Editing Roger Wolcott Sperry (section)

==Nobel Prize==
{{Original research|section|date=June 2014}}Sperry was granted numerous awards over his lifetime, including the California Scientist of the Year Award in 1972, the National Medal of Science in 1989, the Wolf Prize in Medicine in 1979, and the Albert Lasker Medical Research Award in 1979, and the Nobel Prize for Medicine/Physiology in 1981 that he shared with David H. Hubel and Torsten N. Wiesel. Sperry won this award for his work with "split-brain" patients. The brain is divided into two hemispheres, the left and right hemispheres, connected in the middle by a part of the brain called the corpus callosum. In "split-brain" patients, the corpus callosum has been severed due to the patients suffering from epilepsy, a disease that causes intense and persistent seizures.  Seizures begin in one hemisphere and continue into the other hemisphere. Cutting the corpus callosum prevents the seizures from moving from one hemisphere to the other, which then prevents seizures from occurring, thus allowing the patients to function normally instead of suffering from continuous seizures.

Sperry first became interested in "split-brain" research when he was working on the topic of interocular transfer, which occurs when "one learns with one eye how to solve a problem then, with that eye covered and using the other eye, one already knows how to solve the problem".<ref name="National Academy of Sciences"/> Sperry asked the question: "how can the learning with one eye appear with the use of the other?"<ref name="California Technical Institute"/> Sperry cut nerves in the eyes of cats so the left eye was connected to the left hemisphere and the right eye was connected to the right hemisphere; he also cut the corpus callosum. The cats were then taught to distinguish a triangle from a square with the right eye covered.<ref name="National Academy of Sciences"/> Then the cats were presented the same problem with the left eye covered; the cats had no idea what they had just learned with the right eye and because of this could be taught to distinguish a square from a triangle. Depending on which eye was covered, the cats would either distinguish a square from a triangle or a triangle from a square, demonstrating that the left and right hemispheres learned and remembered two different events. This led Sperry to believe that the left and right hemispheres function separately when not connected by the corpus callosum.

Sperry's research with "split-brain" cats helped lead to the discovery that cutting the corpus callosum is a very effective treatment for patients who suffer from epilepsy.  Initially after the patients recovered from surgery there were no signs that the surgery caused any changes to their behavior or functioning. This observation rendered the question: if the surgery had absolutely no effect on any part of the patients' normal functioning then what is the purpose of the corpus callosum?  Was it simply there to keep the two sides of the brain from collapsing, as Karl Lashley jokingly put it? Sperry was asked to develop a series of tests to perform on the "split-brain" patients to determine if the surgery caused changes in the patients' functioning or not.

Working with his graduate student [[Michael Gazzaniga]], Sperry invited several of the "split-brain" patients to volunteer to take part in his study to determine if the surgery affected their functioning. These tests were designed to test the patients' language, vision, and motor skills.  When a person views something in the left visual field (that is on the left side of their body), the information travels to the right hemisphere of the brain and vice versa.  In the first series of tests, Sperry would present a word to either the left or right visual field for a short period of time.  If the word was shown to the right visual field, meaning the left hemisphere would process it, then the patient could report seeing the word.  If the word was shown to the left visual field, meaning the right hemisphere would process it, then the patient could not report seeing the word.  This led Sperry to believe that only the left side of the brain could articulate speech.  However, in a follow-up experiment, Sperry discovered that the right hemisphere does have some language abilities.  In this experiment, he had the patients place their left hands in a tray full of objects located under a partition so the patient would not be able to see the objects.  Then a word was shown to the patient's left visual field, which was processed by the right side of the brain.  This word described one of the objects in the tray, so the patient's left hand picked up the object corresponding to the word.  When participants were asked about the word and the object in their hand, they claimed they had not seen the word and had no idea why they were holding the object.  The right side of the brain had recognized the word and told the left hand to pick it up, but because the right side of the brain cannot speak and the left side of the brain had not seen the word, the patient could not articulate what they had seen.

