cog5 lecppt chapter02
TRANSCRIPT
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© 2013 by W. W. Norton & Co., Inc.
The Neural Basis for Cognition
Chapter 2Lecture Outline
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Chapter 2: The Neural Basis for Cognition
Lecture OutlineCapgras Syndrome: An Initial ExampleThe Principal Structures of the BrainThe Visual System
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Chapter 2: The Neural Basis for Cognition
Brain-behavior functions Imaging of brain activity Impairment after damage
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Capgras Syndrome: An Initial Example
Capgras syndrome Recognize loved ones But think they are impostors May think they were kidnapped (or worse!) May even see slight “defects”
情緒的解讀與認知發生衝突
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Capgras Syndrome: An Initial Example
Capgras syndrome results from a conflict:
Perceptual recognition is intact.
But there is no emotion.
Conflict
Lack of familiarity
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Capgras Syndrome: An Initial Example
Neuroimaging brain areas involved in Capgrass syndrome
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Capgras Syndrome: An Initial Example
Amygdalar damage results in lack of emotional response
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Capgras Syndrome: An Initial Example
Prefrontal cortex damage impairs reasoning Illogical thoughts are not filtered out
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Capgras Syndrome: An Initial Example
Factual and emotional knowledge are dissociated
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Capgras Syndrome: An Initial Example
Cognitive psychology and cognitive neuroscience complement each otherAmygdala linked to emotional processing in
general
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The Principal Structures of the Brain
One process is broken up by the brain and processed by different areas
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The Principal Structures of the Brain
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The Principal Structures of the Brain
Gage’s skull A reconstruction of the lesion
A portrait of Gage
https://www.youtube.com/watch?v=us8nNoGXAc8
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The Principal Structures of the Brain
Loss of a function associated with normal processing
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The Principal Structures of the Brain
Brain
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Hindbrain Midbrain Forebrain
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The Principal Structures of the Brain
Hindbrain.Atop the spinal cordBasic rhythmsAlertnessCerebellum
Movements and balance Sensory and cognitive roles
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The Principal Structures of the Brain
The midbrain sits above the hindbrain Coordinates movement, especially eye movement Includes parts of the auditory pathways Regulates the experience of pain
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The Principal Structures of the Brain
The forebrain includes: Cortex, convolutions Subcortical structures
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The Principal Structures of the Brain
Axes Division Connection
Left-right Longitudinal fissure Corpus callosumAnterior commisure
Anterior-posterior Longitudinal fissure N/A
Frontal-temporal Lateral Fissure
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The Principal Structures of the Brain
Four cerebral lobes Frontal lobe Parietal lobe Temporal lobe Occipital lobe
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The Principal Structures of the Brain
The subcortical parts of the forebrain include: Thalamus Hypothalamus Limbic System
Amygdala Hippocampus
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Lateralization
Brain is roughly symmetricalCommissures connect hemispheres
Corpus callosum is the largest
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Lateralization
Split brain patientsSevering of the corpus callosum
Treatment of epilepsy Limits right-left communication https://www.youtube.com/watch?v=Kqy4XVcCf0w
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The Principal Structures of the Brain
Cortical organization is contralateralThe left side of the
body or perceptual world has more representation on the right side of the brain, and vice versa
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Lateralization
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Left hemisphereproduces language.
Right hemispherecan only point. No language.
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Neuropsychology
NeuropsychologyClinical neuropsychologyLesions
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Data from Neuroimaging
Computerized axial tomography (CT) X-rays https://www.youtube.com/watch?v=gaiCtdo6CLE
Positron emission tomography (PET) Glucose https://www.youtube.com/watch?v=GHLBcCv4rqk
CT vs. PET
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Data from Neuroimaging
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Visual stimulation result in occipital lobe activity
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Magnetic resonance imaging (MRI)
Data from Neuroimaging
https://www.youtube.com/watch?v=1CGzk-nV06g
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Data from Neuroimaging
functional magnetic resonance imaging (fMRI) https://www.youtube.com/watch?v=lLORKtkf2n8
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Data from Neuroimaging
Electroencephalogram (EEG) Buildup of chemical neurotransmitter Firing of action potential in a neuron Millions of neurons create an electrical field https://www.youtube.com/watch?v=8Q57q_kQPQY
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Data from Neuroimaging
EEG cap with electrodes
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Data from Neuroimaging
Every method has its limitationsEEG is sensitive to time, not location fMRI detects location but is not time sensitiveCT and MRI scans detect brain structures, not
activity
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Data from Neuroimaging
Combining techniques is more powerfulEEG timing fMRI location
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Data from Neuroimaging
The fusiform face area (FFA) is active when viewing faces
The parahippocampal place area (PPA) is active when viewing houses
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The Principal Structures of the Brain
Increased activity only appears when person is consciously attending to one or the other
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Data from Neuroimaging
Lesions to this area lead to face blindness
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Data from Neuroimaging
The identified brain region may not be necessary
Activity may be correlated with task. Transcranial magnetic stimulation (TMS)
deactivates an area
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Localization of Function
Specific brain areas have specific functions
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The Cerebral Cortex
Area Function
Primary projection areas
Sensory Input
Motor Output
Rest of cortex Association areas
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The Cerebral Cortex
Primary motor projection areas
Greater precision = more brain area
Less precision = smaller brain area
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The Cerebral Cortex
Primary projection areas of the cortex
