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EYE BRAIN AND VISION - PART 7

Não được nhìn thấy từ trên cao. Ở bên phải một inch hoặc hàng đầu đã được lopped off. Chúng ta có thể nhìn thấy các ban nhạc của corpus callosum quạt ra sau khi vượt qua, và tham gia tất cả các phần của hai bán cầu. (Mặt trước của não ở phía trên của hình ảnh | The corpus callosum is a thick bent plate of axons near the center of this brain section made by cutting apart the human cerebral hemispheres and looking at the cut surface. Here the brain is seen from above. On the right side an inch or so of the top has been lopped off. We can see the band of the corpus callosum fanning out after crossing and joining every part of the two hemispheres. The front of the brain is at the top of the picture. 2 The word commissure signifies a set of fibers connecting two homologous neural structures on opposite sides of the brain or spinal cord thus the corpus callosum is sometimes called the great cerebral commissure. Until about 1950 the function of the corpus callosum was a complete mystery. On rare occasions the corpus callosum in humans is absent at birth in a condition called agenesis of the corpus callosum. Occasionally it may be completely or partially cut by the neurosurgeon either to treat epilepsy thus preventing epileptic discharges that begin in one hemisphere from spreading to the other or to make it possible to reach a very deep tumor such as one in the pituitary gland from above. In none of these cases had neurologists and psychiatrists found any deficiency someone had even suggested perhaps not seriously that the sole function of the corpus callosum was to hold the two cerebral hemispheres together. Until the 1950s we knew little about the detailed connections of the corpus callosum. It clearly connected the two cerebral hemispheres and on the basis of rather crude neurophysiology it was thought to join precisely corresponding cortical areas on the two sides. Even cells in the striate cortex were assumed to send axons into the corpus callosum to terminate in the exactly corresponding part of the striate cortex on the opposite side. In 1955 Ronald Myers a graduate student studying under psychologist Roger Sperry at the University of Chicago did the first experiment that revealed a function for this immense bundle of .