Neuroscience by 1xvXv5


                  A Concise Introduction
                                2nd Edition

                         Richard Griggs
                             Chapter 2

Prepared by
J. W. Taylor V
The Journey…

            The   Neuron
            The   Nervous
               System and the
               Endocrine System
            The   Brain
       The Neuron
 The Structure of a Neuron
How Neurons Communicate
       Drugs, and Poisons
Neurons and Glial Cells
   Neurons are responsible for information
    transmission throughout the nervous system
   Glial cells do not directly transmit
    information, but instead support neurons in
    their work by disposing of waste products of
    neurons, keeping their
    chemical environment
    stable, and insulating
The Structure of a Neuron
              Dendrites are the fibers that
               project out of the cell body,
               receiving information from other
              The cell body contains the
               nucleus of the cell and other
               biological machinery to keep the
               cell alive
              The axon transmits messages
               through the neuron
              The axon terminals are at the
               end of the axon and send
               messages to a different neuron
The Structure of a Neuron
How Neurons Communicate

 Communication   Communication
     within         between
  a neuron is      neurons is
   electrical      chemical
The Electrical Impulse

   Information from the dendrites is either
    excitatory (telling the neuron to generate an
    electrical impulse) or inhibitory (telling the
    neuron not to generate an electrical impulse)
       The impulse is an “all or nothing” event, meaning
        that there either is or is not an electrical impulse
       Stimuli of varying intensities are encoded by the
        quantity of neurons generating impulses and the
        number of impulses generated each second by
        the neurons
The Electrical Impulse

   The myelin sheath is an insulating layer of
    fatty white substance that encases the axon,
    allowing electrical message to be transmitted
    faster within the neuron
     Damage to the myelin sheath will slow
       electrical impulses, and can result in diseases
       like multiple sclerosis
Chemical Communication
Between Neurons
   Axon terminals contains sacs of
       These neurotransmitters are naturally occurring
        chemicals in the nervous system that specialize in
        transmitting information between neurons
   Between the axon terminals of one neuron
    and the dendrites of another neuron is a
    small space called the synaptic gap, across
    which neurotransmitters are sent, allowing
    neurons to communicate
Brain Scans

   Brain scans work because neurons require
    oxygen and other nutrients such as blood
       Positron Emission Tomography (PET) scans
        use a dose of radioactive glucose, which moves
        to the more-active areas of the brain
       Functional Magnetic Resonance Imaging
        (MRI) detects active areas of the brain by
        highlighting those areas that require more
Drugs, and Poisons
Key terms:

        Agonists                 Antagonists

  Drugs and poisons         Drugs and poisons
  that increase the         that decrease the
  activity of one or more   activity of one or more
  neurotransmitters         neurotransmitters
1. Acetylcholine (ACh) is involved in both learning and
   memory and muscle movement
2. Dopmaine impacts our arousal and mood states, thought
   processes, and physical movement
3. Serotonin and norepinephrine are neurotransmitters
   involved in levels of arousal and mood, and play a major
   role in mood disorders such as depression
4. GABA is the main inhibitory neurotransmitter in the
   nervous system; glutamate is the main excitatory
5. Endorphins are a group of neurotransmitters that are
   involved in pain perception and relief
Acetylcholine (ACh)
   Botulinum poison (botulin) is an antagonist that
    blocks the release of ACh at muscle junctures,
    leading to paralysis and even death
   Curare is an antagonist that paralyzes the body by
    occupying the receptor sites for ACh, thereby
    preventing ACh from getting in and carrying its
    message to a neuron
   Black widow spider venom is an agonist for Ach,
    causing the continuous release of ACh, flooding the
   Low levels are associated
    with Parkinson’s disease,
    and excessively high levels
    are associated with schizophrenia
   L-Dopa is an agonist that increases production of
   Anti-psychotic drugs are antagonists that block the
    receptor sites for dopamine so that this neurotransmitter
    cannot send its messages
   Amphetamine acts as an agonist by stimulating the
    release of dopamine from axon terminals
   Cocaine is an agonist that blocks the re-uptake of
Serotonin and Norepinephrine

