Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Chapter 4 Hemispheric Specialization
Gazzaniga Ivry Mangun Cognitive Neuroscience FOURTH EDITION Slide 2
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Science debate: Is it true? Slide 3
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 4 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 5
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 6 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 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 Slide 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. Slide 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. Slide 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. Slide 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. Slide 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. Slide 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.
Slide 14 Cognitive Neuroscience, Fourth Edition Copyright 2014 by
W. W. Norton & Company, Inc. Slide 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. Slide 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. Slide 17 Cognitive
Neuroscience, Fourth Edition Copyright 2014 by W. W. Norton &
Company, Inc. Anatomy of the hemispheres Slide 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. Slide 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. Slide
20 Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Sylvian fissure or Lateral fissure Slide
21 Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Planum temporale The cortical area at
the center of Wernickes area (understanding of language) was larger
in the left hemisphere. Slide 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. Slide 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). Slide 24 Cognitive Neuroscience,
Fourth Edition Copyright 2014 by W. W. Norton & Company, Inc.
Slide 25 Cognitive Neuroscience, Fourth Edition Copyright 2014 by
W. W. Norton & Company, Inc. Slide 26 Cognitive Neuroscience,
Fourth Edition Copyright 2014 by W. W. Norton & Company, Inc.
Slide 27 Cognitive Neuroscience, Fourth Edition Copyright 2014 by
W. W. Norton & Company, Inc. Slide 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. Slide 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). Slide 30 Cognitive
Neuroscience, Fourth Edition Copyright 2014 by W. W. Norton &
Company, Inc. Slide 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.
Slide 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. Slide 33 Cognitive Neuroscience, Fourth Edition
Copyright 2014 by W. W. Norton & Company, Inc. Synchronization
between cortical neurons in two hemispheres Slide 34 Cognitive
Neuroscience, Fourth Edition Copyright 2014 by W. W. Norton &
Company, Inc. Split brain research for interhemispheric
communications Slide 35 Cognitive Neuroscience, Fourth Edition
Copyright 2014 by W. W. Norton & Company, Inc. Slide 36
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Callosal section for epileptic seizure
Slide 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.
Slide 38 Cognitive Neuroscience, Fourth Edition Copyright 2014 by
W. W. Norton & Company, Inc. Slide 39 Cognitive Neuroscience,
Fourth Edition Copyright 2014 by W. W. Norton & Company, Inc.
Slide 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. Slide 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
Slide 42 Cognitive Neuroscience, Fourth Edition Copyright 2014 by
W. W. Norton & Company, Inc. Slide 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. Slide 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. Slide 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 Slide 46
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 47 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc.
Visuospatial task: self vs. familiar other Slide 48 Cognitive
Neuroscience, Fourth Edition Copyright 2014 by W. W. Norton &
Company, Inc. Slide 49 Cognitive Neuroscience, Fourth Edition
Copyright 2014 by W. W. Norton & Company, Inc. Slide 50
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 51 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 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). Slide 53
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 54 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 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. Slide 56 Cognitive Neuroscience, Fourth Edition Copyright
2014 by W. W. Norton & Company, Inc. Hierarchical structure
Slide 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. Slide 58 Cognitive Neuroscience,
Fourth Edition Copyright 2014 by W. W. Norton & Company, Inc.
Slide 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. Slide 60
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 61 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 62
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. Slide 63 Cognitive Neuroscience, Fourth
Edition Copyright 2014 by W. W. Norton & Company, Inc. Slide 64
Cognitive Neuroscience, Fourth Edition Copyright 2014 by W. W.
Norton & Company, Inc. 1. 2. 3. 4. Slide 65 Cognitive
Neuroscience, Fourth Edition Copyright 2014 by W. W. Norton &
Company, Inc. Slide 66 Cognitive Neuroscience, Fourth Edition
Copyright 2014 by W. W. Norton & Company, Inc.
