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Neuroscience:Research Contribution to CS (Brain Research: The Development,…
Neuroscience:
Research Contribution to CS
Brain Plasticity
Surgery to have one side of the brain removed to prevent
seizures.
Someone could be playing and become suddenly rigid
and collapse on the floor
Radical suggestion, radical solution
Hemispherectomy
Removal of half of the brain
Since the left side of the body is controlled by the right side of the brain,
the patient would be paralyzed on the left side when
they are awoke
The brains of children have amazing abilities to
rewire themselves
Phantom Limbs
Sensation that an amputated or missing limb (even an organ, like
the appendix) is still attached to the body and is moving
appropriately with other body parts
Approximately 5-10% of individuals with an amputation
experience phantom sensations in their amputated limb, and the
majority of the sensations are painful
The Neuroscience Approach (Cognitive Neuroscience)
Attempt to explain cognitive
processes in terms of underlying
brain mechanisms
Describe the biological ‘hardware’ upon
which mental ‘software’ supposedly runs
Neuroscientists
Learn more the structures and functions
of the human brain and how they relate
to the behaviors we observe in people:
using language, solving problems, and
remembering
Cognitive Neuroscience:
The Biology of the Mind
Human Brain
Most complex organ of the body
Consists of approximately 10
billion nerve cells (neurons) and
billions of interconnecting fibers
Approximate length = 15 cm
Approximate weight = 1400 g ( 3
pounds/ 1.4 kg)
Newborn = 350 to 400 g
Human Brain: The 3 Main Parts
Cerebrum
The cerebrum is the largest
part of the brain and controls
all conscious thoughts,
experiences, and actions
Divided into right and left
hemispheres, which are joined
by the corpus callosum
Its outer folded layer is called
the cerebral cortex.
The surface of the cerebrum is
the cerebral cortex
Cerebral Cortex
Surface of brain = cortex
(i.e. gray matter)
Decision making organ of
the body
Receives messages from
all sensory organs
Initiates all voluntary
actions
Stores all our memories
Where our knowledge of
language resides
3 mm thick
Very thin layer
The area is a convoluted pattern
packed into a small space inside the
skull.
FOUR MAJOR AREAS
F rontal
Higher
functionslanguage,
thought,
memory, motor
functions,
problem solving,
movement
Extremely vulnerable to injury
due to their location at the front of the cranium
Studies have shown that the frontal area is the most
common region of injury following mild to moderate
traumatic brain injury
P areital
Receive signals from the touch system,
important for vision and attention,
perception of stimuli
Receives info. from the
senses about pressure,
texture, temperature,
and pain
O ccipital
First place in
cortex where
visual
information is
processed
Primary function
Vision
Or visual processing
T emporal
Language, memory, hearing, vision
Primary function:
Hearing
Or auditory processing
Cerebral Hemispheres
Composed of cerebral
hemispheres (left & right),
joined by corpus callosum
Corpus Callosum = large band of fibers that connects the
left and right hemispheres of the cerebral cortex
The left and right hemisphere
are separate, but connected
Contralateral brain
function
Left hemisphere controls right
side of body
Right hemisphere controls left
side of body
Cerebellum
The cerebellum is the
second largest part of the
brain
It controls posture and
balance.
Recent research also
suggests a role in higher
cognitive processes
Brain Stem
It controls processes basic for
survival, such as heart rate,
breathing, digestion, and
sleep.
It is the main route of
communication between the
rest of the brain, the spinal
cord, and the nerves that run
throughout the body
It also has its own set of nerves
that send and receive signals to
the face, mouth, tongue, eye
muscles, ears, and balancesensing
vestibular organs
Brain: The Nervous System
(Vertebrate)
Neurons
nerve cells, specialized to receive and transmit
information in the nervous system
Communicate through stimulation of electric impulses/signals
Soma
: body of the cell.
Contains genetic material
Dendrite
= Receives messages.
