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Behavioral Neuroscience
3
Behavioral Neuroscience
 Learning Objectives
 Chapter Outline
 Key Concepts
 Key Contributors
 Teaching the Chapter
 Lecture/Discussion Suggestions
 Classroom Activities
 Experiencing Psychology
 Critical Thinking Questions
 Video/Media Suggestions
 References
 Sources of Biographical Information
Learning Objectives
After studying this chapter, the student should be able to:
3.1
Describe the purpose of the behavioral neurosciences. (p 59)
3.2
Define evolutionary psychology and describe its purpose, using a study on romantic relationships as
an illustration. (p. 60-61)
3.3
Define behavioral genetics and describe its purpose. (p. 62)
3.4
Explain the difference between genotype and phenotype, including discussion on polygenic
characteristics. (p. 62-63)
3.5
Explain how the concept of heritability helps our understanding of the relative contributions of
heredity and environment to human development. (p. 63)
3.6
Explain the difference between family studies, adoption studies, and studies of identical twins raised
apart, and their relevance to behavioral genetics. (p. 63-65)
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Chapter Three
3.7
Draw a diagram delineating the major divisions of the nervous system and their general functions.
(p. 65-67)
3.8
Explain the functioning of the endocrine system, including the pituitary and adrenal glands, and the
gonads. Include discussion of anabolic steroid use. (p. 67-69)
3.9
Distinguish between endocrine and exocrine glands. (p. 67)
3.10 Describe the functions of three types of neurons, describe their roles in reflexive behavior, and
distinguish neurons from glial cells. (p. 69)
3.11 Draw a diagram of a neuron, labeling its parts and indicating the function of each part. (p. 69-70)
3.12 Describe the neuron at rest, mentioning the chemicals involved in resting potential, and then explain
the changes involved in the action potential, mentioning the all-or-none law and myelin. (p. 70-72)
3.13 Describe the process of synaptic transmission and explain the role of the neurotransmitters in that
process, emphasizing the effects of acetylcholine and six other neurotransmitters. (p. 72-75)
3.14 Summarize the classic study that resulted in the discovery of endorphins and offer an overview of
subsequent research findings regarding endorphins. (p. 75-76)
3.15 Describe how clinical case studies and experimental manipulation can increase our understanding of
brain functioning. (p. 77-80)
3.16 Explain the relevance of brain size, including discussion on phrenology, Einstein’s brain, and
scientific research on brain size and intelligence. (p. 78-79)
3.17 Describe the function and mechanism of action of EEG, PET, CT, MRI, SPECT, and SQUID.
(p. 80-82)
3.18 Draw a diagram of the brainstem, delineating its five structures and their functions. (p. 82-83)
3.19 Draw a diagram of the limbic system, delineating three of its structures and their functions. (p. 83-84)
3.20 Describe the location and function of the four lobes of the cerebral cortex. (p. 84-87)
3.21 Describe in detail the structure and functioning of the motor and sensory areas of the cerebral cortex,
including the concept of the homunculi. (p. 85-87)
3.22 Describe the contributions of Wilder Penfield to our understanding of the distribution of functions in
the cerebral cortex. (p. 86-87)
3.23 Describe the purpose of the association areas, including the relevance of Phineas Gage’s accident.
(p. 87-88)
3.24 Describe the location and function of Broca’s area and Wernicke’s area. (p. 88-89)
3.25 Critically evaluate popular notions of “left-brained” and “right-brained” people, and then summarize
the findings regarding the relationship between handedness and longevity. (p. 89-92)
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Behavioral Neuroscience
3.26 Describe three techniques used to study hemispheric specialization, and explain how studies of
individuals with cerebral damage have also contributed to our understanding of brain functioning.
(p. 92-94)
Extended Chapter Outline
I. Heredity and Behavior
The behavioral neurosciences study the connection between neurology and psychology.
A. Evolutionary Psychology
These researchers use Darwin’s theory of evolution to explain development.
B. Behavioral Genetics
Genetics influence our behavior. The genotype is our genetic makeup. The phenotype is the
outward appearance of the genotype. Behavioral geneticists evaluate heritability of traits.
1. Family Studies
Family studies look at genetic similarities within family groups. The comparison of
fraternal twins (different genes) with identical twins (same genes) yield the most useful
data.
2. Adoption Studies
These studies compare adoptees with their biological and adoptive parents.
3. Studies of Identical Twins Reared Apart
By looking at identical twins reared apart, researchers are able to better separate
environmental influences on behavior from genetic influences. However, factors other
than genetics may also influence the similarities seen in identical twins raised apart.
II. Communication Systems
A. The Nervous System
The nervous system is composed of neurons, which are cells that are specialized for the
transmission and reception of information. The two divisions of the nervous system are the
central nervous system and the peripheral nervous system.
1. Central Nervous System
The CNS is comprised of the brain and spinal cord.
2. Peripheral Nervous System
The PNS is the collection of nerves that allow the CNS to communicate with the rest of
the body. This includes the somatic and autonomic nervous systems, and the autonomic’s
subdivisions: sympathetic and parasympathetic nervous systems.
B. The Endocrine System
This system uses hormones to communicate.
1. The Pituitary Gland
The pituitary, controlled by the hypothalamus is the “master gland” that regulates many
other endocrine glands.
2. Other Endocrine Glands
The adrenal glands and gonads (testes and ovaries) are other glands related to
psychological functioning.
III. The Neuron
Neurons are cells that transmit information. Sensory neurons send messages along sensory nerves
to the brain or spinal cord. Motor neurons send messages along motor nerves to the glands, the
cardiac muscle, and the skeletal muscles, as well as to the smooth muscles of the arteries, small
intestine, and other internal organs. Glial cells are important for the maintenance of the neuron and
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Chapter Three
may even play a role in the transmission of signals. Interneurons are the means of communication
between neurons in the brain and spinal cord. The neuron itself is comprised of a soma, dendrites,
and axon.
