Download the brain - Dr Magrann

THE BRAIN
 ANATOMICAL REGIONS
A. Cerebrum
B. Diencephalon
 Thalamus
 Hypothalamus
C. Brain Stem
 Midbrain
 Pons
 Medulla oblongata
D. Cerebellum
 FUNCTIONAL REGIONS
A. MOTOR AREAS
B. SENSORY AREAS
C. HIGHER FUNCTIONS
Since the brain is so important, it is protected by the skull, cerebrospinal fluid which
cushions it, and meninges which are membranes that surround the brain and only let
certain substances cross through to the brain.
The brain is one of the few organs that can only use glucose to get ATP as its energy
source. Therefore, without some sugar in our bloodstream, the brain will die. That’s one
reason why proper nutrition is so important.
 By the way, geniuses have the same size brain as everyone else; they are just
more efficient at forming synapses. They have more dendrites and more
synapses. You can develop more dendrites and synapses by keeping your brain
active by learning and reading new things. We don’t use 10% of our brains, we
use 100%.
The brain is divided into parts, and is bilaterally symmetrical. In general, the left side
controls the right half of the body, and the right side of the brain controls the left half of
the body. The largest portion is the CEREBRUM, which makes up 80% of the brain.
The cerebrum controls logical thought and conscious awareness of the environment.
It is also the area responsible for the highest sensory and motor activity.
The cerebrum is mostly made up of grey matter (cell bodies, dendrites, and axons).
The surface is not smooth, it’s convoluted. Each bump on the surface of the cerebrum is
called a GYRUS, and each shallow groove on the surface of the cerebrum is called a
SULCUS. This formation increases the surface area, and the surface is where the
information processing is.
The cerebrum is divided into 2 halves called CEREBRAL HEMISPHERES, which are
separated by the LONGITUDINAL FISSURE. The right cerebral hemisphere controls
the activity of, and receives sensory input from the left side of the body.
The left cerebral hemisphere controls the activity of, and received sensory input from the
right side of the body. Each hemisphere is divided into lobes, named for the bones on top
of them.
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The FRONTAL LOBE and PARIETAL LOBE are separated by the CENTRAL
SULCUS. The TEMPORAL LOBE is between the parietal and frontal lobe, separated
by the LATERAL SULCUS. The OCCIPITAL LOBE does not have a real border; it’s
just a region. These are the anatomical areas, but the functional areas are more important.
If you slice the brain down the center in a mid-sagittal section, you will slice through a
white colored tissue called the CORPUS CALLOSUM, which is the area that connects
the right and left halves of the brain; this is the area that is responsible for the right half
of the brain communicating with the left half of the brain. If the corpus callosum was cut,
there would be no communication between the right and left halves of the brain. Autism
is a neurological disease that includes problems with communication between the right
and left cerebral hemispheres.
Phineas Gage
 Phineas was a railroad construction foreman who survived an accident in which a
large iron rod was driven completely through his head, severing connections in
his left frontal lobe.
 It changed his personality; he became emotional and had frequent outbursts.
 This was the first case suggesting that damage to specific regions of the brain
might affect personality and behavior.
 The left side of the brain is responsible for critical thinking, and the right side is
responsible for emotion.
 Since his left frontal lobe was damaged, his emotions went unchecked.
Fun facts:
 Women have a wider corpus callosum than men.
 They tend to use both sides of their brain more than men do.
 That’s why they like to talk more.
 Give a little girl a doll, and she will hold it like a baby.
 Give a little boy a doll, and he will take the head off to see what it looks like.
 This is a difference between using both sides of the brain vs. just one side.
DIENCEPHALON
Consists of two parts:
 THALAMUS
 The superior portion of the diencephalon
 Processes sensory information according to importance
 Major relay station for sensory impulses to the cerebrum
 HYPOTHALAMUS
 The inferior portion of the diencephalon
 Provides homeostatic control over the body (maintains homeostasis)
 Controls hunger/thirst body temperature
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THALAMUS
 The THALAMUS functions to sort out all the sensory information.
 It compares the input and determines what information is worth sending to the
cortex.
 Your body ignores most sensory information.
 Up until now, have you noticed the sound of the air conditioner? It’s not
important, so it goes unnoticed.
 This area also compares information from the right and left eyes for stereoscopic
vision, and the right and left ear to determine direction of sound.
HYPOTHALAMUS
 This small area exerts more control over autonomic functioning than any
other part.
 Makes hormones which provide homeostatic control over the body
 It maintains homeostasis by controlling the autonomic nervous reflexes,
glucose and hormone levels.
 It is also the main visceral control center, so it controls body
temperature, hunger and thirst, and blood pressure.
 The hypothalamus is part of the limbic system, so that’s why a painful
memory can increase blood pressure.
