Neuroanatomy

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Neuroanatomy

• Chapter Two

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A. Neurons

• 1. The long, thin cells of nerve tissue along
  which messages travel to from the brain
• About 100 billion neurons (nerve cells) in the
  human brain
• 2. Transmission occurs whenever cells are
  stimulated past a minimum point and emit a
  signal.
• Either fires or does not fire
• Electrical impulses allow for transmission of
  info within a neuron chemical impulses allow for
  transmission of info between neurons

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B. Parts of a Neuron

• 1. Neurons have many of the same features as
  other cells
• Nucleus
• Cytoplasm
• Cell membrane
• 2. What makes neurons unique is their shape and
  function

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Parts of a Neuron (cont.)

• 1. Cell Body (also called the soma)
• Contains the nucleus and produces the energy
  needed to fuel neuron activity
• Directs all cell activities including the nucleus
  
• 2. Axon
• Carries impulses away from the cell body toward
  surrounding neurons
• 3. Dendrite
• Receive impulses, or messages, from other neurons
  and send them to the cell body

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Parts of a Neuron (cont.)

• 4. Myelin sheath- insulates and protects the axon
  for some neurons
• speeds the transmission of impulses
• In cases of multiple sclerosis, the myelin sheath
  is gone.
• 5. Axon terminals- release neurotransmitters to
  stimulate dendrites of the next neurons
• 6. Neurotransmitters- chemicals contained in the
  terminals that enable neurons to communicate
• 7. Synapse- Space between the terminals of one
  neuron the dendrites of the next neuron

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Structures of a neuron
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LO 2.3 Neuron communication
Menu
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C. How a Neuron Fires

• 1. Ions charged particles.
• Inside neuron negatively charged.
• Outside neuron positively charged.
• 2. Resting potential - the state of the neuron
  when not firing a neural impulse.
• 3. Action potential - the release of the neural
  impulse consisting of a reversal of the
  electrical charge within the axon.
• Allows positive sodium ions to enter the cell.
• 4. All-or-none - referring to the fact that a
  neuron either fires completely or does not fire
  at all.
• 5. Return to resting potential.

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D. Neurotransmitters

• 1. Types of neurotransmitters
• Excitatory causes a neuron to fire
• Inhibitory stops a neuron from firing
• 2. In NS called neurotransmitters
• 3. Outside of NS called hormones
• 4. Often several NTs working at the same terminal
  button

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E. Neuron Activity

• 1. The intensity depends on whether the neurons
  are ON or OFF
• 2. Types
• Afferent
• Sensory neurons
• Relay messages from the sense organs to
• spinal cord brain
• Efferent
• Motor neurons
• Send signals from the brain to the glands and
  muscles
• Interneurons
• Carry information between other neurons only
  found in the brain and spinal cord

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I. The Nervous System

• Chapter Two

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The Big Picture The Nervous System
Peripheral Nervous System
Central Nervous System
Skeletal (Somatic) NS
Autonomic NS
The Spinal Cord
The Brain
Sympathetic NS
Parasympathetic NS
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A. Nervous System

• 1. The Central Nervous System (CNS)
• The brain and the spinal cord.
• 2. Peripheral Nervous System (PNS)
• The smaller branches of nerves that stretch
  throughout the body.

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Spinal Cord
Sensory organs receive the message. Sensory
neurons connect in the back of the spinal cord
and send the information to the spinal cord.
Interneurons take the information and send it
to the brain to motor neurons at the same time.
Motor neurons exit through the front of the
spinal cord and carry the message back to the
muscle.
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B. Voluntary and Involuntary Activities

• 1. Somatic Nervous System
• The part of the peripheral nervous system that
  controls voluntary movement of skeletal muscles.
• Example raising your hand to turn a book page.
• 2. Autonomic Nervous System
• The part of the peripheral nervous system that
  controls internal biological functions.
• Example your heartbeat or blood pressure.

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C. ANS

• 1. Two parts
• Sympathetic
• Prepares the body for dealing with emergencies
  or strenuous activity.
• Parasympathetic
• Works to conserve energy and to enhance the
  bodys ability to recover from strenuous
  activity.

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II. Parts of the Brain

• Chapter Two

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Exploring Psychology

• Early Greeks were not impressed with the brain.
  They suggested that the brains main function was
  to cool the blood. They were much more impressed
  by the heart. They proposed that the heart was
  the source of feelings and thoughts. Hippocrates,
  however, observed the effect of head injuries on
  peoples thoughts and actions and noted, From
  the brain, and from the brain only, arise our
  pleasures, joys, laughter and jests, as well as
  our sorrows, pains, griefs and tears. Through
  it, in particular, we think, see, hearEyes,
  ears, tongue, hands and feet act in accordance
  with the discernment judgment of the brain.

