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CHAPTER TWO
CHAPTER TWO: THE BIOLOGY UNDERLYING BEHAVIOUR
CHAPTER OUTLINE WITH KEY TERMS AND CONCEPTS (O)
Prologue: The Fight of His Life
Looking Ahead
neuroscientists: Psychologists and researchers from diverse fields who study the nervous
system
biopsychologists (behavioural neuroscientists): Psychologists who study the ways
biological structures and body functions affect behaviour
Neurons: The Elements of Behaviour
The Structure of the Neuron
neurons: Nerve cells that serve as the basic elements of the nervous system
glial cells: Cells that hold neurons in place and provide nourishment and insulation
dendrites: Cluster of fibers at one end of a neuron that receive messages from other
neurons
axon: The part of a neuron that carries messages to other neurons
terminal buttons: Small bulges at the end of axons that send messages to other cells
myelin sheath: A series of specialized cells of fat and protein that wrap themselves around
the axon, providing a protective coating
LECTURE LEAD 2.1: Growing New Neurons
CLASSROOM ACTIVITY 2.1: The Benefits of Knowledge about the Brain
Firing the Neuron
all-or-none law: The rule that neurons are either on or off
resting state: The state at which there is a negative electrical charge of about –70
millivolts within the neuron
action potential: An electric nerve impulse that travels through a neuron when it is set off
by a “trigger,” changing the neuron’s charge from negative to positive
CLASSROOM ACTIVITY 2.2: Speed of Neural Transmission
CLASSROOM ACTIVITY 2.3: Speed of Neural Transmission II
Where Neurons Meet: Bridging the Gap
synapse: The space between two neurons where the axon of a sending neuron
communicates with the dendrites of a receiving neuron using chemical messages
neurotransmitter: A chemical that carries messages across the synapse to the dendrite
(and sometimes the cell body) of a receiver neuron
excitatory message: A chemical message that makes it more likely that a receiving neuron
will fire and an action potential will travel down its axons
inhibitory message: A chemical message that prevents a receiving neuron from firing
reuptake: The reabsorption of neurotransmitters by a terminal button
CLASSROOM ACTIVITY 2.4: Information Transmission Across a Synapse
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THE BIOLOGY UNDERLYING BEHAVIOUR
Neurotransmitters: Multitalented Chemical Couriers
acetylcholine (ACh): A common neurotransmitter that produces contractions of skeletal
muscles and is involved in memory
glutamate: A common excitatory neurotransmitter that is related to the chemical basis of
memory
gamma-amino butyric acid (GABA): The nervous system’s primary inhibitory
neurotransmitter, found in the brain and spinal cord
dopamine (DA): A common neurotransmitter that may be involved in a variety of physical
and mental ailments
serotonin: A neurotransmitter associated with the regulation of sleep, eating, mood, and
pain
norepinephrine: A neurotransmitter associated with arousal and depression reduction
endorphins: Chemicals produced by the brain that act to reduce pain
The Nervous System
Central and Peripheral Nervous Systems
central nervous system (CNS): The system made up of the brain and spinal cord
spinal cord: A bundle of nerves from the brain that run down the length of the back. It
provides for transmission of messages between the brain and the body
reflexes: Automatic, involuntary responses to incoming stimuli
sensory (afferent) neurons: Neurons that transmit information from the perimeter of the
body to the central nervous system
motor (efferent) neurons: Neurons that communicate information from the nervous
system to muscles and glands
interneurons: Neurons that transmit information between sensory and motor neurons
quadriplegia: A condition in which voluntary movement below the neck is lost
paraplegia: The inability, as a result of injury to the spinal cord, to voluntarily move any
muscles in the lower half of the body
peripheral nervous system: The part of the nervous system that includes the somatic and
autonomic subdivisions; made up of long axons and dendrites, it branches out from the
spinal cord and brain and reaches the extremities of the body
somatic division: The part of the nervous system that specializes in the control of
voluntary movements and the communication of information to and from the sense organs
autonomic division: The part of the nervous system that controls involuntary movement
(the actions of the heart, glands, lungs, and other organs)
INDEPENDENT PROJECT 2.1: Split Autonomic Nervous System
Activating the Divisions of the Autonomic Nervous System
sympathetic division: The part of the autonomic division of the nervous system that acts
to prepare the body in stressful emergency situations, engaging all the organism’s resources
to respond to a threat
parasympathetic division: The part of the autonomic division of the nervous system that
calms the body after the emergency situation is resolved
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CHAPTER TWO
The Evolutionary Foundations of the Nervous System
hierarchical organization: Organization of the brain in which the newer, more recently
evolved regions of the brain regulate the older and more primitive parts of the nervous
system
evolutionary psychology: The branch of psychology that seeks to identify how behaviour
is influenced and produced by genetic inheritance
Behavioural Genetics
behavioural genetics: The study of the effects of heredity on behaviour
genes: The genetic material that controls the transmission of traits
Pathways Through Psychology Julien Doyon
The Brain
Studying the Brain’s Structure and Functions: Spying on the Brain
electroencephalogram (EEG): A technique that records electrical activity in the brain
through electrodes placed on the outside of the skull
computerized axial tomography (CAT) scan: A computerized scanner that constructs an
image of the brain by combining thousands of separate x-rays taken at slightly different
angles
magnetic resonance imaging (MRI) scan: A scanner that produces a detailed, threedimensional computer-generated image of brain structures and activity by aiming a
powerful magnetic field at the body
superconducting quantum interference device (SQUID) scan: A technique that is
sensitive to tiny changes in magnetic fields that occur when neurons fire, used to pinpoint
the location of neural activity
positron emission tomography (PET) scan: A technique to determine biochemical
activity within the brain at a given moment in time
Applying Psychology in the 21st Century Mind Over Cursor: Using Brain Waves to Overcome Physical
Limitations
The Central Core: Our “Old Brain”