 The hypothalamus synthesizes and secretes hormones, and these in turn
stimulate or inhibit the secretion of pituitary hormones.
 By secreting hormones, the hypothalamus controls blood pressure, body
temperature, hunger, thirst, fatigue, sleep, autonomic nervous reflexes, and
circadian cycles.
BRAIN STEM
MIDBRAIN
PONS
MEDULLA OBLONGATA
MIDBRAIN
 The top of the brain stem is the MIDBRAIN.
 It controls automatic behaviors (fight or flight)
 The midbrain also contains a pigmented area called the substantia nigra.
 The Substantia nigra is involved in addictions and in initiating body movement.
 The substantia nigra secretes the neurotransmitter dopamine.
 When the neurons in the substantia nigra become damaged, dopamine levels
decrease, causing Parkinson's Disease. Treatment is to replace the dopamine
Dopamine
 Remember that acetylcholine is the neurotransmitter that functions to contract
skeletal muscles?
 There are many other types of neurotransmitters as well. One is called dopamine.
 Dopamine is the neurotransmitter that controls the flow of information between
various areas of the brain.
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 Dopamine is lacking in Parkinson's Disease, in which the person has muscular
rigidity and tremors, so they lose the ability to start movements. They need a
service dog to help them get out of a chair or to take a first step. They have a pillrolling tremor at rest.
 Dopamine plays a major role in the brain system that is responsible for rewarddriven learning. Every type of reward that has been studied increases the level of
dopamine transmission in the brain, and a variety of highly addictive drugs,
including stimulants such as cocaine and methamphetamine, act directly on the
dopamine system.
 There is evidence that people with extraverted (reward-seeking) personality types
tend to show higher levels of dopamine activity than people with introverted
personalities.
 Several important diseases of the nervous system are associated with dysfunctions
of the dopamine system. Parkinson's disease, an age-related degenerative
condition causing tremor and motor impairment, is caused by loss of dopaminesecreting neurons in the substantia nigra.
 Schizophrenia has been shown to involve elevated levels of dopamine activity in
the mesolimbic pathway and decreased levels of dopamine in the prefrontal
cortex.
 Attention deficit hyperactivity disorder (ADHD) is also believed to be associated
with decreased dopamine activity.
 Dopamine is available as an intravenous medication acting on the sympathetic
nervous system, producing effects such as increased heart rate and blood pressure.
 However, because dopamine cannot cross the blood–brain barrier, dopamine
given as a drug does not directly affect the central nervous system.
 To increase the amount of dopamine in the brains of patients with diseases such as
Parkinson's disease L-DOPA (the precursor of dopamine) is often given because it
crosses the blood-brain barrier relatively easily.
CORPORA QUADRIGEMINA “Quadruplet bodies”
 They control visual and audio (hearing) reflexes.
 Throw something at your face, you blink = visual reflex. Loud noise (BANG!)
causing a startle, is the audio reflex.
 The two superior bodies are for eye blinking and fast eye movements.
 The two inferior bodies are for sound reflexes
 The corpora quadrigemina are linked to the midbrain.
PONS
Farther down the brainstem is the PONS, which relays sensory information between
the cerebellum and cerebrum.
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MEDULLA OBLONGATA
 At the base of the brainstem is the MEDULLA OBLONGATA, which contains
the cardiac, respiratory, vomiting and vasomotor centers.
 It also effects heart rate, blood pressure, and breathing.
 Damage here causes coma. Swelling from an injury causes pressure, which can
damage this area, which can cause a coma.
 Concussions cause nausea and a decrease in blood pressure; patients with these
symptoms need an MRI to see if this is early signs of damage to medulla
oblongata
 Boxers who are knocked out can recover, but repeated knock-outs can cause
permanent brain damage.
What’s the difference in function between the medulla oblongata and the
hypothalamus?
 The medulla oblongata controls blood pressure directly (using nerves), and the
hypothalamus controls it indirectly (using hormones).
RETICULAR FORMATION
 The reticular formation is a group of cells scattered throughout the brainstem.
 They play a role in rousing and maintaining consciousness.
MELATONIN in animals
 Hormone found in animals, plants, and microbes.
 In animals, circulating levels of melatonin vary in a daily cycle, thereby allowing
the circadian rhythms of several biological functions.
 It allows reptiles to change the color of their skin
 The change in duration of secretion thus serves as a biological signal for seasonal
reproduction, behavior, coat growth, and camouflage coloring in animals.
MELATONIN in humans
 Infants' melatonin levels become regular in about the third month after birth, so
they sleep .
 Production of melatonin by the pineal gland is inhibited by light and permitted by
darkness.
 Secretion peaks in the middle of the night, with normal variations in timing
according to an individual's chronotype.
