the biological perspective

1
2
the biological perspective
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why study the nervous system and the glands?How
could we possibly understand any of our behavior,
thoughts, or actions without knowing something
about the incredible organs that allow us to act,
think, and react? If we can understand how the
brain, the nerves, and the glands interact to
control feelings, thoughts, and behavior, we can
begin to truly understandthe complex organism
called a human being.
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Learning Objectives

• LO 2.1 What are the nervous system, neurons and
  nerves?
• LO 2.2 How neurons use neurotransmitters to
  communicate
• LO 2.3 How brain and spinal cord interact
• LO 2.4 Somatic and autonomic nervous systems
• LO 2.5 Hormones and Behavior
• LO 2.6 How psychologists study the brain and how
  it works
• LO 2.7 Structures and functions of the bottom
  part of the brain
• LO 2.8 Structures that control emotion, learning,
  memory, motivation
• LO 2.9 Parts of cortex controlling senses and
  body movement
• LO 2.10 Areas of the cortex involved in higher
  forms of thought
• LO 2.11 Left and Right brain differences

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Overview of Nervous System
LO 2.1 What are the nervous system, neurons and
nerves?

• Nervous system
• Network of cells carrying information to and from
  all parts of the body
• Neuroscience
• Emphasis on structure and function of neurons,
  nerves, and nervous tissue
• Branch of life sciences

5
Structure of the Neuron
LO 2.1 What are the nervous system, neurons and
nerves?

• Biological psychology (behavioral neuroscience)
• Branch of neuroscience
• Focuses on the biological bases of psychological
  processes, behavior, and learning

6
Figure 2.1 An Overview of the Nervous System
7
Structure of the Neuron
LO 2.1 What are the nervous system, neurons and
nerves?

• Neuron
• Specialized cell in the nervous system
• Sends and receives nervous system messages
• Parts of the Neuron
• Dendrites
• Branch-like structures that receive messages
  from other neurons

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Structure of the Neuron
LO 2.1 What are the nervous system, neurons and
nerves?

• Parts of the Neuron
• Soma
• Cell body of the neuron
• Responsible for maintaining the life of the cell
• Axon
• Long tube-like structure
• Carries the neural message to other cells

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Figure 2.2 The Structure of the NeuronThe
electronmicrograph on the left shows myelinated
axons.
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Other Types of Brain Cells
LO 2.1 What are the nervous system, neurons and
nerves?

• Glial Cells
• Provide support for the neurons to grow on
• Deliver nutrients to neurons
• Remove waste products and dead neurons
• Types include oligodendrocytes and Schwann cells
• Produce myelin to coat axons

11
Myelin Sheath
LO 2.1 What are the nervous system, neurons and
nerves?

• Fatty substances produced by glial cells
• Coats the axons insulate, speed neural impulse
• Oligodendrocytes produce myelin for brain and
  spinal cord
• Schwann cells produce myelin for rest of body
• Multiple sclerosis
• Causes destruction of myelin sheath

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Generating the Message Neural Impulse
LO 2.1 What are the nervous system, neurons and
nerves?

• Neurons are electrically charged with ions
• Ions are located inside and outside of the cell
• More negatively charged inside the cell, more
  positively charged outside the cell
• Difference in charges creates an electrical
  potential

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Generating the Message Neural Impulse
LO 2.1 What are the nervous system, neurons and
nerves?

• Resting potential
• State of neuron when not firing a neural impulse
• Channels for sodium not open
• Action potential
• Release of the neural impulse
• Consists of reversal of electrical charge within
  the axon

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Generating the Message Neural Impulse
LO 2.1 What are the nervous system, neurons and
nerves?

• All-or-none
• Neuron either fires completely or does not fire
  at all

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Figure 2.3 The Neural Impulse Action
PotentialIn the graph below, voltage readings
are shown at a given place on the neuron over a
period of 20 or 30 milliseconds (thousandths of a
second). At first the cell is resting it then
reaches threshold and an action potential is
triggered. After a brief hyperpolarization
period, the cell returns to its resting potential.
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Figure 2.3 (continued) The Neural Impulse
Action PotentialIn the graph below, voltage
readings are shown at a given place on the neuron
over a period of 20 or 30 milliseconds(thousandth
s of a second). At first the cell is resting it
then reaches threshold and an action potential is
triggered. After a brief hyperpolarization
period, the cell returns to its resting potential.
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Sending the Message to Other Cells
LO 2.2 Neuron communication