A. The Neural Impulse
Neuronal activity depends upon the electrical-chemical processes including the resting
potential and the action potential.
1. Resting Potential
During the resting potential, the neuronal membrane is polarized—that is, the inside is
electrically negative relative to its outside.
2. Action Potential
Stimulation of the neurons makes positive sodium ions rush in and depolarize the neuron.
If the neuron depolarizes enough, it reaches its firing threshold and an action potential
occurs. During the action potential, the inside of the neuron becomes positively charged
relative to the outside. Because of the all-or-none law, a neural impulse is conducted
along the entire length of the axon. After an action potential has occurred at a point on the
axonal membrane, the axon repolarizes and its resting potential is restored. A myelin
sheath covering the axon increases the speed of transmission.
B. Synaptic Transmission
Synaptic transmission permits neurons to communicate with each other.
1. Mechanisms of Synaptic Transmission
Synaptic transmission is carried out by a group of chemicals called neurotransmitters.
They are stored in the synaptic vesicles located in synaptic knobs at the end of axons.
After an excitatory neurotransmitter has caused a neuron to fire, they disengage from the
receptor sites and are either broken down by enzymes or taken back into the neurons that
had released them.
2. Neurotransmitters and Drug Effects
a. Acetylcholine is important in muscle movement and memory. Curare blocks
acetylcholine, causing paralysis and suffocation. Alzheimer’s disease destroys
acetylcholine-producing neurons, causing memory loss.
b. Dopamine-producing neurons, important for smooth muscle movement, are destroyed
in Parkinson’s disease. Increasing the availability of dopamine in the brain helps
alleviate symptoms. In schizophrenia, dopamine-producing neurons are hyperactive.
Blocking dopamine may help alleviate symptoms.
c. Norepinephrine and serotonin levels are low in people with depression. SSRIs block
the process of reuptake allowing more serotonin to be available in the synapse.
d. GABA, associated with muscle relaxation, is affected by Valium.
e. Glutamic acid is important in memory formation.
3. Endorphins
Endorphins, acting as both neurotransmitters and neuromodulators, are important in pain
relief.
C. Neural Networks
Clusters of neurons working together allow us to process information quickly.
IV. The Brain
A. Techniques of Studying the Brain
1. Psychology versus Common Sense: What Can We Infer from the Size of the Brain?
a. The Misguided Science of Phrenology
Popular in the nineteenth and early twentieth centuries, phrenologists believed that
bumps on the head corresponded to bumps on the brain which corresponded to
specific psychological functions.
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Behavioral Neuroscience
b. The Furor Over Einstein’s Brain
Differences were found between Einstein’s brain and those of other men. The debate
is over the nature and the meaning of those differences.
c. Scientific Research on Brain Size and Intelligence
Some argue that there are differences between brain size and intelligence where
others argue there are not.
2. Clinical Case Studies
By observing humans with brain damage, researchers are able to gain an understanding of
how the brain works.
3. Experimental Manipulation
By purposefully damaging, electrically stimulating, or observing the effects of drugs on
the brain, researchers are able to monitor the change in behavior.
4. Recording Electrical Activity
The EEG is used to monitor electrical activity in the brain.
5. Brain-Imaging Techniques
PET scans allow researchers to monitor activity in specific brain areas. CT and MRI are
useful for looking at brain structures. SPECT is used to monitor blood flow in the brain.
SQUID monitors changes in magnetic fields within the brain.
B. Functions of the Brain
The brain contains billions of neurons, each of which may communicate with thousands of
other neurons.
1. The Brainstem
The structures of the brainstem help us to carry out some of the most basic life functions.
a. The Medulla
The medulla controls many vital functions, such as heartbeat and breathing.
b. The Pons
The pons helps to regulate the sleep-wake cycle.
c. The Cerebellum
The cerebellum controls the timing of our well-learned sequences.
d. The Reticular Formation
The reticular formation helps maintain vigilance and an optimal level of brain
arousal.
e. The Thalamus
The thalamus routes sensory information to the appropriate brain area.
2. The Limbic System
a. The Hypothalamus
The hypothalamus helps regulate eating, drinking, emotion, sexual behavior, and
body temperature. It regulates the pituitary.
b. The Amygdala
The amygdala helps regulate emotions.
c. The Hippocampus
The hippocampus is important in the formation of new memories.
3. The Cerebral Cortex
Cerebral cortex is divided into two hemispheres. Each hemisphere is comprised of four
lobes: frontal (motor cortex), temporal (auditory cortex), parietal (sensory cortex), and
occipital (visual cortex).
a. Motor Areas
Located in the frontal lobe, the motor areas control muscle movement on the opposite
side of the body.
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Chapter Three
b. Sensory Areas
Located in the parietal lobe, the sensory areas process sensory information from the
opposite side of the body.
c. Association Areas
The rest of the cerebral cortex is devoted to integrating information.
d. Language Areas
Broca’s area, in the frontal lobe, is important in producing speech. Wernicke’s area,
in the temporal lobe, is important in comprehending speech.
C. Cerebral-Hemispheric Specialization
Research has established that the left hemisphere is somewhat superior in performing verbal,
sequential, analytical, rational, and mathematical functions, while the right hemisphere is
somewhat superior at performing spatial, holistic, emotional, and creative functions.
1. Evidence from the Intact Brain
One of the chief methods used to research hemispheric specialization on the intact brain
involves the use of an EEG while subjects perform various tasks.