 A chronotype is an attribute reflecting at what time of the day their physical
functions (hormone level, body temperature, cognitive faculties, eating and
sleeping) are active, change, or reach a certain level. Are you a morning person or
a night owl?
Other effects of melatonin
 Melatonin stimulates the immune system
 It is an antioxidant, protecting mitochondrial DNA
 It increases REM sleep time (dreaming)
 It causes the onset of puberty
 Melatonin is mainly secreted by the pineal body.
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PINEAL BODY (Pineal gland)
 The PINEAL BODY secretes melatonin.
 How much it secretes depends on the sensory information it receives from the
eyes about how many hour of daylight are present.
 The amount of melanin secreted and circulating in the blood then determines the
circadian rhythm, or the biological clock (cycles influenced by light).
 Therefore, the pineal body detects the number of hours of light and dark, and sets
the body’s 24-hour clock.
Jet lag
 When you get jet lag, it’s because the information it gets doesn’t match with
where you are.
 You can help yourself get over jet lag by being outdoors in the daylight and being
indoors at night, and the pineal body with reset the clock.
Chronic Insomnia
 First eliminate caffeine and alcohol, then modify the diet (no sugars) and increase
exercise.
 Ambien (a sleep med) can cause people to sleep walk, and even drive in their
sleep!
CEREBELLUM
 The cerebellum is the second largest portion of the brain, is responsible for
balance and muscle coordination, and is a comparator.
 The cerebellum functions as a comparator: Action potentials from the
cerebral motor cortex descend into the spinal cord to move the muscles.
 There are branches that are sent to the cerebellum to give it information on the
intended movement.
 At the same time, the cerebellum receives information from proprioreception
neurons (sensory, tell what position each body part is in).
 The cerebellum compares all this information to allow smooth movements.
That is why it is called a comparator.
FUNCTIONAL REGIONS
 A. SENSORY AREAS
 B. MOTOR AREAS
 C. HIGHER FUNCTIONS
Cortex and association areas
 Each area of the brain has a region where the sensory information comes in, and
another area where the information is understood.
 The area where the information comes in is a cortex, and the area where it is
understood is the association area.
 Therefore, there will be a visual cortex and association area, an auditory cortex
and association area, and a somatic (sense of touch) cortex and association area,
and a gustatory (taste) cortex and association area. There is also a motor cortex
and association area.
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A. SENSORY AREAS of the cerebral cortex. Somatic = touch
1. PRIMARY SOMATOSENSORY CORTEX is located in the parietal lobe. It
receives signals for touch and pressure. The face is the most sensitive, and the
lips, teeth, and fingers. The primary somatosensory cortex receives sensory
neurons from the body, synapses at the brainstem. Now the info has to be
interpreted.
2. SOMATOSENSORY ASSOCIATION AREA is also in the parietal lobe. Its
function is to interpret the signals for touch and pressure. When I put my hand in
my pocket, I can identify these things I am feeling as keys.
3. PRIMARY VISUAL CORTEX is in the occipital lobe, receives signals from the
eye.
4. VISUAL ASSOCIATION AREA interprets the signals. When I look at my keys,
I can identify them as keys. Within this region is an area called Brodmann areas
18 and 19. Damage to this area results in an inability to recognize what one sees.
The person can see a chair in their way, move around it, but they can’t identify the
object as a chair. Some people with this damage can’t distinguish one person
from another because they can’t recognize their faces. For more information on
these types of brain damages, there’s a book called The Man Who Mistook his
Wife for a Hat.
5. PRIMARY AUDITORY CORTEX receives sounds.
6. AUDITORY ASSOCIATION AREA interprets sounds. When I hear a sound, I
can tell you what it is that I am hearing. These two areas are also involved in
language. This is where language is formed. Language is natural to humans. A
group of deaf children in South America were found to have created their own
language, using nouns, verbs, pronouns, adjectives, and everything, even though
no one there knew any sign language to teach them. There are certain strokes
where the person can’t use adjectives, but everything else is normal!
Broca's area is a region of the brain with functions linked to speech production.
Injury (stroke) in this location causes impairment of understanding language or
speaking certain words. They know what they want to say, they just cannot get the
words out. Not being able to speak at all is called aphasia.
Wernicke’s area does not affect speech, They can say what they want to, but
they cannot comprehend someone else’s speech.
7. PRIMARY GUSTATORY CORTEX (sense of taste)
8. GUSTATORY ASSOCIATION AREA interprets tastes.
Fun Fact
 Deaf people are not using their auditory cortex and association area, but that
region of the brain is not left inactive. Signals from the optic nerve branch out
and synapse there, and they use that area of the brain to develop better peripheral
vision.
 Blind people are not using their visual cortex and association area, so that region
of the brain is used to develop more fine motor connections for their sense of
touch. As they learn to read Braille, they develop synapses for fine touch in the
visual areas of the brain. They can discern the small bumps of print with their
fingers better than a sighted person.
