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Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Chapter 4 Hemispheric Specialization Gazzaniga Ivry Mangun Cognitive.

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Presentation on theme: "Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Chapter 4 Hemispheric Specialization Gazzaniga Ivry Mangun Cognitive."— Presentation transcript:

1 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Chapter 4 Hemispheric Specialization Gazzaniga Ivry Mangun Cognitive Neuroscience FOURTH EDITION

2 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Science debate: Is it true?

3 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

4 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

5 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

6 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

7 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Because our speech center is in the left hemisphere, W.J. can name items presented to his right visual field Speech center

8 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. A picture was flashed to his left visual field, he responded not to see anything. He responded by pressing the key with his left hand (the right hemisphere controls the left hand), when a light was flashed to his left visual field.

9 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The motor apparatus in the left hemisphere which controls the right hand is disconnected to left visual field, right hand do not respond appropriately.

10 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The central nervous system is laterally specialized: Each of the two cerebral hemispheres performs processes that the other does not.

11 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Split-brain research  Split-brain research is a neuroscience subfield to investigate the cognitive and behavioral processes of the patients when their corpus callosum connecting the two hemispheres of the brain is severed to some degree by accidental damage or surgery.  It is an association of symptoms produced by disruption of or interference with the connection between the hemispheres of the brain.  Split-brain research is a neuroscience subfield to investigate the cognitive and behavioral processes of the patients when their corpus callosum connecting the two hemispheres of the brain is severed to some degree by accidental damage or surgery.  It is an association of symptoms produced by disruption of or interference with the connection between the hemispheres of the brain.

12 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The Wada test, (intracarotid sodium amobarbital procedure, ISAP) This test is named after Japanese Canadian neurologist Juhn Atsushi Wada, is used to establish cerebral language and memory representation of each hemisphere. This test is performed to determine in which hemisphere speech center is located.

13 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Wada test procedure  The test is conducted with the patient awake. Essentially, a barbiturate (which is usually sodium amobarbital) is introduced into one of the internal carotid arteries via a cannula or intra-arterial catheter from the femoral artery.  The drug is injected into one hemisphere at a time.  The effect is to shut down any language and/or memory function in that hemisphere to evaluate the other hemisphere ("half of the brain").  Then the patient is engaged in a series of language and memory related tests. The memory is evaluated by showing a series of items or pictures to the patient so that within a few minutes as soon as the effect of the medication is dissipated, the ability to recall can be tested.  The test is conducted with the patient awake. Essentially, a barbiturate (which is usually sodium amobarbital) is introduced into one of the internal carotid arteries via a cannula or intra-arterial catheter from the femoral artery.  The drug is injected into one hemisphere at a time.  The effect is to shut down any language and/or memory function in that hemisphere to evaluate the other hemisphere ("half of the brain").  Then the patient is engaged in a series of language and memory related tests. The memory is evaluated by showing a series of items or pictures to the patient so that within a few minutes as soon as the effect of the medication is dissipated, the ability to recall can be tested.

14 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

15 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Strong bias for language lateralization to the left hemisphere Regions of the right hemisphere are also engaged, especially for language tasks that require higher-level comprehension.

16 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Lessons from Split-brain  Most cognitive processes are redundant and each hemisphere is capable of carrying out those processes.  Two separate but coexisting brains do not result in split personalities, nor do they fight over control of the body. In short, the individual with the split brain does not feel conflicted.  However, the two hemispheres do not reprsent information in an identical manner.  Most cognitive processes are redundant and each hemisphere is capable of carrying out those processes.  Two separate but coexisting brains do not result in split personalities, nor do they fight over control of the body. In short, the individual with the split brain does not feel conflicted.  However, the two hemispheres do not reprsent information in an identical manner.

17 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Anatomy of the hemispheres

18 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The hemispheres of the brain are distinct yet connected. In the medial view are seen the commissures, the large white matter fiber tracts that connect the hemispheres.

19 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The right protrudes in front, and the left protrudes in back. The right is chubbier in the front region, and the left is larger posteriorly in the occipital region.

20 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Sylvian fissure or Lateral fissure

21 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Planum temporale The cortical area at the center of Wernicke’s area (understanding of language) was larger in the left hemisphere.

22 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Asymmetry in homotopic areas  The left hemisphere has greater high-order dendritic branching than that of their homologs in the right hemisphere.  Greater long-range connectivity in the language-associated regions of the left hemisphere.  The left hemisphere has greater high-order dendritic branching than that of their homologs in the right hemisphere.  Greater long-range connectivity in the language-associated regions of the left hemisphere.

23 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Visual examination reveals a subtle difference in the sizes of the largest subgroups of layer III pyramidal cells (stained here with acetylthiocholinesterase): in the left hemisphere they are larger (b) compared to the right (a).

24 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

25 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

26 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

27 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

28 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The corpus callosum is the dense fiber tract (white matter) located below the folds of the cortex (250 million axonal fibers). The anterior portion is the genu, the middle portion is the body, and the posterior portion is the splenium.

29 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Smaller fibers (~0.4micrometer) are located anteriorly (genu), fitfully grading to larger fibers (5 micrometer) located more posteriorly (splenium).

