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The Mind-Brain Relationship
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Biological Psychology is the study of the physiological and genetic basis of behavior.
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Emphasis is placed upon physiological, evolutionary and developmental mechanisms of
behavior.
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A strong emphasis is placed upon brain functioning.
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The Mind-Brain Relationship
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Brain functioning can be explained at a more microscopic level in terms of neuron and glia
activity.
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The Mind-Brain Relationship
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Biological explanations of behavior fall into four categories:
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Physiological- emphasis on brain and other vital organs.
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Ontogenetic- describes the development of a structure or behavior.
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Evolutionary- focuses upon the evolutionary history of a behavior.
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Functional- describes why a structure or behavior evolved as it did.
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Mind – Brain
Physiological
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Mind – Brain
Ontogenetic
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Mind – Brain
Evolutionary
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Mind – Brain
Functional
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Chapter 1
The Major Issues
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The Mind-Brain Relationship
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Deep understanding of a particular behavior is tied to being able to explain the behavior from
each of these perspectives.
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The Mind-Brain Relationship
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Biological explanations of behavior raise the issue of the relationship between the mind and the
brain also know as the “mind-body” or “mind-brain problem”.
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The “mind-brain problem” has a variety of explanations.
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The Mind-Brain Relationship
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Dualism is the belief that there are different kinds of substances and the mind and the body are
separate entities.
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Defended by French philosopher Rene Descartes.
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Most common belief among nonscientists.
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Rejected by most neuroscientists.
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The Mind-Brain Relationship
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Monism is the belief that the universe is only comprised of one type of substance.
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Forms of monism include:
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Materialism- everything that exists is physical by nature.
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Mentalism- only the mind truly exists.
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Identity position- mental processes are the same as brain processes but simply
described in different ways.
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Mind – Brain
Monism
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Materialism – everything is physical by nature
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Mind – Brain
Monism
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Mentalism – Only the mind truly exists. George Berkeley said that the mind is everything,
nothing else really exists.
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Mind – Brain
Identity position
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The Mind-Brain Relationship
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Explanations of the mind-body relationship do not answer some fundamental questions:
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Why is consciousness a property of brain activity?
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What kind of brain activity produces consciousness?
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How does brain activity produce consciousness?
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The Mind-Brain Relationship
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Because “consciousness” is not observable, it’s function is often difficult to define and/ or
explain.
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Solipsism- suggests that “I alone” am conscious
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Difficulty of knowing if others have conscious experiences is known as the “problem of
other minds”.
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The Mind-Brain Relationship
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Chalmers (1995) proposes two problems that must be distinguished when discussing
consciousness:
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Easy problems - focus on differences in conscious states and their mechanisms.
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Hard problems - focus on why and how brain activity is associated with consciousness.
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The Mind-Brain Relationship
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Research approaches to the “hard problems” include:
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Using brain scan techniques to identify specific regions of the brain and the
corresponding amount of activity when a stimulus is consciously detected.
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Monitoring brain activity
when attention is directed
or focused upon varying
competing stimuli.
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The Mind-Brain Relationship
Careers
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Research
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Need Ph.D.
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Hold college or university position
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Or work at government or drug company lab
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May work at lab with only master’s
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Need to read Journals like Neurology, Behavioral Neuroscience and Brain Research
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The Genetics of Behavior
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The Genetics of Behavior
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19th century monk Gregor Mendel demonstrated that inheritance occurs through genes.
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Genes are basic units of heredity that maintain their structural identity from one generation to
another.
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Genes are aligned along chromosomes (strands of genes) and come in pairs.
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The Genetics of Behavior
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A gene is a portion of a chromosome and is composed of deoxyribonucleic acid (DNA).
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The Genetics of Behavior
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RNA is a single strand chemical that can serve as a template/ model for the synthesis of
proteins.
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Proteins determine the development of the body by:
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forming part of the structure of the body.
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serving as enzymes that serve as biological catalysts and regulate chemical reaction in
the body.
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The Genetics of Behavior
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Homozygous for a gene means that a person has an identical pair of genes on the two
chromosomes.
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Heterozygous for a gene means that a person has an unmatched pair of genes on the two
chromosomes.
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The Genetics of Behavior
Dominant-Recessive principle
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Genes are either dominant, recessive or intermediate.
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Examples: eye color, ability to taste PTC
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A dominant gene shows a strong effect in either the homozygous or heterozygous condition.
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A recessive gene shows its effect only in the homozygous condition.
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The Genetics of Behavior
Homozygous and Heterozygous
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The Genetics of Behavior
Chromosomes
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Each chromosome participates in reproduction independently of the others.
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Each species has a certain number of chromosomes.
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Crossing over occurs during meiosis when a pair of chromosomes break apart during
reproduction and reconnects and attaches to the second chromosome.
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BC & bc  Bc & bC
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The Genetics of Behavior
Crossing over
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The Genetics of Behavior
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Types of genes include:
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Autosomal genes - all genes except for sex- linked genes.
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Sex-linked genes - genes located on the sex chromosomes.
In mammals, the sex chromosomes are designated X & Y.
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Females have two X chromosomes (XX).