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The Cerebral Cortex
Orderly representation Space proportional to acuity or precision Contralateral representation
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The Cerebral Cortex
Association Areas Create associations between simple ideas and
sensations
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The Cerebral Cortex
Damage to association cortex results in problems with: Apraxia – movement Agnosia –identifying objects Aphasia –language Neglect syndrome – ignoring half the visual world Prefrontal damage –planning, strategic thinking,
inhibition
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Brain Cells
Detect incoming signals
Nucleus and cellular machinery
Transmits signals to other neurons
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Brain Cells
GliaGuide development of nervous systemRepairs damageControls nutrient flowElectrical insulation speeds signal transmission
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Presynaptic neuron
Postsynaptic neuron
Synapse
Brain Cells
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Brain Cells
Accumulation of neurotransmitter in postsynaptic cleftWill or will not trigger an action potential = all-
or-none effect
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Brain Cells
Synaptic transmissionOne neuron can receive information from
many other neurons Can compare many signals and adjust
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The Visual System
Knowledge acquired through vision Neural bases of vision well understood
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The Visual System
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The Visual System
Photoreceptors
Rods Cones
Lower sensitivity Higher sensitivity
Lower acuity Higher acuity
Color-blind Color-sensitive
Periphery of the retina In the fovea
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The Visual System
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Rods are mostly in the periphery; cones mostly in the center
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The Visual System
A series of neurons communicates information from the retina to the cortex In the eye:
Photoreceptors Bipolar cells Ganglion cells and the optic nerve
In the thalamus: Lateral geniculate nucleus (LGN)
In the cortex: V1, the primary visual projection area, or primary
visual cortex, located in the occipital lobe
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The Visual System
Cell C is more inhibited than cell B
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The Visual System
What we see is not what we perceive
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The Visual System
Single-cell recording
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The Visual System
Stimulus in center leads to faster firing rates
Stimulus in surrounding area leads to slower firing rates
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The Visual System
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The Visual System
Different neurons in area V1 are specialized, resulting in parallel processing, not serial processing.
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The Visual System
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The Visual System
Parallel processing in the visual pathway Parvocellular cellsMagnocellular cells
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The Visual System
Object shape and identity
Object location
Parallel processing in the visual system
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The Visual System
The what and where system projected on the brain surface
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The Visual System
The what system: Identification of objects Occipital-temporal pathway Visual agnosia
The where system: locations of objects and guiding our responses Occipital-parietal pathway Problems with reaching for seen objects
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The Visual System
Parallel processing splits up problem
But we do not see the world as disjointed
Binding problem
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The Visual System
Elements that help solve the binding problemSpatial positionNeural synchrony
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The Visual System
Attention is also critical for the binding of visual featuresWhen attention is overloaded, people will
make conjunction errors
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The Visual System
Our account of vision requires both lower-level activitiesFor example, what happens in individual
neurons and the synaptic connections between them
And higher-level activitiesFor example, the influence of attention on
neural activity
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Chapter 2 Questions
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1. A central problem in Capgras syndrome seems to be a difficulty with
a) an emotional analysis of faces. b) matching faces that are in view to faces
in memory.c) neither a nor bd) both a and b
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2. In the drawing at right, parts A,
B, C, and D, are
a) the frontal lobe, the occipital lobe, the parietal lobe, and the temporal lobe.
b) the occipital lobe, the temporal lobe, the parietal lobe, and the frontal lobe.
c) the parietal lobe, the frontal lobe, the temporal lobe, and the occipital lobe.
d) the temporal lobe, the frontal lobe, the occipital lobe, and the parietal lobe.
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3. Many subcortical structures, such as the hippocampus and amygdala, come in groups of two. Why?
a) Anatomy involves symmetry.
b) There is a hindbrain and midbrain.
c) It has to do with lateralization.
d) none of the above
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4. Which of the following methodologies does not measure brain activity or structure?
a) magnetic resonance imaging (MRI)
b) computerized axial tomography (CT)
c) positron emission tomography (PET)
d) transcranial magnetic stimulation (TMS)
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5. In one study, investigators monitored activity levels in a brain area (the FFA) that seems particularly responsive to pictures of faces, and another area (the PPA), which seems particularly responsive to pictures of places. Their data showed that
a) brain activity in these two regions depended on what the person was consciously perceiving and not just what the stimulus was.
b) if a picture of a face was put in front of one eye and a picture of a different face was put in front of the other, then neither brain area would be highly activated.
c) the activity of these areas could be predicted if one simply knew what stimulus was in front of the person’s eyes.
d) high levels of activation were detected in the FFA even when pictures of houses were shown, illustrating the flexibility of brain function.
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6. If stimulating an area of the brain causes a behavior and disabling it with TMS prevents the behavior, then that area is _____ for that behavior.
a) necessary and sufficientb) necessary but not sufficientc) sufficient but not necessaryd) correlated with, but neither necessary nor
sufficient
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7. Which of the following is the clinical term we use to describe a disturbance in the initiation or organization of voluntary action?
a) aphasia
b) neglect
c) agnosia
d) none of the above