Transcript Lobes of the Brain

Module 5
Modern Myths About the Brain
Myth #1: People only use 10% of their brain
•
While not all of the brain is active all at
once, functional magnetic resonance images
(fMRI) show several brain areas are at work
for any given activity, depending on what
function is needed.
Myth #2: Alcohol kills brain cells
• A lack of thiamine (vitamin B) causes temporary
damage to dendrites  the message-relaying
neurons.
• This reaction accounts for slurred speech, stumbling,
and ill-advised public urination.
• No damage is actually incurred by the brain cells
themselves, and the dendrites eventually recover
MYTH #3: Your brain is all grey
It is grey, white, red, and black.
• Grey matter is, in fact, mostly grey.
• white matter in the form of connective nerve fibers.
• black part, called substantia nigra (“black substance”)
• And the red?
• That’s blood.
MYTH #4: Subliminal messages work on your
brain without you knowing it
• 1957, market researcher inserted messages urging
moviegoers to purchase soda and popcorn into a film in
New Jersey.
• appeared for no longer than 1/300 of a second
• reported that Coca Cola and popcorn sales increased to
the tune of 18 percent and 57 percent, respectively?
• 1990 Judas Priest trial, in which the suicides of two
teenagers were blamed on subliminal messages in the
band’s lyrics,
• all concluded that no scientific evidence
Myth #5: Brain Damage Is Always Permanent
 In some instances, the brain can repair
itself.
 the brain creates new pathways between
neurons
 the phenomenon of brain plasticity
 stroke patients, for example, can regain speech
and motor skills through therapy.
Myth #7: Your brain hurts when you have a
headache
It's not your brain that's hurting when you get a
headache – without pain receptors, your brain
can't feel any pain.
History of the Mind
Phrenology
 Franz Gall suggested, that the study of bumps on the
skull represented mental abilities.
 His theory though incorrect, nevertheless proposed
different mental abilities were modular.
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Data on the Human Brain
 About 3 pounds
 78% water
 Less than 2.5% of
body’s weight
 Uses 20% of body’s
energy
Amazing Brain Numbers
100 billion neurons
1 trillion glial cells
1,000 trillion synaptic
connection points
280 quintillion memories
Studying the Brain: Research Methods
1. Electrical brain stimulation
2. Damage studies/lesioning
3. Electroencephalograms (EEG)
4. Transcranial magnetic stimulation (TMS)
 Brain imaging
1. computerized tomography (CT)
2. positron emission tomography (PET)
3. magnetic resonance imaging (MRI)
4. functional MRI (fMRI)
Electrical stimulation of the brain
• an implantable deep brain stimulation device
• delivers carefully controlled electrical pulses to
precisely targeted areas of the brain involved in
motor control.
• it can reduce muscle tremors
• restore muscle control for those with Parkinson's
Brain lesion experimentally destroys brain
tissue to study animal behaviors after such
destruction.
“deposits” in the brain bank
 Clinical observations help explain a
number of brain disorders.
• Alterations in brain changes due to
neurological and psychiatric diseases
are now being catalogued.
Electroencephalogram (EEG)
An amplified recording of the electrical
waves sweeping across the brain’s
surface, measured by electrodes placed
on the scalp.
Electroencephalogram (EEG)
Test hearing in a baby
Electroencephalogram (EEG)
beta
alpha
theta
delta
Brain Imaging
 CT (computed tomography) Scan
 a series of X-ray photographs taken
from different angles
 combined by computer into a
composite representation of a slice
through the body
 also called CAT scan
• this CAT scan shows extremely severe atrophy.
• The black areas should be white (cerebral cortex)
Whose atrophied brain is this??? She died in 2005
 Terri Schiavo:
 vegetative state 1990 – 2005
 heart attack related to bulimia
Positron-Emission Tomography
PET Scan
 A method for analyzing biochemical activity
in the brain, using injections of a glucose-like
substance containing a radioactive element
 Active areas have increased blood flow
 Sensors detect radioactivity because active
areas consume glucose rapidly
 Different tasks show distinct activity
patterns
PET Scan
PET scan to identify depression and Alzheimer’s Disease
Brain Scan – to locate tumors
Magnetic Resonance Imaging (MRI)
 Method for studying body and brain tissue
using magnetic fields and radio frequencies
 Magnetic fields alight certain ions/compounds
 When field is removed, molecules release
energy as radio waves
 Computer calculates tissue density from radio
waves
 Provides clear 3D image
MRI of the brain – brain injury
Subdural hematoma
MRI
MRI Scan
Top images show ventricular enlargement in a schizophrenic patient.