central core: The “old brain,” which controls such basic functions as eating and sleeping
and is common to all vertebrates
hindbrain: The part of the brain containing the medulla, pons, and cerebellum
medulla: The part of the central core of the brain that controls many important body
functions, such as breathing and heartbeat
pons: The part of the brain that joins the halves of the cerebellum, transmitting motor
information to coordinate muscles and integrate movement between the right and left
halves of the body
cerebellum: The part of the brain above the medulla and behind the pons that controls
balance
reticular formation: The part of the brain from the medulla through the pons made up of
groups of nerve cells that can immediately activate other parts of the brain to produce
general bodily arousal
midbrain: The middle section of the brain
forebrain: The front-most part of the brain
thalamus: The part of the brain located in the middle of the central core that acts primarily
as a busy relay station, mostly for information concerning the senses
hypothalamus: A tiny part of the brain located below the thalamus that maintains
homeostasis and produces and regulates vital, basic behaviour such as eating, drinking, and
sexual behaviour
homeostasis: The steady, internal environment of the body
LECTURE LEAD 2.2: The Causes and Treatments of Parkinson’s Disease
The Limbic System: Beyond the Central Core
limbic system: The part of the brain located outside the “new brain,” which controls
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THE BIOLOGY UNDERLYING BEHAVIOUR
eating, aggression, and reproduction; contains the amygdala, hippocampus, and fornix
The Cerebral Cortex: Our “New Brain”
cerebral cortex: The “new brain,” responsible for the most sophisticated information
processing in the brain; contains the lobes
lobes: The four major sections of the cerebral cortex
frontal lobes: The brain structure located at the front center of the cortex, containing major
motor, speech, and reasoning centers
parietal lobes: The brain structure to the rear of the frontal lobes; the center for bodily
sensations
temporal lobes: The portion of the brain located beneath the frontal and parietal lobes;
includes the auditory sensory areas
occipital lobes: The portion of the brain lying behind the temporal lobes; includes the
visual sensory area
The Motor Area of the Cortex
motor area: The part of the cortex that is largely responsible for voluntary movement of
particular parts of the body
The Sensory Area of the Cortex
sensory area: The site in the brain of the tissue that corresponds to each of the senses, with
the degree of sensitivity relating to the amount of tissue
somatosensory area: The area within the cortex corresponding to the sense of touch and
pressure in particular areas of the body
auditory area: The area within the cortex corresponding to the sense of hearing
visual area: The area within the cortex corresponding to the sense of sight
The Association Areas of the Cortex
association area: One of the major areas of the brain, the site of the higher mental
processes, such as thought, language, memory, and speech
apraxia: A condition resulting in the inability to integrate activities in a rational or logical
manner due to brain injury
aphasia: A disorder resulting in problems with language due to brain injury
Broca’s aphasia: A syndrome in which speech production is disturbed, halting, and
laborious
Wernicke’s aphasia: A syndrome involving problems with understanding and producing
language, resulting in fluent but nonsensical speech
CLASSROOM ACTIVITY 2.5: Learning Functions of Brain Parts
Mending the Brain
Plasticity: The capacity (most common in children) of the brain to reorganize following
injury
CLASSROOM ACTIVITY 2.6: Ethics and Brain Research
INDEPENDENT PROJECT 2.2: Results of Physiological Misfunction or Brain Damage
The Specialization of the Hemispheres: Two Brains or One?
hemispheres: Symmetrical left and right halves of the brain that control the side of the
body opposite their location
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lateralization: The dominance of one hemisphere of the brain in specific functions
LECTURE LEAD 2.3: Francis Gall and Phrenology
Exploring Diversity Human Diversity and the Brain
corpus callosum: A bundle of fibers that connects the hemispheres of the brain, and which
is proportionally larger in women than men
LECTURE LEAD 2.4: Are Men’s and Women’s Brains Different?
The Split Brain: Exploring the Two Hemispheres
split-brain patient: A person who suffers from independent functioning of the two halves
of the brain, as a result of which the sides of the body work in disharmony
LECTURE LEAD 2.5: Brain Surgery to Reduce Neural Transmission
LECTURE LEAD 2.6: Sperry’s Split-Brain Studies
LECTURE LEAD 2.7: Brain Modules
The Endocrine System: Of Chemicals and Glands
endocrine system: A chemical communication network that sends messages throughout
the nervous system via the bloodstream
hormones: Chemicals that circulate throughout the blood and affect the functioning or
growth of other parts of the body
pituitary gland: The “master gland,” the major component of the endocrine system, which
secretes hormones that control growth
INDEPENDENT PROJECT 2.3: Investigating a Gland
LECTURE LEAD 2.8: Disorders of the Pituitary Gland: Acromegaly
Becoming an Informed Consumer of Psychology Learning to Control Your Heart—and Mind—through
Biofeedback
biofeedback: A procedure in which a person learns to control through conscious thought
internal physiological processes such as blood pressure, heart and respiration rate, skin
temperature, sweating, and constriction of particular muscles
Looking Back
Key Terms and Concepts
Psychology on the Web
OLC Preview
Epilogue
LEARNING OBJECTIVES (P)
Neurons: The Elements of Behaviour
1. Understand the significance of the biology that underlies behaviour and identify reasons why psychologists
study these biological underpinnings, especially the brain and the nervous system. (p. 45)
2. Describe the structure of the neuron and its parts. (pp. 45-46)
3. Describe the all-or-none law of neural transmission, the resting state and action potential of the neuron, as well
as the complete transmission of a message from initial stimulation to transmission across the synapse. (pp. 46-47)
4. Name key neurotransmitters and their functions and describe their known or suspected roles in behaviour as
well as illnesses. (pp. 48-51)
The Nervous System
5. Describe the major divisions of the nervous system, including the central and the peripheral, the autonomic and
somatic, and the sympathetic and parasympathetic divisions. (pp. 52--53)
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THE BIOLOGY UNDERLYING BEHAVIOUR
6.
