8b Brain

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                           THE BRAIN

   A. Cerebrum

   B. Diencephalon
      Thalamus
      Hypothalamus

    C. Brain Stem
      Midbrain
      Pons
      Medulla oblongata

    D. Cerebellum
              THE BRAIN



  – Cerebrum
  – Diencephalon
  – Brain Stem
  – Cerebellum
                     The Brain

 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.
                      The Brain

 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%.

Fun Fact: -Scientists say the higher your I.Q. The more
 you dream.

 The brain is divided into parts, and is bilaterally
 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 made up mostly of grey matter
  (cell bodies, dendrites, and unmyelinated axons).
              GYRUS AND SULCUS

 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.
Figure 13.7a

 The cerebrum is divided into 2 halves called
  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
 Each hemisphere is divided into lobes, named for the
  bones on top of them.
The Cerebral Hemispheres and lobes

                               Figure 13.7b, c
The Cerebral Hemispheres and lobes

  Central sulcus               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
             Lateral sulcus     areas are more important.
              CORPUS CALLOSUM

 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
             CORPUS CALLOSUM

 is the area that
 connects the
 right and left
 halves of the
Sheep brain
              Corpus callosum
              CORPUS CALLOSUM

 This is the area that is responsible for the right half
  of the brain communicating with the left half of the
 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
 This was the first case suggesting that
  damage to specific regions of the brain
  might affect personality and behavior.
                     Phineas Gage

 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.
        CORPUS CALLOSUM: Fun Fact

 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
 Give a little boy a doll, and he will take the head off
  to see what it looks like inside.
 This is a difference between using both sides of the
  brain vs. just one side.
Consists of two parts:
 Thalamus
    The superior portion of the diencephalon
    Processes sensory information according to
    Major relay station for sensory impulses to the
 Hypothalamus
   The inferior portion of the diencephalon

   Provides homeostatic control over the body
    (maintains the homeostasis of the body)
   Controls hunger/thirst body temperature
Figure 13.15

 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
 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.


                   Pituitary gland



 This small area exerts more control over
  autonomic functioning than any other part.
 Provides homeostatic control over the body
  (maintains the homeostasis of the body)
 It maintains homeostasis by controlling the
  autonomic nervous reflexes, glucose and hormone
 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
Figure 13.15
  – PONS
 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
   When the neurons in the substantia nigra become
    damaged, dopamine levels decrease, causing Parkinson's
   Treatment is to replace the 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.
 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 pill-rolling tremor at rest.
    Corpora Quadrigemina “Quadruplet bodies”

 They control visual and audio (hearing)
   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


Farther down the
brainstem is the
PONS, which relays
sensory information
between the
cerebellum and
Spinal cord

              Medulla            Midbrain


             Medulla Oblongata

 At the base of the brainstem is the MEDULLA
  OBLONGATA, which contains areas for 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
    What’s the difference in function between the
     medulla oblongata and the hypothalamus?

 The hypothalamus is responsible for certain
  metabolic processes and other activities of the
  Autonomic Nervous System.
 It synthesizes and secretes hormones, and these in
  turn stimulate or inhibit the secretion of pituitary
 By secreting hormones, the hypothalamus controls
  body temperature, hunger, thirst, fatigue, sleep,
  blood pressure, autonomic nervous reflexes, and
  circadian cycles.
    What’s the difference in function between the
     medulla oblongata and the hypothalamus?

 The medulla oblongata contains the cardiac,
  respiratory, vomiting and vasomotor centers and
  also deals with autonomic functions, such as
  breathing, heart rate and blood pressure. However,
  the medulla oblongata does NOT control
  temperature, autonomic nervous reflexes,
  hunger, and sleep…only the hypothalamus
  performs those functions.
 The medulla oblongata controls blood pressure
  directly, and the hypothalamus controls it indirectly,
  by way of hormones.
               Reticular Formation

 The reticular
  formation is a
  group of cells
  throughout the
 They play a role in
  rousing and
               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
   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.
                PINEAL BODY

 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.
Pineal body
Pineal body
                     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!

 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

Functional and Structural Areas of the
           Cerebral Cortex

                                 Figure 13.11a
          MOTOR 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 motor cortex and
  association area, a visual cortex and association
  area, an auditory cortex and association area, and a
  somatic (sense of touch) cortex and association
           MOTOR AREAS



 extend down the spinal cord and synapse on
 LOWER MOTOR NEURONS which then leave
 the spinal cord to innervate every skeletal muscle.
Some muscles have more motor units than others
 (hands, eyes, etc).
Upper and Lower Motor Neurons

 Lower motor neuron is here. The upper
 motor neuron comes down from the brain
 and synapses on this neuron.

                                          Figure 12.11

Located 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. 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.
                       Fun Fact

 Use your right foot to draw a clockwise circle in the
 While keeping your foot going, draw the number “6”
  in the air with your right hand.
 Did your foot start moving counter-clockwise?
Pre-Central Gyrus
                        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.
                   Pre-Central Gyrus

 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 enjoy especially large
  areas of cells in the motor area.
 The reason the face region of the homunculus is so large
  relates to the fact that we have very expressive faces.
 There is also a somatosensory homunculus.
depiction of the
Perhaps this is a
more accurate
depiction of the


  Somatic = touch



1. Primary somatosensory cortex
2. Somatosensory association area
The primary somatosensory cortex receives signals for
     touch and pressure.
The somatosensory                                 2

association area interprets the
sensation. When I put my
hand in my pocket, I know
that is my keys I am feeling.
                 VISUAL AREAS

1. Primary visual cortex
2. Visual association area
The primary visual cortex receives signals from the
     optic nerves.
The visual association area
interprets the signals. When I
look at my keys, I can identify
them as keys.