• Axon terminals
• Branches at the end of the axon
• Synaptic knob
• Rounded areas on the end of axon terminals
• Synaptic vesicles
• Sack-like structures inside the synaptic knob
• Contain chemicals called neurotransmitters

18
Sending the Message to Other Cells
LO 2.2 Neuron communication

• Axon terminals
• Neurotransmitters, when released, affect
  neighboring cells

19
This electromicrograph shows a motor neuron
making contact with muscle fibers.
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Sending the Message to Other Cells
LO 2.2 Neuron communication

• Synapse/synaptic gap
• Fluid-filled space between end axon terminals of
  one cell and surface of the next cell
• Receptor sites
• Ion channels, proteins on dendrite surface
• Shaped to accept specific neurotransmitter

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Figure 2.4 The SynapseThe nerve impulse
reaches the synaptic knobs, triggering the
release of neurotransmitters from the synaptic
vesicles. The molecules of neurotransmitter cross
the synaptic gap to fit into the receptor sites
that fit the shape of the molecule, opening the
ion channel and allowing sodium ions to rush in.
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Neuron Communication
LO 2.2 Neuron communication

• Neural cells can be turned either on or off
• Excitatory synapses
• Cause receiving cell to fire
• Inhibitory synapses
• Cause receiving cell to stop firing

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Neuron Communication
LO 2.2 Neuron communication

• Chemical substances affect neural communication
• Agonists
• Mimic or enhance the effects of a
  neurotransmitter on the receptor sites
• Antagonists
• Block or reduce a cells response to the action
  of other neurotransmitters

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Table 2.1 Some Neurotransmitters and Their
Functions
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Cleaning up the Synapse
LO 2.2 Neuron communication

• Reuptake
• Neurotransmitters are taken back into the
  synaptic vesicles
• Acetylcholine does not go through reuptake
• Needs to be available for quick muscle activity
• Reuptake too slow for process
• Is instead broken down in the synapse by
  enzymatic degradation

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Central Nervous System
LO 2.3 Brain and spinal cord

• Part of the nervous system consisting of the
  brain and spinal cord
• Brain
• Interprets information from senses
• Spinal cord
• Long bundle of neurons
• Carries messages to and from the body to the
  brain
• Also responsible for very fast, lifesaving
  reflexes

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The Reflex Arc Three Types of Neurons
LO 2.3 Brain and spinal cord

• The reflex arc forms a connection between a
  sensory, a motor and an interneuron
• Sensory neuron
• Carries messages from the senses to spinal cord
• Also called afferent neuron

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This electronmicrograph shows a stem cell in the
process of becoming a neuron.
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The Reflex Arc Three Types of Neurons
LO 2.3 Brain and spinal cord

• Motor neuron
• Carries messages from spinal cord to muscles and
  glands
• Also called efferent neuron

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The Reflex Arc Three Types of Neurons
LO 2.3 Brain and spinal cord

• Interneuron
• Found in spinal cord and brain
• Receives information from sensory neurons
• Sends commands to muscles through the motor
  neurons
• Make up the bulk of the neurons in the brain

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Figure 2.6 The Spinal Cord ReflexThe pain from
the burning heat of the candle flame stimulates
the afferent nerve fibers, which carry the
message up to the interneurons in the middle of
the spinal cord. The interneurons then send a
message out by means of the efferent nerve
fibers, causing the hand to jerk away from the
flame.
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Neuroplasticity
LO 2.3 Brain and spinal cord

• Is the ability to change both the structure and
  function of cell involved in trauma
• Implanted nerve fibers from damaged area
• Damaged spinal nerves grow through fiber
  tunnels
• Possibility of transplanting stem cells to repair
  damaged tissue being explored

33
Peripheral Nervous System
LO 2.4 Somatic and autonomic nervous systems

• Consists of nerves and neurons not contained in
  the brain and spinal cord
• Nerves run through the organs and extremities of
  the body
• Divided into
• Somatic nervous system
• Autonomic nervous system

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Figure 2.7 The Peripheral Nervous System
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Somatic Nervous System
LO 2.4 Somatic and autonomic nervous systems

• Division of PNS
• Consists of nerves carrying information
• From the senses to CNS
• From the CNS to voluntary muscles of the body

36
These young soccer players are using their senses
and voluntary muscles controlled by the somatic
division of the peripheral nervous system. What
part of the autonomic nervous system are these
girls also using at this time?
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Somatic Nervous System
LO 2.4 Somatic and autonomic nervous systems

• Division of PNS
• Sensory pathway
• Afferent neurons coming from sensory organs
• Motor pathway
• Efferent neurons coming from the CNS to the
  voluntary muscles