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MOTOR AREAS
 PRIMARY MOTOR CORTEX
 PRIMARY MOTOR ASSOCIATION AREA
A. MOTOR AREAS
1. PRIMARY MOTOR CORTEX is in the frontal lobe in front of the central
sulcus. This area contains UPPER MOTOR NEURONS, which extend down the
spinal cord and synapse on LOWER MOTOR NEURONS in every muscle.
Some muscles have more motor units than others (hands, eyes, etc).
2. PRIMARY MOTOR ASSOCIATION AREA is just anterior to the primary
motor cortex.
a. Learned motor skills: these are preprogrammed skills, like when you know
how to type or swing a golf club. You practiced it so often, it’s now
automatic. When someone asks you how to spell a word, but you can’t do
it until you write it out, it’s because that memory is now a motor skill.
The same happens when you know how to tie your own shoelace or
necktie, but can’t tie another’s; it initially is learned by repetition. Then,
to do it later triggers a series of information which turns on those muscles
in the right order.
b. Motor association area (planning movement): This is when you plan to
reach for a new item. You have not rehearsed it, but you know to extend
your forearms, lift, etc. A signal is sent to the primary motor cortex to
turn on specific motor units to do that. Damage from a stroke= loose
function to that area, but you can compensate by using other muscles, and
re-learn that movement.
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3. PRE-CENTRAL GYRUS
 Within the primary motor area of the brain, there is a structure called the
pre-central gyrus which contains a precise map of the different body parts.
 This map is called a motor homunculus (Latin: little man)
 All the neurons that innervate the lips would have their cell bodies in one
particular region in this area. All the neurons that innervate the hands have
their cell bodies in this area. All those that innervate the back have their cell
bodies here.
 However, we don’t have as many neurons innervating the back as we do for
the lips and hands.
 The homunculus is drawn to represent how many neuron cell bodies we
have that innervate each region of our body.
 Not all body parts are equally represented by cell density in the motor area
in proportion to their size in the body.
 Lips, parts of the face and hands are drawn large because there are many
cells in the motor area that innervate those regions of the body.
 The face region of the homunculus is large so we can have many facial
expressions. The hands and tongue are large, indicating that we have many
fine motor skills in those areas as well.
 There is also a somatosensory homunculus.
C. HIGHER FUNCTIONS (control behavior and emotion)
1. PLANNING AND JUDGMENT: This is coordinated by the frontal lobe. How
much time do you need to be ready for the test? Damage here causes people to become
docile and do what they are told. 1930’s when people were overly aggressive, they did
a frontal lobotomy by going up the eyelid, crack through the skull, and stirring up the
brain. The problem is that it permanently altered their personalities. Lobatomies
were stopped in 1960’s; we do it with drugs now (Ritalin). There was a 16 year old rebel
who shot himself in the head, but went to far forward, and his personality improved!
Ritalin suppresses CNS in children, stimulates it in adults. In a criminal psych ward, an
inmate with a lobotomy got his hand caught in the electric door, and while his hand was
dangling half off, a nurse asked him if it hurt, and he just calmly said, “Yes, quite a lot.”
No emotion.
Remember, when you kill a neuron, it does not regenerate; it’s gone forever.
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2. MEMORY
We talked about motor memory. You can also have memory of events. This is
controlled by the HIPPOCAMPUS (“sea horse”; that’s its shape). The hippocampus
plays a major role in storing and retrieving memories. But memories are not stored there
or in any other single site in the brain. They are stored throughout the brain, especially in
the cerebral cortex.
AMYGDALA
 The amygdala functions to take new memories and store them, making them longterm memories.
 One man, who had severe epilepsy, had his amygdala removed. His seizures
stopped, but he developed anterograde amnesia and could no longer remember
anything new.
 The amygdala functions in emotional and social responses.
 If all your friends remember an event differently than you do (who held the
umbrella that day? They say it was you, but you remember it was Susan), you will
tend to change what you believe is right (I guess it must have been me holding the
umbrella, since everyone else says it was me).
 That is generating a false memory due to social pressure.
 The amygdala is like a bouncer at a nightclub.
 It determines what information is important enough to go into long term storage
by allowing it to go through the hippocampus.
 The memories that carry emotional weight are allowed in.
 These are the memories shape our identity.
 Social pressure will cause us to change our memories to conform, so social
pressure shapes who we are.
 When you first experience a traumatic event, if you try to minimize the strong
emotions you feel, it will not go into long term memory to continue to haunt you.
 For example, if someone does something that bothers you, try to forget it and do
not dwell on it, otherwise it will go into long term memory.
 If you rehearse the event over and over, you will even start dreaming about it.
 The average person spends about 6 years dreaming.