Within the visual association area is a region called Brodmann
    areas 18 +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.
               HEARING AREAS

1. Primary auditory cortex
2. Auditory association area
The primary auditory cortex receives signals from the
The auditory association area
interprets the signals. When I
hear a sound, I can tell you               1   2
what it is that I am hearing.
           AUDITORY AREA

The auditory area 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 that cause injury to this
    area, and the person can’t use adjectives, but
    everything else is normal!
        Auditory Association Area
• The auditory association area contains two special regions
• BROCA'S AREA is a region of the brain that allows for speech.
   – Injury (stroke) in this location causes impairment of
      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 is the region of the brain that allows
  understanding of words.
• It does not affect a person’s speech.
• They can say what they want to, but
   they cannot comprehend
   someone else’s speech.
                       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.


 For a great video of a neurologist describing what it felt like
  when she had a stroke:



 This is coordinated by the frontal lobe: How much
  time do you need to be ready for the test? This is
  calculated by the frontal lobe.
 Damage to the frontal lobe 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.
 Stopped in 1960’s; we do it with drugs now

 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
 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.

 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.
       Memory: Hippocampus


 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
   Prepare
   Listen
   Write notes
   Review daily
   Watch videos
   Do labs
 This allows easy access to that information again
  by going through the hippocampus.

 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)
Sheep brain



         Mammilary body

 Carries signals from the hippocampus to the
 mammillary bodies.

 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 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.

 A hemorrhage in the brain (broken blood
  vessel) deprives an area of the brain of
 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!
           Another problem with memory:
 Dementia is a symptom, not a disease. Dementia is
  loss of memory.
 Alzheimer’s disease is the most common form of
 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.
Normal Brain vs. Alzheimer’s
   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
 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.

 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
   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.
        Learning new things

 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.

 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 the restaurant, the color of the dress, and
    what was spilled. The freshmen filled in the story to
    make a complete memory.
              MEMORY LAPSES

 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.
Attention Deficit Disorder
                     Memory aids

 Place all commonly lost items in a designated
   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.
                   Memory aids

 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.

 The prefrontal lobe and the hippocampus are part
  of a system of structures in the brain.
 The LIMBIC SYSTEM also includes the olfactory
  nerves (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
 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
(everything in orange)

                         Figure 13.23
                   Limbic System

 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.
• These are tissues that cover the entire CNS.
  They are three layers that serve to protect and
  cushion the brain.
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, shiny layer that DOES follow the
  brain surface into the sulci.
 SUBDURAL SPACE is between the dura mater and the
  arachnoid mater.
 The SUBARACHNOID SPACE is between the arachnoid
  and pia mater, and is filled with CEREBRAL SPINAL
  1. DURA MATER (“Tough mother”)

Dense regular connective tissue.
It consists of two layers.
Under the skull is the first layer of dura mater, called the
   PERIOSTEAL LAYER. Just under this is the second
   layer, called the MENINGEAL LAYER. There are these
   two layers everywhere except around the spinal cord, where
   it’s just one layer, the meningeal layer of the dura mater; no
   periosteal layer.
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.
Dural sinus and subarachnoid space
              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,
  HEMORRHAGE, which is potentially fatal.
  Blood accumulates and squeezes the brain.
 Treatment = drill a hole.
 The brain and spinal cord are hollow, filled with CSF = ventricles
  They are extensive. The names are simple.
 LATERAL VENTRICLE is the largest, extends throughout the
 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.
 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.
   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.

                          Figure 13.6a, b

3rd ventricle

                         Mammilary body
                       Lateral ventricle
Cerebral aqueduct

    Fourth ventricle
                                           Sheep brain

  Third ventricle      Lateral ventricle
  (forms a
  number “3”)

Fourth ventricle

                    Cerebral aqueduct
       CerebroSpinal Fluid (CSF)

 CSF is similar to plasma because it is derived from
 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).
        CerebroSpinal Fluid (CSF)

 The CSF that has been depleted of its nutrients is
  absorbed back into the blood through the
 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.

 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).
Protection of the Brain – Cerebrospinal
               Fluid (CSF)

                                  Figure 13.27b

 HYDROCEPHALY is accumulation of CSF inside the
   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
   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 is inflammation of the meninges.
 Can be caused from bacteria (can be fatal in 24 hours) or
    virus (fatal in a week or more).
   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 might 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:

 This is inflammation of the brain.
 It can be caused by mosquito-borne illnesses, or
 Why is infection of the brain so dangerous? 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 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
 Theta (active when just falling asleep)
 Delta (active during deepest stage of sleep)
      Pleasure Centers of the Brain
• Experiment: put a rat on one side of the cage and its food on the
  other side. Put an electric mat on the bottom of the cage so it
  gets shocked if it tries to run across the flood of the cage to get
  to the food.
• One rat has an electrode inserted into its brain to stimulate the
  pleasure center when it reaches the food. Only one stimulation
  per trip, though!
   – This rat will run across immediately, and will run back and
      forth to the food many times, even though it gets shocked on
      the way there, just so it can experience the pleasure jolt.
• Another rat gets no stimulation.
   This rat will starve to death rather than experience the shock.
• You can get a rat to go to an area that you have chosen by
  stimulating its pleasure center every time it goes near there.
              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
           Gamma Knife Therapy

 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.
            Gamma Knife Therapy

 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.
Gamma Knife Therapy
       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
 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

 Alcohol affects the cerebellum (balance area of the
 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.

 Alcohol 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 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.

 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, 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.

 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
 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.

 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

 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
   Long term use can lead to brain impairment.