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CHAPTER 1
WHAT IS BIOPSYCHOLOGY?
The Origins of Biopsychology
Nature and Nurture
THE ORIGINS OF BIOPSYCHOLOGY
• Neuroscience is the study of the nervous system and its role in behavior.
– This identifies the subject matter of the investigation rather than the scientist’s training.
• Biopsychology is the branch of psychology that studies the relationship between behavior and the body, particularly
the brain.
– Biopsychologists try to go beyond the mechanisms of how the brain works and focus on the brain’s role in behavior.
THE ORIGINS OF BIOPSYCHOLOGY
• In 1879, Wilhelm Wundt established the first psychology laboratory in Leipzig, Germany, cementing psychology as its
own discipline.
– Before biological psychology could emerge as a separate subdiscipline, evidence would have to be offered that the
biological approach could answer significant questions about behavior.
THE ORIGINS OF BIOPSYCHOLOGY
• The mind-brain problem deals with what the mind is and what its relationship is to the brain.
• Neuroscientists believe we should think of the mind as simply a collection of things that the brain does, like thinking,
sensing, planning and feeling.
– The impression is that a mind is just an illusion, a sense of mind is nothing more than the awareness of what the
brain is doing.
THE ORIGINS OF BIOPSYCHOLOGY
• Monism is the idea that the mind and the body consist of the same substance.
– Idealism - everything is the non-physical mind.
– Materialism - the body and mind are physical.
• Dualism is the idea that the mind and the brain are separate.
– The mind is nonmaterial and the body is material.
– The mind influences behavior by interacting with the brain.
THE ORIGINS OF BIOPSYCHOLOGY
• A model is a proposed mechanism for how something works.
– Scientists often resort to the use of models to understand whatever they are studying.
• A model can be in the form of a theory.
• A model can also be a simpler organism or system that researchers study in an attempt to understand a more complex
one.
THE ORIGINS OF BIOPSYCHOLOGY
• Descartes reasoned through his use of a hydraulic model that sensations, memories and other mental functions were
produced as animal spirits flowed through “pores” in the brain controlled by the pineal gland.
• He believed the pineal gland was the “seat of the soul,” the place where the mind interacted with the
body.
THE ORIGINS OF BIOPSYCHOLOGY
• Descartes’ lack of anatomical knowledge illustrated how a model or theory can lead researchers astray.
• Empiricism refers to testing ideas through direct observation and experimental manipulation rather than logic, intuition
or other means.
THE ORIGINS OF BIOPSYCHOLOGY
• Luigi Galvani (1700s), and later Guztav Fritsch and Eduard Hitzig (1870) showed
that nerves operated by electricity.
• Hermann von Helmholtz demonstrated that it was not in fact electricity, but neural conduction was a biological phenomenon,
which opened up the functioning of nerves and the brain to scientific study.
THE ORIGINS OF BIOPSYCHOLOGY
• Localization is the idea that specific areas of the brain carry out specific functions.
– Developed from the case of Phineas Gage, and Paul Broca’s discovery of the area in the left side of the brain
responsible for the ability to speak.
• Phrenology, developed by Franz Gall, is the idea that each of the 35 different “faculties” of emotion
and intellect are located in a precise area of the brain.
THE ORIGINS OF BIOPSYCHOLOGY
• Equipotentiality, a position Karl Lashley researched, holds that the brain functions as an undifferentiated whole.
– The extent of the damage, not the location, determines how much function is lost.
• Today’s research tells us that functions are as much distributed as they are localized.
– Behavior results from the interaction of many widespread areas of the brain.
NATURE AND NURTURE
• The nature versus nurture question asks how important heredity is compared to environmental influences in shaping
behavior.
NATURE AND NURTURE
• The gene is the biological unit that directs cellular processes and transmits inherited characteristics.
• Genes are located on chromosomes within the nucleus of a cell, although a few can be found within mitochondria.
– Every human body cell has 46 chromosomes arranged in 23 pairs, including sex chromosomes designated X or Y.
– XX indicates female, XY indicates male.
NATURE AND NURTURE
• Each fertilized egg, or zygote, receives 23 chromosomes from the male parent’s sperm cell and 23 chromosomes
from the female parent’s ova (egg cell), which merge to restore the chromosome number to 46.
• The new organism is referred to as an embryo for the first eight weeks of life, and as a fetus from then until birth.
NATURE AND NURTURE
• Genes are made of deoxyribonucleic acid (DNA), which is a double-stranded chain of chemical molecules that resembles
a ladder that has been twisted around itself.
– Each rung is composed of two of four bases: adenine, thymine, guanine and cytosine (A, T, G, C), ordered to form the
code that carries all our genetic information.
• Genes exert their influence simply by providing the directions for making proteins.
NATURE AND NURTURE
• Because chromosomes are paired, most genes are as well.
– A gene on one chromosome is matched up with one for the same function on the other chromosome.
• A dominant gene will produce its effect regardless of which gene it is paired with.
• A recessive gene will have an influence only when it is paired with the same recessive gene of the other chromosome.
