Department of Psychology, Vanderbilt University, Nashville, TN, USA.
Brain Struct Funct. 2013 May;218(3):805-16. doi: 10.1007/s00429-012-0430-5. Epub 2012 Jun 9.
Cortical expansion, both in absolute terms and in relation to subcortical structures, is considered a major trend in mammalian brain evolution with important functional implications, given that cortical computations should add complexity and flexibility to information processing. Here, we investigate the numbers of neurons that compose 4 structures in the visual pathway across 11 non-human primate species to determine the scaling relationships that apply to these structures and among them. We find that primary visual cortex, area V1, as well as the superior colliculus (SC) and lateral geniculate nucleus scale in mass faster than they gain neurons. Areas V1 and MT gain neurons proportionately to the entire cerebral cortex, and represent fairly constant proportions of all cortical neurons (36 and 3 %, respectively), while V1 gains neurons much faster than both subcortical structures examined. Larger primate brains therefore have increased ratios of cortical to subcortical neurons involved in processing visual information, as observed in the auditory pathway, but have a constant proportion of cortical neurons dedicated to the primary visual representation, and a fairly constant ratio of about 45 times more neurons in primary visual than in primary auditory cortical areas.
皮质扩张，无论是在绝对意义上还是相对于皮质下结构，都被认为是哺乳动物大脑进化的一个主要趋势，具有重要的功能意义，因为皮质计算应该为信息处理增加复杂性和灵活性。在这里，我们研究了 11 种非人类灵长类动物视觉通路上的 4 个结构的神经元数量，以确定适用于这些结构及其之间的缩放关系。我们发现，初级视觉皮层（V1 区）以及上丘（SC）和外侧膝状体核（geniculate nucleus）在质量上的扩张速度快于神经元的增加速度。V1 区和 MT 区与整个大脑皮层成比例地获得神经元，并代表了所有皮质神经元的相当恒定的比例（分别为 36%和 3%），而 V1 区获得神经元的速度比两个研究的皮质下结构都要快得多。因此，较大的灵长类动物大脑具有更高的处理视觉信息的皮质到皮质下神经元的比例，就像在听觉通路上观察到的那样，但专门用于初级视觉表示的皮质神经元的比例保持不变，大约有 45 倍的神经元数量更多的初级视觉皮质区比初级听觉皮质区。