Adapted from Psychology by Peter Gray, 1999.
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The Question

• How did Hippocrates help change the notion that
  the brain, not the heart, was the source of
  thoughts and feelings?

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A. The Hindbrain

• Location- Rear base of the skull
• 2. Role- Involved in most basic processes of life
• Includes
• Cerebellum- helps control posture, balance, and
  voluntary movements
• Medulla- controls breathing, heart rate, and a
  variety of reflexes
• Pons- functions as a bridge between the spinal
  cord and the brain produces chemicals the body
  needs for sleep

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B. The Midbrain

• Location- Small part of the brain above the pons
• 2. Role- Collects information from the senses and
  sends it upward
• Includes the medulla, pons, and midbrain (all
  make up the brain stem)
• Reticular Activating System (RAS) spans across
  these structures
• Alerts the rest of the brain to incoming signals
  and is involved in the sleep/wake cycle

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C. The Forebrain

• Location- Covers the brains central core
• Includes
• Thalamus- Relay station for information traveling
  to and from the cortex (all sensory info except
  smell)
• Hypothalamus- Controls hunger, thirst, and sexual
  behavior
• Makes us sweat when we are hot and shiver when we
  are cold.
• 2. High thinking processes are also housed in the
  forebrain
• Cerebral cortex- outer layer of the forebrain
• Gives you the ability to learn and remember
• Cerebrum- inside layer of the forebrain
• (Both go around the hindbrain and brain stem like
  a mushroom surrounds its stem)

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D. The Limbic System

• Location- Found in the core of the forebrain
  (sits atop the brainstem but surrounded by
  cerebral cortex)
• 2. Role- Composed of different structures in that
  regulate emotions and motivations
• Includes the hypothalamus amygdala (controls
  violent emotions) thalamus and hippocampus
  (important in the formation of memories)

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E. Cerebrum

• Consists of two hemispheres, or halves
• Resembles a small brain
• 2. The hemisphere is connected by a band of
  fibers called the corpus callosum
• 3. Each hemisphere has deep grooves that mark
  regions known as lobes
• Both hemispheres have the same four lobes

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F. The Lobes

• Cerebral cortex gray wrinkled surface divided
  into 4 main lobes
• Occipital Lobe
• Controls vision
• Damage could cause visual problems
• Parietal Lobe
• Concerned with information from the senses all
  over the body
• Temporal Lobe
• Concerned with hearing, memory, emotion, and
  speaking
• Frontal Lobe
• Organization, planning, and creative thinking.
• 2. Some other sources say that frontal lobe
  controls behavior, thought emotion (instead of
  temporal lobe)

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G. Other Parts of Cerebral Cortex

1. Prefrontal cortex most frontal region of frontal
   lobe (emotional control, planning)
2. Motor cortex Strip of frontal lobe specialized
   for controlling voluntary actions of muscles
3. Somatosensory cortex Strip of parietal lobe
   specialized for processing sensations of touch
4. Brocas area Portion of motor cortex found only
   in the left hemisphere specialized in
   coordinating muscles used in speech
5. Wernickes area Portion of temporal lobe found
   only in the left hemisphere involved in
   processing understanding speech

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Overview of the Brain Parts Function
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Sensory Homonculus a map showing how different
cortical segments control parts of the body
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The amount of cortex devoted to sensory, motor,
and association areas differs with more complex
species.
Humans chimpanzees rely on integrating signals
for survival.
Rats cats rely on their instincts more for
survival.
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III. Right/Left Brain
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A. Hemisphere Lateralization

• 1. Each hemisphere controls receives info from
  the opposite side of body
• 2. Each hemisphere of the brain is specialized to
  promote efficient work
• Left hemisphere involved in tasks that require
  logic, order, critical thinking or analysis
  (writing, science, math)
• Right hemisphere- require artistic or creative
  skills (visual spatial skills) helps with
  recognition of faces

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B. Split-Brain Research

• Patients with severe epilepsy had their corpus
  callosum split to control seizures
• They appear to be normal (cognitive, motor,
  intellectual skills remain intact)
• Personality mood are unaffected by surgery
• Some unusual effects occur after surgery
• Patients cannot orally report info only presented
  to the right hemisphere (since language centers
  are in the left)

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Language Areas of the Left Hemisphere
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C. Important Figures Associated with the Brain

• Paul Broca- discovered that the speech production
  center of the brain is located in the frontal
  lobe
• Carl Wernicke- studied the effects of brain
  disease on speech language
• All language deficits are result of damage to
  Brocas area
• Roger Sperry- worked on split-brain research
• Michael Gazzaniga- made advances in understanding
  lateralization in the brain

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IV. How Psychologists Study the Brain
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• On September 13, 1848 Gage was a 25 year old
  foreman of a blasting crew preparing a railroad
  bed outside Cavendish, Vermont. He used his 3
  foot 7 inches, 13 1/4 pound iron rod to tamp
  gunpowder and sand into a hole in the rock. On
  this day something went horribly wrong. The rod
  striking the stone caused a spark and the
  resulting explosion sent the rod flying up and
  through his left cheek and out the top of his
  head. To the amazement of everyone he was not
  killed and lived for more than eleven years.
• His limbic system was separated from his
  frontal lobe during this accident. He lost
  control of his emotions became impulsive
  animalistic.

