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Chapter 2

Abnormal Psychology- Chapter 2 Notes

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Konstantine Zakzanis

Chapter Two: THE ROLE OF PARADIGMS:  Paradigm is the conceptual framework or approach within which the scientist works. A paradigm is 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.  The four major types of paradigms are: - Biological - Cognitive-behavioural - Psychoanalytic - Humanistic- existential THE BIOLOGICAL PARADIGM:  The biological paradigm of abnormal behaviour is a continuation of the somatogenic hypothesis. This broad perspective holds that aberrant biological processes cause mental disorders. This paradigm has often been referred to as the medical model or disease model.  In the biological paradigm people looked to the body as the source of disorders, therefore certain organs, which were assumed to be the cause of disorders, were removed as a means of ridding or reducing the disorder. For examples the removal of ovarian cysts or the entire ovaries was employed as treatment for melancholia, mania, and delusions. CONTEMPORARY APPROACH TO THE BIOLOGICAL PARADIGM  Heredity probably predisposes a person to have an increased risk of developing schizophrenia, 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, and dementia can be traced to impairment structure of the brain.  Those working with the biological paradigm assume that answers to puzzles of psychopathology will be found within the body.  We will be looking at three areas of research within this paradigm: behaviour genetics, molecular genetics, and biochemistry. Behaviour Genetics:  Genes: the carriers of the genetic information (DNA) passed from parents to child.  Behavioral genetics: is the study of individual differences in behaviour that are attributable in part to differences in genetic makeup.  Genotype: the total genetic makeup of an individual consisting of inherited genes.  Phenotype: is the totality of his or her observable, behavioural characteristics, such as level of anxiety. The phenotype changes over time and is viewed as the product of an interaction between the genotype and the environment.  It is critical to recognize that various clinical syndromes are disorders of the phenotype not of the genotype.  Though people may inherit a predisposition, also known as a diathesis, they do not inherit the disease itself.  The study of behaviour genetics has relied on 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 adoptees, and linkage analysis.  The family method can be used to study a genetic predisposition among members of a family because the average number of genes shared by two blood relatives is known.  People who share 50% of their genes with a given individual are called first- degree relatives of that person. Nephew and nieces share 25% of the 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. 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 [identical twins, whom develop from a single fertilized egg and are genetically the same] and dizygotic (DZ) twins [fraternal pairs develop from separate eggs and are on average 50% alike genetically.] are compared.  When twins are similar diagnostically, they are said to be concordant.  Concordance for the disorder should be greater in genetically identical MZ pairs than in DZ pairs. When the MZ concordance rate is higher than the DZ rate, the characteristic being studied is said to be heritable.  The ability to offer a genetic interpretation of data from twin studies hinges on what is called the equal environment assumption. The equal environment assumption is that the environmental factors that are partial causes of concordance are equally influential for MZ pairs and DZ pairs.  Only environmental factors contribute to exposure to events involving non- assaultive traumas (E.g. Motor vehicle accidents, natural disasters) but both genetic and environmental factors contribute to exposure to assaultive traumas (E.g. sexual assault)  Adoptees method: study children with abnormal disorders who were adopted and reared apart from their parents. 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 the particular gene or genes involved and the precise functions of these genes.  The term “allele” refers to any one of several DNA codings that occupy the same position or location on a chromosome. A person’s genotype is his or her set of alleles.  Genetic polymorphism: refers to variability among members of a 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 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.  Gene-environment interactions: the notions that a disorder or related symptoms are the joint product of a genetic vulnerability and specific environment experiences or conditions.  There is an association between obsessive-compulsive disorder (OCD) and the gamma-aminobutyric acid (GABA) type B receptor 1.  There is a link among the serotonin transporter promoter (5-HTTLPR) genotype, the development of cognitive vulnerabilities, stressful events, and depression. Neuroscience and Biochemistry In the Nervous System  Neuroscience: is the study of the brain and the nervous system  Neurons: 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 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 of the sending axon and the cell membrane of the receiving neuron, there is a small gap called synapse.  For a nerve impulse to pass from one neuron to another and for communication to occur, the impulse must have a way of bridging the synaptic gap. 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.  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. Not all of the released neurotransmitter has found its way to postsynaptic receptors. Some of what remains in the synapse is broken down by enzymes and some is pumped back into the presynaptic, cell through a process called reuptake.  Norepinephrine: a neurotransmitter involved in producing states of high arousal and thus may be involved in anxiety disorders.  Serotonin: maybe involved in depression  Dopamine: maybe involved in schizophrenia  GABA: inhibits some nerve impulses and may be involved in anxiety disorders. Structure and Function of the Human Brain  Meninges: the three membranes (the dura mater, arachnoid, and pia mater) that line the skull and vertebral canal and enclose the brain and spinal cord.  