Functional MRI images
This image shows brain regions when a
participants lies.
• Anterior Cingulate Cortex:
• active w/conflicting urges
Brain Regions and Their Functions
Hindbrain (continuation of the spinal cord)
- vital function
- medulla; reticular formation; pons; cerebellum
Midbrain (above the hindbrain)
-small area between hindbrain and forebrain
to relay info eyes, ears and skin that controls
certain automatic behaviors
Forebrain (front part of the brain)
-most highly developed part of brain
-responsible for most complex aspects of
behavior – thinking and decision making
Older Brain Structures
Brainstem the oldest part of the brain,
beginning where the spinal cord swells
and enters the skull. Responsible for
automatic survival functions.
 Pons
Parts of the Brain Stem
 Involved in sleeping, waking, dreaming
 relay station for the cerebral cortex and the
medulla
 Medulla
 Responsible for certain automatic functions
(breathing, heart rate)
 Reticular Activating System
 Arousal/alertness
• Cerebellum
Cerebellum
1. the “little brain” attached to the rear of the
brainstem
2. Regulates balance and coordination of
movement
3. Plays a part in:
 analyzing sensory info
 voluntary movements
 nonverbal learning & memory
Thalamus
1. the brain’s sensory switchboard, located on
top of the brainstem.
2. Relays incoming sensory messages (except
olfactory) to higher areas (cerebral cortex)
3. Slow during sleep/speed up to produce
waking consciousness
Thalamus
Limbic System
1. a doughnut-shaped system of neural structures
at the border of the brainstem and cerebrum
2. associated with emotions such as fear,
aggression
3. center for motivation
Main Parts of the limbic system
 Amygdala
 Hypothalamus
 Hippocampus
The Limbic System
Brain stimulation to reward for turning right or left!!
When the limbic system is manipulated
rat will navigate fields or climb up a tree
The Amygdala
1. two almond-shaped neural clusters linked to
emotion of fear and anger.
2. Responsible for:
 Arousal
 Regulation of emotion
3. Involved in:
 Emotional memory
 Influence fear & aggression
4. psychosurgery in humans reduces rage but
has devastating after effectsunethical
Stimulate the Amygdala
Hypothalamus & Pituitary Gland
 Hypothalamus (“below” thalamus)
1. Involved in emotions and drives
vital to survival (hunger, sex)
2. Directs maintenance activities
- hunger, thirst, motivation
3. Pituitary Gland
 Small endocrine gland which
releases hormones and regulates
other endocrine glands
 Governed by hypothalamus
Hypothalamus
Lateral hypothalamus

hunger center causes us to eat when
stimulated. (“start”)
 If area destroyed, no hunger; will
starve to death unless forced to eat.
Ventromedial Hypothalamus
 satiety center: causes us to stop eating when
stimulated. (“stop”)
If area is destroyed, eat unless we are deprived
of food.
Hypothalamus - Motivation
Rats cross an electrified grid for selfstimulation, when electrodes are placed
in the reward (hypothalamus) center
The Hippocampus
 “Gateway to memory”
Responsible for:
Storage of new information in memory
Enabling us to form spatial memories
for navigating the environment
Hippocampus
Stop!
• Cerebral Cortex
• The outermost layer of gray matter making
up the superficial aspect of the cerebrum
• The body’s ultimate control and information
processing center.
Cerebral Cortex
The Cerebral Cortex
• Glial Cells
 cells in the nervous system that
support, nourish, and protect neurons
Front of the Brain
Back of the Brain
Cerebral Features:
Gyri – Elevated ridges “winding” around the brain.