 Making a new memory is like writing a word on paper with an ink pen. At first,
the ink is wet (the memory is fresh) and you can smear it with your thumb so you
can’t read the word (don’t dwell on the memory and it will not become a firm
memory).
 But once the ink is dry (the memory is stored), the memory can be retrieved.
 Every time you recall a memory, it is like creating a brand new memory. It is like
tracing over the old word in fresh ink. It becomes bolder, stronger, easier to read.
 When you want to remember something, go over and over it throughout the day,
every day.
 If it is a painful memory, write it down and read it out loud every day while in a
relaxed environment, followed by a logical discussion of the event.
 Try to eliminate the emotional distress of the memory during this time.
 That will retrain your brain so it does not recall the event as being so emotionally
disturbing. Therefore, it will not cause as many bad dreams.
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MEMORY
 Memory consists of four processes
 Encoding: during exposure to new thing
 Consolidation: short-term memory forms; retained for a few seconds to a
few minutes. The average person can only remember about 7 new things
at a time in a few minutes. When new information is presented, old
information in short term memory is eliminated. If temporal lobe is
damaged, consolidation may not occur and the person only remembers
things learned in the last few minutes plus things stored in long-term
memory, before the injury.
 Storage: long-term memory forms for a few minutes to permanently,
depending on how often it is retrieved and used.
 Retrieval: using the stored information
To convert short-term memory into long-term memory, you should learn things in a
variety of ways This allows easy access to that information again by going through the
hippocampus:
 Prepare
 Listen
 Write notes
 Review daily
 Watch videos
 Do labs
MEMORY
 The reason we sleep is to allow our brains to form memories.
 Anything with a strong emotional attachment will form a stronger memory during
the sleep process.
 Whatever you are afraid of during the day, you will dream about more, and
remember more.
 You will have more nightmares if you watch a disturbing TV show before going
to bed. If you have nightmares about your personal life, stop dwelling on those
things during the day! Resolve your conflicts while you are awake, and you will
sleep better.
 The best way to remember what you study is to go over it before going to bed.
Study with fear and you will remember it more!
MAMMILARY BODIES
 A pair of small round bodies at the anterior end of the fornix
 Part of the diencephalon; they form part of the limbic system.
 They relay information (recognition memory) from the hippocampus. They also
add the element of smell to memories.
 Damage to the mammillary bodies due to thiamine deficiency or alcohol causes
Wernicke-Korsakoff syndrome (anterograde amnesia)
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FORNIX
 Carries signals from the hippocampus to the mammillary bodies.
ANTEROGRADE AMNESIA
 Damage to the mammillary bodies or hippocampus; they remember things before
the injury occurred, but all new information is lost within minutes.
 Nemo’s fish friend, Dori, has this type of amnesia.
 You can get around it by motor memory. Give an amnesiac a new puzzle; they’ll
do it in 30 mins. The next day, they don’t recognize the puzzle, but they do it in
20 mins, the next day in 10. Therefore, they are learning by motor memory.
They can learn their route from home to the market by repetition. But they can’t
make a detour, and if anything bumps them off track, they’ll be lost.
RETROGRADE AMNESIA
 Retrograde amnesia is a form of amnesia where someone is unable to recall
events that occurred before the development of the amnesia.
 Retrograde amnesia is caused by trauma that results in brain injury.
 Retrograde amnesia is often temporally graded, meaning that remote memories
are more easily accessible than events occurring just prior to the trauma.
 Events nearest in time to the event that caused memory loss may never be
recovered.
 They can remember new things.
STROKES
 A hemorrhage in the brain (broken blood vessel) deprives an area of the
brain of oxygen.
 This is called a stroke.
 It is one of the most likely causes of amnesia.
 Amnesia that is caused by a blow to the head is not cured by a second blow!
ALZHEIMER’S DISEASE
 Dementia is a symptom, not a disease. Dementia is loss of memory.
 Alzheimer’s disease is the most common form of dementia.
 About 10% of people over the age of 65 and 50% of people over the age 85 suffer
from it.
 It is irreversible, incurable, and fatal (6th leading cause of death in the USA,
surpassing diabetes). The person dies because they can no longer eat, swallow,
etc. There are treatments to delay symptoms.
Alzheimer’s disease vs. other dementia
 Alzheimer's disease is typically a slowly progressive disorder that involves
memory for recent information (short-term memory) and one or more other
abilities, such as speech and language, personality, decision-making and judgment
or awareness and ability to interact with the environment.
 Abilities that are typically not impaired in a patient with Alzheimer's disease
include memory for information of long ago (long-term memory), vision, ability
to feel things and muscle strength.
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More about memory
 Even when these memory systems are working well, some memories will be
stored or recalled more easily than others.
 A memory with a strong emotional component, such as where you were on
September 11, 2001, will likely be retained for the rest of your life.
