Roger Sperry

6 Key excerpts on "Roger Sperry"

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  Brain and Behaviour

  Revisiting the Classic Studies

  • Bryan Kolb, Ian Whishaw, Bryan Kolb, Ian Whishaw, Author(Authors)
  • 2016(Publication Date)
  • SAGE Publications Ltd

    (Publisher)

  6 Revisiting Sperry: What the split brain tells us Michael C. Corballis In 1961, Roger W. Sperry published a paper in Science entitled “Cerebral organization and behavior” that heralded an astonishing era in behavioral neuroscience. The focus of the article was the splitting of the brain through cutting the corpus callosum, by far the largest and most important of the commissures connecting the two sides. The effect of this so-called split-brain operation was to have profound influences on our understanding of the nature of consciousness and on the different ways in which the two sides of the brain operate—influences that extended beyond neuroscience to such diverse disciplines as anthropology, art, literature, philosophy, psychology, and even business. Twenty years after publication of the Science article, Sperry belatedly received the Nobel Prize in Physiology or Medicine “for his discoveries concerning the functional specialization of the cerebral hemispheres.” The 1961 article summarized the work that Sperry and his colleagues had carried out on split-brained cats and monkeys. By splitting the optic chiasm as well as the corpus callosum, the researchers were able to present visual information to one side of the brain by presenting it to just one eye (see Figure 6.1). Thus a visual input to the left eye would be projected to the left brain, and input to the right eye only to the right brain. The results revealed a remarkable disconnection. If the split-brain animal learned to make a visual discrimination, such as responding to a cross but not to a circle, when viewing with one eye, it was then unable to make that discrimination when tested with the other eye. The memory for the discrimination was therefore contained entirely within the trained hemisphere of the brain, and inaccessible to the other

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  Principles Of Biopsychology

  • Simon Greene(Author)
  • 2013(Publication Date)
  • Psychology Press

    (Publisher)

  Sperry demonstrated that the right hemisphere can carry out sophisticated visuo-spatial functions, and should not be seen as simply the “poor relation” to the dominant left hemisphere. His work led to an explosion of interest in hemisphere functions, especially the lateralisation of abilities to one or other side. Because of the small numbers of split-brain subjects this necessarily involved work with normals, but before moving on to this there are some problems with the split-brain work that should be mentioned.

  Problems with the Split-Brain

  Since its introduction in the 1940s only about 60 patients have had split-brain surgery. They have all had severe and chronic epilepsy for months or years, and it is assumed that in most cases it was caused by brain damage at birth or later. (Prolonged birth can lead to oxygen starvation in the baby, which is known to damage the brain—although not immediately obvious, the injured area can, years later, become the focus for epileptic attacks.) So the studies of Sperry and others were on subjects with abnormal brains before the operation; brains that have had to adjust to early damage and to the effects of repeated epileptic seizures and years of drug therapy. The operation itself can vary. Sometimes the callosum is cut in two stages, involving two separate operations. Sometimes the other commissures mentioned earlier are also cut, sometimes they are left intact. Although they are small, it is possible that they could allow for some communication between the hemispheres.

  The data is therefore collected from a varied (heterogeneous) and small sample of subjects whose brains were not strictly comparable with normal brains even before the operation. It must be interpreted with caution. But this is not to dispute the value of Sperry’s work (he received the Nobel prize in 1981). He demonstrated that the hemispheres can function independently, and that although we are a language-dominated species, non-verbal functions are equally worthy of study and their localisation to the right hemisphere means that the concept of hemisphere dominance

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  Creativity

  Theories and Themes: Research, Development, and Practice

  • Mark A. Runco(Author)
  • 2014(Publication Date)
  • Academic Press

    (Publisher)

  Sperry’s (1964) study because the patients were epileptic. That is why they had the surgery—to minimize their proclivity for grand mal seizures. It also was a small sample (29 patients), which further precludes generalizations. As a matter of fact the specializations uncovered by Sperry—the left playing a role in language, for example—did not even characterize all the individuals in his small sample! Then there is the impressive fact that they all had a commissurotomy. This puts a complete kibosh on generalizations. In the strictest sense, generalizations should apply only to other epileptics who received the same surgery. There are additional data suggesting specialization of certain brain structures, and these have utilized other noninvasive technologies, which is one reason why the idea of hemispheric specialization is widely accepted.

  It is clear, then, that we should not generalize specifically from Sperry’s (1964) initial study. This point is labored here because there are a number of published recommendations and even treatment and enhancement programs (reviewed by Atchley et al. 1999 ) that make unwarranted generalizations. These are usually easy to identify. If they say something like “learn to use your right hemisphere,” you might ask how someone who has not had a commissurotomy can disconnect the left hemisphere. (If they offer you surgery to that end, decline and beat a rapid retreat.) For that matter, why would anyone want to rely on the right hemisphere, given that creativity (and any other important function you can name, including language) requires both hemispheres?