2. Evidence from the Damaged Brain
Case studies of people who have suffered damage to one cerebral hemisphere, often as the
result of a stroke, are the oldest source of evidence on hemispheric specialization.
3. Evidence from the Split Brain
By severing the corpus callosum, researchers have found that although subjects behave
normally in their everyday lives, their left and right hemispheres can no longer
communicate with each other.
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Behavioral Neuroscience
Key Concepts
behavioral neuroscience
neglect syndrome
pituitary gland
testes
Heredity and Behavior
behavioral genetics
evolutionary psychology
genotype
heritability
phenotype
The Neuron
action potential
all-or-none law
Alzheimer’s disease
axon
axonal conduction
dendrites
Communication Systems
endorphins
autonomic nervous system
glial cell
brain
interneuron
central nervous system
motor neuron
nerve
myelin
nervous system
neurotransmitters
neuron
Parkinson’s disease
parasympathetic nervous system resting potential
peripheral nervous system
sensory neuron
reflex
soma
somatic nervous system
synapse
spinal cord
synaptic transmission
sympathetic nervous system
The Brain
The Endocrine System
amygdala
adrenal glands
association areas
endocrine system
auditory cortex
gonads
Broca’s area
hormones
cerebellum
ovaries
cerebral cortex
cerebral hemispheres
computed tomography (CT)
corpus callosum
electroencephalograph (EEG)
frontal lobe
hippocampus
hypothalamus
limbic system
magnetic resonance imaging (MRI)
medulla
motor cortex
occipital lobe
parietal lobe
phrenology
pons
positron-emission tomography
(PET)
primary cortical areas
reticular formation
single photon emission computed
tomography (SPECT)
somatosensory cortex
split-brain research
superconducting quantum
interference device (SQUID)
temporal lobe
thalamus
visual cortex
Wada test
Wernicke’s area
Key Contributors
Heredity and Behavior
Charles Darwin
Francis Galton
The Neuron
Luigi Galvani
Stephen Hales
Alan Hodgkin and Andrew
Huxley
Otto Loewi
Candace Pert and Solomon
Snyder
Charles Sherrington
Santiago Ramón y Cajal
The Brain
Hans Berger
Paul Broca
Gustav Fritsch and Eduard
Hitzig
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Michael Gazzaniga
Hippocrates
Heinrich Kluver and Paul Bucy
Jerry Levy
Giuseppe Moruzzi and Horace
Magoun
James Olds and Peter Milner
Wilder Penfield
Roger Sperry
Karl Wernicke
Chapter Three
Teaching the Chapter
Some students will find material on the biological basis of behavior to be intimidating, whereas others will
be awestruck by the fact that our experience of the world happens “up there.”
Consider using neurological case studies (e.g. Oliver Sacks’ work) to illustrate how damage to the various
brain areas alters perceptions and behavior. Students often gain a new appreciation for their own brains
once they realize how much damage to it can alter their experiences.
For neuronal functioning, after talking about how the neuron works, mention how a few drugs work.
Morphine is an endorphin agonist. Nicotine is an agonist of acetylcholine’s nicotinic receptors. Prozac
blocks the reuptake of serotonin. By connecting the neuron’s function to familiar drugs, students begin to
see the neuron as more than an abstract concept.
Because students often find the terminology intimidating, it may be worth it to spontaneously quiz your
students during your lecture. For example, once you have covered the brainstem and have moved on to the
limbic system, stop and ask “What structure in the brainstem is responsible for heartbeat and breathing?”
Lecture/Discussion Suggestions
1.
Twin Studies – What Do They Tell Us? The presentation of the twins-reared-apart study is very
good at arousing student interest. It also presents only a very rosy picture about the results of such
studies. Perhaps a presentation of the criticisms offered by Leon Kamin would help balance this
material.
a.
b.
c.
In the studies of twins-reared-apart, the monozygotic twins were typically placed in very similar
home environments.
In the studies of adoptees and their parents vs. biological families (parents raising their own
children), Kamin again argues that selective placement may account for the results. Kamin is
arguing that, since the home placement is very similar to that of the biological home, the cause
of similarities is actually environmental rather than biological. He points to two studies (in
Texas and Minnesota) that used more random assignment of children to homes. These studies
showed that the relationship between parents and their biological children wasn’t much greater
than between parents and their adopted children. He also points out that a study comparing
biological sibling pairs to biological-adoption sibling pairs showed little difference.
One of Kamin’s primary arguments is that a large portion of the data suggesting high
heritability (that of Burt) is fraudulent.
Kamin’s arguments are not held too closely by most developmental psychologists but are suggestive
that more work needs to be done; and it needs to be done more carefully.
Lewontin, R., Rose, S., & Kamin, L. (1984). IQ: The rank ordering of the world. In Not in our
genes: Biology, ideology, and human nature. New York: Pantheon.
2.
Interaction of Genes and Environment. Perhaps one of the most difficult problems for the student to
grasp is the genetic-environment interaction model. This seems to be due to the fact that an interaction
of genes and environment is so obvious. What seems to inhibit understanding for many of our students
is that they grasp a very superficial understanding and, therefore, fail to include the concepts of
genotype and phenotype out of the genes’ half of the interaction. For this reason and others, we
believe you would be wise to emphasize the importance of a full understanding of the nature-nurture
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Behavioral Neuroscience
problem to the students before the exam.
The example of a person having “medium tall” genes but living in a poor environment is a good one
for expressing this genotype/phenotype distinction. The gene(s) for “medium-tallness” is the genotype
whereas the actual resulting height is the phenotype. Points of importance to bring out are 1) genotype
can often be thought of as the “limit” of possibilities (keeping in the same line of thought as the
example), 2) the more divergent phenotype and genotype are, usually the poorer or more interfering
the environment, and 3) the closer the match between phenotype and genotype, usually the better or
richer the environment. Again, it would be wise to use several examples and remind the class
constantly of the importance of definitions over examples. A person with a definition well learned can
create examples. A person with only an example committed to memory is limited to the quality
(usually not very high) of the example.