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Males have an X and a Y chromosome (XY).
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The Genetics of Behavior
Karyotype of a male human
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The Genetics of Behavior
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During reproduction:
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Females contribute an X chromosome.
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Males contribute either an X or a Y chromosome that determines the sex of the child.
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If an X chromosome is contributed by the male, the off-spring is female.
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If a Y chromosome is contributed by the male, the off-spring will be male.
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The Genetics of Behavior
Sex linked traits
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The Genetics of Behavior
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Sex linked are those that are located on X and Y chromosomes
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Sex-limited genes are genes that are present in both sexes but mainly have an effect on one sex
(Chest hair, breast size, etc.). Sex limited are those traits that are affected by being male or
female.
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The Genetics of Behavior
Sources of variation in a species that allows for evolution to occur include:
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Recombination refers to a new combination of genes in the off-spring that yield characteristics
not found in either parent.
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Mutation refers to a change in a single gene that is rare, random and often independent of the
needs of the organism.
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The Genetics of Behavior
Recombination
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The Genetics of Behavior
Mutation
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The Genetics of Behavior
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Almost all behaviors have both a genetic component and an environmental component.
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Researchers study monozygotic and fraternal twins to infer how much of a genetic component
exists for a particular behavior.
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Researchers also study adopted children and their resemblance to their biological parents
versus adoptive parents to infer the influence of heredity.
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The Genetics of Behavior
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The Genetics of Behavior
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Estimates of hereditary influences are often difficult to infer and are prone to error.
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Sources of error include the following:
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The inability to distinguish between the effects of genes and prenatal influences.
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Environmental factors can inactivate genes.
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The Genetics of Behavior
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Sources of error (con’t)
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Multiplier effect – genetic tendencies that guide behavior will result in a change in the
environment that magnifies the original tendency.
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Traits with a strong hereditary influence can by modified by environmental intervention.
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Eg. “elevated plus maze”, PKU
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The Genetics of Behavior
Genes  Behavior
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Genes do not directly produce behaviors (think back to the beginning of this section).
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Genes produce proteins that increase the probability that a behavior will develop under certain
circumstances.
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Genes can also have an indirect affect.
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Genes can alter your environment by producing behaviors or traits that alter how
people in your environment react to you.
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The Genetics of Behavior
Scarr - Influence of Genes on the Environment
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Passive – Parents who give you your genes also shape your environment
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Evocative – as you grow adults around you realize your potential – your genes evoke an
appropriate response from the environment that fosters them
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Active – as you grow into adulthood you actively seek out environments that foster your
particular talents etc.
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The Genetics of Behavior
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Evolution refers to a change in the frequency of various genes in a population over generations
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Evolution attempts to answer two questions:
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How did some species evolve?
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How do species evolve?
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The Genetics of Behavior
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How species did evolve involves the tentative construction of “evolutionary trees”.
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The Genetics of Behavior
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How species do evolve rests upon some assumptions:
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Offspring generally resemble their parents for genetic reasons.
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Mutations and recombination of genes introduce new heritable variations that help or
harm the chance of survival and reproduction.
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Certain individuals successfully reproduce more than others do.
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The Genetic of Behavior
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Common misconceptions about evolution include the following:
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Lamarckian evolution - “The use or disuse of some structure or behavior causes an
increase or decrease in that behavior.”
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“Humans have stopped evolving.”
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“Evolution means improvement.”
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“Evolution acts to benefit the individual or the species.”
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The Genetics of Behavior
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Evolutionary psychology (sociobiology) focuses upon functional explanations of how behaviors
evolved.
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Assumes that behaviors characteristic of a species have arisen through natural selection and
provide a survival advantage.
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Examples: differences in peripheral/color vision, sleep mechanisms in the brain, eating
habits, temperature regulation.
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The Genetics of Behavior
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Some behaviors are more debatable regarding the influence of natural selection.
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Examples include:
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Life span length
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Gender differences in sexual promiscuity
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Altruistic behavior – a behavior that benefits someone other than the actor
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Explanations: reciprocal altruism & kin selection
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The Use of Animals in Research
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Animal research is an important source of information for biological psychology but remains a
highly controversial topic.
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Animal research varies on the amount of stress and/ or pain that is caused to the animal itself.
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The Use of Animals in Research
Reasons for studying animals include:
1. The underlying mechanisms of behavior are similar across species and often easier to
study in nonhuman species because
a. Animals have simpler structures
b. Animals have shorter lifespans
2. We are interested in animals for their own sake.
3. What we learn about animals sheds light on human evolution.
4. Some experiments cannot use humans because of legal or ethical reasons.
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The Use of Animals in Research
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Opposition to animal research varies:
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“Minimalists” favor firm regulation on research and place consideration upon the type
of animal used and the amount of stress induced.
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“Abolitionists” maintain that all animals have the same rights as humans and any use of
animals is unethical.
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The Use of Animals in Research
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Justification for research considers the amount of benefit gained compared to the amount of
distress caused to the animal.
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No clear dividing line exists.
Colleges and research institutions in the United States are required to have an Institutional
Animal Care and Use Committee.
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Oversees and determine acceptable procedures.