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Chapter 2

Chapter 2: Current Paradigms & the Role of Cultural Factors

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Mark Schmuckler

B32: Abnormal Psychology Chapter 2: Current Paradigms & the Role of Cultural Factors Paradigm- set of basic assumptions, a general perspective, that defines how to conceptualize and study a subject, how to gather and interpret relevant data, even how to think about a particular subject; the conceptual framework or approach within which the scientist works. THE ROLE OF PARADIGMS Paradigms are a set of basic assumptions that outline the particular universe of scientific inquiry. Paradigms specify what problems scientists will investigate and how they will go about the investigation. o It injects inevitable biases into the definition and collection of data and may also affect the interpretation of facts. o There are five paradigms: Biological Psychoanalytic Humanistic and existential Learning Cognitive THE BIOLOGICAL PARADIGM Biological paradigm- a broad theoretical view that holds that mental disorders are caused by some abberant somatic process or defect. Aka medical model or disease model For a time, the germ theory was the paradigm of medicine, but it soon became apparent that this theory could not account for all diseases. Contemporary Approaches to the Biological Paradigm More sophisticated approaches are used today, and there is now an extensive literature on biological factors relevant to psychopathology. Heredity probably predisposes a person to have an increased risk of developing schizo, depression may result from chemical imbalances within the brain, anxiety disorders may stem from a defect within the autonomic nervous system that causes a person to be too easily aroused. There are 3 areas of research within this paradigm, in which the data are particularly interested: 1- behavior genetics 2- molecular genetics 3- biochemistry 1 www.notesolution.com Behaviour Genetics Chromosomes are made up of thousands of genes, the carriers of the genetic information (DNA) passed from parents to child. Beheaviour genetics- the study of individual differences in behaviour that are attributable in part to differences in genetic makeup. Genotype- an individuals unobservable, genetic constitution; the totality of genes possessed by an individual. Phenotype- the totality of observable characteristics of a person. The phenotype changes over time and is viewed as the product of an interaction between the genotype and the environment. Any measure of intelligence is best viewed as an index of the phenotype. It is critical to recognize that various clinical syndromes are disorders of the phenotype, not of the genotype. o Thus it is not correct to speak of the direct inheritance of schizo or anxiety disorders; at most only the genotypes for these disorders can be inherited o Whether these genotypes will eventually engender the phenotypic behaviour disorder will depend on environment and experience. o A predisposition, also known as a diathesis, may be inherited, but not the disorder itself. Four basic methods to uncover whether a predisposition for psychopathology is inherited: 1. family method 2. twin method 3. adoptees method 4. linkage analysis 1. Family Method family method- a research strategy in behaviour genetics in which the frequency of a trait or of abnormal behaviour is determined in relatives who have varying percentages of shared genetic background. On average, siblings as well as parents and their children are identical in 50% of their genetic background. o People who share 50% of their genes with a given individual are called first-degree relatives of that person. o Newphews and nieces share 25% of their genetic makeup of an uncle and are called second degree relatives The starting point in such investigations is the collection of a sample of individuals who bear the diagnosis in question. o These people are referred to as index cases, or probands. index cases (probands)- the person who in a genetic investigation bears the diagnosis or trait in which the investigators are interested. 2 www.notesolution.com 2. Twin Method twin method- research strategy in behaviour genetics in which concordance rates of monozygotic and dizygotic twins are compared monozygotic twins- genetically identical siblings who have developed from a single fertilized egg; always the same sex; sometimes called identical twins. dizygotic twins- birth partners who have developed from separate fertilized eggs and who are only 50% alike genetically, no more so than siblings born from different pregnancies; sometimes called fraternal twins. When the twins are similar diagnostically, they are said to be concordant, to the extent that a predisposition for a mental disorder can be inherited, concordance for the disorder should be greater in genetically identical MZ pairs than in DZ pairs. The ability to offer a genetic interpretation of data from twin studies hinges on what is called the equal environment assumption. o The equal environment assumption is that the environmental factors that are partial causes of concordance are equally influential for MZ pairs and DZ pairs. o The equal environment assumption would assert that MZ pairs and DZ pairs have equivalent numbers of stressful life experiences. 3. Adoptee Method adoptee method- research method that studies children who were adopted and reared completely apart from their abnormal parents, thereby eliminating the influence of being raised by disordered parents. If a high frequency of panic disorder were found in children reared apart from parents who also had panic disorder, we would have support for the theory that a genetic predisposition figures in the disorder. * this situation occurs so rarely that there is virtually no research using this method to study psychopathology; used to study personality traits. Molecular Genetics molecular genetics tries to specify the particular gene or genes involved and the precise functions of these genes. Allele- refers to any one of several DNA codings that occupy the same position or location on a chromosome. o A persons genotype is his/her set of alleles. The term genetic polymorphism refers to the variability among members of the species. o It entails mutations in a chromosome that can be induced or naturally occurring. 4. Linkage Analysis 3 www.notesolution.com linkage analysis- a technique in genetic research whereby occurrence of a disorder in a family is evaluated alongside a known genetic marker; used to study people. They collect diagnostic information and blood samples from affected individuals and their relatives and use the blood samples to study the inheritance pattern of characteristics whose genetics are fully understood, referred to as genetic markers. The greatest success of the method thus far has been in identifying specific genes on several chromosomes that are extremely important in Alzheimers disease. Note that researchers in this area often hypothesize gene-environment interactions. This is the notion that a disorder or related symptoms are the joint product of a genetic vulnerability and specific environmental experiences of conditions. Neuroscience & Biochemistry in the Nervous System The nervous system is composed of billions of neurons. o Neuron- a single nerve cell. o Although neurons differ in some respects, each neuron has four major parts: 1. the cell body, 2. several dendrites, 3. one or more axons of varying lengths, 4. terminal buttons on the many end branches of the axon o When a neuron is appropriately stimulated at its cell body or through its dendrites, a nerve impulse, which is a change in the electric potential of the cell, travels down the axon to the terminal endings. o Nerve impulse- a change in the electric potential of a neuron; a wave of depolarization spreads along the neuron and causes the release of neurotransmitter. o Between the terminal endings of the sending axon and the cell membrane of the receiving neuron, there is a small gap, called the synapse. o Synapse- a small gap between two neurons where the nerve impulse passes from the axon of the first to the dendrites, cell body. The terminal buttons of each axon contain synaptic vesicles, small structures that are filled with neurotransmitters, chemical substances that allow a nerve impulse to cross the synapse. The cell membrane of the postsynaptic cell contains proteins, called receptor sites, that are configured so that specific neurotransmitters can fit into them. When a neurotransmitter its into a receptor site, a message can be sent to the postsynaptic cell. What actually happens to the postsynaptic neuron depends on its integrating thousands of similar messages. 4 www.notesolution.com
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