Outline the major developments in the evolution of the nervous system and describe the associated fields of
evolutionary psychology and behavioural genetics. (pp. 53--54)
The Brain
7. Name the techniques used to map and study the brain. (pp. 54-55)
8. Name the components of the central core and the limbic system and describe the functions of their individual
parts. (pp. 57-58)
9. Name the major areas of the cerebral hemispheres, especially the lobes and the cortex areas, and describe the
roles of each area in behaviour. (pp. 59-62)
The Specialization of the Hemispheres: Two Brains or One?
10. Discuss the issues involved with brain specialization, brain lateralization, and the split-brain operation,
including what has been learned about the two hemispheres from that procedure. (pp. 67-68)
11. Discuss differences in brain lateralization as influenced by gender and culture. (pp. 68-69)
The Endocrine System: Of Chemicals and Glands
12. Describe the function of the endocrine system, including its relationship to the hypothalamus and the functions
of the pituitary gland. (pp. 71--72)
13. Describe how biofeedback can be used to control some of the basic biological processes.
(p. 72)
LECTURE LEADS
Lecture Lead 2.1: Growing New Neurons (W)
One of the oldest beliefs in neuroscience is that all the neurons of a vertebrate are formed when the brain is growing
and that an adult cannot develop new neurons. Therefore, when neurons are lost because of injury or disease, there
may be a permanent loss of the function that those neurons performed. This belief may have to be changed because
of the work of Fernando Nottebohm (1989). Nottebohm’s research shows that new neurons are produced
(neurogenesis) throughout the lifetime of canaries and zebra finches. The cells are formed near the ventricle of the
forebrain and migrate along fibers of cells known as radial glia. After migrating, a young neuron detaches itself from
the radial glial fiber and becomes part of an existing circuit.
Reynolds and Weiss (1992) have taken cells from the striatum of mice and treated the cells with epidermal
growth factor (EGF). Some of the treated cells divided and formed immature glia and neurons; some of the cells
formed new neurons. While this has not been possible to accomplish with an intact brain, researchers are hopeful
that findings like these will lead to better treatments for damaged brains in the future. As yet, there is no evidence
that neurogenesis occurs in humans or other primates.
Nottebohm, F. (1989). From bird song to neurogenesis. Scientific American, 260(2), 74–79.
Reynolds, B. A., & Weiss, S. (1992). Generation of neurons and astrocytes from isolated cells of the adult
mammalian central nervous system. Science, 255, 1707–1710.
Lecture Lead 2.2: The Causes and Treatments of Parkinson’s Disease (W)
The symptoms of a shaking palsy were described by a London physician, James Parkinson, in 1817 (Kolb &
Whishaw, 1985), and the syndrome was named for him. The incidence of the disease is about 100 per 100,000
people, and it is higher in older people (Thompson, 1985). Symptoms of Parkinson’s disease include tremors while
not engaging in voluntary movement, muscular rigidity, involuntary movements, postural disorders, difficulty in
standing up, short and shuffling footsteps that may start slowly and gradually become faster and faster (festination),
difficulty with making the movements of speech, and akinesia (a slowness or lack of movement). Examples of
akinesia include a blank facial expression, a lack of blinking, a lack of arm swinging while walking, and sitting
motionless for hours (Kolb & Whishaw, 1985).
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The cause of these symptoms is damage to the substantia nigra, a midbrain structure located above the
medulla. The substantia nigra has dark-coloured cells (the name means “black substance”). It makes the
neurotransmitter dopamine and sends it to the basal ganglia, which are above the hypothalamus and function in
initiating voluntary movements. When the basal ganglia do not get enough dopamine, a person has the rigidity and
akinesia of Parkinson’s disease.
Three categories of causes of the reduced production of dopamine by the substantia nigra seem to exist.
One category is a virus, such as the virus that produces sleeping sickness. Another is drugs, such as major
tranquilizers. The third category of causes is unknown. It appears that the amount of dopamine has to be reduced by
80 percent before symptoms appear (Kolb & Whishaw, 1985).
There is no known cure for Parkinson’s disease. The treatment that is usually applied is a drug called Ldopa. When this drug is carried to the brain cells by the blood, it is converted into dopamine. The dopamine is used
by the basal ganglia to initiate voluntary movement, and the symptoms of Parkinson’s disease are reduced. But other
parts of the brain, such as the frontal lobes and the limbic system, also use dopamine as a neurotransmitter. When
they get an extra dose of dopamine from the L-dopa, symptoms of schizophrenia appear. These may include
hallucinations, delusions, and paranoia; these symptoms disappear when administration of L-dopa is stopped
(Bloom, Lazerson, & Hofstadter, 1985).
A newer and still experimental treatment is to inject dopamine-producing cells from other parts of the body
into the area around the basal ganglia. This was done first in Sweden, using adrenal gland cells (Kolata, 1982).
Recent studies in transplantation of tissue from the adrenal medulla in Parkinson’s patients have proved promising
(Goetz et al., 1990). In addition to transplanting dopamine-producing cells, there is some research into transplanting
fetal brain matter into rats with lesions induced by surgical ablation. These studies have been successful in rats,
restoring much of the lost function (Lee & Rabe, 1988; Sprick, 1991).
Bloom, F. E., Lazerson, A., & Hofstadter, L. (1985). Brain, mind, and behaviour. New York:
W. H. Freeman.
Goetz, C. G., Tanner, G. M., Penn, R. D., & Stebbens, G. T. (1990). Adrenal medullary transplant to the striatum of
patients with advanced Parkinson’s disease: One year motor and psychomotor data. Neurology, 40, 273–276.
Kolata, G. (1982). Grafts correct brain damage. Science, 217, 342–344.
Kolb, B., & Whishaw, I. Q. (1985). Fundamentals of human neuropsychology. 2nd ed. New York: W. H. Freeman.
Lee, M. H., & Rabe, A. (1988). Neocortical transplants in the microencephalic rat brain: Morphology and behaviour.
Brain Research Bulletin, 21, 813–824.
Sprick, U. (1991). Transient and long-lasting behavioural effects of grafts in the damaged hippocampus of rats.
Behavioural Brain Research, 42, 187–199.