• An X-linked characteristic is one produced by an unpaired gene on the X chromosome.
NATURE AND NURTURE
• Dominance and recessiveness can be illustrated through the results of two different matings of brown-eyed individuals.
– All four parents have brown eyes, but one has two genes for brown eyes and the other three have a gene for blue eyes
and a gene for brown eyes.
– The parent who has identical genes for eye color is homozygous for eye color.
– Each of the others has different genes for eye color and is heterozygous for eye color.
NATURE AND NURTURE
• In this case even though all four parents have the same phenotype (characteristic) of brown eyes, their genotypes
(combination of genes) are different.
– The first couple can produce only brown-eyed children because one parent has only dominant brown-eyed genes to offer.
– The second couple has one chance in four of producing a blue-eyed child.
– The heterozygous parents are carriers for blue eyes.
NATURE AND NURTURE
• Some genes blend their effects rather than showing dominance and recessiveness
– For example, type AB blood.
• Many characteristics are determined by several genes rather than a single gene pair – they are polygenic.
– For example, height and behavioral characteristics such as intelligence and psychological disorders.
NATURE AND NURTURE
• Genes do not provide the script for behaving intelligently or instructions for homosexual behavior.
• They control the production of proteins.
• The proteins in turn affect the development of brain structures, the production of neural transmitters and the receptors
that respond to them, and the functioning of the glandular system.
NATURE AND NURTURE
• In 1990 a consortium of geneticists at 20 laboratories around the world began a project to identify all the genes
in our chromosome, or the human genome.
• The goal of the International Human Genome Project (IHGP) was to map the location of all the genes on the human chromosomes,
and to determine the genes’ codes, that is, the order of bases within each gene.
NATURE AND NURTURE
• In 2000 the IHGP and a private organization simultaneously announced “rough drafts” of the human genome.
• Three years later the IHGP had brought the map to 99% completion and reduced the number of gaps from 150,000 to 341.
• The gene map doesn’t answer what genes do, but it does make it easier to find the genes responsible for a particular
disorder or behavior.
NATURE AND NURTURE
• Natural selection – those whose genes endow them with more adaptive capabilities are more likely to survive
and transmit their genes to more offspring.
NATURE AND NURTURE
• The effects of the genes themselves are not necessarily rigid; they can be variable over time and circumstances.
– A large number of genes change their functioning late in life.
– The functioning of some genes is even controlled by experience.
• Genes also have varying degrees of effects.
– Some determine the person’s characteristics and others only influence them.
NATURE AND NURTURE
• Heritability is the percentage of the variation in a characteristic that can be attributed to genetic factors.
• The calculation of heritability is based on a comparison of how often identical twins share the characteristic with
how often fraternal twins share the characteristic.
– The reason for this comparison is that identical twins develop from a single egg and therefore have the same genes,
while fraternal twins develop from separate eggs and share just 50 percent of their genes.
NATURE AND NURTURE
• Heritability is not an absolute measure, but tells us the proportion of genetic influence relative to the amount of
environmental influence.
• Vulnerability means that genes contribute a predisposition for the disorder which may or may not exceed the threshold
required to produce the disorder.
– For example, environmental challenges such as neglect or emotional trauma may combine with a person’s inherited
susceptibility to exceed that threshold.
NATURE AND NURTURE
• Psychologists no longer talk about heredity versus environment, as if the two are competing with each other for importance.
• Both are required, and they work together to make us what we are.
Chapter One
Biological Psychology
• Study of the physiological,
evolutionary, and developmental mechanisms of behavior and experience
– emphasis on the study
of areas and sub-areas of the brain
– brain area’s function
depends on communication among neurons, the “building blocks of behavior”
– neuron activity somehow
produces behavior and experience
Neroscience is multisciplinary
Biological Explanations of Behavior
• Physiological: relates
a behavior to the activity of the brain and other organs (area of brain enables bird to sing)
• Ontogenetic: describes
the development of the structure or behavior (why genes and environment both necessary for bird to sing)
• Evolutionary: examines
a structure or a behavior in terms of evolutionary history (two different species of birds with similar songs have same ancestor)
• Functional: describes
why a structure or behavior evolved as it did (singing improves bird’s chances of mating)
Mind-Body Problem
•
Dualism: mind and body are different kinds of substances, that exist independently but somehow
interact
–
René Descartes proposed that mind and brain interact in the pineal gland
•
Monism: there is only one kind of existence
–
materialism: everything is material or physical
–
mentalism: only the mind exists
–
identity: mental processes are the same thing as certain kinds of brain processes, but described
in different terms (e.g., fear is the same as the accompanying pattern of neural activity in the brain)
Mind-Body Problem cont.
• What is consciousness
and how is it produced?
• Hard problem: the question
of why and how any kind of brain activity is associated with consciousness
• Easy problems: determining
the difference between wakefulness and sleep, or identifying brain mechanisms that enable us to focus our attention
Mind-Body Problem cont.