38
Autonomic Nervous System
LO 2.4 Somatic and autonomic nervous systems

• Division of PNS
• Functions automatically
• Sympathetic division (fight-or-flight system)
• Reacts to stressful events and bodily arousal

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Figure 2.8 Functions of the Parasympathetic and
Sympathetic Divisions of the Nervous System
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Autonomic Nervous System
LO 2.4 Somatic and autonomic nervous systems

• Division of PNS
• Functions automatically
• Parasympathetic division
• Restores body to normal functioning after arousal
  
• Responsible for the day-to-day functioning of the
  organs and glands

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Snowboarder Shaun White of the U.S.A. 2010
Olympics Team won the gold medal in the halfpipe
competition in Vancouver. What part of the
autonomic nervous system is likely to be working
as Shaun flies through the air, as in this
picture?
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The Endocrine Glands
LO 2.5 How hormones interact with the nervous
system and affect behavior

• Are glands that secrete chemicals called hormones
  directly into the bloodstream
• Endocrine communication is slower than synaptic
  communication
• Hormones
• Chemicals released into the bloodstream by
  endocrine glands

43
The Endocrine Glands
LO 2.5 How hormones interact with the nervous
system and affect behavior

• Pituitary gland
• Located in the brain
• Secretes human growth hormone
• Influences all other hormone-secreting glands
  (also known as the master gland)

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Figure 2.9 The Endocrine GlandsThe endocrine
glands secrete hormones directly into the
bloodstream, which carries them to organs in the
body, such as the heart, pancreas, and sex organs.
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The Endocrine Glands
LO 2.5 How hormones interact with the nervous
system and affect behavior

• Pineal gland
• Located near the base of the cerebrum
• Secretes melatonin
• Thyroid gland
• Found in the neck
• Regulates growth and metabolism
• Pancreas
• Controls the levels of sugar in the blood
• Secretes insulin and glucagons

46
When the pancreas does not secrete enough
insulin, the result is diabetes. Many diabetic
people must give themselves insulin shots to
supply enough of the hormone.
47
The Endocrine Glands
LO 2.5 How hormones interact with the nervous
system and affect behavior

• Gonads
• Sex glands
• Secrete hormones that regulate sexual behavior
  and reproduction
• Ovaries - female gonads
• Testes - male gonads

48
The Endocrine Glands
LO 2.5 How hormones interact with the nervous
system and affect behavior

• Adrenal glands
• Located on top of each kidney
• Secrete over 30 different hormones
• Deals with stress
• Regulates salt intake
• Provides secondary source of sex hormones during
  adolescence

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Looking Inside the Living Brain
LO 2.6 Study of the brain

• Lesioning studies
• Deep lesioning
• Insertion of a thin, insulated wire into the
  brain
• Electrical current destroys brain cells at tip of
  wire
• Shallow Lesioning
• Cells are destroyed on the surface of the brain

50
Looking Inside the Living Brain
LO 2.6 Study of the brain

• Electrical stimulation of brain (ESB)
• Mild electrical current passed through probe
• Causes neurons to react as if had received a
  message

51
Electrical Stimulation of Brain (ESB)
LO 2.6 Study of the brain

• Deep Brain Stimulation (DSB)
• Electrodes inserted in brain are attached to a
  pacemaker-like device
• Helpful in treatment of Parkinsons disease

52
Electrical Stimulation of Brain (ESB)
LO 2.6 Study of the brain

• transcranial Direct Current Stimulation (tDCS)
• Uses scalp electrodes to pass very low amplitude
  direct currents to the brain
• Changes the excitability of cortical neurons
  directly below the electrodes

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A researcher at the National Institute of Mental
Health in Bethesda, Maryland, uses an
electromagnet as part of an experimental
treatment for depression. This treatment, called
Repetitive Transcranial Magnetic Stimulation
(rTMS), excites neurons in the brain, triggering
activity.
54
Mapping Brain Structure
LO 2.6 Study of the brain

• Computed Tomography (CT)
• Multiple X-rays of brain
• Mapping with computer assistance
• Can show stroke damage, tumors, injuries,
  abnormal brain structure
• Magnetic Resonance Imaging (MRI)
• More detail than CT scan
• Uses radio waves and magnetic fields to produce
  detailed images