The cerebral hemispheres together constitute most of the cerebrum, which is the thinking centre of the brain.  The major connection between the two hemispheres is a band of nerve fibres called the corpus callosum.  Cerebral Cortex: The cerebral cortex is the outermost sheet of neural tissue of the cerebrum of the brain in some vertebrates. It covers the cerebrum and cerebellum, and is divided into left and right hemispheres. The cerebral cortex plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness.  The cortex is vastly convoluted (rolled longitudinally upon itself) the ridges are called gyri, and the depressions between them sulci or fissures.  Frontal lobe: lies in front of the central sulcus and is associated with reasoning and other higher mental processes, as well as the regulation of fine voluntary movement. It is responsible for executive functioning, such as planning, inhibition, and emotion. The right side can give rise to manic like episodes, while the left side of the brain can give rise to depressed like states. The left frontal lobe is important for encoding and memory, the right frontal lobe is responsible for retrieval. Speech is also an important function associated with the frontal lobe.  Parietal lobe: is behind it and above the lateral sulcus. It is responsible for visual spatial and constructional functioning. Damage to the left side results in difficulties in following language or verbal demand such as understanding movement, damage to the right side results in visual spatial neglect for example people will neglect whatever they see on their left side and only eating whatever is on the right side of their plate.  Temporal lobe: is located below the lateral sulcus and is involved in the discrimination of sounds, it is also important for learning, on the left side we have bronchi’s area or the area of comprehension of verbal sound. The right side interoperates language. A place in the temporal lobe that stamps information and stores it is the hippocampus.  Occipital lobe: lies behind the parietal and temporal lobes and is involved in vision.  Much of the interior of the brain is white matter, made up of large tracts of bundles of myelinated (sheathed) fibres that connect cell bodies in the cortex with those in the spinal cord and other centres lower in the brain.  These centres are pockets of grey matter referred to as nuclei which serve both as a way stations, connecting tracts from the cortex with other ascending and descending tracts, and as integrating motor and sensory control centres.  Deep within the brain are cavities called ventricles, these are continuous with the central canal of the spinal cord and are filled with cerebrospinal fluid. Surface of the left cerebral hemisphere, indicating the lobes and the two principal fissures of the cortex 1. The diencephalon connected in the front with the hemisphere and behind the midbrain, contains the thalamus, and the hypothalamus. The thalamus is a relay station for all sensory pathways except the olfactory. The hypothalamus is the highest centre of integration for many visceral processes, regulating metabolism, temperature, perspiration, blood pressure, sleeping, and appetite. 2. The midbrain is a mass of nerve-fibre tracts connecting the cerebral cortex with the pons, the medulla oblongata, the cerebellum and the spinal cord. 3. The brain stem comprises the pons and the medulla oblongata and functions primarily as a neural replay station. The pons contains tracts that connect the cerebellum with the spinal cord and with motor areas of the cerebrum. The medulla oblongata serves as the main line of traffic for tracts ascending from the spinal cord and descending from the higher centres of the brain. In the core of the brain stem is the reticular formation sometimes called the reticular activating system because of the important role it plays in arousal and alertness. 4. The cerebellum receives sensory information from the inner ear and from muscles, tendons, and joints. The information received and integrated relates to balance, posture, equilibrium, and to the smooth coordination of the body when in motion. 5. The fifth important part of the brain, the limbic system, which controls the visceral and physical expressions of emotion (e.g. quickened heartbeat, alterations in facial expressions . . .) as well as appetite (e.g. hunger, mating . . .)  Attention deficit hyperactivity disorder (ADHD) is said to be due to a dopamine deficit believed to be genetic in origin. BIOLOGICAL APPROACHES TO TREATMENT:  An important implication of the biological paradigm is that prevention or treatment of mental disorders should be possible by alternating bodily functioning. Certainly, if a deficiency in particular biochemical substance is found to underlie or contribute to some problem, it makes sense to attempt to correct the imbalance by providing appropriate doses of the deficient chemical. In such cases, a clear connection exists between the cause of the disorder (a biological defect) and its treatment (a biological intervention) EVALUATING THE BIOLOGICAL PARADIGM:  Reductionism: refers to the view that whatever is being studied can and should be reduced to it most basic elements or constituents. THE COGNITIVE-BEHABIOURAL PARADIGM: THE RISE OF BEHAVIOURISM  John B. Watson is a key figure in the rise of behaviourism, which is defined as an approach that focuses on observable behaviour rather than on consciousness. Classical conditioning  Is one type of learning, which was discovered by Ivan Pavlov.  He conducted an experiment in which he conditioned dogs to salivate to natural stimulus. Operant conditioning  Was introduced my B. F Skinner, so named as it applied to behaviour that operates on the environment.  He formulated the law of effect, which states that a behaviour is acquired by virtue of its consequences.  Skinner’s contention that stimuli do not so much get connected to responses as they become the occasions for responses to occur, if in the past they have been reinforced. Skinner introduced the concept of discriminative stimulus to refer to external events that in effect tell an organism that if it performs certain behaviour, a certain consequence will follow.
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