Integrative Approach to Abnormal Behavior Chapter 2

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Transcript of Integrative Approach to Abnormal Behavior Chapter 2

  • Integrative Approach to Abnormal BehaviorChapter 2

  • Nature v. Nurture?Nature (biological influences) and nurture (psychosocial influences) are one-dimensional models. Issue is one of Causality? What leads to abnormal behavior???? Our tendency is to simplify.Result in incomplete understandings of psychological disordersMultidimensional models allow for a more complete understanding of psychopathology. They are systemic!Integrated model attempts to understand of the complex interaction of multiple influencesAbnormal behavior is multiply determined by multiple pathways

  • psychological disorder

  • The Interaction of Genetic and Environmental EffectsModels of InteractionThe Diathesis-Stress ModelGenetic vulnerabilities that are only expressed in the presence of certain environmental stressorsThe smaller the vulnerability, the greater the life stress needed to result in the disorder, and conversely.Reciprocal Gene-Environment ModelNewer model, proposes that genetic influences behavior to increase likelihood of encountering activating stimuli. Genetic endowment increases the likelihood of encountering stressful life events. Non-Genomic Inheritance of BehaviorGenes are not the whole story. Early learning (parenting styles and nurturance) may over-ride genetic predisposition.

  • Neuroscience Contributions to PsychopathologyThe Field of NeuroscienceThe role of the nervous system in disease and behaviorThe Central Nervous System (CNS)Brain and spinal cordThey process all information received from sense organsThe Peripheral Nervous System (PNS)Somatic and autonomic branches

  • Neuroscience and the Central Nervous System The NeuronSoma Cell bodyDendrites Branches that receive messages from other neuronsAxon Trunk of neuron that sends messages to other neuronsAxon terminals Buds at end of axon from which chemical messages are sentSynapses Small gaps that separate neuronsNeurons Function Electrically, but Communicate ChemicallyNeurotransmitters are the chemical messengers, and have been critically involved in psychological disorders.

  • Neuroscience: Functions of MainTypes of NeurotransmittersFunctions of NeurotransmittersTo understand functions, we have studied effects of agonists, antagonists, and inverse agonistsMost drugs are either agonistic or antagonisticAgonists increase the activity of a neurotransmitter by mimicking its effects; antagonists decrease or block a neurotransmitter; inverse agonists produce effects oposite to those produced by the neurotransmitter. Main Types and Functions of Neurotransmitters Serotonin (5HT)- 5 hyroxytryptomine. Regulates behavior, mood and thought processes. Associated with depression, impulsivity, and over-reactivity. Gamma aminobutyric acid (GABA) and benzodiazepines. Best known for their effects on anxiety reduction. Norepinephrine and beta blockers. Regulation of physiological responses, such as heart rate and respiration. Dopamine and L-Dopa-activate other neurotransmitters, and an excess have been implicated in schizophrenia.

  • Implications of Neuroscience for PsychopathologyRelations Between Brain and Abnormal BehaviorExamples include obsessive compulsive disorder and schizophreniaExperience Can Change Brain Structure and FunctionTherapy Can Change Brain Structure and FunctionMedications and psychotherapy

  • Diathesis-stress model: diathesis is a pre-existing condition, necessary but not sufficient for disorderStress a stressor is activated, this in combination with the diathesis then is sufficient for a disorderReciprocal gene-environment model genetic endowment that increases the probability that will experience stressful life eventInherit both a predisposition to blood-injury phobia and trait of impulsiveness; rush thru activities and therefore have moreaccidents so more likely to see own blood and injury; similar example with divorce and personality characteristics that maypromote behavior that increases the likelihood of divorceInfluence of environment may be equally or more important; cross-fostering of stressed vs calm rats & monkeysShould discuss heritable contribution in context of past and present environmentTo understand neuroscience contributions throughout the course, we need to understand a few fundamental things about the nervous system. This will likely be review for some things you covered in intro.

    The nervous system is composed of a complex collection of specialized cells called neurons. Neurons have several parts soma, dendrites, axons, and axon terminals. Synapses are the tiny space between neurons. Neurons function electically through changes in what are called electron potentials along the cell surface, but communicate with each other (and thereby propogate electrical messages thoughout the nervous system) via chemicals called neurotransmitters.

    [Play animation]

    Within a given circuit, when a cell gets excited, that is it is electrically stimulated, it releases neurotransmitters into the synapse that excites the next cell and sends the message down the line.This figure demonstrates the complex process of neurotransmitter production and release in a cell.

    (Describe process)

    This model also gives us some ideas about the potential ways in which drugs may affect this process. First, a drug may stimulate production of the neurotransmitter. Second, it may stimulate the release of more neurotransmitter into the synapse. Third, a drug may affect receptors by increasing the number of receptors, enhancing the affinity of those receptors for the neurotransmitter, or enhancing the strength of the binding to the receptors. Fourth, a drug may increase the availability of neurotransmitters in the synapse by preventing reuptake. Finally, drugs may enhance the process by preventing breakdown of neurtransmitters in the cell body.Although this is something of an oversimplification, we can think of different systems of neurotransmitters as having different effects on the function of the brain and the body.

    We have learned a lot about these functions by administering different drugs that act specifically on a given system. Agonist drugs enhance or exaggerate the effect of the neurotransmitter, antagonists inhibit the system, and inverse aganoists produce opposite effects.

    There are four general types of drugs you will hear about in this class serotonin, GABA, norepinepherine, and dopamine.

    Serotonin circuits are widely found in the brain cortex, and it has important effects upon regulating our behavior. Serotonin plays an important role in coordinating the complex interplay between emotion, cognition, and behavior that characterizes human behavior. Low serotonin levels have been implicated in anxiety and mood disorders, but also in other areas of problematic behavior likes sociopathy (aggressiveness, homicide, and sexual predation).

    GABA is the primary player in behavioral inhibition systems in the brain. Enhancing the GABA system leads to feelings of relaxation and calm. Benzodizapenes are drugs that produce calm by enhancing the ability of GABA to bind to neuron receptors sensitive to them.

    Norephinepherine is largely responsible for arousal or activation of the brain and the body. Increases in norepenipherine lead to increases in blood pressure and heart rate, for example. Norepinepherine is also part of the endocrine system and can be circulated through the body in the bloodstream.

    Lastly dopamine is like the traffic cop of the nervous system, and is involved in switching on or off different circuits in the brain. Some of the most exciting findings are documenting functional changes in the nervous system following treatment, which can be manipulated experimentally. We know that experience changes brain structure and functionlearning changes the brain. We also know that therapy, both medication and psychotherapy can change the brain in dramatic ways. People are relatively less surprised to find this with medications, but there is increasing evidence that effective psychosocial therapies can change the brain dramatically.