3.
Some Tentative Answers to Nature vs. Nurture. As reported in U.S. News and World Report,
researchers at the Minnesota Center for Twin and Adoption Research have reported estimates of the
extent to which certain personality traits appear to be determined by heredity. Investigators gave a
lengthy test called the Multidimensional Personality Questionnaire to hundreds of identical twins and
compared the results with those from the population at large, using standard computer programs to
analyze statistical variation. The following traits were isolated, along with the estimated percentage of
the inherited trait:
 Extroversion (mixes easily, affable, likes to be the center of attention): 61%
 Conformity (respects tradition and authority; follows the rules): 60%
 Worry (is easily distressed and frustrated; feels vulnerable and sensitive): 55%
 Creativity (has tendency to become lost in thought and abstraction): 55%
 Paranoia (keeps to oneself; feels exploited, thinks “world is out to get me”): 55%
 Optimism (is confident, cheerful, upbeat): 54%
 Cautiousness (avoids risks and dangers; takes safe route, even if more difficult): 51%
 Aggressiveness (tends to be physically violent; has a taste for revenge): 48%
 Ambitiousness (works hard at setting and achieving goals; a perfectionist): 46%
 Orderliness (plans carefully; tries to make rational decisions): 43%
 Intimacy (prefers emotional closeness): 33%
“Extroverts are born, not made.” April 13, 1987, U.S. News and World Report.
4.
Using Twins to Study the Nature vs. Nurture Issue with Weight. Is weight determined by heredity
or lifestyle? In one report, researchers analyzed weight and height records from the Swedish
Adoption/Twin Study of Aging (Stunkard, et al., 1990). Using 247 identical and 426 fraternal pairs of
twins, twin siblings ended up with similar body weights regardless of whether they were raised
together or apart. In fact, the correlation in body-mass index of identical twins reared apart was only
slightly less than that of identical twins reared together. They also were more similar in weight to the
biological parents than to the adopting parents. When both biological parents were fat, 80% of
offspring were fat. Childhood environment was shown not to have an important effect.
Canadian researchers fed 12 pairs of identical twins 1,000 calories above their normal daily intake for
84 days. Weight gains ranged from 4 kg to 13 kg (9 lbs. to 29 lbs.). The difference in the amount
gained was much less between twins than between nonsiblings. In other words, considerable
variability in weight gain and fat distribution was seen between different twin pairs, but little
variability was seen within each pair. Bouchard (1990) concluded, “It seems genes have something to
do with the amount you gain when you are overfed.”
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Chapter Three
Bouchard, C., Tremblay, A., Despres, J., Nadeau, A, & Lupien, P.J. (1990). The response to
long-term overfeeding in identical twins. The New England Journal of Medicine, 322(21).
Stunkard, A.J., Harris, J.R., Pedersen, N.L., & McClearn, G.E. (1990). The body-mass index of
twins who have been reared apart. The New England Journal of Medicine, 322(21).
5.
Understanding the Corpus Callosum/Split-Brain Research. The corpus callosum is the largest
tract of fibers in the brain. On the average, it contains over 200 million fibers and serves as the main
connection between the two hemispheres of the neocortex. As recently as the late 1940s or early
1950s, the structure was very poorly understood; in fact many psychologists believed it could be
destroyed with no loss of function. Ronald Myers, working at the University of Chicago, first
perfected a procedure for surgically separating the optic chiasma, the structure where information
from the two eyes is mixed on its way to the occipital cortex. Further, Myers and Sperry (1958)
demonstrated that an animal that learned a discrimination with one eye could respond correctly using
the untrained eye even when its optic chiasma had been severed. Myers and Sperry continued their
research and eventually showed that the corpus callosum was allowing the two hemispheres to
communicate. Further, Ahelaitis did a study in 1944 which suggested that epileptic humans who had
their corpus callosum cut showed little or no functional loss, neurologically or psychologically.
In the early 1960s, Joseph Bogen, a surgical resident at a hospital in Los Angeles, reviewed this work
and suggested (although he was not the first) sectioning the corpus callosum to reduce
interhemispheric epilepsy. On his very first patient, immortalized in the literature as W. J. Bogen, he
and a surgeon named Vogel achieved successful reduction of epilepsy.
Gazzaniga (1970) and Gazzaniga and LeDoux (1978) have shown that studies of patients who have
experienced a callostomy (severing of the corpus callosum) revealed some very interesting results. An
image flashed to the right visual field (left hemisphere) can be named, whereas one flashed to the left
visual field (right hemisphere) cannot. If asked “What did you see?” after a left visual field stimulus,
the person often responds “Nothing.” Following or preceding the response, a brief period of confusion
is often experienced. According to Gazzaniga, it is this period of confusion that is most important. The
argument is that the person's right hemisphere knows the answer but cannot get it to the left
hemisphere where the verbal centers are located. Occasionally a patient would assume a position
associated with the word and then correctly verbalize the answer. For example, a patient might have
the word boxer delivered to the left visual field. He/she would answer, “I saw nothing,” appear
confused, assume the posture and mannerisms of a boxer, and finally say, “I saw the word boxer.”
If the visual stimulus is a color, the results are different. The patient shown a color to the right visual
field will show confusion and give incorrect responses, whereas the patient shown the color and asked,
for example, “Is it red?” will answer correctly about 50 percent of the time and incorrectly about 50
percent. When incorrect, the patient will again show confusion.