• Research may not solve
problem soon because consciousness is not directly observable
– I know that I am conscious
but I can only infer that you have conscious experience
– solipsism: the belief
that only I exist
• Where and when does
consciousness occur?
– do all animals have
conscious experiences? plants? rocks?
– when does the human
embryo experience consciousness?
– could we build a robot
that experiences consciousness?
Models
Decartes and the Seat of the Soul
Picture of Decartes Model
Role of Brain in Behavior: Discovery
Localization and Phineas Gage
Localization
Genetics of Behavior
•
Mendel (19th century): inheritance occurs through genes
–
chromosomes are strands of genes, normally in pairs
–
genes are units of heredity that maintain their structural identity across generations
–
a genotype is an expression of a gene pair (e.g., BB, Bb, or bb)
•
Deoxyribonucleic acid (DNA):
–
when DNA exists as a double strand in a helix, it makes up a chromosome
–
when DNA exists in a single strand, it serves as a template for the synthesis of RNA
DNA/ RNA
How DNA controls the development of an organism. The sequence of bases along a strand
of DNA determines the order of bases along a strand of RNA; RNA in turn controls the sequence of amino acids in a protein
molecule.
Genetics of Behavior cont.
•
Genotype expression (B=brown eyes; b=blue eyes)
–
homozygous: having an identical pair of genes on two chromosomes (BB or bb)
–
heterozygous: having an unmatched pair of genes on two chromosomes (Bb)
–
dominant gene: expressed in either the homozygous or heterozygous condition (Bb or BB will be
expressed as brown eyes)
–
recessive gene: only expressed in the homozygous condition (bb is the only condition where blue
eyes will be expressed)
•
When genes are close together on the same chromosome they are usually inherited together, e.g.,
BC or bc
–
“crossing over” occurs during reproduction when a pair of chromosomes exchange parts
with each other, e.g., BC and bc become Bc and bC
•
Sex-linked genes on X and Y chromosomes
–
male (XY) has only one X chromosome and will always express X-linked recessive genes (8% have
red-green color blindness)
–
female (XX) will express a recessive gene only if it occurs on both of her X chromosomes (1% have
color blindness)
Genetics of Behavior cont.
• Sex-limited genes
X Linkage
– present in both sexes
but effect is limited or almost limited to one sex (chest hair, breast size)
– genes expressed only
after activation by sex hormones
• Sources of variation
– recombination: some
genes from two parents combine to yield characteristics not found in either parent
– mutation: a random change
in a single gene
– crossing over creates
unique characteristics not found in either parent
•
Heritability
–
an estimate of how much of the variance in a population characteristic is due to heredity (ranges
from 0 to 1)
–
if 0, heredity accounts for none of the observed variations in that characteristic (e.g., in a
population with similar genes, most differences are due to environment)
–
if 1, heredity accounts for all of the variations in that characteristic (e.g., in identical environments
most differences are due to genes)
–
if 0.5, both components contribute
• How heritability is
determined
– compare similarities
in monozygotic twins versus dizygotic twins
– compare adopted children
with their biological and adoptive parents
– findings support high
heritability in many areas but we may underestimate the effect of environment and interaction between geneotype and environment
Genetics of Behavior cont.
• Can heritability be
modified?
– PKU, caused by genetic
inability to metabolize phenylalanine, can be minimized with proper diet
Monozygotic and Dizygotic
Prenatal development of monozygotic and dizygotic twins. In most cases, monozygotic
(identical) twins develop in a single placenta and have the same blood supply. Dizygotic (fraternal) twins develop in separate
placentas. Therefore, monozygotic twins have the sane prenatal environment as well as the same genetic inheritance, and dizygotic
twins differ in both respects.
Evolution of Behavior
•
Change over generations in the frequencies of various genes in a population
•
Change occurs through mutations, recombinations and any new genes that are successfully reproduced
•
Artificial selection limits reproduction to animals that possess a desired trait, ensuring its
survival
Misunderstandings about Evolution
• “Lamarckian evolution”
is mistaken belief that we acquire characteristics through use and lose them through disuse.
• If “survival of
fittest” no longer applies, has evolution stopped?
– no, reproduction, not
survival is key
• Does evolution mean
improvement?
– maybe; your genes got
you here but they may not be advantageous tomorrow
• Does evolution act to
benefit the individual or the species?
– neither; it acts to
spread the genes
Careers in Biological Psychology
for Psychologists
• Behavioral neuroscientist:
investigates how functioning of the brain and other organisms affect behavior
• Neuroscientist: studies
anatomy, biochemistry, and physiology of the nervous system
• Neuropsychologist: conducts
behavioral tests to determine what brain damaged people can and cannot do
• Psychophysiologist:
measures heart rate, breathing rate brain waves, and other body processes that change as a function of people’s activities
and information processing
Careers in Biological Psychology
for Physicians (MDs)
• Neurologist: treats
people with brain damage or diseases of the brain
• Neurosurgeon: performs
brain surgery
• Psychiatrist: helps
people with emotional distress or troublesome behaviors, sometimes using drugs or other medical procedures
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