Kubke M Fabiana, Massoglia Dino P, Carr Catherine E
Department of Biology, University of Maryland, College Park, Md., USA.
Brain Behav Evol. 2004;63(3):169-80. doi: 10.1159/000076242. Epub 2004 Jan 15.
Increases in the size of the neuronal structures that mediate specific behaviors are believed to be related to enhanced computational performance. It is not clear, however, what developmental and evolutionary mechanisms mediate these changes, nor whether an increase in the size of a given neuronal population is a general mechanism to achieve enhanced computational ability. We addressed the issue of size by analyzing the variation in the relative number of cells of auditory structures in auditory specialists and generalists. We show that bird species with different auditory specializations exhibit variation in the relative size of their hindbrain auditory nuclei. In the barn owl, an auditory specialist, the hindbrain auditory nuclei involved in the computation of sound location show hyperplasia. This hyperplasia was also found in songbirds, but not in non-auditory specialists. The hyperplasia of auditory nuclei was also not seen in birds with large body weight suggesting that the total number of cells is selected for in auditory specialists. In barn owls, differences observed in the relative size of the auditory nuclei might be attributed to modifications in neurogenesis and cell death. Thus, hyperplasia of circuits used for auditory computation accompanies auditory specialization in different orders of birds.
介导特定行为的神经元结构的增大被认为与增强的计算性能有关。然而，尚不清楚哪些发育和进化机制介导了这些变化，也不清楚给定神经元群体大小的增加是否是实现增强计算能力的一般机制。我们通过分析听觉专家和非专家听觉结构细胞相对数量的变化来解决大小问题。我们发现，具有不同听觉特化的鸟类物种，其后脑听觉核的相对大小存在差异。在听觉专家谷仓猫头鹰中，参与声音定位计算的后脑听觉核表现出增生。这种增生在鸣禽中也有发现，但在非听觉专家中未发现。体重较大的鸟类中也未观察到听觉核的增生，这表明听觉专家中细胞总数是经过选择的。在谷仓猫头鹰中，听觉核相对大小的差异可能归因于神经发生和细胞死亡的改变。因此，用于听觉计算的回路增生伴随着不同鸟类目听觉特化的出现。