Gazzaniga often argues that we can experience these struggles between the hemispheres if we pay
attention. For example, sometimes one response will “feel” right, although another seems logical.
When playing “21,” many good players will hit a 16 even when it isn't logical because, “I had a
hunch!”
Mention should be made to the students that, although not uncommon, the surgery is performed only
on patients with little other hope. It is not done routinely or without carefully exploring many other
treatments first.
Gazzaniga, M.S. (1970). The bisected brain. New York: Appleton-Century-Crofts.
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Behavioral Neuroscience
Gazzaniga, M.S. (1983). Right hemisphere language following brain bisection: A 20-year
perspective. American Psychologist, 38, 520–537.
Gazzaniga, M.S. & LeDoux, J.E. (1978). The integrated mind. New York: Plenum.
Myers, R. E., & Sperry, R. W. (1958). Interhemispheric communication through the corpus
callosum. Archives of Neurology and Psychology, 80, 298-303.
6.
Growing Human Brain Cells. Researchers at the Johns Hopkins School of Medicine have reported
successfully growing human brain cells in their laboratory. The cells came from the cortex of an 18month-old girl who suffered uncontrollable seizures and had one-third of her right cortex removed.
The individual cells were soaked in a combination of growth hormones and nutrients. Researchers
believe that this approach will permit scientists to explore the causes of Alzheimer’s disease,
Huntington’s disease, and multiple sclerosis. Researchers are also excited at the prospect of being able
to introduce new genes into brain cells. For example, researchers are already attempting to insert a
gene to stimulate the production of dopamine into the brains of patients with Parkinson’s disease.
A window on the mind. Time, May 14, 1990, p. 66.
7.
Ethnicity as Viewed by Sociobiologists. The sociobiological perspective tries to explain human
behavior in terms of the Darwinian evolutionary theory. Since “culture” is generally seen as “learned
information,” and ethnic groups are seen as “culturally segregated groups,” most people do not see
any connection between the evolutionary theory and culture. However, Pierre van den Berghe (1981)
argues that most ethnic groups are kinship groups, and do claim a common ancestry, however
“mythical” it might appear to be.
In 1973, Cavelli-Sforza and Feldman linked the study of cultural transmission and evolution. Since
then the field has expanded, and in 1981 Lumsden and Wilson, two biologists, proposed a
mathematical model known as the Gene-Culture Co-evolution Model (Laland, 1993). They argue that
interaction between genetic and cultural transmission makes culture itself an evolutionary process.
Cultural variants are generated, selected, and socially transmitted by an interaction between the
environment and co-existing selection pressures. They see culture as generated by biological
imperatives, while biological traits are simultaneously altered by genetic evolution in response to
cultural innovation.
A culturegen is defined as a unit of culture, and according to this theory, the rate at which individuals
adopt alternative culturegens is determined by the product of an innate bias for one’s existing culture,
and a bias for the other “to be adopted” culture. The theory states that as more people adopt one
culturegen, the probability of others adopting it increases exponentially. A genotype's “fitness” is seen
as the function of the resources (food, etc.) it gathers versus the cost of building and running the
appropriate brain structures. “Fitness” is seen as reproductive ability. Sociobiologists also hold as
credible the principle delineated by Edward O. Wilson, which states that the rate of change in a
particular set of cultural behaviors reflects the rate of change in the environmental features to which it
was keyed.
Although all of the above thoughts and arguments are rational and profound, there are curious cultures
which seem to have overcome these natural predispositions. In Japan, for example, a man’s loyalties
lie more to his employer, or his neighbor, or people who live in the same housing unit, than to his
blood relatives (Nakane, 1963). Psychologists with a predominantly sociobiological viewpoint would
have a hard time explaining such extreme cultural variations, based on “survival of the gene pool,” or
“behaviors being keyed to environmental factors.”
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Chapter Three
Going back to van den Berghe’s argument given above, since different cultural groups do claim
different mythical ancestors, it might indeed help all of us if we knew more about those myths. In this
predominantly Judeo-Christian culture many students, especially those who rely heavily on the Bible,
see Adam and Eve as the ancestral pair, and often are unaware of “origin myths” from other cultures.
An interesting discussion can be generated if the instructor mentions a couple of other creation myths,
held dear by other cultures and claimed to be “revealed truths.”
For example, the Japanese claim descent from twin parents Izanagi and Izanami (Pigott, 1987), the Lo
Dagaa of West Africa believe that Mankind was made from mud and okra seeds by God (Linton,
1945), and according to the Yoruba myth, the world was created by Olorun in four days, which
explains their four-day workweek, and Man was made of clay. The Central Australian Aranda on the
other hand tell it like it is. They claim descent from a giant, red-skinned god with emu’s feet, and a
retinue of wives who had dog’s feet! (Duffell, 1960). In Tahiti, Mankind descended from Ta’aroa,
who made himself, an artisan god Tu, and mother goddess named Hina. After he created man, Ta’aroa
shook off the red and yellow feathers growing from his own body, and these became plants growing
on the land (Oliver, 1974). The Rig Veda from India gives several myths, but also says “whence this
creation came from, nobody knows” (Radhakrishnan & Moore, 1957).
According to sociobiologists, ethnocentrism and the formation of ethnic groups can be explained by
evolutionary mechanisms, if we consider the survival of the gene pool rather than the survival of the
individual. They argue that the ultimate unit of replication is the gene rather than the organism. The
existence of an organism comes to an end, but his genes can continue almost forever through his
offspring. Likewise, even if an organism dies in his effort to save his own kin, he ensures the survival
of his gene pool. Therefore, genes that carry a trait for “nepotism” are selected because their survival
is ensured via the kin of a nepotistic organism, even if it be at the cost of individual organisms.
