cog5 lecppt chapter02

© 2013 by W. W. Norton & Co., Inc.

The Neural Basis for Cognition

Chapter 2Lecture Outline

Chapter 2: The Neural Basis for Cognition

Lecture OutlineCapgras Syndrome: An Initial ExampleThe Principal Structures of the BrainThe Visual System

Chapter 2: The Neural Basis for Cognition

Brain-behavior functions Imaging of brain activity Impairment after damage

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

Capgras Syndrome: An Initial Example

Capgras syndrome results from a conflict:

Perceptual recognition is intact.

But there is no emotion.

Conflict

Lack of familiarity

Capgras Syndrome: An Initial Example

Neuroimaging brain areas involved in Capgrass syndrome

Capgras Syndrome: An Initial Example

Amygdalar damage results in lack of emotional response

Capgras Syndrome: An Initial Example

Prefrontal cortex damage impairs reasoning Illogical thoughts are not filtered out

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

The Principal Structures of the Brain

One process is broken up by the brain and processed by different areas

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

The Principal Structures of the Brain

Loss of a function associated with normal processing

The Principal Structures of the Brain

Brain

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Hindbrain Midbrain Forebrain

The Principal Structures of the Brain

Hindbrain.Atop the spinal cordBasic rhythmsAlertnessCerebellum

Movements and balance Sensory and cognitive roles

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

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

The Principal Structures of the Brain

Four cerebral lobes Frontal lobe Parietal lobe Temporal lobe Occipital lobe

The Principal Structures of the Brain

The subcortical parts of the forebrain include: Thalamus Hypothalamus Limbic System

Amygdala Hippocampus

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

Lateralization

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Left hemisphereproduces language.

Right hemispherecan only point. No language.

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

Data from Neuroimaging

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Visual stimulation result in occipital lobe activity

Magnetic resonance imaging (MRI)

Data from Neuroimaging

https://www.youtube.com/watch?v=1CGzk-nV06g

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

The Principal Structures of the Brain

Increased activity only appears when person is consciously attending to one or the other

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

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

The Cerebral Cortex

Primary motor projection areas

Greater precision = more brain area

Less precision = smaller brain area

The Cerebral Cortex

Primary projection areas of the cortex

The Cerebral Cortex

Orderly representation Space proportional to acuity or precision Contralateral representation

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

Brain Cells

Detect incoming signals

Nucleus and cellular machinery

Transmits signals to other neurons

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

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

The Visual System

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

The Visual System

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Rods are mostly in the periphery; cones mostly in the center

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

The Visual System

Cell C is more inhibited than cell B

The Visual System

What we see is not what we perceive

The Visual System

Single-cell recording

The Visual System

Stimulus in center leads to faster firing rates

Stimulus in surrounding area leads to slower firing rates

The Visual System

The Visual System

Different neurons in area V1 are specialized, resulting in parallel processing, not serial processing.

The Visual System

The Visual System

Parallel processing in the visual pathway Parvocellular cellsMagnocellular cells

The Visual System

Object shape and identity

Object location

Parallel processing in the visual system

The Visual System

The what and where system projected on the brain surface

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

The Visual System

Parallel processing splits up problem

But we do not see the world as disjointed

Binding problem

The Visual System

Elements that help solve the binding problemSpatial positionNeural synchrony

The Visual System

Attention is also critical for the binding of visual featuresWhen attention is overloaded, people will

make conjunction errors

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

Chapter 2 Questions

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 

 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.

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

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)

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.

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

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