   Some antidepressant drugs work by blocking
    the reuptake of serotonin and norepinephine
   Anti-depressant drugs like Prozac, Paxil,
    and Zoloft are selective serotonin reuptake
GABA and Glutamate
   Anti-anxiety drugs are agonists for GABA
   Lack of GABA may contribute to epilepsy, a
    brain disorder resulting in uncontrolled
    movement and convulsions
   Glutamate is involved in memory storage
    and pain perception.
   Excessive glutamate can lead to neuron
    death; deficient glutamate has been
    proposed to explain schizophrenia
   Morphine and heroin are agonists that bind
    to receptor sites, thereby increasing
    endorphin activity
  The Nervous and
Endocrine Systems
    The Central Nervous System
  The Peripheral Nervous System
 The Endocrine Glandular System
              Emotions and the
     Autonomic Nervous System
Nervous System Subdivisions
Types of Neurons

   Interneurons exist only in the central
    nervous system
   Sensory neurons carry information to the
    central nervous system from sensory
    receptors in the eyes, muscles, and glands
   Motor neurons carry movement commands
    from the central nervous system to the rest of
    the body
The Central Nervous System
Consists of the spinal cord and the brain
          The spinal cord has two functions

              Conduit for incoming sensory data
               and outgoing movement commands
              Provides for spinal reflexes, which
               are simple automatic actions not
               involving the brain
          The brain is the control center for the
            entire nervous system
The Peripheral Nervous System

   Gathers information about the external
    environment and the body’s internal
    environment for the brain through sensory
   Serves as the conduit for the brain’s
    commands to the rest of the body through
    motor neurons
The Peripheral Nervous System
Consists of two parts:
     The somatic (or skeletal) nervous system carries
      sensory input from receptors to the CNS and relays
      commands from the CNS to the skeletal muscles to control
      their movement
     The autonomic nervous system regulates our internal
      environment and consists of two parts
       The sympathetic nervous system is in control when we
        are very aroused and prepares us for defensive action
        (such as running away or fighting)
       The parasympathetic nervous system is in control when
        the aroused state ends to return our body to its normal
        resting state
The Endocrine Glandular System

   Not part of the nervous system
   Works with the autonomic nervous system in
    responding to stress, and plays a role in basic
    behaviors and bodily functions such as sex,
    eating, metabolism, reproduction, and growth
   Endocrine glands secret hormones, which are
    chemicals carried by the bloodstream to target
    sites throughout the body
The Endocrine Glandular System
   Endocrine glands are controlled by the
    hypothalamus, which controls the most influential
    gland, the pituitary
       Releases hormones essential for human growth and that
        direct other glands to release their hormones
   Some other glands:
       Thyroid gland affects our growth and maturation
       Adrenal glands are involved in metabolism and help
        trigger the “fight or flight” response with commands from
        the autonomic nervous system
       The pancreas is involved in digestion and maintaining
        blood-sugar levels
The Endocrine Glandular System
Components of Emotion
     An emotion is a complex psychological
      state that involves three components:

 Physical            Behavioral              Cognitive

 A physiological        An outward         An appraisal of the
state of arousal   expression including   situation to determine
triggered by the    facial expressions,   which emotion we are
    autonomic         movements and       experiencing and how
nervous system           gestures                intensely
Components of Emotion
   The physical component
       Includes the “fight or flight” response of the autonomic nervous
       Heart rate and breathing increase, blood pressure surges, start
        sweating, pupils dilate, digestion slows
   The behavioral component
       Is the product of motor neurons
       The facial-feedback hypothesis assumes that the facial muscles
        send messages to the brain, allowing the brain to determine
        which emotion is being experienced
   The cognitive component
       Includes an appraisal of the situation to determine what emotion
        we are experiencing
Theories of Emotion