In small social groups, humans decide who their kin are based on direct knowledge. In large social
groups, they determine their kin by phenotype. Even though all living things must ultimately have
some common ancestor, the ecological niche in which we live brings about morphologically different
forms. The phenotype, then, is due to an interaction between the genotype and the environment. There
is a significant amount of evidence that in hot, dry climates, the physique tends to become linear, and
increased lung capacity is seen in high altitudes, etc. (Dawson-Binnie et al., 1981). Most humans
select phenotypically similar people to lavish their “nepotism” on. In environments where there is
fierce competition for scarce resources, people “share” these with their kin, and eliminate non-kin
from competition primarily to ensure reproductive continuity. The entire process of acculturation is
seen as adapting to circumstances in such a way as to foster reproductive success of phenotypically
similar organisms first and individual organisms next, while competing for scarce resources.
Currently, some nations such as China have curtailed human reproduction by imposing and rigorously
enforcing a one child per couple limit. Under such circumstances, the few children become the
precious carriers of reproductive success. In an environment of fierce competition for dwindling
resources, it becomes imperative that the child become successful. Apparently the behavior of some
parents in China is reflecting the results of the enforcement of a “one child per couple” constraint.
Here is the real-life story of Xia Hui, as reported by Er Xia (1993).
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Behavioral Neuroscience
One child, Xia Hui, stopped to play at a factory on his way to school. The guard at the factory
confiscated his satchel, so instead of going to school without his books, the child returned home. That
evening, when the child’s father went to pick him up from school, he learned of the child’s absence
that day. When he returned home, as punishment, he tied a nylon rope round the boy’s chest and
hoisted him to the ceiling rafter. The father then hurriedly got on his bike, and rode to the factory to
retrieve the child's school satchel from the guard! In the meantime the child must have tried to escape,
for when the father came home, he discovered that the rope had slid round the child's neck, and the
child was dead.
Er Xia (1993), argues that a combination of the excessive importance given to doing well in school,
and the fact that a parent has only one child to continue the family lineage, that brought about the
tragedy. He also finds that poor understanding of children’s needs and abilities is driving Chinese
parents to excesses; a recent survey in Shanghai found that over 90% of Chinese school children take
extra classes after the long school day to become proficient in either school work or other arts, in lieu
of relaxing or playing.
Dawson-Binnie, J.K.M., Blowers, G.H., & Hoosain, R. (1981). Perspectives in asian crosscultural psychology. Lisse: Swets & Zeitlinger.
Laland, K.N. (1993). The mathematical modeling of human culture and its implications for
psychology and the human sciences. British Journal of Psychology, 84, 145-169.
Linton, R. (1945). The cultural background of personality. New York: Appleton-Century-Crofts.
Nakane, C. (1963). Japanese society. Berkeley: University of California Press.
Oliver, D.L. (1974). Ancient Tahitian society. Honolulu: The University Press of Hawaii.
Pigott, J. (1987). Japanese mythology. New York: Peer Bedrick Books.
Radhakrishnan, S. & Moore, C.A. (1957). A source book in Indian philosophy. Princeton, NJ:
Princeton University Press.
van den Berghe, P.L. (1981). The ethnic phenomenon. New York: Elsevier.
Xia, E. (1983). Who killed Xia Hui? China Today. North American edition. XUI (5) May.
8.
The Developing Brain. Researchers are beginning to appreciate how the environment influences the
hardwiring of the brain. In recognizing the importance of the environment, they are likewise
suggesting that there are critical periods during which the environment has the opportunity to
influence brain development. For example, it is widely held that the circuitry for vision undergoes a
growth spurt in infants between 2 and 4 months of age and peaks at 8 months, when each neuron is
connected to 15,000 other neurons. A baby who has cataracts that are not removed before the age of 2
will be blind forever. Researchers believe that the cerebral development of cognitive abilities is
similar to sensory abilities.
With regard to language abilities, dedicated circuits in the auditory cortex corresponding to phonemes
the child hears repeatedly are wired by the age of 1. By 6 months of age, infants in English-speaking
homes have different auditory maps than those in Swedish-speaking homes. Children thus become
functionally deaf to sounds absent from their native tongue. These findings have important
implications for learning a second language. The perceptual map of the first language potentially
constrains the ability to learn a second language. The clear implication: introduce the second language
as early as possible.
Similarly dramatic findings are found with regard to musical ability. MRI research from Germany
suggests that the amount of somoatosensory cortex dedicated to the fingering digits of string players
was significantly larger than those of nonplayers. The key factor in the development of this cortical
map was not the amount of daily practice time, but the age at which the child was introduced to the
instrument.
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Chapter Three
Research at U.C. Irvine suggests a “Mozart effect.” Preschoolers given piano or singing lessons
dramatically improved in spatial reasoning compared with a control group. Similar research supports
an environmental influence on the development of emotions and on physical movement.
Discuss the implications of this type of research, especially on public policy in the schools. How
important are music and P.E.? Do schools wait too long to begin instruction in second languages?
Sharon Begley. (February 2, 1996). Your child’s brain. Newsweek, pp. 55–62.
9.
Hippocampus. The hippocampus, a structure in the limbic system, is important for the storage of new
explicit memories, such as people, places, and things. If the hippocampus is damaged, the individual
is stuck in the past and a present that lasts but a few minutes. Oliver Sacks reports on a man named
Jimmie who developed Korsakof’s syndrome; Korsakof’s results from heavy alcohol use. Jimmie,
because of the damage to his hippocampus, was unable to form new memories. He can tell you about
his past and what happened a couple minutes ago, but nothing in between. Interestingly, Jimmie could
learn how to do things without knowing he had done so. For instance, he was given a paper and pencil
maze and asked to solve it. After Jimmie solved it, the maze was taken away. A few minutes later he
was given another copy of the same maze. Jimmie had no knowledge that he had seen the maze, yet
he solved it faster. On repeated trials, he continued to solve it faster. Our memories for how to do
things--implicit memory--appears to be stored by the cerebellum rather than the hippocampus.
