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University of Toronto Scarborough
Konstantine Zakzanis

CHAPTER2: CURRENT PARADIGMS AND THE ROLE OF CULTURAL FACTORS A paradigm is a 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 ROLE OF PARADIGMS Central to any application to of scientific principles, in Kuhns view, is the notion ofm, the conceptual framework or approach within which the scientists work. Paradigms specify what problem scientists will investigate and how they will go about the investigation. Five paradigms: biological, psycho analytic, humanistic and existential, learning, and cognitive. Current thinking about abnormal behaviour tends to be multi-faceted, and contemporary views of abnormal behaviour and its treatment tend to integrate several paradigms. THE BIOLOGICAL PARADIGM The biological paradigm of abnormal behaviour is a continuation of the somatogenic hypothesis. This broad perspective holds that mental disorders are caused by aberrant biological processes. This paradigm has often been referred to as the medical model or disease model. Heart disease is one example. May factorsgenetic makeup, smoking, obesity, life stress, and perhaps even a persons personalityare causes of heart disease. Medical illness can differ widely from one another in their causes. However, they all share one characteristic: in all of them some biological process is disrupted or not functioning normally. That is why we call this the biological paradigm. The biological paradigm was the dominant paradigm in Canada and elsewhere from the late 1800s until at least the middle of the 20 century CONTEMPORARY APROACHES TO THE BILOGICAL 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 schizophrenia, depression may result from clinical imbalances within the brain, anxiety disorders may stem from a defect within the autonomic nervous system that causes a person to be easily aroused, and dementia can be traced to impairments in structures of the brain. In each case, the psychopathology is viewed as caused by the disturbance of some biological process. Those working with the biological paradigm assume that answers puzzles of psychopathology will be found within the body. www.notesolution.com BEHAVIOUR GENETICS Behaviour genetics is the study of individual differences in behaviour that are attributable in part to differences in genetic makeup. The total genetic makeup of an individual, consisting of inherited genes, is referred to as the genotype. Individual genotype is his or her unobservable genetic constitution; in contrast, an individualsphenotype is the totality of his or her observable, behavioural characteristics, such as level of anxiety. It is critical to recognise that various clinical syndromes are disorders of the phenotype, not the genotype. Thus, it is not correct to speak of the direct inheritance of schizophrenia or anxiety disorders; at most, only the genotypes for these disorders can be inherited. The study of behaviour genetics has relied of four basic methods to uncover whether a predisposition for psychopathology is inherited: comparison of members of a family, comparison of pairs of twins, the investigation of a adoptees and the linkage analysis. The family method can be used to study a genetic predisposition among members of a family because the average the number of genes shared by two blood relatives is known. The starting point in such investigations is the collection of a sample of individuals who bear the diagnosis in question. These people are referred to as index cases, or probands. Then, relatives are studied to determine the frequency with which the same diagnosis might be applied to them. In the twin method, both monozygotic (MZ) twins and dizygotic (DZ) twins are compared. MZ, or identical, twins develop from a single fertilised egg and genetically the same. DZ, or fraternal, pairs develop from separate eggs and are on average only fifty percent alike genetically, no more alike then any other two siblings. MZ twins are always the same sex but DZ twins can be either the same or the opposite sex. When the twins are similar diagnostically, they are said to be concordant. The ability to offer a genetic interpretation of data from twins studies hinges on what is called the equal environment assumption. The equal environment assumption is that environmental factors that are partial causes of concordance are equally influential for MZ pairs and DZ pairs. Other factors can also complicate the results of twin research. In a study of post-traumatic stress disorder in community residence, identified three factors as biasing heritability estimates: violation of equal environments assumption, the sex of the participant and his or her age when the assumption took place. When the controlled statistically for the effects of age and sex differences, they found that genetic and non- shared environmental factors contributed to symptoms of post-traumatic stress disorder. Researchers using the adoptees method study children who were adopted and reared apart from the parents with abnormal disorders. Though infrequent, this situation has the benefit of eliminating the effects of being raised by disordered parents. www.notesolution.com MOLECULAR GENETICS Molecular genetics is a highly advanced approach that goes beyond mere attempts to show whether a disorder has a genetic component; it tries to specify a particular gene or genes involved and the precise function of these genes. The term allele refers to any one of several DNA codings that occupy the same location on a chromosome. A persons genotype is his or her set of allele. The term genetic polymorphism refers to variability among members of the species. It involves differences in the DNA sequence that can manifest in very different forms among members in the same habitat. It entails mutations in a chromosome that can be induced or naturally occurring. Linkage analysis is a method in molecular genetics that is used to study people. Researchers using this method typically study families in which a disorder is heavily concentrated. They collect diagnostic information in blood samples from affected individuals and their relatives and use the blood samples to study the inheritances pattern characteristics whose genetics are fully understood, referred to as genetic markers. Eye colour, for example, is known to be controlled by a gene in a specific location on a specific chromosome. 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 in specific environmental experiences or conditions. NEUROSCIENCE AND BIOCHEMISTRY IN THE NERVOUS SYSTEM The nervous system is composed of billions of neurons. Although neurons differ in some respects , each neuron has four major parts: (1) the cell body; (2) several dendrites (the short and thick extensions); (3) one or more axons of varying lengths (usually only one long and thin axon extending a considerable distance from the cell body); and (4) terminal buttons on the many end branches of the axon. 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. Between the terminal endings the sending axon and the cell membrane of the receiving neuron, there is a small gap, called the synapse. The terminal buttons of each axon contains synaptic vesicles, small structures that are filled with neurotransmitters, chemical substances that allow a nerve impulse to cross the synapse. Nerve impulses cause the synaptic vesicles to release molecules of their transmitter substances, and these molecules flood the synapse and diffuse toward the receiving, or postsynaptic, neuron. www.notesolution.com When a neurotransmitter fits 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. Sometimes these messages are excitatory, leading to the creation of a nerve impulse in the postsynaptic cell; at other times the messages can be inhibitory, making the postsynaptic cell less likely to fire. Once a presynaptic neuron (the sending neuron) has released its neurotransmitter the last step is for the synapse to be returned to its normal state. Some of what remains in the synapse is broken down by enzymes, in some is pumped back into the presynaptic cell through a process called reuptake. Several key neurotransmitters have been implicated in psychopathology. Norepinephrine, a neurotransmitter of the peripheral sympathetic nervous system, is involved in producing states of high arousal and thus may be involved in anxiety disorders. Both serotonin and dopamine are neurotransmitters in the brain. Serotonin may be involved in depression, and dopamine in schizophrenia. Another important brain transmitter GABA, which inhibits some nerve impulses and may be involved in anxiety disorders. Maturational changes influence neurotransmitter levels. For instance, the onset of puberty in adolescents results in a decrease in serotonin and a decrease dopamine activity in certain cortical areas. BIOLOGICAL APPROACHES TO TREATMENT an important implication of the biological paradigm is that prevention or treatment of mental disorders should be possible by altering bodily functioning. Antidepressants such as Prozac, now the most widely prescribed psy
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