   James-Lange Theory

          Cannon-Bard Theory

                  Two-Factor Theory
James-Lange Theory
   Contends that autonomic nervous system
    physiological arousal is a response to a stimulus, and
    that such a physiological response is subsequently
    interpreted as the emotion
                       For example, if you are crossing
                        the street and see a car speeding
                        toward you, your autonomic
                        nervous system is aroused (e.g.,
                        increased heart rate). Based on
                        this arousal, you interpret the
                        stimulus as threatening and pick
                        up your pace across the street.
Cannon-Bard Theory
   Contends that arousal patterns for different
    emotions are too physiologically alike to be
    able to determine what emotion is being
   Instead, an emotion-provoking stimulus
    sends messages to both the peripheral
    nervous system and the brain
       The brain produces the emotional feeling, the
        autonomic nervous system produces the
        physiological response, and the motor neurons
        produce the behavioral response
Two-Factor Theory

   Contends that there are two important
    determinants of emotion:
       Physiological arousal tells us how intense the
        emotion is
       The cognitive appraisal of the entire situation
        allows us to identify the emotion, leading to the
        emotional feeling
Integrating the Theories

   LeDoux (1996) contends that there are
    different brain systems for different emotions
       Fear, for example, does not require higher-level
        cognitive processing and is generated almost
        instantaneously by the amygdala
       More complex emotions, however, such as love
        or guilt, that do not require instantaneous
        responding for survival, may require higher-level
               The Brain
        Going up the Brain Stem
Processing in the Cerebral Cortex
            Specializations of the
     Left and Right Hemispheres
             Consciousness and
              the Sleeping Brain
Case 1: A Landscape Artist
   Scenario            Neuroanatomy                 Related Function
Anne the             Left motor cortex         Controls right hand
landscape            Left frontal lobe         Contains motor cortex
artist is            Visual cortex             Used for vision
standing at her
easel, painting      Both occipital lobes      Contain visual cortex
with her right       Auditory cortexes         Used to hear music
hand as she          Both temporal lobes       Contain auditory cortexes
looks out the        Right hemisphere          Spatial ability for painting
window at her        Thalamus                  Relays sensory information
garden. She’s
listening to         Frontal lobes             Deciding what to paint
classical            Left sensory cortex       Feeling the paintbrush
music as she         Left parietal lobe        Contains sensory cortex
paints.              Cerebellum                Coordinates moving arm
Case 2: A Professional Wrestler
     Scenario                Neuroanatomy                   Related Function
Crazy Eddie, the         Both motor cortexes        Move muscles
professional             Frontal lobes              Contain motor cortexes
wrestler, is in the      Both sensory cortexes      Needed for sense of touch
ring wrestling. The      Parietal lobes             Contain sensory cortexes
                         Visual cortexes            Used for vision
crowd is yelling
                         Both occipital lobes       Contain visual cortexes
and his is taunting
                         Right hemisphere           Spatial ability for wrestling
him. Eddie yells         Wernicke’s area            Understanding taunts
back at his              Left temporal lobe         Contains Wernicke’s area
opponent. The two        Broca’s area               Produces speech (yells)
of them are out of       Left frontal lobe          Contains Broca’s area
breath and               Thalamus                   Sensory relay
sweating                 Frontal lobes              Decision making & attention
profusely. They          Medulla                    Regulates heart and breathing
continue their           Amygdala                   Aggression and fear
                         Reticular formation        Controls arousal
                         Cerebellum                 Balance and coordination
series of wrestling      Hypothalamus               Regulates temperature
moves.                   Hippocampus                Memory for moves
Case 3: A Student

