Chapter 2: The Brain Brain Insult: Neglect

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The Brain
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Chapter 2: The
Brain
Introduction
History
Individual
Differences
Neurons
Function
Structure
Imaging &
Recording
Hindbrain
Age
Gender
Other
Lateralization
Midbrain
Localization
TMS
Brain
Imaging
Forebrain
Split-Brain
EEG ERP
Phrenology
Aphasia &
Other Mapping
CAT Scans
MRI
Neural Foundations
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• Long history of interest in neural underpinnings
of cognitive processes (e.g., Freud, +1)
• Initially, limited methods to image brain action,
and determine regions involved in cognitive tasks
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– Brain Injury: bullet wounds during wars, accidents,
surgery, stroke, … (+2, +3)
– Brain stimulation of animals or during operations on
humans (e.g., for epilepsy)
– Autopsies
– Animal studies (+4)
– Experimental studies: e.g., stimuli presented only to
left or right visual field (lateralization section)
Combat & Noncombat Brain Injury
PET
fMRI
• Freud’s early neuroscience work linked to his
clinical interests (Freud, 1895, Project for a
Scientific Psychology)
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– e.g., representation of experiences & memories of
Emma, woman who cannot enter shops alone, due
to being molested as child by shop-keeper
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Brain
Insult:
Neglect
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Animal
Studies:
Stimulus
and Brain
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Neurons
• Transducers (e.g., rods8
& cones)
• Brain consists of many
– Initiate neuronal
neurons and support
reaction when
structures
stimulated physically
– ~85 Billion neurons
– ~85B glial cells and
other non-neurons
Stimulus shown to
animals (top ) and
regions of brain
affected (bottom ),
as determined postmortem or Lashley’s
work on memory and
amount of brain loss
– Neurotransmitters:
Excitatory or Inhibitory
– Multiple inputs
– Graded activation
Synaptic Summation
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– Medulla:
• Life Support
– Pons
• “Bridges” right & left
sides of brain;
Balance, Sleep,
Arousal; Visual &
Auditory information
– Cerebellum
• Coordinates muscle
activity; attention
• Midbrain (+1 dash)
– Relay center &
Arousal
– All or None
– Refractory Period
• Synaptic transmission
(+2)
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• Hindbrain (+1 oval)
• Axonal transmission
(+1)
Structures of Brain
• Forebrain (+1 square)
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F2.1
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Forebrain
– Thalamus: Relay
– Hypothalamus
• Controls pituitary gland,
regulates other glands
• Homeostatic Behaviors:
Sleep, Temperature,
Eating, Drinking, …
– Hippocampus (+2)
• Involved in memory
– Amygdala
Hindbrain
• Emotional memories
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Forebrain Detail
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Forebrain: Cerebral Cortex
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Front
Humunculus
Executive
Functioning
Localization
of Function
Phrenology (Gall &
Spurzheim)
• Aphasias (-1)
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– Broca’s area: nonfluent
aphasia (inability to
produce words)
– Wernicke’s area: fluent
aphasia (unable to
understand speech or
produce meaningful
speech)
• Different parts of
brain control
different functions
• Size of brain region
& skull!! correspond • Humunculus (-1)
to its power
• Complications
• Different faculties
– Complex cognitive tasks
(functions) are
– Brain plasticity
independent
Brain Imaging
Techniques
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• Computerized Axial
Tomography (CAT) Scan
– Series of cross-sectional
x-rays or scans used to
construct 3D image
• Magnetic Resonance
Imaging (MRI)
– Strong magnetic field
detects oscillations of
atoms
– Enhanced if subject
digests agent
• Images Structure
Back
Lateralization of
Function
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• Left Hemisphere
– Language
– Analysis
• Right Hemisphere
– Spatial skills
– Synthesis
• Split Brain Studies
– Corpus Callosum
severed or missing
(F2.1 slide 9)
– Sperry & Gazzaniga
research (video)
Brain Imaging
Techniques
• Positron emission
tomography (PET)
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– Measures blood flow to
brain regions
– Uses radiation
– Shows which region most
active ( top)
• Functional magnetic
resonance imaging
(fMRI) ( bottom, +1)
– Tap: both hands or left
– Relies on magnetic
properties of blood; does
not involve radiation
– Measures blood flow to
various brain regions
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fMRI
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Other Brain
Recording
Techniques
• Electroencephalography 20
(EEG)
– Record brain activity from
scalp ( )
– Detects different states of
consciousness
• Event-Related Potential
(ERP) (+1)
– Measure brain activity
before & after stimulus
presentation
ERP and Sentence Comprehension
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• ERPs for Predictable (solid line) and Anomalous
(dashed) endings
– I like my coffee with cream and … sugar / socks
• Marked difference at N400, meaning Negative (up
is negative) dip at 400ms
• N400 reduced for high frequency words and
primed words
1 Second
Discussion
• Wide range of tools for imaging brain
– Vary in how Invasive
• Exposure to x-rays, injections of tracer chemicals, …
– Vary in Spatial and Temporal resolution
• ERPs measure to ms (1/1000 of second)
– Imaging Structure (static) vs Function (dynamic)
– Measurement vs Manipulation (TMS)
• Tremendous growth in knowledge of brain
• Sometimes exaggerated claims and
expectations or misuse of “neuro” label
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Transcranial
Magnetic
Stimulation (TMS)
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• Electromagnetic coil
disrupts localized
brain activity ( top)
• Video
• Risk taking on
gambling task
increased with TMS
of Right Prefrontal
Cortex ( bottom)
Individual
Differences
• Many factors
contribute to brain
development and
organization
Young Brain
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Old Normal Brain
– Age: Aging ( ),
Adolescence ( ), …
– Gender:
testosterone
– Brain insult: earlier
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