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A. Ways of Studying Brain

• Accidents- How does one behave after suffering a
  brain injury (Ex. Phineas Gage)
• Recording- Electrodes inserted into brain to
  record neurons
• Lesioning- removal or destruction of part of
  brain
• Two types
• Brain destruction to determine the after
  behavior as compared to the before behavior
• Most popular- frontal lobotomy
• 4. Stimulation
• Electrodes used to stimulate brain to pinpoint
  problems areas in order to repair
• Example epilepsy and pain relieve

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B. EEG

1. Stands for electroencephalograph
2. Created in 1929 by Hans Berger
3. Records brains electrical activity/firing of
   neurons
4. Multiple electrodes are pasted to outside of head
5. Adv- Detects rapid changes in electrical activity
   
6. Dis- Can not pinpoint exact source of activity
7. Can be done while the person is awake or even
   sleeping

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EEG
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C. CAT/CT Scan

1. Stands for computerized tomography
2. Uses several X-ray cameras that rotate around the
   brain combine all the pictures into a 3-D
   picture of the brains structure
3. Most commonly used when identifying tumors,
   tissue degeneration skull fractures
4. Adv- Provide greater clarity reveal more
   details than regular x-ray exams
5. Dis- Chance of getting radiation not for
   pregnant women

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CAT
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D. PET Scan

• Stands for positron emission tomography
• Lets researchers see what areas of brain are most
  active during certain tasks
• Can do while brain is at rest, sleeping, etc.
• Involves injection of radioactive dye into
  bloodstream that can be traced detected to
  monitor blow flow to various regions of brain
• Useful for investigating abnormal brain activity
  (seizures, following strokes, etc.)

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PET
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E. MRI

1. Stands for magnetic resonance imaging
2. Use magnetic fields to measure the density
   location of brain material
3. Computer then converts the signals into highly
   detailed images of tissue structures in the
   brain (no function)
4. Adv- No exposure to radiation brain, spinal cord
   nerves can be seen clear than x-rays
5. Dis Some patients cant have them no metal
   allowed in room

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MRI
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F. fMRI

1. Stands for Functional MRI
2. Combines elements of MRI PET scans
3. Shows details of brain structure with info about
   blood flow in brain, tying brain structure to
   brain activity during cognitive tasks
4. Adv- No exposure to radiation
5. Dis- Maps produced are not created in real time

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V. Endocrine System
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A. Definition

• Collection of glands which secrete hormones into
  bloodstream that target have effects on
  specific organs in body
• Allows for communication between the brain
  specific organs in the body (in conjunction with
  ANS)
• Under control of hypothalamus

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B. Hormones vs. Neurotransmitters

• 1. Distance traveled between release target
  sites
• hormones travel longer distances
• neurotransmitters - travel across a synaptic
  cleft
• 2. Speed of communication
• hormones - slower communication
• neurotransmitters - rapid, specific action

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C. Parts of the Endocrine System

• Pineal gland
• Secretes melatonin which regulates sleep-wake
  cycle
• 2. Pituitary gland
• Referred to as master gland because it
  regulates many other glands
• 3. Ovaries testes
• Produce our sex hormones
• Estrogen for women testosterone for men
• 4. Adrenal glands produce adrenaline
• Signals rest of the body to prepare for fight or
  flight

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VII. Genetics
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A. Definition

• Affects human thought behavior
• Traits result from
• Nature
• The characteristics one inherits
• Ones biological makeup
• Nurture
• Environmental Factors
• Family, culture, education, individual experiences

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B. Basic Principles of Genetics

• 1. Chromosomes
• Strands of DNA molecules that carry genetic
  information
• 2. The numbers
• 46 chromosomes in each human body.
• Operate in 23 pairs (with one chromosome of each
  pair contributed by each parent).
• Organic molecule arranged in a double-helix.
• Contains the code of life

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C. Human Behavior Genetics

• 1. Family studies
• Assume that close family members share more of a
  trait than non-relatives
• Used to assess heritability of psychological
  disorders or traits
• 2. Twin studies
• Used to determine how heritable a trait or
  disorder may be
• Identical twins would have highest heritability