Brings information to the cell
body
Axon
= Sends message. Takes
information away from the cell
body
Synapse
= a small gap
separating 2 neurons
a link from one neuron to
another
Neuron connections
Huge number of interacting
neurons in the brain
This makes the brain the most
complex organ and most complex
structure in this universe
Neurotransmitters
Chemical signals that are released
across the synapse so that neurons
can communicate with each other
This makes our brain work
determine how we feel, think and
act
Brain Research: The Development
Late 18th & Early 19th Century
Gall
Conclusion that structure & function were related
Structure of brain & people’s behavior
Phrenology
Emergence of theory of localization
Broca’s Area
Wernicke’s Area
Late 19th & Early 20th Century
Hughlings-Jackson’s
observation of recurrent
patterns of epileptic seizures in patients -
connection between stimulus event in
specific brain areas and muscular response of
specific body side
Localization of function in the two
hemispheres
Theory of contralateral control (opposite-side)
Evidence in support of the theory based on
Fritsch & Hitzig’s
experiments on dogs
Muscle movement stimulated by direct electricity
application to brain
Late 19th & Early 20th Century
David Ferrier
continued experiments on other
species (i.e. monkeys, frogs, guinea pigs) to find
out whether the theory can be generalized
Used the method of ablation (surgical removal) or
also called localized destruction
Extended investigations beyond “motor centers” to
include sensory centers
E.g., vision (perception) and hearing
Brain – the organ of the mind
Overall – primary investigative techniques
employed include electrical stimulation or
removal of specific brain areas
Theory of localization of function
Insights from Psychology: Sheperd Ivory Franz
Challenged theory of localization of function based on
findings on study of experimental animals’ behavior
Training of animals in new habit after removal of brain
parts (frontal lobe)
New habits lost but old ones retained
Animals could relearn lost new habits
Generalized to human
Functional restitution or reeducation after brain lesions –
evidence showed that lost function can be recovered (i.e.
functions could not have resided in damaged area alone)
Brain = integrated whole
Insights from Psychology: Karl Lashley
Theory of localization – oversimplified; argued instead that
functions of every center dependent on its relation to rest
of intact nervous system
Based on findings from experiments with white rats which
investigated their learning & intelligence
Intelligence = global function because learning can recur
(relearn)
Proposed 2 principles to explain his conclusion
Principle of Equipotentiality
Principle of Mass Action
Proposed Principles
Principle of Equipotentiality
Parts of the brain have the
equal potential to fulfill the
function of a damaged part
The intact part of the brain
can carry out the functions
that were lost in the
damaged part. This capacity
varies from one area to
another and from one
function to another.
Principle of Mass Action
When a functional area of
cortex is damaged, its ability to
perform previously mastered
complex functions may be lost
in proportion to the extent
of the injury
The Living Human Brain: The
Neurosurgeons
Brain Research from Neurosurgeons
Sought to investigate ‘the pulsation of the brain’
Procedure conducted while the patient was still
conscious
inserted the electrode (with weak electric current)
in the human brain
Findings = stimulating localized brain areas could
produce specific muscular contractions
Conscious patients could provide information during
procedure
Discovered that stimulations could also trigger
sensation, without muscular movements
Insights from Wilder Penfield
Surgeon + experimenter
Professor of neurology
400 operations on the brain.
Patients with epileptic seizures and brain tumors.
Insights from Wilder Penfield
(Neural Cartographer)
Continued brain exploration based on opportunities
presented while treating patients (i.e. epileptic seizures,
brain tumors)
Construct MAP of brain areas
Localization of various functions
that displayed:
Muscular contractions
Tingling sensations in selected body parts
Mental phenomena – Hearing Music
Memory - Recall of past experience
Psychical states – feelings of fear, loneliness
Neuroscience:
Modern Technology &
Research
Brain Mapping
Attempt to provide a
complete picture about
how the brain works
Relate the brain's
structure to its
function
Find what parts of the
brain give us certain
abilities.