Thompson, R. F. (1985). The brain: An introduction to neuroscience. New York: W. H. Freeman.
Lecture Lead 2.3: Francis Gall and Phrenology (R)
Students are always fascinated by the study of phrenology. Phrenology involves studying the mind and its capacities
by measuring different areas of the human head. Gall’s hypothesis was that there was a relationship between mass of
a part of the brain and the amount of function or faculty a person had. He further hypothesized the shape of the skull
fit like a glove over the brain. Therefore a bump indicated a large amount of brain matter below and a recess
indicated a lack of brain matter in that region. For example, Gall reasoned that the part of the brain responsible for
verbal memories was directly behind the eyes, in the frontal lobe. This was confirmed by his noting that those who
were good at memorizing had large protruding eyes. He noted that the area just above and in front of the ears was an
area he called acquisitiveness. A bump in this region would indicate a potential thief, whereas a depression in this
area would indicate honesty. Some of the other areas he mapped include destructiveness (just above the ear),
language (just below the eyes), secretiveness (just above destructiveness), and cautiousness (just above
secretiveness).
Gall’s phrenology fell out of favor in the mid 1800s but was very popular for a long time. Some people
even asked that job applicants bring a phrenological reading with them when filling out an application. People still
find this topic very interesting, although there is no relationship between areas of mass in the brain and the shape of
the skull. In fact, at a recent fundraiser, members of the department I work at set up a phrenology booth, explaining
the theory of phrenology and that it was found to no longer be true. There was a long line of people who still wanted
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THE BIOLOGY UNDERLYING BEHAVIOUR
to have their heads “read.” By the way, charts of Gall’s functions (or faculties) can be found in many history of
psychology books.
Fancher, R. E. (1990). Pioneers of psychology. 2nd Ed. New York: W. W. Norton.
Lecture Lead 2.4: Are Men’s and Women’s Brains Different? (R)
Springer and Deutsch (1985) have reviewed much of the research on brain lateralization and have concluded that
differences seem to exist between the brain operations of males and females. Males tend to be more lateralized for
verbal and spatial abilities, whereas women show greater bilateral representation for both types of functions
(Springer & Deutsch, 1985, p. 183). Why would this be? What effect would it have on men and women? Springer
and Deutsch (1985) review research that shows that men have superior spatial abilities. Is this because they process
all their spatial information in the right hemisphere? Why would this be an advantage? Because women generally
have better verbal skills than men, why would men’s greater lateralization of language to the left hemisphere be a
disadvantage? Perhaps language requires both sides of the brain. Perhaps a high degree of lateralization makes it
easier to concentrate.
One of the problems with the examination or differences between men and women is that the differences
can easily be construed as opposites, where in fact they should be understood as differences only. One style may not
have an advantage over the other. They are simply different. However, a body of data does exist that describes sexbased differences in cognitive skills that could be founded on biological differences. The gender differences reported
by Eleanor Maccoby and Carol Nagy Jacklin in their book, The Psychology of Sex Differences (1987) have been
analyzed by Janet Hyde, using meta-analysis. Hyde’s analysis led to the conclusion that “no more than 1 to 5 percent
of the population variance was due to gender difference” (in Paludi, 1992, p. 39). Paludi (1992) argues that much of
the difference may be a result of researchers using college students (taking introductory psychology) in their
investigations.
Kimura, D. (1999). Sex and Cognition. Cambridge, Mass: Bradford.
Maccoby, E., & Jacklin, C. N. (1987). The psychology of sex differences. 2nd Ed. Stanford, California:
Stanford University Press.
Paludi, M. (1992). The psychology of women. Dubuque, Iowa: WCB Brown and Benchmark.
Springer, S. P., & Deutsch, G. (1985). Left brain, right brain. Rev. ed. New York. W. H. Freeman.
Lecture Lead 2.5: Brain Surgery to Reduce Neural Transmission (W)
Psychology has a long history of operating on the brain in order to decrease neural transmission. The first
widespread use of psychosurgery was the prefrontal lobotomy, developed in the 1930s by a Portuguese physician,
Egas Moniz. Moniz found that cutting the connections between the frontal lobe and the emotional areas found deep
inside the brain calmed uncontrollably emotional and violent patients by reducing the spread of neural activity.
During the 1940s and 1950s, tens of thousands of people underwent this procedure (Valenstein, 1986). This
procedure declined in the 1950s as drug therapies became the preferred method of treatment.
In the early 1960s, another procedure emerged. Neurosurgeons Joseph Bogen and Phillip Vogel noted that
for epileptic patients, bursts of electrical activity would often spread from one hemisphere to the other, resulting in
brain damage and, at times, death. For patients who had not responded to drug treatment, they severed the corpus
callosum. This procedure continues to be performed today, although surgeons are localizing seizure activity as much
as possible and removing parts of the brain, as opposed to severing the connections between the two hemispheres.
When this procedure involves removing all, or most, of a lobe of the brain, it is referred to as a lobectomy.
These researchers, while helping patients by reducing seizures, are also learning about what the different
parts of the brain do (Braun et al., 1994; Naugle et al., 1993). In one research report, Miller and Milner (1985)
investigated risky decisions following lobectomies and noted that people seem more cautious when the right
hemisphere is receiving the information, and are more willing to make risky decisions when their left hemisphere is
more active than the right.
Research in this area does appear to help individuals who do not respond to drugs for treatment of seizures,
and researchers are learning a great deal about the brain in the process. However, the issue of ethics remains. It is
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CHAPTER TWO
easy to question the ethics of Moniz performing thousands of lobotomies as an outpatient surgery by inserting an ice
pick in the corner of the eye. A valuable discussion with the students is to ask how people might view the
psychosurgeries of today 40 years from now.
Baaun, C. M, Denault, C, Cohen, H., & Rouleau, I. (1994). Discrimination of facial identity and facial affect by
temporal and frontal lobectomy patients. Brain and Cognition, 21, 198–212.