     Scenario                  Neuroanatomy                         Related Function
Jill is a law                 Hippocampus                    Remembering and learning
student                       Wernicke’s area                Language comprehension
studying for
her exam. She                 Left temporal lobe             Contains Wernicke’s area
is reading                    Amygdala                       Anger and fear about cases
about violent                 Frontal lobes                  Decision making & attention
rape and
                              Hypothalamus                   Regulates hunger and thirst
murder cases.
She is snacking               Angular gyrus                  Needed for reading
on popcorn
and drinking
Source: Sheldon, J. P. (2000). A neuroanatomy teaching activity using case studies and collaboration.
Teaching of Psychology, 27, 126-128.
The Central Core
   The brain stem
       The medulla links the spinal cord to the brain and is involved in
        regulating heartbeat, blood pressure, digestion, and swallowing
       The reticular formation is a network of neurons running up the
        center of the brain stem and into the thalamus that is involved in
        controlling our different levels of arousal and awareness
   The cerebellum is involved in the coordination of our
    movements, our sense of balance, and motor and
    procedural learning
   The thalamus, located at the top of the brain stem,
    serves as a relay station for incoming sensory
    information (except smell)
       The basal ganglia are on the outer sides of the thamalus and are
        concerned mainly with the initiation and execution of physical
The Central
 Core Brain
The Limbic System

   Plays a role in our survival, memory, and
       The hypothalamus control the pituitary gland,
        the autonomic nervous system, and plays a
        major role in regulating basic drives such as
        eating, thirst, and sex
       The hippocampus is involved in the formation
        of memories
       The amygdala plays a major role in regulating
        our emotional experiences, especially fear,
        anger, and aggression
The Limbic System
Processing in
the Cerebral Cortex
   The cerebral cortex
    is the most important
    brain structure, serving
    as the information
    processing center for
    the nervous system
       Is where perception, language, memory, decision
        making, and all other higher-level cognitive processing
       Consists of two hemispheres connected by a band of
        neurons called the corpus callosum, allowing the two
        hemispheres to communicate
Brain Lobes
    1. The frontal lobe is the area in the
       front of each hemisphere and in front of
       the central fissure and above the lateral
    2. The parietal lobe is the area located
       behind the central fissure and above the
       lateral fissure
    3. The temporal lobe is located beneath
       the lateral fissure
    4. The occipital lobe is located in the
       lower back of each hemisphere
The Four Lobes and the
Sensory-Motor Processing Areas
The Motor Cortex
   The frontal lobe strip of cortex, directly in front
    of the central fissure in each hemisphere,
    allows us to move different parts of our body
                 Each hemisphere controls the voluntary
                  movement of the opposite side of the
                  body (a contralateral relationship)
                 Amount of motor cortex devoted to a
                  specific body part is related to the
                  complexity and precision of movement
                  of which that part is capable
The Somatosensory Cortex
   The parietal lobe strip of cortex, directly
    behind the central fissure in each
    hemisphere, is where body sensations
    of pressure, temperature, limb
    position, and pain are processed
       Contralateral relationship
       Amount of sensorimotor cortex devoted
        to a body part is directly proportionate to
        the sensitivity of that body part
Homunculi for the Motor Cortex
and the Somatosensory Cortex
Visual Cortex
and Auditory Cortex
   The visual cortex is located in the occipital lobes at
    the back of the hemispheres
   The auditory cortex is in the temporal lobes
   These primary areas pass the
    results of their analyses on to
    areas in the other lobes to complete
    the brain’s interpretation of the
    incoming visual or auditory information
       These secondary cortical processing
        areas are part of what is termed the
        association cortex
Association Cortex

   Consists of the other 70% of the cortex not
    in one of the previously mentioned areas
   This is where the higher-level processing
    such as decision making, reasoning,
    perception, speech, and language occurs
       All of which require integration of various types
        of information
The Case of Phineas Gage
         Phineas Gage was railroad worker
          who survived when a metal tamping
          iron flew through his left cheek and
          head, exiting through his frontal
         He became irresponsible,
          impulsive, disorderly, indecisive,
          and cursed, leading neuroscientists
          to think the frontal lobes are
          important in such behaviors