Brain Mapping Techniques
Structural
X-ray Techniques
Cerebral Angiography
Computed Tomography
Computer Axial Tomography
(CAT)
Useful in detecting disorders associated with
abnormalities in brain arteries
Example: hemorrhage (heavy bleeding)
Loss of oxygen in that area
A procedure that uses a special dye
(contrast material) and x-rays to see how
blood flows through the brain.
Injection of a dye into the vertebral artery
or carotid artery in the neck carried to
brain arteries
Paths of arteries surrounding brain tissue
X-rays of skulls then locate malfunctioning
artery – damaged area
Computer Axial Tomography (CAT)
Developed in early 1970s
Less radiation than traditional x-ray.
Computer technology enable
‘deblurring’ of picture &
reconstruction of a complete brain
image from multiple views
Development of CAT enable
process of imaging brain internal
structure to become safer & more
precise– 3D
Advantages
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Disadvantage
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Magnetic Resonance Imaging
(MRI)
Uses a magnetic field to take
images of the inside of your body.
Assumes atoms in the body will
react to magnetic field
Based on radio signals emitted by
the protons in the human body
Advantages
No X-rays or radioactive
material is used (unlike
CAT or PET)
Resolution of the image is
sharper / clearer than
CAT scans
Flexibility – allows the
researcher to distinguish
different structures of the
brain – gray/white matter
and cerebrospinal fluid
Disadvantages
Slow – for an image to be
generated.
An image generated at a given
time will no longer depict a
situation precisely as it was at the
time of the imaging
Cannot be used in patients with
metallic devices, like
pacemakers
May cause claustrophobic
reaction in some patients
Functional
Electrophysiological Techniques
Electroencephalography
Event-Related Potentials (ERPs)
Electroencephalography
A test of the function of the brain itself
records the electrical activity on the brain's
surface.
image the brain while it is performing
cognitive task.
detect the location and magnitude of brain
activity involved in the various types of
cognitive functions
Non-invasive and painless procedure
Take brief patient history
Apply electrode leads to the patient's scalp
Run the test
Advantages
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Disadvantages
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Electroencephalograms (EEGs)
Tracings/Recordings of
patterns of electrical
activity in the brain view and record the changes
in brain activity during
performance of cognitive
task
Provide fine
-tuned reading
of rapidly occurring
changes (MRI too slow to
do this)
Event-Related Potential (ERP)
Subject presented with a
stimulus during EEG process
Record voltage change around
the stimulus (before and after
it ends)
Repetitions of event – average
the values
Evoked response provides a
picture of neural activity
changing over time as the
brain processes information
Blood-Flow Techniques
Positron Emission Tomography
(PET)
Single Photon Emission
Computed Tomography (SPECT)
Functional Magnetic Resonance
Imaging (fMRI)
Functional Magnetic Resonance Imaging (fMRI)
Also known as real time or
dynamic MRI – available in
1990s
Decade of the Brain
Detect changes in magnetic
state of blood using MRI
scanners with fast imaging
techniques
Record changes in oxygen
level & blood flow in various
brain locations as subjects
perform various cognitive tasks
FMRI is a technique for determining which parts of the
brain are activated by different types of physical sensation
or activity, such as:
sight
sound
movement of a subject's fingers
mental imagery
calculation
Advantages
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Positron Emission Tomography (PET scan)
Method of measuring
cerebral blood flow while
subject carries out cognitive
tasks
Uses radioactive isotopes
(i.e. positrons)
PET scans look at bodily
process by detecting the
decay products from
radioactive tracers injected
into the body.
