Genes And Cerebral Structures In Language Acquisition

The cerebral structures and genes in language acquisition, which attract many researchers, are still unclear. We first built an online computer-assistant research system and then applied some methodologies of neuropsychology, behavioral genetics and neuroimaging to answer these questions:is Mandarin passives acquired after five? Does it have any cerebral or genetic basis? Does words age of acquisition associate with different cerebral areas or pathways?In the first part, we studied on 151 children (including 54 pairs of twins) to acquire evidence for genetic basis in passives. The results showed that children acquired non-actional passives after 5 years old. Only genetic factors affected accuracy in non-actional passives. Compared to heritability, environment effect was higher in actional short passives but was equal in actional long passives. These data suggests that acquiring of non-acitonal passives might be guided by genetic factors, while comprehension of actional passives might associate with adjective strategy.In the second part, we tried to comprehend the projection pathway of foveal visual words in a rare case of pure hemialexia, in order to provide theoretic and technological basis. Diffuse tensor imaging shown that few fibers remained in the right ventroposterior part of the splenium. The correct naming scores of the characters presented completely in the right fovea were significantly higher than the correct naming scores of other stimuli. These phenomena support the split fovea theory and can not be easily explained by the bilateral projection theory. In the third part, we tried to present sentences in different visual field for 200 ms to explore the relationship between hemispheres and different types of passives in 56 adults. The results shown that in the picture-sentence verification task, actional passives related with right hemisphere, while non-actional passives related with left hemisphere. The trends were totally revealed in the sentence-picture verification task. Based on previous research, these subjects might rely on visual-spatial working memory in the first task, thus the syntactic working memory of non-actional passives might rely on left hemisphere but its visual working memory associated with right hemisphere, whereas these reversions in working memory of actional passives were revealed by our data. We did not find any relationship between actives and cerebral hemispheres.In the final part, we tried to explore cerebral basis of words age of acquisition (words acquired before or after 5 years old).The results shown that AOA was not significant in the total recovery although it played an important role in the early recovery, while familiarity was always significant. Right BA 37 was more active when the patient retrieved the word and was able to name. Our hypothesis was that pictures’ information was collected by bilateral BA 18 and then sent to angular gyrus through left BA 37/19. Right BA 18 usually sent the information to right BA 37/19 and then to left BA 37/19 through corpus callosum. Low AOA words might be sent directly to angular gyrus to angular gyrus, however, the pathway was absent in health subjects.