Cerebral Assymetry

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Cerebral Asymmetry
Introduction
Cerebral Asymmetry can be defined as the disequilibrium in the functionality of the two sides of the brain although the two sides are nearly of similar shape and size. The two hemispheres perform different functions and are also used in different ways. The brain asymmetry means physiological, anatomical and behavioral differences between the right and the left hemispheres. The dominant hemisphere is one which is larger, superior and more active in the performance of duties. Normally, the hemisphere that is situated on the left side usually functions to gearshifts all muscles that are adjacent on the right side part, on the other hand, the major role of right hemisphere is mainly to regulate the movement of the muscles that are on the adjacent side of human body,( Longa et al ,1989).
Structure of the Hemispheres
Division of the brain into suture into and two hemispheres that are located on the right and the left hemispheres links the sensory and motor nerve fibers cross each other. Also, at the hypothalamus of the brain, the right hemisphere is linked to the muscles on the adjacent leftward side of the brain are linked to those muscles that are located on the adjacent right side part of the body, (Downer, 1956). Every part of each hemisphere is specialized to control the specific behavior of an individual. However, the two hemispherical sections interconnect via millions of nerve fibers that link the two hemispheres and it is called corpus callosum which is situated in the central region of the human brain just above the brainstem, (Mahadik, et al.

, 1984).
The Broca’s Area
This is a specific area on that is situated mainly on the left part of the human brain, and its major function is to control the speech and the language. When this area is damaged, one cannot speak well. The name of this region of the brain was named after two neurologists Paul Broca and Karl Wernicke who were researching on the effect of damage to this area. The neurologists confirmed that when people have damaged the Broca’s area on the rightward side of the brain does not experience any language problems, (Paula, et al. 2009). There is another region of the brain important for language. The region is called Wernicke’s area named after the neurologist Karl Wernicke.
Confirming the Broca’s specific location, Paul Broca had performed an autopsy on a patient who had epilepsy when he was still alive. The epileptic patient had a lesion in his posterior portion of the left inferior frontal gyrus. The defect had resulted in Broca’s aphasia.
Wernicke’s area
When people have damaged Wernicke’s area, they eventually experience problems in comprehension of spoken language and usually talk nonsense words called Wernicke’s aphasia. The splitting of the corpus callosum helps in understanding specific functions of various areas of the brain.
Slit-Brain Experiment
The surgery of the corpus callosum is done to patients who have epilepsy. The splitting of the corpus callosum is done to prevent the spread of the epileptic seizures. It is done to separate the right hemisphere from the left one. When people with epilepsy had the corpus callosum split, they appeared normal in that they could talk, walk and play sports just like a normal person.
The Visual Field
The right visual field of the brain is at the periphery of the left cerebral hemisphere while the right one is in the right cerebral hemisphere. Every eye has both right and left visual field which enables visualization of the whole world in the front. In an experiment conducted to investigate the specific regions of the brain used to visualize objects, a spoon was placed just in front of a split-brain patient. The spoon was then flashed to the right of the dot. The result obtained was that the information of the vision of the spoon crossed the optic chiasm to the left hemisphere. The patient here could identify the spoon specifically as being a spoon. When the reverse was done, directly opposite results were obtained but could not see anything in front of him. The patient could directly pick the spoon when asked to do so with the left hand but could not tell what was in his hand because the right hemisphere cannot talk.
Extemporaneous Variables
Handedness
It was researched and found out that more that have the population of people are primarily right-handed. In 99% of these individuals language is commonly interpreted in left part of the cerebral hemisphere and the remaining ten percent of the left-side people, language is interpreted in the left cerebral hemisphere. To predict the effect of linguistic stimuli presented to either hemisphere should take into consideration the sidedness of the participants except for those who are not sided. To carry out this experiment half of the participants will have to do the computer-based experiment first while the rest will have to complete the sidedness questionnaire. The first half opens the Psyc shared folder from the dock and double clicks Cerebral Asymmetries and then double clicks CAwords.psySript as provided by the procedure. Finally, the experiment is saved as a text and copied in a spreadsheet.
The participants are then let to fill the form from what they see, and the data is entered in the spreadsheet. The data obtained is determined by the sidedness of the participants. There should be only two possible results in the experiment which explains the sidedness hypotheses.
Fixation and Anticipatory Eye movements
In the experiment, words were randomly presented to the participants. Both the left and the right visual fields were examined. In the same experiment, the presentation of words was increased 200 ms times. To remove the errors of the eye movement, many techniques like masking was performed. Changing of word type and pronounceability were other techniques applied to minimize the possible errors. Other extemporaneous variables that needed control include priming or word repetition, and word length and word frequency. Priming is a presentation of the same stimulus twice which may alter the effects on both accuracy and time response.
In conducting the speed-Accuracy trade –off of the eye movement chosen to collect data, it was found out that the response was rapid although it had a lot of errors when speed was the participants’ favor. When accuracy was used in the experiment, the response was accurate but slow.
Conclusion
The two brain hemispheres are separated by a septum of corpus callosum which contains a thick band of millions of fibers. Important to understand is that the two brain hemispheres are specialized to perform different functions, (Carlson, et al. 1989). The human brain is divided symmetrically into three lobes namely the frontal, the parietal and the occipital lobes. Each lobe is specialized in one activity. The occipital lobe is liable for interpreting and perceiving visions and images.
References
Longa, E. Z., Weinstein, P. R., Carlson, S., & Cummins, R. (1989). Reversible middle cerebral artery occlusion without craniectomy in rats. stroke, 20(1), 84-91.
Myers, R. E. (1956). Function of corpus callosum in interocular transfer. Brain, 79(2), 358-363.
Downer, J. D. C. (1959). Changes in visually guided behaviour following midsagittal division of optic chiasm and corpus callosum in monkey (Macaca mulatta). Brain, 82(2), 251-259.
Downer, J. D. C. (1959). Changes in visually guided behaviour following midsagittal division of optic chiasm and corpus callosum in monkey (Macaca mulatta). Brain, 82(2), 251-259.
Zhang, R. D., Price, J. E., Fujimaki, T., Bucana, C. D., & Fidler, I. J. (1992). Differential permeability of the blood-brain barrier in experimental brain metastases produced by human neoplasms implanted into nude mice. The American journal of pathology, 141(5), 1115.
Karpiak, S. E., & Mahadik, S. P. (1984). Reduction of cerebral edema with GM1 ganglioside. Journal of neuroscience research, 12(2‐3), 485-492.
Paula, S., Vitola, A. S., Greggio, S., de Paula, D., Mello, P. B., Lubianca, J. M., … & Dacosta, J. C. (2009). Hemispheric brain injury and behavioral deficits induced by severe neonatal hypoxia-ischemia in rats are not attenuated by intravenous administration of human umbilical cord blood cells. Pediatric research, 65(6), 631-635.
Rice, J. E., Vannucci, R. C., & Brierley, J. B. (1981). The influence of immaturity on hypoxic‐ischemic brain damage in the rat. Annals of neurology, 9(2), 131-141.
Lin, T. N., He, Y. Y., Wu, G., Khan, M., & Hsu, C. Y. (1993). Effect of brain edema on infarct volume in a focal cerebral ischemia model in rats. Stroke, 24(1), 117-121.
Shen, L. H., Li, Y., Chen, J., Zhang, J., Vanguri, P., Borneman, J., & Chopp, M. (2006). Intracarotid transplantation of bone marrow stromal cells increases axon-myelin remodeling after stroke. Neuroscience, 137(2), 393-399.