Nobel_Prize Roger_Wolcott_Sperry

sperry granted numerous awards on lifetime, including california scientist of year award in 1972, national medal of science in 1989, wolf prize in medicine in 1979, , albert lasker medical research award in 1979, , nobel prize medicine/physiology in 1981 shared david h. hubel , torsten n. wiesel. sperry won award work split-brain patients. brain divided 2 hemispheres, left , right hemispheres, connected in middle part of brain called corpus callosum. in split-brain patients, corpus callosum has been severed due patients suffering epilepsy, disease causes intense , persistent seizures. seizures begin in 1 hemisphere , continue other hemisphere. cutting corpus callosum prevents seizures moving 1 hemisphere other, prevents seizures occurring, allowing patients function instead of suffering continuous seizures.

sperry first became interested in split-brain research when working on topic of interocular transfer, occurs when 1 learns 1 eye how solve problem then, eye covered , using other eye, 1 knows how solve problem . sperry asked question: how can learning 1 eye appear use of other? sperry cut nerves in eyes of cats left eye connected left hemisphere , right eye connected right hemisphere; cut corpus callosum. cats taught distinguish triangle square right eye covered. cats presented same problem left eye covered; cats had no idea had learned right eye , because of taught distinguish square triangle. depending on eye covered, cats either distinguish square triangle or triangle square, demonstrating left , right hemispheres learned , remembered 2 different events. led sperry believe left , right hemispheres function separately when not connected corpus callosum.

sperry’s research split-brain cats helped lead discovery cutting corpus callosum effective treatment patients suffer epilepsy. after patients recovered surgery there no signs surgery caused changes behavior or functioning. observation rendered question: if surgery had absolutely no effect on part of patients normal functioning purpose of corpus callosum? there keep 2 sides of brain collapsing, karl lashley jokingly put it? sperry asked develop series of tests perform on split-brain patients determine if surgery caused changes in patients functioning or not.

working graduate student michael gazzaniga, sperry invited several of split-brain patients volunteer take part in study determine if surgery affected functioning. these tests designed test patients language, vision, , motor skills. when person views in left visual field (that on left side of body), information travels right hemisphere of brain , vice versa. in first series of tests, sperry present word either left or right visual field short period of time. if word shown right visual field, meaning left hemisphere process it, patient report seeing word. if word shown left visual field, meaning right hemisphere process it, patient not report seeing word. led sperry believe left side of brain articulate speech. however, in follow-up experiment, sperry discovered right hemisphere have language abilities. in experiment, had patients place left hands in tray full of objects located under partition patient not able see objects. word shown patient s left visual field, processed right side of brain. word described 1 of objects in tray, patient s left hand picked object corresponding word. when participants asked word , object in hand, claimed had not seen word , had no idea why holding object. right side of brain had recognized word , told left hand pick up, because right side of brain cannot speak , left side of brain had not seen word, patient not articulate had seen.

in series of experiments further examining lateralization of language in left , right hemispheres, sperry presented 1 object left visual field , different object right visual field of split-brain patients. patient’s left hand put under partition , patient asked draw left hand had been shown. patients draw had seen in left visual field, when asked had drawn describe had been shown right visual field. these tests proved when corpus callosum severed, breaks connection between left , right hemispheres, making them unable communicate each other. not unable communicate each other, without corpus callosum connecting them 1 hemisphere has no idea other hemisphere exists. there evidence of outside laboratory when of patients reported that, while left hand unbuttoning shirt, right hand follow along behind , button again. these experiments beneficial numerous people in many different ways.

in words, each hemisphere is:

indeed conscious system in own right, perceiving, thinking, remembering, reasoning, willing, , emoting, @ characteristically human level, , . . . both left , right hemisphere may conscious simultaneously in different, in mutually conflicting, mental experiences run along in parallel

this research contributed understanding lateralization of brain function. in 1989, sperry received national medal of science. afterwards in 1993, sperry received lifetime achievement award apa.

in addition contribution in establishing lateralized function of brain, sperry noted chemoaffinity hypothesis , has not been influential in formation of testable hypotheses in how precise neuronal wiring diagram established in brain, hypothesis has been verified numerous experiments.

cells , fibers of brain must carry kind of individual identification tags, presumably cytochemical in nature, distinguished 1 almost, in many regions, level of single neurons

in words of 2009 review article in science magazine: suggested gradients of such identification tags on retinal neurons , on target cells in brain coordinately guide orderly projection of millions of developing retinal axons. idea supported identification , genetic analysis of axon guidance molecules, including direct development of vertebrate visual system. confirmed in seventies marshall w. nirenberg s work on chick retinas , later on drosophila melanogaster larvae.

the experiments conducted sperry focused on 4 major ideas called turnarounds : equipotentiality, split brain studies, nerve regeneration , plasticity, , psychology of consciousness.