 Information is also more likely to be stored properly when it is recognized as
important.
 New information is also more likely to be retained and recalled if it is related to
information that is already stored.
 The links between the new and old information serve as retrieval clues.
 The more numerous the links and the stronger the associations, the more
accessible and clear the memory will be.
 However, if the new information is too similar or two different from an existing
memory, it may be discarded.
 Forging new memories depends in large part on staying interested, active, and
alert.
Learning new things
You can’t learn anything brand new; you have to either use repetition or do something to
put the new information in your head by associating it with something you are already
familiar with. That’s why mnemonics are good. The word “supinate” was a brand new
word, but it sounds like “soup”, and its motion looks like you’re holding a bowl of soup,
so it’s easy now to remember.
If the word “cerebrum” is a brand new word, it sounds like “Sir read broom”, which are
words you already know and can visualize. Think of Harry Potter asking a wizard to read
the strange words on his new broom: “Sir read broom”, and the wizard scratches his brain
(cerebrum) as he tries to read the words. Now it’s easy to remember because you can
relate it to something you already know and can picture.
Implanted memory
All memories are created; there is no such thing as real memory.
When the Challenger shuttle exploded in the 1980’s, a freshman college professor told
his students to write down where they were and what they were doing when they heard
about it. Four years later, he asked them again. 65% answered the same way, but 35%
remembered it completely differently, but the students insisted they were right.
Another college professor found all the freshmen students with older siblings at the
college, and he told the older siblings to tell this story to their younger siblings: “When
you were 5, we went to a fancy restaurant to celebrate mom’s birthday, and you spilled
something on her dress and you were really embarrassed.” A few weeks later, the
professor asked the freshmen to write down a story about anything embarrassing that
happened to them when they were five, and to include all the details they remembered.
The freshmen recounted the fake story as though it was real because they thought they
remembered it. They also included details that they were not told, such as the name of
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the restaurant, the color of the dress, and what was spilled. The freshmen filled in the
story to make a complete memory.
Memory lapses
Lapses are more likely to occur when a person is tired, sick, distracted, or under stress.
People who are depressed are also more likely to have memory problems.
The brain contains about 100 billion neurons. Only a few neurons die over a person's
lifetime, but they do shrink. This shrinkage may partially explain why mental
functioning slows down in middle and older age.
Memory aids
Place commonly lost all items in a designated spot.
Write things down
Concentrate and relax
Get plenty of sleep
Say words out loud: saying” I have turned off the stove” after you have done so will give
you a verbal reminder when you later charged recall whether the stove is still on.
Incorporating people’s names into the conversation immediately after you have met them
serves the same purpose.
Use memory aids: use a pocket notepad, personal digital assistant, wristwatch alarm, or
voice recorder to help you remember what you need to do more to keep track of
information.
Use visual images: when learning new information, such as a persons name, create a
visual image in your mind to make the information more vivid and more memorable. If
you have just been introduced to Mr. Hackman, visualize him hacking his way through a
dense jungle with a machete.
Group items using mnemonics: when memorizing lists, names, addresses, and so on,
alphabetize them or group them into an acronym -- a word made from the first letter of a
series of words. You could also use the first letter of each word to create new words to
form sentences or phrase. You can use rhymes or create a story that connects each
element to be remembered. The more compact or meaningful the mnemonic, the easier it
will be to remember the information.
3. EMOTIONS
The prefrontal lobe and the hippocampus are part of a system of structures in the brain.
The LIMBIC SYSTEM also includes olfactory lobes (sense of smell). Therefore,
memory, emotion, and smell are linked. Crayolas are created today with the same scent
because it reminds people of their happy times in childhood. Why is the brain formed so
that smell and emotions are tied together? Because pheromones are tied to emotions and
behavior, so they need the link.
 The limbic system includes the olfactory cortex (sense of smell), and portions of
the diencephalon and cerebrum
 It influences emotions, motivations, and mood
 It is functionally associated with the hypothalamus
 It initiates responses necessary for survival, such as hunger and thirst.
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MENINGES
These are tissues that cover the entire CNS. They are three layers that serve to protect
and cushion the brain.
MENINGES
1. DURA MATER is the thickest and most superficial of the meninges.
2. ARACHNOID MATER is the middle layer and is not nearly as dense. It also does
not go down into the sulci, it only covers over the top of the gyri.
3. PIA MATER is the thin layer that DOES follow the brain surface into the sulci.
 SUBDURAL SPACE is between the dura mater and the arachnoid mater.
 SUBARACHNOID SPACE is between the arachnoid and pia mater, and is filled
with CEREBRAL SPINAL FLUID (CSF).