Ask students, “If you were unable to form new memories, would you ever change?”
Sacks, O. W. (1998). The man who mistook his wife for a hat and other clinical tales. New York:
Simon & Schuster.
10. Stem Cell Research. Stem cell research has come under fire in the U.S. “Stem cells are building blocks
for all human tissue, and scientists say research with them could lead to revolutionary therapies. The most
useful cells are derived from embryos discarded at fertility clinics, and abortion opponents say it is wrong
to use them for research.” Stem cells can become neurons, potentially providing ways to alleviate the
symptoms of diseases such as Alzheimer’s and Parkinson’s.
“Congress has barred federal money for research that destroys embryos, but the Clinton administration
concluded that the National Institutes of Health could pay for research using cells that had been extracted
with private money… The Bush administration remains undecided whether to allow continued funding,
although President Bush has suggested that he opposes it.”
After discussing the chapter, ask your students where they stand on this issue and why.
AP. (March 8, 2001). “H.H.S. Secretary Troubled by Stem Cell Ban.” New York Times.
11. Spinal Cord Repair. Why neurons are unable to repair themselves remains a mystery. Researchers,
undaunted, are looking for ways to encourage neuronal regeneration. “Molecules in the myelin, a jellylike
substance that encases and insulates nerves in the spine, inhibit these cells from regenerating.” Sam David,
McGill University, has developed a vaccine made from myelin. When vaccinated mice had the nerves that
control a foot reflex severed, “more than half the immunized mice regenerated some of their spinal-cord
nerves and regained the lost reflex.” There is a concern that the vaccination may cause the immune system
to attack healthy myelin. “David plans to focus the vaccine so that it targets only the inhibitor molecules,
not the myelin itself” (Glausiusz, 2000).
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Behavioral Neuroscience
In the meantime, giving methylprednisolone within 3 hours, but no later than 8 hours, of a spinal cord
injury, greatly reduces the amount of damage done to the spinal cord. Why, isn’t exactly clear, but there
appear to be two mechanisms of action. First, methylprednisolone acts to suppress the immune system,
reducing swelling around the site of the injury, swelling that could further damage the spinal cord. Second,
it may block the formation of free radicals, ions that form at the site of the injury and wreak havoc on the
nearby healthy cells.
Current Treatment for Human Spinal Cord Injury. Washington, DC: National Institutes of Health.
Retrieved March 11, 2001, from the World Wide Web:
http://science-education.nih.gov/nihHTML/ose/snapshots/multimedia/ritn/spinal/current.html
Glausiusz, J. (2000). “This is Spinal Vac.” Discover, 21(5).
Classroom Activities
1.
The Neuron. I found that some students were having a rough time understanding neurons and how
they work, so I devised a fairly simple, get-the-students-involved type of demonstration.
Materials needed: one deck of playing cards, one bag of Hershey Kisses per class, one bag of Hershey
Hugs (optional), one bag of Hershey Kisses with Almonds (optional)
I have five students who are willing to eat chocolate come to the front of the room (four represent
dendrites and one the cell body). I pull another five or so from the class to act as the axon, and two or
three more to act as terminal fibers. If you have enough students and space to form another neuron,
arrange them so that the terminal fibers of your first neuron are near the dendrites and cell body of
your second neuron.
Acting as a nearby neuron, I toss Hershey Kisses (neurotransmitter) in the direction of the dendrites
and cell body (into the synapse). The dendrites and cell body pick up the kisses and pop them in their
mouths followed by picking up one of several cards (positive ions) I have tossed around the room.
When neurotransmitter enters the receptor site, a chemical change takes place, allowing the membrane
to open up and the positive ions to flow in.
Once three cards (positive ions) have been picked up, the neuron reaches threshold (demonstrating
both the concept of threshold and the all-or-none response), and the first person in the axon picks up a
card (positive ions flow into the first segment of the axon). The dendrites and cell body drop their
cards. The next person in the axon picks up a card, the first person drops theirs, and so on down the
line. Once the end of the axon has been reached, the terminal fibers toss the Hershey Kisses
(neurotransmitter) they've been given in the direction of the dendrites and cell body of the nearby
neuron, repeating the process.
Then you could use Hershey Kisses with different wrappers to illustrate agonistic and antagonistic
drugs. I use Hugs (silver wrappers, brown stripes) as agonists and Hershey Kisses with Almonds
(gold wrapper) as antagonists. And if you’re feeling particularly into it, you could wrap a couple of
sections of your axon in plastic (myelin) to demonstrate how the signal would be sent more quickly.
To illustrate reuptake, have students imagine the terminal fibers pulling out vacuum cleaners to sweep
up the excess neurotransmitter from the synaptic gap. You may describe the enzyme action in the
synaptic gap as rats eating up what’s left. Afterward, I toss up the overheads and again draw the
connections between the demonstration and the neuron itself.
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Chapter Three
(A version of this demonstration was presented as a poster titled “The Students as Neuron: A
Classroom Demonstration” at the American Psychological Society’s Institute on the Teaching of
Psychology, Washington, D.C., May 1997.)
Experiencing Psychology: What are the functions of brain structures?