Miller, L., & Milner, B. (1985). Cognitive risk-taking after frontal or temporal lobectomy: The synthesis of
phonemic and semantic information. Neuropsychologia, 23, 371–379.
Naugle, R., Chelune, G. J., Cheek, R., Luders, H., & Awad, I. A. (1993). Detection of changes in material-specific
memory following temporal lobectomy using the Wechsler Memory Scale—Revised. Archives of Clinical
Neuropsychology, 8, 381–395.
Valenstein, S. (1986). Great and desperate cures: The rise and decline of psychosurgery. New York: Basic Books.
Lecture Lead 2.6: Sperry’s Split-Brain Studies (W)
Roger Sperry’s studies of the split brain began with a study of the effect of splitting the optic chiasm of a cat (Sperry
worked with Ronald Myers on this study). To be certain that communication did not continue between the two sides
of the brain, they also split the cat’s corpus callosum. Sperry and Myers were able to show that this operation
established two learning centers in the cat’s brain (Schwartz, 1986). Sperry later followed his work with the cat by
conducting similar experiments with monkeys while at the California Institute of Technology (Lindsley, 1988).
The view that two separate centers were established was challenged by A. J. Akelaitis, who had worked
with twenty-six human patients in the 1940s whose corpus callosums were cut to treat severe epilepsy. Akelaitis
found no effect on behaviour, and the surgery was also thought to have little effect on the seizures. This appeared to
end the matter, until two neurosurgeons, Joseph Bogen and Phillip Vogel, invited Sperry to study a patient, “W. J.,”
whom they had operated on to sever the corpus callosum. The success of the operation had led to a number of other
patients receiving the same treatment. Sperry and Michael Gazzaniga designed a number of apparatuses that could
be used to isolate the information going into each half of the brain. With the information isolated, they found that
each side responds differently; the verbal left side can state objects or words shown, while the mute right side can
only point (Schwartz, 1986).
Though his Ph.D. was awarded in zoology, Sperry was awarded a Nobel Prize for his psychological
studies, one of only a few given for psychological research.
Lindsley, D. (1988). Physiological psychology. In H. Hilgard (Ed.), Fifty years of psychology: Essays in honor of
Floyd Ruch. Boston: Scott, Foresman and Co., pp. 27–55.
Schwartz, S. (1986). Classic studies in psychology. Palo Alto, California: Mayfield Publishing.
Lecture Lead 2.7: Brain Modules (W)
There is a tremendous degree of localization of function in the brain. An article by Michael Gazzaniga (1989), one
of the pioneers in the study of split-brain patients, provides an up-to-date summary of some recent research on
localization and provides a framework for conceptualizing the way in which different brain areas interact during
cognition. Briefly, Gazzaniga proposes that the brain is composed of a large number of discrete “modules” that each
carry out specific functions in human thought. Some of these modules may be quite small and specialized. One case
Gazzaniga describes is that of a woman who suffered a small stroke that damaged portions of the large language
“module” in her left hemisphere. After a general neurological exam, she seemed to have no language-related
impairments. However, after careful study, she did show a very specific problem as a consequence of the stroke: She
was unable to name the colour of fruits that are red. For example, if you asked her the colour of a banana, she
quickly replied yellow. If you asked her the colour of a fire engine, she said red. But, if asked the colour of an apple,
she did not know. Gazzaniga interprets this sort of finding as reflecting the disconnection of small modules of
“knowledge” from the rest of the brain.
A final and very interesting point made in this paper has to do with our perception of unity in
consciousness. Current neuropsychological data indicate that cognition is the product of the parallel operation of a
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large number of brain “modules,” each making specific contributions to information processing. Why is it, then, that
we do not experience these many parallel operations taking place? Why is our subjective experience of
consciousness unified? Gazzaniga proposes that this sense of unity in consciousness is supplied by the left
hemisphere, which generates theories about one’s own behaviour and attempts to interpret the overall activity and
output of the brain. In other words, the left hemisphere “observes” the activity of the rest of the brain and overt
behaviour and attempts to integrate and make logical sense out of this large amount of neural and behavioural
activity.
Gazzaniga, M. S. (1989). Organization of the human brain. Science, 245, 947–952.
Lecture Lead 2.8: Disorders of the Pituitary Gland: Acromegaly (W)
There are several disorders of the pituitary gland that students will find fascinating. One disorder is called
acromegaly, a condition of excess secretion of the human growth hormone (GH). It is most common in middle-aged
adults because the normal growth period is long over in this age group. (Excess secretion of GH while a person is
still in the growth period causes a form of giantism [extreme height] and is much rarer.) Physical symptoms include
enlargement of the hands and feet (due to soft tissue swelling), protrusion of the brow and lower jaw, enlarged nasal
bone, and increased spacing of the teeth, all occurring gradually. In fact, the onset of symptoms is so slow that this
disorder is often not diagnosed correctly.
The overgrowth of bone can lead to other symptoms such as arthritis, carpal tunnel syndrome, thickened
and oily skin, deepening of the voice, increased snoring, and enlargement of several body organs. More serious
health risks for people with acromegaly are diabetes, high blood pressure, and increased risk of heart disease.
The cause of acromegaly is essentially the overproduction of GH by the pituitary gland for a prolonged
period of time. Since the pituitary is the master gland, affecting all other endocrine glands, bodily functions other
than growth can be affected, as in the diabetes mentioned earlier. Most of the time, the pituitary’s oversecretion is
caused by a tumor, normally benign, called an adenoma. The tumor itself produces GH, and as it expands, it
compresses the brain tissues surrounding it, causing symptoms such as headaches and even visual disturbances (if it
presses on the optic nerve). The growth rate of these tumors varies, with younger patients having more aggressive
tumors. This is typically not an inherited condition, but instead a spontaneous mutation in the genes that regulate the
pituitary.
About 3 out of every 1 million people develop acromegaly each year, although this number may be
artificially small because of the tendency to misdiagnose acromegaly as some other disorder. Diagnosis includes a
fasting blood test for the level of GH, repeated several times. A glucose tolerance test is also used, and is felt by
many to be more reliable in diagnosing acromegaly. CT scans can be used to locate the tumor.