DURA MATER (“Tough mother”) is very dense regular connective tissue. It is the
tough layer that forms the outer layer of the meninges, and consists of two layers. Under
the skull is the first layer of dura mater, called the PERIOSTEAL LAYER (it is
touching the periosteum of the bone). Just under this is the second layer, called the
MENINGEAL LAYER. These two layers are everywhere except around the spinal
cord, where it’s just one layer, the meningeal layer; no periosteal layer. The dura mater
runs on top of the convolutions of the brain. Between the meningeal and periosteal layers
of the dura mater are DURAL SINUSES, which are filled with venous blood which is
drained from the brain.
Clinical Significance
 In the spinal cord, between L3 and L4, a doctor can inject anesthetic above the
dura mater, so only the nerves are affected. What is that called? Epidural.
 The dura and arachnoid mater both have lots of blood vessels, which might
rupture in an injury, called a SUBDURAL or SUBARACHNOID
HEMORRHAGE, which is potentially fatal. Blood accumulates and squeezes
the brain.
 Treatment = drill a hole.
VENTRICLES OF THE BRAIN
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The brain and spinal cord are hollow, filled with CSF = ventricles (blue areas on the PPT
photo). They are extensive. The names are simple.
1. LATERAL VENTRICLE is the largest, extends throughout the cerebrum.
2. THIRD VENTRICLE: in a sheep, it forms a figure “3” under the fornix and
around the corpora quadrigemina. In a human model, it looks like a cavity
between the fornix and a red arch.
3. FOURTH VENTRICLE is at the base of the cerebellum; it is continuous with
the central canal of the spinal cord, and also with the subarachnoid space.
a. CEREBRAL AQUEDUCT: connects the 3rd and 4th ventricles.
The ventricles, subarachnoid space , and cerebral aqueduct are filled with CSF. The
subdural space is NOT filled with CSF; it is filled with venous blood.
CEREBRAL SPINAL FLUID
 CSF is similar to plasma because it is derived from plasma.
 CSF is made in the ventricles by a group of capillaries called the CHOROID
PLEXUS.
 The choroid plexus capillaries have holes that allow the blood plasma to leak into
the subarachnoid space. It is now called cerebrospinal fluid (CSF).
 The CSF that has been depleted of its nutrients is absorbed back into the blood
through the ARACHOID GRANULATIONS.
 Arachnoid granulations are small protrusions of the arachnoid mater (the thin
second layer covering the brain) through the dura mater (the thick outer layer).
 They protrude into the venous sinuses of the brain, and allow cerebrospinal fluid
(CSF) to exit the brain, and enter the blood stream.
800ml of CSF is made per day, but there is actually only 150 ml there because the extra is
continually absorbed in the dural sinus through the arachnoid villa, which are valves that
release the CSF back into the blood.
The functions of CSF are as follows:
1. Allows the brain to float. The brain has the consistency of Jell-O, and weighs
three pounds. Its weight would crush the inferior structures if it didn’t float.
2. It cushions. In sudden movement, like riding a bike into a tree, and hitting the
head on the tree, the brain hits inside the skull in the front, and then in recoil it
hits the back of the skull = closed head injury, not necessarily with a fracture.
3. Acts as the lymphatic system of the brain (it doesn’t have one).
HYDROCEPHALY
 It is usually congenital, caused by a blockage of the cerebral aqueduct. The CSF
is made but can’t leave, and the brain gets expanded.
 The skull bones in a newborn can expand, so although it CAN damage the
brain, it does NOT cause mental retardation. The head becomes enlarged.
 Treatment is to put in a tube to drain it.
 Hydrocephaly in adults can be caused by a tumor, and since the skull no longer
expands, it’s very dangerous.
MENINGITIS
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This is when the meninges become infected. Can be caused from virus (not that bad) or
bacteria (can be fatal). The main symptom is a headache, so when this occurs in an
infant, they can’t say where they hurt. So when an infant presents with a high fever of
104˚ with no other symptoms, they will usually test for meningitis, because if they miss
it, it’s fatal. The test is a SPINAL TAP, where a needle is inserted between L4 and L5
because that is below the level of the spinal cord. They draw the CSF to look at. It it’s
cloudy or bloody, it’s usually meningitis. Untreated meningitis can lead to this next one:
ENCEPHALITIS
This is infection of the brain. It can be caused by mosquito-borne illnesses, or bacteria.
Why is infection of the brain so dangerous? It’s very dangerous because the swelling
crushes the brain. Any injury may lead to brain swelling. Treatment is to remove a piece
of the skull bone to allow the swelling.
AGING
Aging affects the nervous system
 Decline in sensory functions
 Decline in motor functions
 Insomnia
 Decline in short-term memory
ELECTROENCEPHALOGRAM (EEG)
Brain Wave Activity is recorded on an EEG
Not to be confused with an EKG, which is for the heart.