Using pencils of different colors, modeling clay of different colors, and any reference material you require,
draw and sculpt the following brain structures. Use different colors for the different structures. Write a
description of the functions of each of the structures. This exercise will reinforce what you have learned
from class lectures and the textbook by providing you with two-dimensional, three-dimensional, and verbal
understanding of the major brain structures and their functions.
1. Cerebral Cortex Structures
a. The corpus callosum
b. The language areas
c. The sensory areas
d. The motor areas
2. Limbic System Structures
a. The hippocampus
b. The amygdala
c. The hypothalamus
3. Brainstem Structures
a. The thalamus
b. The cerebellum
c. The pons
Critical Thinking Questions
1.
What are the implications of the research regarding identical twins reared apart?
2.
Neurons are not able to regenerate. What might be the evolutionary advantage to this?
3.
What are the evolutionary advantages and disadvantages of having specialized functions in various
parts of the brain?
4.
Why have the notions about hemispheric specialization (right-brained and left-brained functions)
become so popular with the public?
5.
What are the advantages of humans having an autonomic system that operates largely automatically?
6.
Imagine taking a bite of pizza. Briefly discuss the role that each part of the brain plays in this simple
act.
Video/Media Suggestions
Advancements in traumatic brain injury. (Films for the Humanities and Sciences, 1996, 18 minutes) Dr.
George Zitnay, president of the Brain Injury Association, and other experts discuss the various types
of brain injuries within the context of new diagnostic methods and treatments.
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Behavioral Neuroscience
Alzheimer’s: The tangled mind. (Films for the Humanities and Sciences, 1997, 23 minutes) Researchers
discuss how new drugs, close to approval, and old drugs, such as anti-inflammatories, are being used
to alleviate symptoms of Alzheimer’s disease.
49
Chapter Three
The central nervous system and brain. (Insight Media, 1997, 29 minutes) Presents the primary
components of the human central nervous system. Identifies the main structures of the brain and
explains their roles in controlling body systems and maintaining homeostasis. Also examines the
effects of physical injury, chemical imbalances, and drug usage on the brain.
Journey to the centers of the brain. (Films for the Humanities and Sciences) A series of five videos that
explores what we know and what mysteries remain in our efforts to understand the brain. Includes
the following:
The electric ape. Demonstrates what the brain looks like, how it generates electricity, and how it uses
chemicals to process information.
Through a glass darkly. Discusses the development of the increasingly sophisticated techniques used
to observe the living brain.
Bubble, bubble, toil and trouble. Describes the activities of the neuron, communication between
neurons, neuronal response to drugs, and so on.
The seven ages of the brain. Focuses on brain development, progressing from a fertilized egg
through old age.
The mind’s I. Through examples of memory and language, demonstrates that, although the brain can
be divided into regions, these regions are not independent; they work together as a cohesive
whole.
Nerve impulse conduction. (Insight Media, 1997, 29 minutes) Explores the electrochemical nature of
nerve impulse conduction and transmission. Uses simulations to analyze the different stages of
membrane potential and presents research on how chemicals affect membrane potential.
The peripheral nervous system. (Insight Media, 1997, 29 minutes) Illustrates how the human body senses
and responds to its internal and external environments. Describes the structures and functions of the
peripheral nervous system, examines current research on nerve regeneration, and reveals how
polygraphs and biofeedback apparatus measure responses of the autonomic nervous system.
References
Farah, M.T. & Feinberg, T. (Eds.) (2000). Patient-based approaches to cognitive neuroscience.
Cambridge, MA: MIT Press.
Gazzaniga, M. S. (1998). The mind’s past. Berkeley, CA: University of California Press.
Gazzaniga, M. S. (Ed.) (2000). The new cognitive neurosciences. Cambridge, MA: MIT Press.
Gazzaniga, M. S., Ivry, R.B. & Mangun, G.R. (1998). Cognitive neuroscience: The biology of the mind.
New York : W.W. Norton.
Gazzaniga, M. S., & LeDoux, J. E. (1978). The integrated mind. New York: Plenum.
Greenfield, S. (1998). The human brain. New York: Basic Books.
Gross, C.G. (1999). Brain, vision, memory: Tales in the history of neuroscience. Cambridge, MA: MIT
Press.
LeDoux, J. (1996). The emotional brain: The mysterious underpinnings of emotional life. New York:
Simon & Schuster.
Ramachandran, V.S. & Blakeslee, S. (1998). Phantoms in the brain: Probing the mysteries of the human
mind. New York : William Morrow.
Sacks, O. W. (1995). An anthropologist on Mars: Seven paradoxical tales. New York: Knopf.
Sacks, O. W. (1998). The man who mistook his wife for a hat and other clinical tales. New York: Simon
& Schuster.
Schacter, D.L. (1996). Searching for memory: The brain, the mind, and the past. New York: Basic
Books.
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Sources of Biographical Information
Finger, S. (2000). Minds behind the brain. New York: Oxford University Press.
Koenigsberg, L. (1906/1965). Hermann von Helmholtz. New York: Dover.
Lewis, J. (1981). Something hidden: A biography of Wilder Penfield. Garden City, NY: Doubleday.
Macmillan, M. (2000). An odd kind of fame: Stories of Phineas Gage. Cambridge, MA: MIT Press.
O’Connor, W. J. (1988). Founders of British physiology: A biographical dictionary, 1820-1885. New
York: St. Martin’s Press.
Olmsted, J. M. D. (1945/1981). Francois Magendie. New York: Arno.
Ramon y Cajal, S. (1937/1989). Recollections of my life. Cambridge, MA: MIT Press.
Schiller, F. (1979). Paul Broca: Founder of French anthropology, explorer of the brain. Berkeley, CA:
University of California Press.
Skelton, R. (1987). Charles Darwin. Hauppauge, NY: Barron.
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