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Figure 2.10 Mapping Brain StructureFig 2.10a
CT scan from an 8-year-old girl with a skull
fracture (indicated by the red arrow) Fig 2.10b
same CT scan depicting the brain and swelling
associated with the head injury.
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Figure 2.10 (continued) Mapping Brain
StructureContrast the brain detail of Fig 2.10b
with the MRI scan in Fig 2.10c (different, adult
individual). Note the scans are in the horizontal
plane, separating the brain into upper and lower
portions.
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Figure 2.10 (continued) Mapping Brain
StructureFig 2.10d uses the same MRI data to
provide an estimate of what the left external
surface of the brain looks like. Fig 2.10a, b,
c images created with OsiriX software 2.10d
cortical reconstruction was performed with the
Freesurfer image analysis suite. CT and MRI data
courtesy of N. White.
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Mapping Brain Structure
LO 2.6 Study of the brain

• Other techniques with MRI as basis
• MRI spectroscopy
• Allows researchers to estimate concentration of
  chemicals and neurotransmitters in the brain
• Diffusion Tensor Imaging (DTI)
• Measure connectivity in brain by imaging white
  matter tracts

59
Mapping Brain Function
LO 2.6 Study of the brain

• Electroencephalogram (EEG)
• Electrical activity of brain is amplified and
  output is displayed via computer
• Output forms waves that reveal stages of sleep,
  seizures, presence of tumors
• Event Related Potentials (ERPS)
• Measures brain response to stimulus events
• Allows for study of different stages of cognitive
  processing

60
Figure 2.11 Mapping Brain FunctionVarious
methods for mapping brain function. An EEG record
is shown in 2.11a
61
Mapping Brain Function
LO 2.6 Study of the brain

• Positron Emission Tomography (PET)
• Person is injected with radioactive glucose
• Metabolism of glucose measured
• Single Photon Emission Computed Tomography
  (SPECT)
• Similar to PET
• Uses radioactive tracer to examine brain blood
  flow

62
Figure 2.11 (continued) Mapping Brain
FunctionVarious methods for mapping brain
function. A PET scan image in 2.11b, and an image
from an fMRI study in 2.11c.
63
Mapping Brain Function
LO 2.6 Study of the brain

• Functional Magnetic Resonance Imaging (fMRI)
• Computer tracks changes in oxygen levels of blood

64
The Brain Stem
LO 2.7 Structures of the bottom part of brain

• Medulla
• First large swelling at top of spinal column
• Responsible for life-sustaining functions such
  as breathing, swallowing, and heart rate

65
The Brain Stem
LO 2.7 Structures of the bottom part of brain

• Pons
• Larger swelling above the medulla
• Connects top of brain to bottom
• Involved in sleep, dreaming, leftright body
  coordination, and arousal

66
Figure 2.12 The Major Structures of the Human
Brain
67
The Brain Stem
LO 2.7 Structures of the bottom part of brain

• Reticular formation (RF)
• Runs through the middle of the medulla and pons
• Responsible for selective attention, ignoring
  repetitive stimuli

68
The Brain Stem
LO 2.7 Structures of the bottom part of brain

• Cerebellum
• Controls and coordinates involuntary, rapid, fine
  motor movement.
• Maintains posture, muscle co-ordination, balance

69
This pitcher must count on his cerebellum to help
him balance and coordinate the many fine motor
commands that allow him to pitch the baseball
accurately and swiftly. What other kinds of
professions depend heavily on the activity of the
cerebellum?
70
Structures Under the Cortex
LO 2.8 Structures controlling emotion, learning,
memory, and motivation

• Limbic system
• Brain structures located under the cortex
• Involved in learning, emotion, memory, and
  motivation
• Thalamus
• Relays sensory information from the lower part of
  the brain to areas of cortex
• Processes some sensory information

71
Structures Under the Cortex
LO 2.8 Structures controlling emotion, learning,
memory, and motivation

• Limbic system
• Hypothalamus
• Regulates body temperature, thirst, hunger,
  sleeping and waking, sexual activity, emotions
• Controls pituitary gland

72
This young womans thirst is regulated by her
hypothalamus.
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Structures Under the Cortex
LO 2.8 Structures controlling emotion, learning,
memory, and motivation

• Limbic system
• Hippocampus
• Curved structure located within each temporal
  lobe
• Responsible for the formation of long-term
  memories, storage of memory for location of
  objects

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Structures Under the Cortex
LO 2.8 Structures controlling emotion, learning,
memory, and motivation

• Limbic system
• Amygdala
• Located near the hippocampus
• Responsible for fear responses and memory of fear

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Structures Under the Cortex
LO 2.8 Structures controlling emotion, learning,
memory, and motivation

• Limbic system
• Cingulate Cortex
• Important role in emotional and cognitive
  processing
• Implicated in several psychological disorders
  such as ADHD, schizophrenia

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Figure 2.13 The Limbic System
77
Cortex
LO 2.9 Parts of cortex controlling senses and
movement

• Outermost covering of the brain
• Consists of densely packed neurons
• Responsible for higher thought processes and
  interpretation of sensory input
• Corticalization
• Wrinkling of the cortex
• Allows the large area of cortical cells to exist
  in the small space inside the skull

78
Cerebral Hemispheres
LO 2.9 Parts of cortex controlling senses and
movement

• Are the two sections of the cortex on the left
  and right sides of the brain.
• Corpus callosum
• Thick band of neurons connecting right and left
  cerebral hemispheres.