Advantages
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Disadvantages
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Evidence from Brain Mapping Research
: Insights into Human Cognition
Language
Neural organization of language quite similar for
language learned in ordinary way (i.e. hearing &
speaking) and for signed language acquired by deaf
individuals
Insight from fMRI images on Broca’s & Wernicke’s
Areas confirm hypotheses about involvement of
these areas in human language function
Left hemisphere’s involvement in language is the
same, whether the language is seen or heard
The intact hemisphere can take over tasks of
damaged/removed brain hemisphere
Different parts of brain involved in processing
content (nouns) & function words
Aphasia
(ASL)
Localization
of Brain
Brain
Plasticity
Processing of
Content &
Function Words
Memory
Functions of
Working
Memory
Role of
Hippocampus
Implicit &
Explicit
Memory
Long Term
Memory
Two distinct functions of working memory (i.e. retrieval &
coding) are performed in different locations within the
brain area associated with working memory
working memory NOT generalized; different sorts of
processes carried out in different regions
Investigate role in explicit (i.e. conscious recollection) &
implicit (i.e. unconscious recollection) memory of events
Activation associated more with actual/explicit recollection of
event (i.e. conscious) rather than in effort trying to remember it
Significant role of prefrontal cortex in explicit memory
Greater activation at higher levels of load (higher
memory load lasts longer - continuing activation)
Amount of memory load = amount of information to be
remembered
Concept
Categories
Categorization
Task
Name finding
Disorders
Bipolar &
Unipolar
Disorder
Mood – Bipolar (normal mood alternated with both depression
& mania) & Unipolar (only depression)
Role of neurotransmitter - Missing or deficient
chemical level or substances
Neurochemical and autonomic abnormalities.
Schizophrenia- severe mental disorder (hallucinations
& delusions)
Structural image differences between patient with
childhood onset schizophrenia & adult
Medication has effect in patients’ brain (caudate –
basal ganglia)
Language dysfunction due to deficit in language
processing ability (unable to integrate context –
incoherence)
Autism
developmental brain disorder affecting brain function –
affect social interaction (social & communication deficits)
Greater brain volume found in autistic subjects – possible
causes
Increased production of neurons
Neurons do not die off in great numbers as in
normal development
Increased production of non-neural brain
tissue (e.g. blood vessel)
Dyslexia
Brain-based type of learning disability – affect reading
Unawareness of associations between phonological
segments (sounds) in construction of words
Inability to decode
Insights from Donald O. Hebb
Attempted to explain how neural circuits work
(i.e. underpins cognitive processes)
Any two cells or systems of cells that are repeatedly active at the
same time will tend to become ‘associated’, so that one activity
facilitates the other
Cell Assembly
Brain Research: 1960s & Beyon
d
The visual system
David Hubel
Torsten Wiesel
Visual field = an area that is visible to you while
your eyes are not moving
Area of the visual field that will produce a response
in a given cell = receptive field
Hubel & Wiesel found neurons that specially detect
certain features => feature detectors
E.g.: optic nerves of frogs have “bug detectors.”
Connections to neuron impeded when the use of
the organ (i.e. eye) is also impeded
Connections between the eye and cortical neurons are
permanently disrupted when kitten is deprived of the
use of one eye for a period, by closing its eyelid.
That particular brain area becomes impeded.
Split-Brain Research
Roger Sperry
Research that includes severing of the corpus
callosum
Specialization of the hemispheres
Left side
Reasoning
Language
Writing
Reading
Logic
Mathematics
Linear
Analysis
Right side
Recognition of faces
and patterns
Art
Rhythm
Visual
Creativity
Synthesis
Investigated the role of the two hemispheres
In a normal brain, stimuli entering one hemisphere
is rapidly communicated by way of the corpus
callosum to the other hemisphere
Brain functions as a unit
Research by removing the corpus callosum was originally
done on monkeys.
After surgery, the monkeys behaved normally.
Procedure was then employed with human patients who
suffered from epileptic (sawan) seizures
For his split-brain research, Roger Sperry shared
the 1981 Noble Prize in Physiology and Medicine
with David Hubel and Torstein Wiesel.
if the two hemispheres of the brain are
separated by severing the corpus callosum
the transfer of information between the
hemispheres ceases.
the coexistence in the same individual of two
functionally different brains can be
demonstrated.