Department of Biological and Visual Sciences, SUNY College of Optometry, New York, NY, 10036, United States.
Division of Biology and Biological Engineering, Caltech, Pasadena, CA, 91125, United States.
Nat Commun. 2022 Apr 28;13(1):2303. doi: 10.1038/s41467-022-29433-y.
The cerebral cortex receives multiple afferents from the thalamus that segregate by stimulus modality forming cortical maps for each sense. In vision, the primary visual cortex maps the multiple dimensions of the visual stimulus in patterns that vary across species for reasons unknown. Here we introduce a general theory of cortical map formation, which proposes that map diversity emerges from species variations in the thalamic afferent density sampling sensory space. In the theory, increasing afferent sampling density enlarges the cortical domains representing the same visual point, allowing the segregation of afferents and cortical targets by multiple stimulus dimensions. We illustrate the theory with an afferent-density model that accurately replicates the maps of different species through afferent segregation followed by thalamocortical convergence pruned by visual experience. Because thalamocortical pathways use similar mechanisms for axon segregation and pruning, the theory may extend to other sensory areas of the mammalian brain.
大脑皮层从丘脑接收多种传入信息，这些传入信息通过刺激方式进行分离，为每种感觉形成皮质图谱。在视觉中，初级视觉皮层将视觉刺激的多个维度以跨物种变化的模式进行映射，其原因尚不清楚。在这里，我们引入了一种皮质图谱形成的一般理论，该理论提出，图谱多样性源于丘脑传入密度在感觉空间中对感觉输入的采样的物种差异。在该理论中，传入信息采样密度的增加会扩大代表相同视觉点的皮质区域，从而允许通过多个刺激维度来分离传入信息和皮质靶标。我们使用传入信息密度模型来说明该理论，该模型通过传入信息的分离，以及随后通过视觉经验修剪的丘脑皮质会聚，准确地复制了不同物种的图谱。由于丘脑皮质通路使用类似的轴突分离和修剪机制，因此该理论可能扩展到哺乳动物大脑的其他感觉区域。
