Chapter 2: Brain and Behavior

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Chapter 2 Brain and Behavior
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Neuron and Its Parts

• Neuron Individual nerve cell 100 billion in
  brain
• Dendrites Receive messages from other neurons
• Soma Cell body body of the neuron
• Axon Carries information away from the cell body
• Axon Terminals Branches that link the dendrites
  and soma of other neurons

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Figure 2.1
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More on Nerves

• Ion Channels Tiny holes through the axon
  membrane
• Negative After-Potential When a neuron is less
  willing to fire
• Synapse Microscopic space between two neurons
  over which messages pass

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Figure 2.4
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Nerves and Neurons

• Nerves Large bundles of axons and dendrites
• Myelin Fatty layer of tissue that coats axons
• Multiple Sclerosis (MS) occurs when myelin layer
  is destroyed numbness, weakness, and paralysis
  occur

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Neural Networks

• Central Nervous System (CNS) Brain and spinal
  cord
• Peripheral Nervous System All parts of the
  nervous system outside of the brain and spinal
  cord

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Two Divisions of the Peripheral Nervous System

• Somatic System Links spinal cord with body and
  sense organs controls voluntary behavior
• Autonomic System Serves internal organs and
  glands controls automatic functions such as
  heart rate and blood pressure

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Two Divisions of the Autonomic Nervous
System

• Sympathetic Arouses body emergency system
• Parasympathetic Quiets body most active after
  an emotional event

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Figure 2.7
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Figure 2.8
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Figure 2.9
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The Spinal Cord

• Spinal Nerves 31 of them carry sensory and
  motor messages to and from the spinal cord
• Cranial Nerves 12 pairs that leave the brain
  directly without passing through the spinal cord
  also work to communicate messages

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The Spinal Cord and Behavior

• Reflex Arc Simplest behavior in which a stimulus
  provokes an automatic response
• Sensory Neuron Nerve cell that carries messages
  from the senses toward the CNS
• Motor Neuron Cell that carries commands from the
  CNS to the muscles and glands
• Effector Cells Cells capable of producing a
  response

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Researching the Brain

• Ablation Surgical removal of tissue
• Deep Lesioning A thin wire electrode is lowered
  into a specific area inside the brain
  Electrical current is then used to destroy a
  small amount of brain tissue
• Electrical Stimulation of the Brain (ESB) When
  an electrode is used to activate target areas in
  the brain
• Electroencephalograph (EEG) A device that
  detects, amplifies, and records electrical
  activity in the brain

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Brain Imaging Techniques

• Computed Tomographic Scanning (CT)
  Computer-enhanced X-ray of the brain or body
• Magnetic Resonance Imaging (MRI) Uses a strong
  magnetic field, not an X-ray, to produce an image
  of the brain and body

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More Brain Imaging Techniques

• Functional MRI (fMRI) MRI that makes brain
  activity visible
• Positron Emission Tomography (PET)
  Computer-generated color image of brain activity,
  based on glucose consumption in the brain

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Figure 2.16
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Structures and Functions of the Brain
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Cerebral Cortex

• Outer layer of the cerebrum
• Cerebrum Two large hemispheres that cover upper
  part of the brain
• Cerebral Hemispheres Right and left halves of
  the cerebrum
• Spatial Neglect Right hemisphere stroke victims
  pay no attention to the left side of visual space

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Right Brain/Left Brain

• Humans use 95 percent of our left brain for
  language

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The Left Hemisphere

• Left hemisphere is better at math, judging time
  and rhythm, and coordinating order of complex
  movements
• Processes information sequentially

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The Right Hemisphere

• Right hemisphere is good at perceptual skills,
  and at expressing and detecting others emotions
• Processes information simultaneously

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Figure 2.20
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Figure 2.30
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Structures and Functions of the Brain

• Hindbrain
• Located at the base of the skull.
• Medulla
• Controls breathing, heart rate, and reflexes
  controlling upright posture.
• Pons
• Balance, hearing, influences sleep and arousal
• Cerebellum
• Controls muscle tone and muscular coordination.
  (balance, movement, postures)
• Midbrain
• Serves as a reflex center for eyes ears.