In another series of experiments further examining the lateralization of language in the left and right hemispheres, Sperry presented one object to the left visual field and a different object to the right visual field of the "split-brain" patients.  The patient's left hand was put under a partition and then the patient was asked to draw with their left hand what they had been shown.  The patients would draw what they had seen in their left visual field, but when asked what they had drawn would describe what had been shown to their right visual field.  These tests proved that when the corpus callosum is severed, it breaks the connection between the left and right hemispheres, making them unable to communicate with each other.  Not only are they unable to communicate with each other, but also without the corpus callosum connecting them one hemisphere has no idea that the other hemisphere even exists.  There was even evidence of this outside the laboratory when some of the patients reported that, "while their left hand was unbuttoning their shirt, the right hand would follow along behind and button it again."<ref>{{cite book|last=Mook|first=Douglas|title=Classic Experiments in Psychology|year=2004|publisher=Greenwood Press|location=Westport, CT|page=[https://archive.org/details/classicexperimen0000mook/page/67 67]|isbn=978-0313318214|url=https://archive.org/details/classicexperimen0000mook/page/67}}</ref> These experiments were beneficial to numerous people in many different ways.

In his words, each hemisphere is:

{{Blockquote|indeed a conscious system in its own right, perceiving, thinking, remembering, reasoning, willing, and emoting, all at a characteristically human level, and ... both the left and the right hemisphere may be conscious simultaneously in different, even in mutually conflicting, mental experiences that run along in parallel|Roger Wolcott Sperry|''1974''}}

This research contributed greatly to understanding the [[lateralization of brain function]]. In 1989, Sperry also received the [[National Medal of Science]]. Afterwards in 1993, Sperry received the Lifetime Achievement Award from APA.

In addition to his contribution in establishing the lateralized function of the brain, Sperry is noted for his "[[chemoaffinity hypothesis]]", which has not only been influential in formation of testable hypotheses in how precise neuronal wiring diagram is established in the brain, but the hypothesis itself has been verified by numerous experiments.

{{blockquote|The cells and fibers of the brain must carry some kind of individual identification tags, presumably cytochemical in nature, by which they are distinguished one from another almost, in many regions, to the level of the single neurons|Roger Walcott Sperry<ref>{{cite journal|pmid=14077501|pmc=221249|year=1963|last1=Sperry|first1=R. W|title=Chemoaffinity in the Orderly Growth of Nerve Fiber Patterns and Connections|journal=Proceedings of the National Academy of Sciences of the United States of America|volume=50|issue=4|pages=703–10|doi=10.1073/pnas.50.4.703|bibcode=1963PNAS...50..703S|doi-access=free}}</ref>}}

In the words of a 2009 review article in ''Science'' magazine: "He suggested that gradients of such identification tags on retinal neurons and on the target cells in the brain coordinately guide the orderly projection of millions of developing retinal axons. This idea was supported by the identification and genetic analysis of axon guidance molecules, including those that direct development of the vertebrate visual system." This was confirmed in the seventies by [[Marshall W. Nirenberg]]'s work on [[chicken|chick]] retinas and later on ''[[Drosophila melanogaster]]'' [[larva]]e.<ref>"[http://profiles.nlm.nih.gov/JJ/Views/Exhibit/narrative/homeobox.html From Neuroblastoma to Homeobox Genes, 1976–1992]". The Marshall W. Nirenberg Papers. Profiles in Science, National Library of Medicine. Accessed on 2010-02-16.</ref>

The experiments conducted by Sperry focused on four major ideas which were also called "turnarounds": equipotentiality, split brain studies, nerve regeneration and plasticity, and psychology of the consciousness.<ref>Kimble, Gregor A. and Wertheimer, Michael (eds.) (2000). ''Portraits of Pioneers in psychology'', vol. 4. {{ISBN|0805838546}}</ref>