Treatment of acromegaly includes surgery to remove the tumor, drug therapy, and radiation therapy of the
pituitary to reduce the size of the tumor.
Further Readings:
Ezzat, S., Forster, M. J., Berchtold, P., Redelmeier, D. A., Boerlin, V., & Harris, A. G. (1994). Acromegaly: Clinical
and biochemical features in 500 patients. Medicine, 73(5): 233–240.
Ezzat, S. (1992). Living with acromegaly. Endocrinology and Metabolism Clinics of North America, 21, 753–760.
Jaffe, C. A., & Barkan, A. L. (1994). Acromegaly: Recognition and treatment. Drugs, 47(3), 425–445.
Melmed, S. (1990). Acromegaly. New England Journal of Medicine, 322, 966–977.
Molitch, M. E. (1992). Clinical manifestations of acromegaly. Endocrinology and Metabolism Clinics of North
America, 21(3), 597–614.
CLASSROOM ACTIVITIES
Classroom Activity 2.1: The Benefits of Knowledge about the Brain (Student
Study Guide Essay Question 2.1) (W)
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CHAPTER TWO
Describe the specific benefits of our knowledge of brain function and the effect of injury on the brain.
What are the possible consequences of research in neurotransmitters, biofeedback, and even sex
differences in the brain?
This essay can be used to elaborate on a number of the sections of the text. One line of development would be to
expand on the issue of pain and the brain’s natural painkillers.
Pain
Humans receive pain messages through the skin, in internal organs, around muscles and bones, in the corneas—
everywhere except in the brain itself (Bloom, Lazerson, & Hofstadter, 1985; Thompson, 1985). The receptors are
connected to two types of neural pathways that send pain messages to the brain. The fast pathway is myelinated; it
sends messages to the thalamus and then to the motor and sensory areas of the cerebral cortex. This pathway seems
to give us a sensation of sharp pain and allows us to determine where an injury is located and how serious the tissue
damage might be. These fast pain fibers are connected to receptors in the skin and mucous membranes.
The second pathway, the slow pathway, is unmyelinated. It sends information to the reticular formation, the
medulla, the pons, the midbrain, the hypothalamus, and the thalamus. Connections allow information to go to the
amygdala in the limbic system. This slow pathway gives the sensation of diffuse, nagging pain to remind us that
activity should be restricted. These slow pain fibers are connected to receptors in the skin and all other body tissue
except the brain, which is insensitive to pain (Thompson, 1985).
When pain messages go through the slow pathway to synapses in the spinal cord, a neurotransmitter called
substance P is released. Substance P seems to be the specialized transmitter of pain-related information. The spinal
cord also contains neurons that release endorphins. The endorphin binds to the pain-transmitting neuron and inhibits
the release of substance P. The result is that the receiving neuron gets less stimulation because it receives less
substance P. The neurons that release endorphin appear to be stimulated by pathways from the brain, so the brain
may be able to control the amount of pain input it receives from the slow pathway via the spinal cord (Thompson,
1985). This is one of the mechanisms that controls the “gate” in the gate-control theory of pain that is mentioned in
Chapter 2.
The slow pathway contains opiate receptors and is affected by endorphins and morphine. The fast pathway
does not have opiate receptors and is insensitive to morphine (Thompson, 1985).
Bloom, R. E., Lazerson, A., & Hofstadter, L. (1985). Brain, mind, and behaviour. New York:
W. H. Freeman.
Thompson, R. F. (1985). The brain: An introduction to neuroscience. New York: W. H. Freeman.
Classroom Activity 2.2: Speed of Neural Transmission (E)
Overhead Masters or Handout Masters are provided with this activity.
To show that the speed of neural transmission is measurable, a simple demonstration has become a very common
occurrence in many introductory psychology classrooms. All you need to do this demonstration is a stopwatch and a
calculator. Have at least 15 students stand in a line, all facing in the same direction (that is, each person will be
looking at the back of the person in front of them). If you have a large lecture room that is mostly full, you can still
do this demonstration by having everyone stand up and face down the rows of seats. The even rows should face in
one direction and the odd rows should face in the opposite direction. Then simply connect the rows at the aisles and
you will have a long snake-like chain of students.
Next, have each student put his or her hand on the right shoulder of the person in front of them. Tell the
students that when they feel the person behind them squeeze their shoulder, they should gently, but firmly, squeeze
the shoulder of the person in front of them. If any of the students can see students in the line behind them (if you
have to, curve around the room), have the students close their eyes to reduce visual cues. Finally, go to the back of
the row and squeeze the shoulder of the last person in the row and start the stopwatch at the same time. Walk to the
front of the line and stop the watch when the neural impulse gets to you. Do this 10 times and take the average
amount of time. Record your response times on Overhead Master 2.1. Ask the students approximately how far
neurons must transmit information to complete this task. The answer is approximately 3 feet (or 1 meter): It must
travel from your shoulder to your head and out to your hand. If you divide the average speed by the number of
44
THE BIOLOGY UNDERLYING BEHAVIOUR
students and then that result by 3 (feet) you will have an approximate speed of neuron transmission per foot for this
task.
Another task that is commonly done is the hand squeeze. Have the students hold hands and do the same
task: when their left hand is squeezed by the person to the left, they then squeeze the hand of the person to their
right. Before you complete this task, ask the students to guess what the result will be and then calculate the
approximate response time. Do this task 10 times and take the average. For this task, the information must travel
roughly twice the distance, so it should take more time to complete.
There are a number of variations on this task. Rozin and Jonides (1977) report using ankles to test neural
speed. You can try various body parts. Keep in mind that in some cases you may be able to test simple reflexes. For
example, if the same procedure as described above is used—except that each student grasps the forearm of the
person in front of them—the speed should be very quick. Instead of the information going to the brain and back out
the same arm, the information will be sent simultaneously to the hand and the brain. If we were not wired with such
reflexive responses, it would take approximately the same amount of time as the hand-squeeze chain described
above.