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Structures and Functions of the Brain

• Forebrain
• Structures are part of Limbic System System
  within forebrain closely linked to emotional
  response and motivating behavior
• Thalamus Relays sensory information on to the
  cortex switchboard
• Processes visual and auditory information.
• Hypothalamus Regulates emotional behaviors and
  motives (e.g., sex, hunger, rage, hormone
  release)
• Involved in eating, drinking, sexual behavior,
  regulation of body temperature, consciousness.
  Maintains bodily functions such as blood pressure
  and heart beat.
• Limbic System
• Involved in emotion, motivation, and some aspects
  of learning and memory.

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Central Cortex Lobes

• Areas bordered by major grooves or fissures or
  defined by their functions
• Occipital Lobe Back of brain vision center
• Parietal Lobe Just above occipital bodily
  sensations such as touch, pain, and temperature
  (somatosensory area)

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The Last Two Lobes

• Temporal Lobe Each side of the brain auditory
  and language centers
• Frontal Lobe Movement, sense of smell, higher
  mental functions
• Contains motor cortex controls motor movement

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Figure 2.23
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Functions of the Four Lobes

• Frontal Lobes
• Planning, organization, speech.
• Parietal Lobes
• Touch movement sensations.
• Contains Somatosensory area
• Temporal Lobes
• Hearing, emotion, memory.
• Occipital Lobes
• Vision.

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Brocas Area

• Language area related to grammar and
  pronunciation
• If damaged, person knows what s/he wants to say
  but cant say the words

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Wernickes Area

• Wernickes Area Related to language
  comprehension in left temporal lobe
• If damaged, person has problems with meanings of
  words, NOT pronunciation

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Forebrain

• Structures are part of Limbic System System
  within forebrain closely linked to emotional
  response and motivating behavior
• Thalamus Relays sensory information on to the
  cortex switchboard
• Hypothalamus Regulates emotional behaviors and
  motives (e.g., sex, hunger, rage, hormone release)

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More Forebrain Structures

• Amygdala Associated with fear responses
• Hippocampus Associated with storing permanent
  memories helps us navigate through space

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Figure 2.27
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Figure 2.26
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Endocrine System

• Glands that pour chemicals (hormones) directly
  into the bloodstream or lymph system
• Pituitary Gland Regulates growth via growth
  hormone

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Pituitary Problems

• Too little means person will be smaller than
  average
• Hypopituitary Dwarfs As adults, perfectly
  proportioned but tiny
• Treatable by using growth hormone will add a few
  inches
• Treatment is long and expensive

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Endocrine System (cont.)

• Too much growth hormone leads to giantism
  (excessive body growth)
• Acromegaly Enlargement of arms, hands, feet, and
  facial bones due to too much growth hormone
  released late in growth period
• Andre the Giant
• Pituitary also governs functioning of thyroid,
  adrenals, and gonads

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Figure 2.29
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The Pineal Gland

• Regulates body rhythms and sleep cycles
• Releases hormone melatonin, which responds to
  daily variations in light

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The Thyroid Gland

• Thyroid In neck regulates metabolism
• Hyperthyroidism Overactive thyroid person tends
  to be thin, tense, excitable, nervous
• Hypothyroidism Underactive thyroid person tends
  to be inactive, sleepy, slow, obese

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The Adrenal Glands

• Adrenals Arouse body, regulate salt balance,
  adjust body to stress, regulate sexual
  functioning located on top of kidneys
• Releases epinephrine and norepinephrine (also
  known as adrenaline and noradrenalin)

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The Adrenal Glands (cont.)

• Adrenal Medulla Source of epinephrine and
  norepinephrine
• Adrenal Cortex Produces hormones known as
  corticoids
• Regulate salt balance
• Deficiency in some types will cause powerful salt
  cravings in humans

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Adrenal Hormones

• Epinephrine arouses body is associated with fear
• Norepinephrine arouses body is linked with anger

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Adrenal Problems

• Oversecretion of adrenal sex hormones can cause
  virilism exaggerated male characteristics
  (Bearded woman)
• May also cause premature puberty if occurs early
  in life