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Chapter 2 Neuroscience Approaches to Understanding Psychopathology 1 The Growing Importance of Neuroscience Genetics and an Evolutionary Perspective Neuroscience Research Found objective markers in diagnosis and treatment of mental illnesses Describes cognitive emotional and motor processes in both health and illness Better brain sampling techniques No technique to clearly diagnose an individual in terms of mental disorders 2 The Growing Importance of Neuroscience Genetics and an Evolutionary Perspective Neuroscience Research To understand mental illness as a brain disease methods needed to show how brain is involved in psychopathology Research techniques with strong emphasis on brain imaging genetics and an evolutionary perspective allows this Allow researchers to study individuals with mental disorders on a number of levels simultaneously 3 The Growing Importance of Neuroscience Genetics and an Evolutionary Perspective Neuroscience research timeline Till 1800 scientists waited for patients to die to understand the brain Early part of 20th century animals were used EDA Later part of 20th century use of ECG and Today noninvasive techniques that show a better role of brain in psychopathology 4 The Growing Importance of Neuroscience Genetics and an Evolutionary Perspective Human brain leads to our abilities to perform a variety of tasks Highly complex with 86 billion neurons and more than 100 000 kilometers of interconnections Genetic and brain mechanisms that create and remove neurons are responsible for the development of mental disorders 5 Brain Anatomy Neurons and Neurotransmitters A Quick Review of Brain Anatomy and Function 6 Brain Anatomy Neurons and Neurotransmitters 7 Brain Anatomy Neurons and Neurotransmitters 8 Brain Anatomy Neurons and Neurotransmitters Basic characteristics of a neuron 9 Brain Anatomy Neurons and Neurotransmitters Neurons and Neural Transmission Synapse A biochemical connection between two neurons Release molecules with an electrical charge More electrical charges greater the action potential At critical point action potential travels down the axon in one direction Speed of travel depends on width of axon and presence of myelin sheath 10 Brain Anatomy Neurons and Neurotransmitters 2 major types of synapse Chemical synapse secretion from the previous neuron of various types of neurotransmitters These neurotransmitters create a current flow This changes the physiological state of the next postsynaptic neuron such that it is more likely excitatory or less likely inhibitory to create an action potential Electrical synapse Current flows through special channels that connect the gap between the two neurons 11 Brain Anatomy Neurons and Neurotransmitters Neurons and Neural Transmission How Does the Neuron Pass Information Neurotransmitters created and stored Action potential travels down axon to terminal Neurotransmitter is released in the gap between the two neurons next neuron Neurotransmitter binds with specific proteins in the Either increases or decreases possibility of next neuron creating an action potential Gap between the two neurons must be made neutral 12 Brain Anatomy Neurons and Neurotransmitters Neurons and Neural Transmission How Does the Neuron Pass Information These neurotransmitters lead to anxiety processes or depression Most medications used to treat mental illness influence neurotransmitters at synapses Psychotherapy and learning new skills can influence structure and function of synaptic processes Most addictive drugs increase dopamine amount in the gap between the neurons 13 Brain Anatomy Neurons and Neurotransmitters Neurons and Neural Transmission Major Neurotransmitters Transmit signals from one neuron to another Psychotropic medications largely influence these at the synapse More than 100 neurotransmitters identified Most neurons utilize more than one type of neurotransmitter 14 Brain Anatomy Neurons and Neurotransmitters Major Neurotransmitters classified on structure and function Structure in terms of size Glutamate and GABA single amino acid Neuropeptides Larger protein molecules which can be made up of 3 to 36 amino acids Neuropeptides tend to be involved in slower ongoing synaptic functions Function three types Those that mediate communication between neurons Those that influence communication of information Those that influence the activity of large populations of neurons 15 Brain Anatomy Neurons and Neurotransmitters NEUROTRANSMITTER FUNCTION Transmitter at muscles in brain involved in learning etc Acetylcholine Monoamines Serotonin Dopamine Norepinephrine Epinephrine Amino Acids Involved in mood sleep and arousal aggression depression obsessive compulsive disorder and alcoholism Contributes to movement control and promotes reinforcing effects of food sex and abused drugs involved in schizophrenia and Parkinson s disease A hormone released during stress Functions as a neurotransmitter in the brain to increase arousal and attentiveness to events in the environment involved in depression A stress hormone related to norepinephrine plays a minor role as a neurotransmitter in the brain TABLE 2 1 Some Representative Neurotransmitters 16 Brain Anatomy Neurons and Neurotransmitters NEUROTRANSMITTER FUNCTION Glutamate Gamma aminobutyric acid GABA Glycine Neuropeptides Endorphins Substance P Neuropeptide Y The principal excitatory neurotransmitter in the brain and spinal cord Vitally involved in learning and implicated in schizophrenia The predominant inhibitory neurotransmitter Its receptors respond to alcohol and the class of tranquilizers called benzodiazepines Deficiency in GABA or receptors is one cause of epilepsy Inhibitory transmitter in the spinal cord and lower brain The poison strychnine causes convulsions and death by affecting glycine activity Neuromodulators that reduce pain and enhance reinforcement Transmitter in neurons sensitive to pain Initiates eating and produces metabolic shifts 17 Brain Anatomy Neurons and Neurotransmitters NEUROTRANSMITTER FUNCTION Gas Nitric oxide One of two known gaseous transmitters along with carbon monoxide Can serve as a retrograde transmitter influencing the presynaptic neuron s release of neurotransmitters Viagra enhances male erections by increasing nitric oxide s ability to relax blood vessels and produce penile engorgement 18 Brain Anatomy Neurons and Neurotransmitters Neurons and Neural Transmission Encoding Information By means of action potentials in terms of Spike trains Number


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USC PSYC 360 - Chapter 2: Neuroscience Approaches to Understanding Psychopathology

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