Cerebral Cortex Functional Localization

Objective To observe activated cerebral areas during the task of writing in second language by early and late acquisition bilinguals and explore the neuropsychological mechanism. Methods Twelve subjects were divided into group of early acquisition high proficiency bilinguals(EAHP) and group of late acquisition high proficiency bilinguals(LAHP). Each subject carried out the task of pseudo-writing and English writing. After functional imaging,statistical parametric mapping was used to compare data of the two tasks through paired- t test in both two groups. A conjunction analysis was conducted between the two groups also. Areas where the metabolism of glucose changed were analyzed. Then, the corresponding images about activated cerebral regions were obtained.Results Cerebral areas where the metabolism of glucose increased in EAHP: bilateral middle frontal gyrus( Z=4.35/2. 01 ), bilateral cerebellum ( Z = 2.97/2.53 ) and left head of caudate nucleus ( Z = 3.07 ), etc. Cerebral areas where the metabolism of glucose increased in LAHP: right superior frontal gyrus(Z=4.06), right cerebellum( Z=4.63), left putamen(Z=2.70) ,etc. Cerebral areas where the metabolism of glucose increased in compared data of LAHP with data of EAHP: right frontal gyrus ( Z = 2.92 ), right temporal lobe( Z = 2.31 ), etc. Conclusion Extensive cerebral cortex and subcortical structures participate the process of writing in the second language. Age of bilingual acquisition is one of the factors affecting cerebral localization of writing in second language. Key words: Second language; Writing; Bilingual; Localization

In 1870, Eduard Hitzig and Gustav Fritsch performed experiments on dogs by which they were able to produce movement through electrical stimulation of specific parts of the cerebral cortex. Contemporaries regarded the experiment as a milestone in the controversially discussed issue of cerebral localization of functions even though this experiment came as a surprise to the community of experimental physiologists who had rejected localization for several decades after the antiphrenological work of the physiologist Pierre Flourens. In this article, I will argue that the context in which this experiment emerged was not so much the French localization debate of the 1860s but rather practical demands in clinical medicine, notably in electrotherapy. At the time of the experiment, Hitzig worked as a medical practitioner in Berlin and was interested in an anatomical and physiological explanation of the specific symptoms of one of his patients. The unpredictable outcome of this interest was the discovery of the electrical excitability of the cortex. Whereas experimental physiologists dominated the discussion on cerebral localization in Germany before 1870, the situation shifted after the publication of Fritsch and Hitzig's paper. Concrete medical necessities forced the discussion about localization and it was mainly due to the authority of clinical physicians that the localization of mental qualities in the brain became a cornerstone of brain research.

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The cerebral cortex, or outer cell layer of the brain, is divided into a mosaic of discrete areas with different functions: specific regions control vision, sensory and motor function, hearing, and language. Cortical degeneration, abnormality and disease affect brain function and behaviour.

I have much pleasure in thanking Professor Victor Horsley for allowing me to conduct the experiments which form the subject of this paper at the Pathological Laboratory of University College. It has always appeared to me contrary to the best established facts with regard to the cerebral localisation of motor processes that some abduction of the vocal cords should not be represented in the cerebral cortex. That abduction should be less powerfully represented in the cortex than adduction seemed clear, but that there should be no centre at all to subserve this function in the cerebral cortex seemed strange. I therefore decided to test the matter on the lines suggested to me by Dr. Hughlings Jackson in connection with a recent investigation of eye movements, when, after excluding the possibility of the lateral movements of the eyes to the opposite side from the hemisphere stimulated taking place, by dividing the muscles which bring about these movements, I found that it was possible to evoke many other movements of the eyes which hitherto could not be obtained. The conclusion which appeared warranted by these results was that the lateral movements of the eyes are so powerfully represented in the cerebral cortex that they overpower all other movements under normal circumstances.

Louis Victor Leborgne ("Tan").

A brief history of electrical brain stimulation in humans.