人类和其他灵长类动物的视觉在背侧和腹侧视觉皮层中获得并行处理流,已知支持空间和对象处理,分别。这些溪流是桥接的,然而,在一个突出的白质区域,枕骨垂直束(VOF),在经典神经解剖学和最近的弥散加权磁共振成像(dMRI)研究中发现。了解VOF的演变可能会阐明其起源,函数,以及在视觉引导行为中的作用。为此,我们从某些哺乳动物的大脑中获得了高分辨率的dMRI数据,包括类人猿和链球菌灵长类动物,树泼妇,啮齿动物,和食肉动物。在每个物种中,我们试图在首先定位枕骨白质中的视神经辐射后描绘VOF。在所有被检查的灵长类动物中,光学辐射的侧面侧面是可识别为VOF的突出且连贯的白质束。相比之下,等效分析应用于来自与灵长类动物相同的超序的四个非灵长类动物物种(树sh,地松鼠,Paca,和rat)未能在等效位置显示白质束。在两个较大的食肉动物物种(雪貂和狐狸)中也没有明确的VOF证据。尽管我们不能排除在非灵长类物种中存在次要或不同组织的同源纤维途径,结果表明VOF已经大大扩展,或者可能出现了,在灵长类谱系。这种适应可能促进了灵长类动物独特的视觉引导行为的进化,对手动物体操纵有直接影响,社交互动,和树栖运动。
Vision in humans and other primates enlists parallel processing streams in the dorsal and ventral visual cortex, known to support spatial and object processing, respectively. These streams are bridged, however, by a prominent white matter tract, the vertical occipital fasciculus (VOF), identified in both classical neuroanatomy and recent diffusion-weighted magnetic resonance imaging (dMRI) studies. Understanding the evolution of the VOF may shed light on its origin, function, and role in visually guided behaviors. To this end, we acquired high-resolution dMRI data from the brains of select mammalian species, including anthropoid and strepsirrhine primates, a tree shrew, rodents, and carnivores. In each species, we attempted to delineate the VOF after first locating the optic radiations in the occipital white matter. In all primate species examined, the optic radiation was flanked laterally by a prominent and coherent white matter fasciculus recognizable as the VOF. By contrast, the equivalent analysis applied to four non-primate species from the same superorder as primates (tree shrew, ground squirrel, paca, and rat) failed to reveal white matter tracts in the equivalent location. Clear evidence for a VOF was also absent in two larger carnivore species (ferret and fox). Although we cannot rule out the existence of minor or differently organized homologous fiber pathways in the non-primate species, the results suggest that the VOF has greatly expanded, or possibly emerged, in the primate lineage. This adaptation likely facilitated the evolution of unique visually guided behaviors in primates, with direct impacts on manual object manipulation, social interactions, and arboreal locomotion.