  Why was the right hemisphere labeled the creative one? It may be because often creativity is assumed to be illogical or at least nontraditional in its logic. Traditional logic or sequential processing was assigned to the left hemisphere, and left creative logic for the right (or nondominant) hemisphere. Perhaps it was also the holistic processing of the right hemisphere, for that can play a role in many of the arts (e.g., the visual arts). Yet the need for a collaborating brain is clear, even in the visual arts. In Flaherty’s (2005)

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  Brain Lateralization and Developmental Disorders

  A New Approach to Unified Research

  • Ivanka Asenova, Ivanka V. Asenova(Authors)
  • 2018(Publication Date)
  • Routledge

    (Publisher)

  Over the years, these initial speculations underwent multiple changes to reach the current conception of the functional specialization of the cerebral hemispheres and their close collaboration in the processing of any complex mental activity [ 2, 37, 38, 40, 209, 213, 214 ]. Empirical basis for the concept of the functional specialization of the brain Contemporary conceptions of functional specialization of the human brain are based on an impressive amount of empirical data generated from clinical observations and experimental studies that use a wide variety of research methods. Main approaches to characterizing hemispheric specialization may be summarized as following [ 190 ]: (a) post-mortem studies of human brains which focus on structural differences between homotopic regions of the two cerebral hemispheres; (b) in vivo studies of both structural and functional brain asymmetries using a variety of techniques: electroencephalography (EEG), magnetoencephalography, evoked potentials (EPs), magnetic resonance imaging (MRI) morphometry, functional MRI (fMRI), positron emission tomography (PET), transcranial Doppler sonography (TSD), functional TSD (fTSD), single positron emission computed tomography; (c) neuropsychological assessment of patients with focal brain lesions or split-brain patients and (d) neuropsychological assessment of hemispheric performance differ ences using tachistoscopic visual or dichotic auditory stimulus presentation

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  The Brain and the Inner World

  An Introduction to the Neuroscience of Subjective Experience

  • Mark Solms, Oliver Turnbull(Authors)
  • 2018(Publication Date)
  • Routledge

    (Publisher)

  So-called “split-brain” studies (mentioned briefly in chapter 3) were extremely influential in the 1960s and 1970s. At that time, a surgical procedure had been introduced for the treatment of intractable epilepsy: the corpus callosum (the fiber band that connects the two hemispheres; see chapters 1 and 7) was cut to isolate the seizures and prevent them from spreading to the healthy hemisphere (see chapter 6). This operation (known as “commisurotomy”) was performed for purely clinical reasons, but it provided a unique scientific opportunity for neuropsychologists to study the functions of the two hemispheres independently. However to investigate the problem systematically, some methodological problems had to be overcome. The main problem arises from eye movements: if the eyes can move freely when looking at objects placed in front of them, both hemispheres receive information about the objects. This can be controlled by asking the patient to fixate on a spot and then briefly presenting the desired stimulus to one visual field while obscuring the other, thereby restricting the information to one hemisphere. Another problem is that the patients who underwent commisurotomy did so because their brains had preexisting abnormalities. The performance of “split-brain” patients therefore presumably does not reflect the functioning of neurologically normal individuals. This can be controlled by combining the results of split-brain studies with those derived from other methods and accepting only the converging evidence. Every scientific method has its limitations. In split-brain studies, then, the isolated left hemisphere would be presented with (for example) images of printed words, such as “PEN” or “GLOVE,” and the patients would be able to read these words. However, when the same images were presented to the isolated right hemisphere, the patients were not able to decipher them

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  The Divided Therapist

  Hemispheric Difference and Contemporary Psychotherapy

  • Rod Tweedy(Author)
  • 2020(Publication Date)
  • Routledge

    (Publisher)

  Chapter 10

  The formation of two types of contexts by the brain hemispheres as a basis for a new approach to the mechanisms of psychotherapy

  Vadim S. Rotenberg

  The investigation of brain asymmetry has developed in two different directions. On the one hand, neurologists for a century and a half collected data of the role of local brain structures of both hemispheres in the realization of some definite mental and behavioural functions. This direction of investigation is now equipped with modern methods of brain investigation such as positron emission tomography and fMRI (see Craik et al., 1999).

  The investigations performed on epileptic patients with bisected brains also brought much unexpected data. It was shown that in these patients, even in right-handed subjects, the right hand could not copy simple geometric figures and was unable to build simple constructions of child bricks, while the left hand performed all these tasks easily. With closed eyes, the patient could not recognize even quite familiar objects with the right hand, while the left hand did this immediately. If the information was presented to the left visual field (right hemisphere) the subject’s behaviour was relevant to the content of this information, but the subject was unable to explain the reasons for his/her behaviour. Moreover, patients with bisected brains periodically demonstrated the behavioural signs of inner motivational conflict which was not realized. Thus, one patient complained that he volitionally embraced his wife with his right hand (managed by the left hemisphere), and at the same time unexpectedly pushed her away with his left hand – a story which in another condition in subjects with undivided brains might immediately bring a psychodynamic interpretation.

  The first attempts to interpret the data of investigations performed on these patients were superficial and ignored the possible relationships of this data to essential psychological functions. The most popular assumption proposed that brain hemispheres deal with different types of information: the left hemisphere processes special signs like those present in natural and artificial languages, while the right hemisphere processes the natural nonverbal information such as images, melodies, and intonations of voice, and is responsible for orientation in space and within the subject’s own body. This concept seemed to be confirmed by the outcomes of the organic damages of left and right brain hemispheres. For instance, damage to the left temporal lobe is accompanied by motor and sensory aphasia while damage to the right parietal lobe is associated with disorientation in space.

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