BRAIN WAVES
Types of brain waves
 Alpha (active during wakeful relaxation of closed eyes, such as meditation,
prayer). When you pray or meditate for a long time, you feel refreshed!
 Beta (active when learning, thinking and concentrating)
 Theta (active when just falling asleep)
 Delta (active during deepest stage of sleep)
Human Experiments
 We can figure out how the brain works by examining people’s motor and sensory
abilities after a head injury, and comparing them to normal.
 A brain tumor can sometimes cause epilepsy. If the surgery does not show
where the tumor is, the patient needs to be under mild sedation only, so they can
probe the area, get feedback from the patient, and see the results. That’s how
they can find the tumor.
BRAIN TUMOR THERAPIES
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Gamma Knife
 The gamma knife and its associated computerized treatment planning software
enable physicians to locate and irradiate relatively small targets in the head
(mostly inside the brain) with extremely high precision. Intense doses of radiation
can be given to the targeted area(s) while largely sparing the surrounding tissues.
 The gamma knife is usually unsuitable for targets larger than three or four
centimeters in size. The target is placed exactly in the center of approximately 200
precision-aimed, converging beams of (Cobalt-60 generated) gamma radiation.
Treatment takes anywhere from several minutes to a few hours to complete
depending on the shape and size of the target and the dose required. Patients do
not feel the radiation. Following treatment the headframe is removed and the
patient may return to normal activity.
Tumor-Starving Therapy: Avastin
 Avastin is an innovative tumor-starving therapy designed to block the VEGF
(Vascular Endothelial Growth Factor) protein that is produced by normal cells
and overproduced by cancer cells, and is needed for cell growth.
 Avastin is not chemotherapy and therefore works differently.
 VEGF is important for the formation of blood vessels. Tumors rely on blood
vessels to get the nutrients and oxygen they need to survive.
HOW DO DRUGS AFFECT THE BRAIN?
 Alcohol
 Drugs
 Nicotine
DRUG ABUSE
 Many drugs can alter the mood or emotional state, but they also have other side
effects.
 Drug abuse quickly leads to dependence, which is when a person spends much
time thinking about the drug or arranging to get it and they take more of the drug
than was intended because they develop tolerance to it and then need more to get
the same effect.
 They get withdrawal symptoms when they try to stop.
 Drug use occurs when people want to avoid dealing with their personal problems
and unpleasant emotions.
ALCOHOL
 Alcohol affects the cerebellum (balance area of the brain)
 You can see that area of the brain has been affected by alcohol because you
cannot walk a straight line or close your eyes and touch your finger to your nose.
This is metabolized (broken down) in the liver, where it disrupts the normal working of
the liver so that fats cannot be broken down, and they accumulate. This fat
accumulation, which is the first stage of liver deterioration, begins after only one
night of heavy drinking. If the drinking continues, scar tissue appears in the second stage.
If the drinking stops, the liver can still recover and become normal again. If not, the final
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stage, CIRRHOSIS Of the liver occurs, and the liver cells die and harden and cannot be
repaired. Alcohol crosses the placenta in pregnant women and causes FETAL
ALCOHOL SYNDROME, which is characterized by mental retardation.
NICOTINE
This is from tobacco, and it quickly goes into the entire nervous system and is highly
addictive. It also increases the heart rate and blood pressure. Withdrawal symptoms
include headache, stomach pain, irritability, and insomnia. LUNG CANCER has
passed breast cancer as a cause of death. Nicotine also causes harm to the fetus.
Interestingly, alcohol is the most toxic drug available (more toxic than illegal drugs) and
tobacco is the most addictive, yet these two substances are legal.
COCAINE
A cocaine binge can go on for days, after which the individual suffers from a crash. The
cocaine high is followed by depression because it depletes dopamine. That’s why their
mood does not just return to normal. During the binge, the person has no desire for food
or sleep. During the crash, the user is tired, depressed, irritable, and has memory
and concentration problems. It usually winds up causing a loss of sex drive and
impotence. Too much can cause seizures and cause the heart to stop beating and the
lungs to stop breathing. Babies born to addicts suffer brain and developmental problems.
If someone uses cocaine every day for 30 days, there is a 100% chance of becoming
addicted.
HEROIN
Side effects include nausea, vomiting, and a decrease in breathing and circulation, which
can cause death. The user becomes so tolerant to it, they have to take more and more of it
just to prevent the withdrawal symptoms. These symptoms include sweating, shakes,
abdominal cramps, and an increase in heart rate. Infants born of addicts also suffer
these withdrawal symptoms.
MARIJUANA
This causes alteration in vision, judgment, and motor coordination. Causes
distortions of space and time. They lack motor coordination, including the ability to
speak in a way that is understandable. Heavy use causes hallucinations, anxiety,
depression, body image distortion, paranoia and loss of sense of reality. Long term use
can lead to brain impairment.
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