Rozin, R., & Jonides, J. (1977). Mass reaction time: Measurement of the speed of the nerve impulse and the duration
of mental processes in class. Teaching of Psychology, 4, 91–94.
Classroom Activity 2.3: Speed of Neural Transmission II (E)
Years ago, my dad came home and played a trick on me. He told me to lay my arm across the table with my hand
just over the edge (wrist to elbow on the table) and put my finger and thumb 1 inch apart. (Your hand in this position
should be as though you were holding a broom handle with the broom on the floor.) He then pulled out a dollar bill
and held the dollar at one end and put about the top 1 inch of the dollar bill even with my thumb and forefinger
(about where the eagle is on the back of the bill). He then dropped the bill. He told me that if I caught the dollar bill
two times in a row, I could keep it (sometimes a person will guess right and close his or her fingers just as you let it
go). Try it with a friend before you go into class. You will pay out very few dollars with this trick. Ask your students
to explain why this is such a difficult task. I ask my students to explain the path the neurons must travel for a person
who sees an object, decides response, and then executes a response.
This can also be done with a plastic (or wooden) ruler to measure the distance the ruler falls before a person
closes his or her finger and thumb.
Classroom Activity 2.4: Information Transmission Across a Synapse (E)
This demonstration gives students an idea of the importance of the synapse in transmitting information. To do this
demonstration, you need a few spray bottles (they can be purchased or you can use a well-washed window-cleanertype bottle) and a piece of cardboard (8 x 11 inches will work). Although I will explain the most simple
demonstration, you may make your neural connections as complicated as you wish.
Form a line of seven students. Have six of the students line up across the front of the room facing the class.
Tell the students to stretch their arms out and stand at a distance so that their hands just overlap. The first two
students will make up one neuron and the other four will make up the second neuron (neurons are not all the same
length). Separate students 2 and 3 an additional 6 inches. This will be the synapse. Inform them that student 1 and 3
are dendrites and students 2 and 6 are axon terminals. Ask the seventh student to stand by the outstretched hand of
the first student (side away from the student-formed neurons). This student will serve as the stimulus input (perhaps
the sensory neuron).
Tell the line of students that the stimulus input neuron will spray the bottle toward the next student’s hand
(adjust the bottles to get the finest mist possible). When that student feels the mist of water, they are to gently, but
quickly, slap the hand of the next person. This person then sprays the mist at the hand of the next person. When they
feel the water, that person will slap the hand of the next person, who will slap the hand of the final person. At that
point, a stimulus input has made it across two synapses. Have the students practice this a few times. When they are
proficient at transmitting information, have all except the first student with the first spray bottle close their eyes. Tell
the first student to watch you. By doing this they cannot see the information coming. When you wish to start an
impulse, simply nod to the first student and he or she can spray the bottle.
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CHAPTER TWO
You can also show how substances in the body can inhibit a neural transmission, such as with endorphins
and painkillers. Tell the class that the neurons will carry a message that some part of the body is in pain. Nod to the
first person to start a transmission of information signaling pain. Before the second-synapse water mist is fired,
insert the cardboard between the spray bottle and the next student’s hand. Explain that information dies there and the
brain would not receive the message of pain. Other substances can mimic neurotransmitters and cause a neuron to
tire even though there is no stimulus input from the external world. In this case, do not nod to the first student.
Instead, spray your bottle at the point of the second synapse and ask the final student where the information came
from. That student will not know if it was from you or the student with the spray bottle. Note that the last neuron
fired, even though the previous neuron did not.
Classroom Activity 2.5: Learning Functions of Brain Parts (E)
Overhead Masters or Handout Masters are provided with this activity.
In this demonstration, I write down the name of components of the brain on cards and pass them out to students.
Photocopy Overhead Master 2.2 to get you started. It is all right to have more than one student with the same card.
It actually provides for good discussion when, for example, one person with the limbic-system card holds up the
card and another person with the same card does not. Some examples of cards include occipital lobe, thalamus,
frontal lobe, somatosensory area, Broca’s area, cerebellum, and hippocampus (basically, whatever you include in
your lecture). I then describe an action (see below) and tell the students to raise their hand quickly if their brain
component is involved in that activity. I then call on one or two students and ask them why they feel they would be
involved. I also often call on a part I don’t see in the air (when it should be) and ask them why they were not
involved. After several trials, I shuffle the cards and redistribute them.
Sample actions:
1. Look at a picture.
2. Answer an exam question.
3. Stand up.
4. Write a letter to a friend.
5. Kick a can.
6. Yell at someone who cuts you off in traffic.
7. Raise your hand.
8. Hear someone call you and turn your head.
9. Decide you are hungry.
Classroom Activity 2.6: Ethics and Brain Research (Student Study Guide Essay
Question 2.2) (R)
Several recent developments raise important questions for ethical consideration. What are the problems that arise
when surgery separates the two hemispheres? What are the potential dangers of transplanting tissue into the brain?
Discuss these ethical and moral issues. Are there other issues? The primary consideration that the student should
focus on should concern the effects of the research, not the knowledge. To deepen the discussion, you might ask
whether the knowledge gained (in whatever particular example each student has used) justifies any potential effects
on the patient.
The next step is the concern over the extent to which follow-up research in cases of split-brain work or
transplanted tissue unfairly interferes with the privacy of the individual. Will a patient become a subject out of some
sense of obligation to the medical researcher because of a sense of “owing” something, or will the patient become a
subject out of authentic concern for science? How does one determine these motives and ensure that the subject is
not subtlety coerced?
This discussion could be linked easily to Lecture Lead 2.4 and Lecture Lead 2.6.
