Models of Abnormal behavior

1. Models of Abnormal behavior Naomi Wagner, PhD

2. Categories of Explanations of Abnormal Behavior • Biological: genetics, brain anatomy, biochemical imbalance, central nervous system, etc • Psychological: Emotions, thoughts. Personality, learning • Social: issues with relationships • Sociocultural: norms for behavior, expectations, cultural climate

3. What is a Model? • Etiology: • Cause or origin of a disorder • Model: • An analogy used by scientists, usually to describe or explain a phenomenon or process they cannot directly observe • Model, viewpoint, and perspective are often used interchangeably • A multipath model considers interactions among all possible layers of causes • Etiology: • Cause or origin of a disorder • Model: • An analogy used by scientists, usually to describe or explain a phenomenon or process they cannot directly observe • Model, viewpoint, and perspective are often used interchangeably

4. Models (cont-d) • These one-dimensional views are overly simplistic: • Set up a false “either-or” dichotomy between nature and nurture • Fail to recognize the reciprocal influences of one on the other • Mask the importance of acknowledging the contributions of all four dimensions in the origin of mental disorders

5. The Biopsychosocial Model • Interaction between the possible causes • Multiple pathways to any disorder • Not all causes contribute equally to a disorder • People exposed to the same factors may not develop the same disorder • People exposed to different factors may develop similar disorders

6. The Structure of the nervous System

7. The Structure of the Nervous system • The Central Nervous System: The brain and spinal cord • The Peripheral Nervous System: • A. The Somatic NS • B. The Autonomic NS (sympathetic and para-sympathetic.)

9. Neural Transmission How is information transmitted in the brain • Neurons are separated by a gap (synapse) • The neurons “communicate” at the synapse • Neuron structure: dendrite, cell-body, axon • Electrical signals are transmitted chemically across the synapse • The signals stimulate the “pockets” at the tip of the axon to release neurotransmitter

10. Cont-d • Electro- chemical transmission • The signal stimulates the vesicles • Vesicles release the neurotransmitter into the synapse • Neurotransmitter: Chemical substance released from a neuron into the synaptic cleft it drifts across the synapse and is absorbed by the receiving neuron • The signal “floats” on the neurotransmitter to the next neuron • Neurons form inter-connected pathways

11. Cont-d • The neurotransmitters can either excite or inhibit the neuron receiving the signal • The activity of the neuron depends on the balance between “on” and “off” signals • Serotonin is implicated in depression and the OCD. • Dopamine is implicated in schizophrenia (too much) and Parkinson (too little) • GABA (an inhibitory) is implicated in anxiety

12. Biochemical Theories • Basic premise: • Chemical imbalances underlie mental disorders • Dendrites: • Receive signals from other neurons • Axons: • Send signals to other neurons

13. Neural Transmission

14. Selected Neurotransmitters Involved in Some Mental Disorders

15. Abnormalities in Brain Structure • It is not always possible to connect brain structures to psychological symptoms researchers believe that abnormally developed brain structures • In 1848 an explosion during the paving of a rail road caused a metal rod to pierce Phineas Gage eye socket and to enter his brain • As a result he showed significant changes in personality

17. The Human Brain

18. Functions of the brain • The forebrain: • Controls all the higher mental functions, such as learning, speech, thought, and memory • Thalamus: • “Relay station;” transmits nerve impulses throughout brain • Hypothalamus: • Regulates bodily drives and body conditions • Limbic system: • Involves experiencing and expressing emotions and motivation

19. Cont-d • The midbrain: • Involved in vision and hearing, and along with the hindbrain, controls sleep, alertness, and pain • Manufactures serotonin, norepinephrine, and dopamine • The hindbrain: • Controls heart rate, sleep, and respiration • Manufactures serotonin

20. Genetic Influences • Each cell of our body contains 46 chromosomes • They are made of DNA our genetic material • A gene is a segment of DNA along the length of the chromosome that contain the instructions for forming proteins which in turn determine how the cell works • Proteins are the building blocks of our body

21. Human Chromosomes

22. Genetics (cont-d) • Genetic abnormalities can come about through: • Inheritance of particular combinations of genes • Faulty copying when cells reproduce • Mutations that a person acquires over the course of life • Cells possess the ability to repair many of the mutations • The 46 chromosomes are arranged in 23 pairs • One chromosome from mother and one from father

23. Genetics (cont-d) • Genetic makeup plays an important role in developing abnormal conditions • Autonomic nervous system reactivity may be inherited • Hereditary factors are implicated in alcoholism, schizophrenia, and depression

24. What do genes do? • Genes control the manufacturing of neurotransmitters as well as the way the neurotransmitters behave at the synapse • Genes also determine how the brain structures develop throughout life • Any factor that can alter the genetic code can alter how those structures perform

25. Genotype and Phenotype • The 46 chromosomes are arranged in 23 pairs • Twenty-two of the pairs are identical (the 23rd pair is the sex chromosomes XX and XY ) • It means that the same gene is located in the same place on each of the chromosomes • Two forms of the same gene are called alleles • The Genotype is the overall genetic makeup • The Phenotype is the expression in your physique and psychological attributes

26. Dominant Recessive Relationship • The Alleles are related to each other in Dominant- Recessive relationship • a dominant allele prevails over a recessive allele • However, human characteristic and psychological disorders are polygenic- more than one gene participates in determining a given characteristic • Epigenetics is the attempt to understand how the environment affects genes to produce genotypes

27. PATTERN OF DOMINANT-RECESSIVE TRAIT INHERITANCE

28. Genes-environment Interactions • Interactions between genes and the environment • Passive exposure: Children are exposed to environments that their parents create based on the parents’ genetic predisposition • The child’s genetically- based traits elicits responses from the environment • Niche-Picking: the child seeks out an environment that gratifies his/her genetically- based inclinations

29. Diathesis-Stress Model • Proposal that people are born with a predisposition that places them at risk for developing a psychological disorder if exposed to certain extremely stressful life experiences.

30. Assessment of Genetic Factors • Family inheritance studies: Researchers compare the disorder rates across relatives who have varying degrees of genetic relatedness • Usually comparing Identical twins who share 100% of their genes to Fraternal twins who share 50% of their genes • Studies comparing parents and children are confounded because of possible environmental effect

31. Biologically- Based Therapis • Psychopharmacology: • Study of effect of drugs on mind and behavior • Electroconvulsive therapy: • Application of electric voltage to the brain to induce convulsions • Psychosurgery: • Brain surgery for the purpose of correcting a severe mental disorder