30 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

31 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The caudal surface of a coronal section of brain roughly through the premotor cortical area. Homotopic callosal fibers (blue) connect corresponding sections of the two hemispheres via the corpus callosum; heterotopic connections (green) link different areas of the two hemispheres of the brain. In primates, both types of contralateral connections (blue and green), as well as ispilateral connections (red), start and finish at the same layer of neocortex.

32 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Interhemispheric communication: cooperation or competition?  Cooperation Perceptual categorization (right) vs. sementic categorization (left)  Competition Primary mode of corpus callosum: inhibition Processing delays inherent in transcollosal communication (175mm, 6.5m/s = 30ms) may limit the extent to which the two hemispheres can cooperate.  Cooperation Perceptual categorization (right) vs. sementic categorization (left)  Competition Primary mode of corpus callosum: inhibition Processing delays inherent in transcollosal communication (175mm, 6.5m/s = 30ms) may limit the extent to which the two hemispheres can cooperate.

33 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Synchronization between cortical neurons in two hemispheres

34 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Split brain research for interhemispheric communications

35 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

36 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Callosal section for epileptic seizure

37 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The split-brain patient reports through the speaking hemisphere only the items flashed to the right half of the screen and denies seeing left- field stimuli or recognizing objects presented to the left hand. Nevertheless, the left hand correctly retrieves objects presented in the left visual field, about which the patient verbally denies knowing anything.

38 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

39 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

40 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Functional consequences of the split brain procedure  Visual or tactile information presented to one half of the brain was not available to the other half.  Verbal IQ and problem solving capacity is intact after callosotomy.  Visual, tactile, and auditory sensory information is transferred by posterior half of callosum.  The anterior part of callosum transfers semantic information about the stimulus.  Visual or tactile information presented to one half of the brain was not available to the other half.  Verbal IQ and problem solving capacity is intact after callosotomy.  Visual, tactile, and auditory sensory information is transferred by posterior half of callosum.  The anterior part of callosum transfers semantic information about the stimulus.

41 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Letter priming: response latency between compatible (h-H) versus incompatible (t-H) trials

42 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

43 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The capacity of the right hemisphere to make inferences is extremely limited. Two words are presented in serial order, and the right hemisphere (left hand) is simply required to point to a picture that best depicts what happens when the words are causally related. The left hemisphere finds these tasks trivial, but the right cannot perform the task.

44 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Data from three patients show that the right hemisphere is more accurate than the left in recognizing unfamiliar faces.

45 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Emotional prosody  Emotional Prosody is characterized as an individual's tone of voice in speech that is conveyed through changes in pitch, loudness, timbre, speech rate, and pauses which is different from linguistic and semantic information.  It can be isolated from linguistics and interacts with verbal content (i.e. sarcasm). It is perceived or decoded slightly worse than facial expressions but accuracy varies with emotions. Anger and sadness are perceived most easily followed by fear and happiness, with disgust being the most poorly perceive  Emotional Prosody is characterized as an individual's tone of voice in speech that is conveyed through changes in pitch, loudness, timbre, speech rate, and pauses which is different from linguistic and semantic information.  It can be isolated from linguistics and interacts with verbal content (i.e. sarcasm). It is perceived or decoded slightly worse than facial expressions but accuracy varies with emotions. Anger and sadness are perceived most easily followed by fear and happiness, with disgust being the most poorly perceive

46 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

47 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Visuospatial task: self vs. familiar other

48 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

49 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

50 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

51 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

52 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Pictures drawn by split-brain participant J.W.’s left hand in response to stimuli presented to the left and right visual fields (LVF and RVF). (a) Drawing of the LVF word Toad (ipsilateral to the drawing hand). (b) Drawing of the RVF Saw (contralateral to the drawing hand). (c) Drawing combining both words: Scraper and Sky (ipsilateral + contralateral).

53 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

54 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

55 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. As more items are added to a set, for split brain patients the increase in reaction time for bilateral arrays is only half as fast as when all objects are confined to one side.

56 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Hierarchical structure

57 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. The left hemisphere is more adept at representing local information and the right hemisphere is better with global information.

58 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

59 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. Theory of mind: Ann and Sally experiment Theory of mind is on the right hemisphere.

60 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

61 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

62 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

63 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

64 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc. 애국가 1. 동해물과 백두산이 마르고 닳도록 하느님이 보우하사 우리나라 만세 무궁화 삼천리 화려 강산 대한 사람 대한으로 길이 보전하세 2. 남산 위에 저 소나무 철갑을 두른 듯 바람 서리 불변함은 우리 기상일세 무궁화 삼천리 화려 강산 대한 사람 대한으로 길이 보전하세 3. 가을 하늘 공활한데 높고 구름 없이 밝은 달은 우리 가슴 일편단심일세 무궁화 삼천리 화려 강산 대한 사람 대한으로 길이 보전하세 4. 이 기상과 이 맘으로 충성을 다하여 괴로우나 즐거우나 나라 사랑하세 무궁화 삼천리 화려 강산 대한 사람 대한으로 길이 보전하세

65 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.

66 Cognitive Neuroscience, Fourth Edition Copyright © 2014 by W. W. Norton & Company, Inc.


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