MULTIMEDIA
46
THE BIOLOGY UNDERLYING BEHAVIOUR
Online Learning Center Preview
Instructors should check the Online Learning Center for applicable PowerPoint slides and other resources relevant to
this chapter. Tables and figures available from the Image Gallery for this chapter are:
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TABLE 2-1: Some Major Neurotransmitters
FIGURE 2-3: Changes in the Electrical Charge of a Neuron
FIGURE 2-5: A Schematic Diagram of the Relationship of the Parts of the Nervous System
FIGURE 2-6: The Central Nervous System
FIGURE 2-7: The Major Functions of the Autonomic Nervous System
FIGURE 2-12: The Cerebral Cortex of the Brain
In-Psych Student CD-ROM
The In-Psych Student CD-ROM is organized according to the textbook chapter outlines and features exercises
chosen to illustrate especially difficult core introductory psychology concepts. Each exercise showcases one of three
types of media assets—an audio clip, a video clip, or a simulation—and includes a pre-test, follow-up assignments,
and Web resources. The CD-ROM also includes chapter quizzes, a student research guide, and an interactive
timeline that puts events, key figures, and research in psychology in historical perspective. As these
features effectively engage the student and help reinforce new knowledge retention, they function superbly as
homework or extra-credit assignments. The following [is/are] available on the CD-ROM for this chapter:
[Chapter 2 The Biology Underlying Behaviour]
Timeline
Neural Functioning (Interactive Activity)
Sensorimotor Neural Circuits (Interactive Activity)
Parts of the Brain (Interactive Activity)
Chapter Quiz
Video Resources
FILMS FOR THE HUMANITIES AND SCIENCES
The Development of the Human Brain (40 minutes)
Dopamine Seduction: The Limbic System (25 minutes)
The Brain: An Inside Look (20 minutes)
Inside Information: The Brain and How It Works (58 minutes)
Journey to the Centers of the Brain (Five-part series, 58 minutes each)
Mind Over Matter: Advances in Brain Research (47 minutes)
Mind Talk: The Brain’s New Story (59 minutes)
Brain and Nervous System: Your Information Highway (25 minutes)
The Human Brain (three-part series, 21-35 minutes each)
Body Chemistry: Understanding Hormones (three-part series, 50 minutes each)
(Contact information for this material can be found in the Preface of this manual.)
PsychLink
www.mcgrawhill.ca/college/feldman
47
CHAPTER TWO
INDEPENDENT PROJECTS
Independent Project 2.1: Split Autonomic Nervous System (W)
Students should identify activities they undertake through the day that require their sympathetic and parasympathetic
systems to work. After identifying these activities, they should then answer the following questions: What would
you be like if the sympathetic and the parasympathetic divisions of the autonomic nervous system did not work in
harmony? Could you lead a normal life? What if one division were only half as active as normal?
The sympathetic division of the autonomic nervous system prepares us for stressful emergency situations.
The parasympathetic division calms us down. The specific activity of each division is described as follows (the
activity of the parasympathetic division is given in parentheses). It may surprise a few students.
The sympathetic dilates (constricts) cerebral blood vessels.
The sympathetic dilates (constricts) the pupil of the eye.
The sympathetic decreases (stimulates) secretions of the salivary glands.
The sympathetic dilates (constricts) peripheral blood vessels.
The sympathetic speeds and strengthens (slows) the heartbeat.
The sympathetic erects (relaxes) body hair. This is called the piloerection response.
The sympathetic increases (reduces) sweat gland activity.
The sympathetic decreases (increases) contractions of the stomach.
The sympathetic stimulates (decreases) secretions from the adrenal glands.
The sympathetic decreases (increases) motility in the digestive tract.
The sympathetic relaxes (contracts) the bladder.
The sympathetic excites the genital organs to orgasm (relaxes those organs).
Bloom, F. E., Lazerson, A., & Hofstadter, L. (1985). Brain, mind, and behaviour. New York: W. H. Freeman.
Independent Project 2.2: Results of Physiological Misfunction or Brain Damage
(W)
Have students research and report back about some result of physiological brain damage in humans. There are many
articles and some very interesting cases in print, as well as a plethora of information available on the Internet.
Suggest that the students try not to focus on medical or psychological journals that present very technical
information. The goal is to find different types of diseases and describe briefly the cause of the disorder. I will often
give my students some token reward if they are the only one to find a given disorder, which may result in some very
obscure finds. Some symptoms include agnosia, apraxia, ataxia, amnesia, and aphasia. They may also find diseases
or disorders such as a stroke, Parkinson’s disease, Alzheimer’s disease, seasonal affective disorder, MS, and MD. Be
aware that most teachers of general or introductory psychology are not neuroscientists. I tell my students before this
assignment that I will not know all aspects pertaining to the information they find. The goal is to identify the
multitude of ways the body can be damaged. This activity should make students really appreciate the fact that most
of us are lucky enough to have the physiology in our bodies work as it should for many years.
Independent Project 2.3: Investigating a Gland (W)
The glands are often glossed over in an introductory psychology text, since the functioning of the human brain is so
complex and usually requires so much time to teach. One way to interest students in the endocrine system, and to
give them a better understanding of its importance in human behaviour, is to have students pick one endocrine gland
and research it in some detail. Students should not only describe the location of the gland and the hormone or
hormones that it secretes, but also its effect on the body and nervous system. Diseases associated with that gland
should also be reported (for example, a student picking the pancreas should make certain to discuss the various
forms of diabetes and hypoglycemia). This project could take the form of a class presentation, a paper, or perhaps
even a poster presentation that could be put up in the classroom for all to see.
48
OVERHEAD MASTER 2.1 (USE WITH CLASSROOM ACTIVITY 2.2)
Speed of Neural Impulse
Hand to Shoulder Time
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11. Sum of items 1–10
12. Average time: Divide item 11 by item 10.
13. Time per student: Divide item 12 by number of students.
14. Approx. time/foot: Divide item 13 by 3.
Note: Use same form for Hand-to-Hand Chain and/or other chains to calculate speed.
OVERHEAD MASTER 2.2 (USE WITH CLASS ACTIVITY 2.5)
Thalamus
Cerebellum
Limbic System
Motor Area
Somatosensory Area
Auditory Area
Occipital Lobe
Association Area
Broca’s Area
Wernicke's Area