• Sulci – Small grooves dividing the gyri
– Central Sulcus – Divides the Frontal Lobe
from the Parietal Lobe
• Fissures – Deep grooves, generally dividing
large regions/lobes of the brain
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Longitudinal Fissure – Divides the two
Cerebral Hemispheres
–
Transverse Fissure – Separates the
Cerebrum from the Cerebellum
–
Sylvian/Lateral Fissure – Divides the Temporal
Lobe from the Frontal and Parietal Lobes
–
Gyri (ridge)
Sulci
(groove)
Fissure
(deep groove)
Longitudinal Fissure
Transverse Fissure
Specific Sulci/Fissures:
The Cerebrum
1. Largest brain structure
2. Two cerebral hemispheres connected by
the corpus callosum
3. Surrounded by cerebral cortex (thin
layers of cells – gray matter)
4. Responsible for higher forms of thinking
5. 2 cerebral hemispheres separated by
longitudinal fissure (L/R hemispheres)
The Cerebrum - Two Hemispheres
Cerebral Hemispheres –corpus
collosum separates the hemispheres
Left hemisphere – verbal processing:
language, speech, reading, writing
Right hemisphere – nonverbal
processing: spatial, musical, visual
recognition
Frontal
Parietal
Temporal
Occipital
Lobes of the Brain - Frontal
 located at the top front part of the skull
•
It plays an integral role in the following
functions/actions:
Decision Making/Reasoning
- Personality
- involved in speaking; muscle movement
motor cortex (Broca’s area)
-
- Association
area: cerebral cortex NOT
devoted to sensory or motor function
Frontal Lobe
• Broca’s Area
– controls facial neurons,
speech, and language comprehension.
•located in left frontal lobe.
Aphasia: impairment of expression or
comprehension of language
–Broca’s Aphasia – Results in the ability to
comprehend speech, but the decreased motor
ability (or inability) to speak and form words.
–
Lobes of the Brain - Parietal Lobe
 The parietal lobe of the brain is located behind
the frontal lobe
• plays major role in following functions/action:
 Pleasure, pain, touch, temperature
 include the sensory cortex
-
Spatial awareness and perception
- Proprioception - Awareness of body/ body
parts in space and in relation to each other
Lobes of the Brain – Occipital Lobe
•located at the back of the brain
•Its primary function is the processing,
integration, interpretation, etc. of VISION and
visual stimuli.
Occipital Lobe – Cortical Regions
 Primary Visual Cortex – This is the primary
area of the brain responsible for sight recognition of size, color, light, motion,
dimensions, etc.
• Visual Association Area – Interprets
information acquired through the primary
visual cortex.
Visual Function
 Functional MRI
scan shows the
visual cortex
activated as the
subject looks at
faces
Lobes of the Brain – Temporal Lobe
 The temporal lobes are located on the sides of
the brain
• play
an integral role in the following functions:
- hearing
- organization and comprehension of
language
Temporal Lobe – Cortical Regions
 Primary Auditory Cortex – Responsible for
hearing
• Wernicke’s Area
– language comprehension.
located on the left temporal lobe.
- Wernicke’s Aphasia – Language comprehension
is inhibited.
-Words and sentences not clearly understood, and
sentence formation inhibited or non-sensical.
Functions & locations in the brain
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Functions of the Cortex
Motor Cortex: area at the rear of
the frontal lobes controls voluntary
movements.
Sensory Cortex: (parietal lobe)
receives information from skin
surface and sense organs.
The cerebral cortex in humans
Stimulation of Motor Cortex
Caused movement when applied to an
arch-shaped region in back of frontal
lobe
Parts in the left or right hemisphere,
specific body parts moved on the
opposite side of the body
William Penfield creates a brain map
NO pain receptors in the brain!!
The Cerebral Cortex
Where are incoming messages received
in the cortex?
1. brain area receives info from skin senses and
from movement of body parts
2. located at the front of the parietal lobe
3. the more sensitive the areathe greater
sensory cortex area
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Auditory Function
Functional MRI scan shows the auditory cortex
is activate in patients who hallucinate.
Association Areas
 More intelligent animals have increased
“uncommitted” or association areas of the
cortex
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Specialization & Integration
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Brain activity when hearing, seeing, and
speaking words – association areas
Phineas Gage
 Gage was a railroad construction foreman
 An 1848 explosion forced a steel tamping
rod through his head
 Others said he was “no longer Gage” –
previously mild-mannered/friendly and
became ill-tempered and undependable
 Lost his job, worked as a sideshow exhibit
 Learned frontal lobe effects personality
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Brain Reorganization
 Plasticity
 the brain’s capacity for modification,
as evident in brain reorganization
following damage
 especially in children
 other brain areas learn to control
functions
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Our Divided Brain
1. our brain is divided into two hemisphere
2. left hemisphere processes reading,
writing, speaking, mathematical,
comprehension skills
3. right hemisphere is typically responsible
for spatial relationships and analyses
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Left Brain
Functions
Right Brain
Governs right side of your body
Logic
Words
Parts and specifics
Analysis (breaking apart)
Sequential thinking
Tends to be time-bound
Higher levels of norepinephrine
Prove it to me!