   Broca’s area, in the left hemisphere’s temporal
    lobe, is responsible for fluent speech production
       When damaged, people cannot generate fluent speech,
        but can still understand speech easily
       Singing and musical abilities seem to be housed in the
        right hemisphere because damage to Broca’s area does
        not impair these abilities
   Wernicke’s area is in the left temporal lobe and is
    responsible for the comprehension of speech and
Studying the Two Hemispheres
   Light waves from the left visual field go to the
    right half of each eye, and light waves from the
    right visual field go to the left half of each eye
     The right half of each eye connects with the
       right hemisphere, and the left half of each eye
       connects with the left hemisphere
Pathways for
in the Left
and Right
Visual Fields
Studying the Two Hemispheres
          With split-brained people, the information
           cannot transfer between hemispheres
           because the corpus callosum has been cut
          Split-brain people can only identify
           information orally when it is presented
           briefly in the right visual field (and thus
           processing in the left hemisphere)
            If a spoon was flashed in the left visual
              field, split-brained people could not say it
              was a spoon
            If the person was blind-folded and told to
              find the object from a group of objects
              with the left hand, s/he can do this
What we know…
   Left hemisphere
       Language
       Math and logic skills
       More analytical, analyzing wholes into pieces
   Right hemisphere
       Spatial perception
       Solving spatial problems
       Drawing
       Face recognition
What we know…
   Remember, however, that these differences
    in hemispheric performance are for people
    whose two hemispheres can no longer
   When normal people are performing a task,
    the two hemispheres are constantly
    interacting and sharing information
   This is why it is not very accurate to say
    someone is “left-brained” or “right-brained”
   Rather, nearly all of us are “whole brained”
and the Sleeping Brain
   Consciousness is a person’s subjective awareness
    of both their inner thinking and feeling and their
    external environment
   The five stages of sleep were determined by use of
    an electroencephalogram (EEG), which records a
    real-time graph of a person’s cortical electrical
    activity in the brain
       As we slip into sleep and pass through the first four
        stages, our brain waves change, in general becoming
        progressively slower, larger, and more irregular, especially
        in Stages 3 and 4
Five Stages of Sleep
   Stage 1: Lasts about 5 minutes
   Stage 2: Lasts about 20 minutes
       Characterized by sleep spindles, rapid bursts of
        mental activity
   Stage 3: Also known as transitional sleep
    and is characterized by delta waves, which
    are large, slow waves
   Stage 4: Lasts about 30 minutes
       Parasympathetic nervous system is active, as
        muscles relax, heartbeat slows, blood pressure
        declines, and digestion speeds up
Five Stages of Sleep
   Stage 5: REM (rapid eye movement sleep) occurs
    after we leave stage 4 sleep and return through the
    earlier stages of sleep
       Called paradoxical sleep because your muscles are relaxed, but
        other body systems, including the brain, are active, much like a
        waking pattern
       Characterized by very rapid brain waves somewhat like those of
        Stage 1 sleep, but one is still sound asleep
       If awakened during REM sleep, people often report having been
       Most dreams are emotional and unpleasant, perhaps because
        the visual cortex and frontal lobe are inactive during REM sleep;
        the limbic system structures are active, however, creating
        irrational imagery and emotional experiences of our dream world
       REM sleep accounts for 20–25% of total sleep time
of Sleep
Five Stages of Sleep

   These 5 stages (the sleep cycle) repeat
    themselves about every 90 minutes, with
    Stages 3 and 4 getting shorter with each cycle,
    and REM and Stage 2 getting longer with each
   REM sleep rebound effect is a significant
    increase in the proportion of REM sleep
    following deprivation of REM sleep
Why do we sleep and dream?

   Sleep deprivation results in:
       Impaired concentration and a general bodily feeling of
        weakness and discomfort
       Suppression of the immune system, lessening one’s
        ability to fight off infection and disease
       Increased vulnerability to accidents
       Increased difficulty in concentrating, studying, and
        taking exams
Why do we sleep and dream?

   Explanations for dreaming :
       Sigmund Freud proposed that dreams were
        disguised outlets for inner conflicts of our
        unconscious mind, a view not accepted by modern
        sleep researchers
       The activation-synthesis hypothesis contends that
        dreams are merely the sleeping brain’s attempt to
        make sense of random neural activity without the
        rational interpretation of the frontal lobe

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