Middlebrooks J C, Dykes R W, Merzenich M M
Brain Res. 1980 Jan 6;181(1):31-48. doi: 10.1016/0006-8993(80)91257-3.
The spatial distribution of neurons with different binaural response properties has been studied within the three dimensions of the primary auditory cortex (AI) in the cat. Using dichotic stimulation, 92% of neurons encountered could be classified into either the excitatory/excitatory (EE) or excitatory/inhibitory (EI) interaction class. In nearly all of almost 800 penetrations introduced along radial axes, all neurons encountered along a given penetration were of the same binaural response class. Neurons of different binaural interaction classes were spatially segregated within the plane of the cortex. Electrode penetrations made parallel to isofrequency contours traversed the mediolateral extent of AI through the middle layers of the cortex. A sharp segregation of units by binaural response class was observed in these penetrations, i.e. sequences of neurons that were all of the EE class alternated with sequences of EI neurons. The regions of uniform response to binaural stimulation formed radially organized topographical subunits that were elongated along the rostrocaudal dimension of AI. These binaural interaction bands intersect the lines of re-representation of the cochlear sensory epithelium ('isofrequency contours') and, thus, create subdivisions of AI that each contain a representation of the entire audible frequency domain. The implications of these results for the concept of AI as a unitary element in auditory processing are discussed.
在猫的初级听觉皮层（AI）的三维空间内，研究了具有不同双耳反应特性的神经元的空间分布。使用双耳刺激，所遇到的92%的神经元可被归类为兴奋性/兴奋性（EE）或兴奋性/抑制性（EI）相互作用类别。在沿径向轴进行的近800次穿刺中，几乎在所有穿刺中，沿给定穿刺所遇到的所有神经元都属于同一双耳反应类别。不同双耳相互作用类别的神经元在皮层平面内呈空间隔离分布。与等频率轮廓平行的电极穿刺穿过AI的中外侧范围，经过皮层的中间层。在这些穿刺中观察到单位按双耳反应类别明显隔离，即所有属于EE类别的神经元序列与EI神经元序列交替出现。对双耳刺激的均匀反应区域形成了沿AI的前后维度拉长的径向组织的地形亚单位。这些双耳相互作用带与耳蜗感觉上皮的重表示线（“等频率轮廓”）相交，从而创建了AI的细分区域，每个细分区域都包含整个可听频域的表示。讨论了这些结果对将AI视为听觉处理中一个统一元素这一概念的影响。
