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Chapter 2

PSYB32H3 Chapter Notes - Chapter 2: Central Sulcus, Lateral Sulcus, Parietal Lobe

Course Code
Konstantine Zakzanis

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Chapter 2-Current Paradigms and the Role of Cultural Factors
The Role of Paradigms
A paradigm is a set of basic assumptions that outline the particular universe of scientific
inquiry (a conceptual framework)
They specify what problems scientists will investigate and how they will go about this
It injects particular biases into definitions and collection of data
The Biological Paradigm
The biological paradigm of abnormal behaviour is a continuation of the somotgenic
hypothesis. Holds that mental disorders are caused by biological processes.
Often referred to as the medical model, or disease model
For a time the germ theory was the paradigm of medicine, but it soon became evident
that this theory could not account for all diseases
Hall believed the removal of the ovarian cysts was a treatment for melancholia, mania,
and delusions
Contemporary Approaches to the Biological Paradigm
There are three areas within the biological paradigm: Behaviour genetics, molecular
genetics, and biochemistry
Behaviour Genetics
Each chromosome is made up of thousands of genesthe carrier for genetic info
Behaviour genetics is the study of individual differences in behaviour that are
attributable (in part) to individual differences in genetics
The total genetic makeup is the genotype
The phenotype is the observable behavioural characteristics
The phenotype changes over time and is viewed as the product of the genotype and the
Various clinical disorders are disorders of the phenotype
A predisposition (known as a diathesis) may be inherited but not the disorder itself
Weather the genotype will become a phenotypic disorder depends on environment and
The study of behaviour genetics has relied on four basic methods to uncover wether a
predisposition for a psychopathology is inherited: comparison of family, twins,
investigation of adoptees, and linkage analysis

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Family method used to study genetic predisposition of members of a family
On average siblings as well as parents and their children are identical in 50% of their
genetic backgroundknown as first-degree relatives
Nephews and nieces share 25% of the genetic makeup of an uncleknown as second-
degree relatives
The starting point of these investigations is a collection of people with the diagnosis in
question known as index cases or probands
If a genetic predisposition for the disorder being studied is present then the first degree
relatives of the index cases should have the disorder at a higher rate than the general
In the twin method, both monozygotic twins (MZ) and dizygotic twins (DZ) are
When twins are similar diagnostically they are said to be concordant
To the extent that a predisposition for a disorder can be inherited, concordance for the
disorder should be greater in the genetically identical MZ pairs
Twin studies depends on equal environment assumptionenvironmental factors that
are partial causes for concordance are equally influential for both MZ and DZ pairs (ex.
Equal number of stressful experiences)
The adoptees method studies children who were adopted and reared apart from their
parents with abnormal disorders. It eliminates the effects of being reared by disordered
If a high frequency of children reared apart from parents who have a disorder have a
disorder as well then there would be a genetic predisposition for the disorder
Molecular Genetics
Tries to specify the genes or genes involved
Allele refers to any one of several dNA codings that occupy the same position on a
chromosome. Genotype=set of alleles
Genetic polymorphism refers to variability among members of the same species
It involves differences in DNA sequences
Linkage analysis is a method in molecular genetics used to study people
Researches study blood samples from families in which a disorder is heavily
concentrated and study the inherited pattern of characteristics whose genetics are fully
understoodgenetic markers
If the occurrence of a psychopathology goes along with the occurrence of a genetic
marker than it is concluded that the gene predisposing individuals for the
psychopathology is located near the gene for the other characteristic (genetic marker)

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Gene environment interactionsthe notion that a disorder or related symptoms are
the joint product of genetic vulnerability and environmental experiences
Neuroscience and Biochemistry in the Nervous System
Each neuron has four major parts:
o Cell body
o Dendrites
o One or more axons
o Terminal buttons on end branches of axons
When a neuron is stimulated at the cell body/dendrites it sends a nerve impulsea
change in electric potential of the cell
Between the terminal buttons of the sending neuron and the membrane of the
receiving neuron there is a small gap known as a synapse
The terminal buttons contain structures that have neurotransmitterschemical
substances that allow a nerve impulse to cross the synapse
The cell membrane of the postsynaptic cell contains receptor sites that are configures so
specific neurotransmitters can fit
A message is sent to the postsynaptic neuron which can be excitory or inhibitory
Some remaining neurotransmitter is broken down by enzymes and some is pumped
back to presynaptic cell via reuptake
Norepinephrine is a neurotransmitter of the sympathetic nervous system and is involved
in producing high levels of arousal, thus it may be involved in anxiety disorders
Serotonin may be involved in depression and dopamine in schizophrenia. GABA inhibits
some nerve impulses and may be involved in anxiety disorders
The onset of puberty in adolescents results in a decrease in serotonin and a decrease in
dopamine activity contributing to a increased risk for psychopathology during
A given disorder is caused by too much or too little of a particular neurotransmitter
This could result from an error in the metabolic steps in the synthesis of a
A disturbance in the amount of a neurotransmitter can also occur when there is a failure
in reuptake leaving excess neurotransmitter molecules in the synapse
Some receptors are too numerous or too easily excited producing psychopathology (Ex.
There is an over-abundance of dopamine receptors in people with schizophrenia)
Structure and Function of The Human Brain
Brain is enveloped in three membranes known as meninges
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