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Figure 2.14 The Lobes of the Brain Occipital,
Parietal, Temporal, and Frontal
80
Four Lobes of the Brain
LO 2.9 Parts of cortex controlling senses and
movement

• Occipital lobes
• Visual center of brain
• Primary visual cortex
• Processes visual information from the eyes
• Visual association cortex
• Identifies, interprets visual information

81
Four Lobes of the Brain
LO 2.9 Parts of cortex controlling senses and
movement

• Parietal lobes
• Contains centers for touch, taste, and
  temperature sensations
• Somatosensory cortex
• Processes information from skin and internal body
  receptors for touch, temperature, body position,
  and possibly taste

82
Four Lobes of the Brain
LO 2.9 Parts of cortex controlling senses and
movement

• Temporal lobes
• Hearing, meaningful speech
• Primary auditory cortex
• Processes auditory information from the ears
• Auditory association cortex
• Identifies, makes sense of auditory information

83
Four Lobes of the Brain
LO 2.9 Parts of cortex controlling senses and
movement

• Frontal lobes
• Higher mental processes, decision making,
  production of fluent speech
• Motor cortex
• Sends motor commands to muscles

84
Figure 2.15 The Motor and Somatosensory
CortexThe motor cortex in the frontal lobe
controls the voluntary muscles of the body. Cells
at the top of the motor cortex control muscles at
the bottom of the body, whereas cells at the
bottom of the motor cortex control muscles at the
top of the body. Body parts are drawn larger or
smaller according to the number of cortical cells
devoted to that body part. For example, the hand
has many small muscles and requires a larger area
of cortical cells to control it. The
somatosensory cortex, located in the parietal
lobe just behind the motor cortex, is organized
in much the same manner and receives information
about the sense of touch and body position.
85
Figure 2.12 The Major Structures of the Human
Brain
86
Association Areas of Cortex
LO 2.10 Parts of cortex responsible for higher
thought

• Are areas within each lobe of the cortex
• Responsible for
• Coordination and interpretation of information
• Higher mental processing

87
Association Areas of Cortex
LO 2.10 Parts of cortex responsible for higher
thought

• Brocas Aphasia
• Results from damage to Brocas area
• Usually in left frontal lobe
• Causes affected person to be unable to speak
  fluently
• Mispronounces words, speaks haltingly

88
Association Areas of Cortex
LO 2.10 Parts of cortex responsible for higher
thought

• Wenickes Aphasia
• Left temporal lobe damage
• Speech is fluent but nonsensical
• Unilateral Spatial Neglect
• Result of damage to the parietal lobe association
  areas on one side of the cortex, usually the
  right side
• Person ignores information from opposite side of
  body or visual field

89
As this woman brushes the right side of her hair,
is she really seeing the left side? If she has
spatial neglect, the answer is no. While her
eyes work just fine, her damaged right hemisphere
refuses to notice the left side of her visual
field.
90
Split Brain Research
LO 2.11 Left side and right side of brain

• Robert Sperry (1968)
• Demonstrated left and right hemispheres of the
  brain specialize in different activities and
  functions
• Corpus callosum severed in patients to contain
  epileptic seizures
• Messages are sent to only one side of the brain
• Two hemispheres cannot coordinate information

91
Figure 2.16 The Split-Brain ExperimentRoger
Sperry created this experiment to demonstrate the
specialization of the left and right hemispheres
of the brain.
92
Table 2.2 Specialization of the Two Hemispheres
93
Understanding ADHD
LO 2.11 Left side and right side of brain

• Developmental disorder involving behavioral and
  cognitive aspects
• Inattention, impulsivity, and hyperactivity
• Some aspects of attention may be normal with ADHD
  (Nigg, 2010)

94
Understanding ADHD
LO 2.11 Left side and right side of brain

• Problem areas for individuals with ADHD
• Vigilance
• Staying on task
• Maintaining effort
• Self-control