Governs left side of your body
Emotions
Pictures
Wholes/relationships among parts
Synthesis (putting together)
Simultaneous and holistic thinking
Tends to be time free
Higher levels of dopamine
Anything is possible!
•A number of brain scan studies
have shown normal individuals
engage their right brain when they
engage in a perceptual task, (see it)
•and
•left brain when carrying out a
linguistic task (say it)
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Copyright: Gary Larson
Q: Assuming this comical situation was factually accurate,
what Cortical Region of the brain would these doctors be
stimulating?
Split Brain Procedure
The two hemispheres of the brain are isolated by
cutting the connecting fibers between them.
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Divided Brain – Split brain
Lateralization of Function
1. Damage to the corpus callosum interferes
with the exchange of information between
right and left hemispheres.
2. Epilepsy is a condition characterized by
repeated episodes of excessive
synchronized neural activity.
3. Mainly due to decreased release of the
inhibitory neurotransmitter GABA.
4. Physicians once cut the corpus callosum to
prevent seizures
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Lateralization of Vision
1.The left half of each retina connects to
the left hemisphere (right visual field)
2. The right half of each retina connects to
the right hemisphere (left visual field)
3. Half of the axons from each eye cross
to the opposite side of the brain at the
optic chiasm.
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Left visual field
Visual input with split-brain – Roger Sperry and others
Split-Brain Experiment
1. Subjects were presented information to
one or the other side of their brains
- (right: hammer/left: cow)
2. Patients identified verbally the pictures
to the right visual field (hammer)
3. When patients were asked to point to the
image seen on left, patients point to the
picture on left w/left hand (cow)
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What should this person be able to do?
 With the corpus callosum severed
 objects (apple) presented in the right
visual field can be named.
 Objects (pencil) in the left visual
field cannot
 But left hand can touch it!!
Split Brain
Split-Brain Experiment
Results
Sperry Experiments on Split Brain
1. Roger Sperry (1974) revealed subtle
behavioral differences for split brain people.
2. Because the left side of the brain is dominant
for language in most people, most split brain
people:
3. Have difficulty naming objects briefly
viewed in the left visual field.
3. But yet can touch the object w/ left hand!!
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Try drawing two shapes with both
of your hands simultaneously.
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What happens when we
confuse our brains????
LOOK at the chart on the right
say the word from left to rt. (make many mistakes?)
Now say the color…(make many now???)
The left brain will try to say the color while the right brain
will read the word!
If the woman appears to be rotating
clockwise you tend to be right brain
dominant.
If the woman appears to be rotating counterclockwise you tend to be left brain
dominant.
If the woman seems to change the direction
of her rotation back and forth you are one of
those rare individuals who use both side of
their brain equally.
We all, of course, what hand we
are…when we hold a pen, but how
far does this bias extend throughout
your body?
Are you left-eared?
Left eyed?
Let’s have some fun...
For a change!!!
 Imagine the centre of your back is
itching. Which hand do you scratch it
with?
 Interlock your fingers. Which thumb is
uppermost?
 Imagine you are applauding. Start
clapping your hands. Which hand is
uppermost?
 Wink at an imaginary friend straight in
front of you. Which eye does the
winking?
 Fixate a small distant object with your eyes
and point directly at it with your forefinger.
Now close one eye. Now close other eye.
 Which eye was open when the fingertip
remained in line with the small object?
 (When the other eye, the non-dominant
one, is open and the dominant eye is closed,
the finger will appear to move to one side of
the object.)
Phantom Limb Syndrome
 http://www.youtube.com/watch
?v=8AcDXnzmsMc
 http://nobelprize.org/education
al/medicine/splitbrain/index.html
 http://www.youtube.com/watch
?v=MZnyQewsB_Y
What happens when lobes of
the brain are injured?
Brain Structures and their Functions