Institut de Physiologie, Université de Lausanne, 1005 Lausanne, Switzerland.
Hum Brain Mapp. 1997;5(5):347-54. doi: 10.1002/(SICI)1097-0193(1997)5:5<347::AID-HBM3>3.0.CO;2-3.
Very little is known about the connectivity of the human cerebral cortex. Nonhuman primates often serve as a model, but they are very unsatisfactory when it comes to specifically human functions. Evidence from (human) lesion and activation studies indicates that Broca's and Wernicke's areas play a critical role in language functions, whereas the inferior temporal cortex of the right hemisphere tends to be associated with high-level visual recognition. We describe here monosynaptic interhemispheric input from the right inferior temporal cortex to Wernicke's and Broca's areas. The connections were traced in a brain with a right inferior temporal infarction by means of the Nauta method for anterogradely degenerating axons. Afferents were found both in Broca's and Wernicke's areas, with a higher density in the latter. Three organizational principles emerge from this study. First, the presence of direct connections from the right inferior temporal cortex to the speech areas indicates that human interhemispheric connections can be widely heterotopic. Second, the fact that connections from the inferior temporal cortex terminate in both Wernicke's and Broca's areas speaks in favor of parallel pathways in visuo-verbal processing. And third, the patchy distribution of visual interhemispheric afferents in Wernicke's area hints at a possible functional compartmentalization within this area.
关于人类大脑皮层的连接性，我们知之甚少。非人类灵长类动物通常作为模型，但在涉及特定人类功能时，它们非常不理想。来自（人类）损伤和激活研究的证据表明，布罗卡区和韦尼克区在语言功能中起着关键作用，而右半球的下颞叶皮层往往与高级视觉识别有关。我们在这里描述了来自右颞下回的单突触大脑半球间输入到韦尼克区和布罗卡区的情况。通过顺行变性轴突的 Nauta 方法，在一个右颞下梗死的大脑中追踪到了这些连接。在布罗卡区和韦尼克区都发现了传入纤维，后者的密度更高。这项研究得出了三个组织原则。首先，从右颞下回到言语区的直接连接的存在表明，人类半球间的连接可以广泛地异位。其次，下颞叶皮层的连接终止于韦尼克区和布罗卡区这一事实表明，在视-语处理中有平行的通路。第三，韦尼克区视觉半球间传入纤维的斑片状分布暗示该区域可能存在功能分区。
