
虽然非人类灵长类动物的听觉皮层已经细分为多个具有不同功能的听觉皮层区域（ACFs），但人类 ACFs 的边界和功能特异性尚未确定。在当前的研究中，我们评估了一个被广泛接受的灵长类听觉皮层模型是否可以解释皮质表面上对不同频率、位置和强度的注意和非注意声音的 fMRI 激活的局部调谐特性。听觉皮层的边界由对非注意声音显示出显著激活的体素定义。确定了三个具有镜像对称音调组织的中心区域，并将其分配给灵长类模型的三个核心区域，而周围的激活则根据与猕猴 fMRI 研究中使用的程序类似的方法分配给带区域。然后分析了核心、内侧带和外侧带区域组的功能特性。通过音调组织、频率选择性、强度敏感性、对侧性、双耳增强、注意力调制和半球不对称性来区分区域组。一般来说，核心区域对声音特性的敏感性大于带区域，而带区域对注意力的调制大于核心区域。在相邻核心区域 A1 和 R 之间可以看到强度敏感性和对侧性的显著差异，而在相邻核心和带区域之间的边界上可以明显看出调谐特性的多个差异。不同区域和区域组之间的功能特性的可靠差异表明，人类听觉皮层组织的基本灵长类模式得以保留。对人类和猕猴中功能定义的 ACFs 的大小进行比较表明，人类外侧带区域的相对扩张明显，而外侧带区域与言语处理有关。
