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Lecture 2. Neuroscience_Lecture_-_ACE_version

Lecture 2. Neuroscience_Lecture_-_ACE_version - Last...

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Unformatted text preview: Last Week… What is psychology? Where did psychology come from historically? How has the discipline developed? How is psychology scientific? So many questions! How do psychologists work to answer them? Modules 4-7 and 18-20 Week Two Neuroscience & Behavior States of Consciousness Psychology 101 – Section 004 Modules 4 & 5 – Neural Systems & The Brain Modules 6 & 7 – Nature versus Nurture Modules 18 to 20 – Sleep, Hypnosis and Drugs Modules 4-7 and 18-20 Today’s Overview How does the mind “talk” to the body? What biological structures allow this conversation? In what ways can this be interfered with? Diseases… Drugs… How are the mind’s functions tied to the brain? How is sleep important to the brain’s functioning? How do our environments and genetics influence who we are? Modules 4-7 and 18-20 Building Blocks of Behavior What we do… Family, Culture Experiences Biology The Neuron The Nervous System The Brain Modules 4-7 and 18-20 The Neuron Cell Body Soma Dendrites Axon Myelin Sheath Nodes of Ranvier Terminal Buttons http://www.botany.uwc.ac.za/sci_ed/grade10/mammal/images/neuron.gif Modules 4-7 and 18-20 How the Neurons Communicate Action Potential – Message is fired from one neuron to another via a brief electrical charge that travels down the axon Resting Potential – inside of the neurons is more negatively charged During the action potential, channels open and close causing this balance to be shifted Modules 4-7 and 18-20 The Importance of Myelin Each neuron’s axon is wrapped by a myelin sheath At each Node of Ranvier, not insulated section, the electrical pulse has to jump and the pulse loses strength Fatty insulation of myelin helps the impulse gain its strength Modules 4-7 and 18-20 Multiple Sclerosis (MS) http://www.youtube.com/watch?v=qgySDmRRzxY Immune system turns on the body Causes hardening of the myelin insulation Environmental and genetic factors are contributors Positive correlation between risk and distance from equator Identical twins have 33% chance of developing MS Symptoms typically develop between 20 and 40 years Women are 3 times as likely as men to develop MS Modules 4-7 and 18-20 MS: Symptoms Visual, Sensory, Motor symptoms… Optic Neuritis - painful vision loss Reduced balance and fine motor control Constant state of tiredness Numbness or tingling in the extremities Symptoms exacerbated in high temperature and high humidity Perhaps cause a further slowing in neuronal transmission Modules 4-7 and 18-20 MS: Treatments No cure is yet available for this disease Focus is on treatment of symptoms and modifying the course of the disease Corticosteroids – decreases intensity of the body’s reaction to the myelin in the central nervous system. Interferons - substances produced by the body to regulate the immune system Injected either subcutaneously or intramuscularly Modules 4-7 and 18-20 How do Neurons Communicate? VIDEO Gaps between neurons – Synapses Chemical Messengers that travel this gap – Neurotransmitters Neurotransmitters are uniquely shaped Can only bind to certain receiving dendrites If enough of the neurotransmitter is absorbed in the receiver – another action potential is initiated Any remaining neurotransmitter in the synapse is reabsorbed by the sending neuron Modules 4-7 and 18-20 Neurotransmitters and Functions Acetylcholine Serotonin Muscle Contraction – Present in skeletal/muscle junctions Role in learning and memory Affects mood, hunger, sleep etc… Low levels of serotonin in depression - Prozac raises serotonin The body’s natural pain-killer - an endogenous morphine Endorphins Dopamine Involved in learning, emotion, attention and movement Abnormal levels in schizophrenia, ADHD and Parkinson’s Modules 4-7 and 18-20 Parkinson’s Parkinson’s Disease (PD) http://www.youtube.com/watch?v=q458IgW-lLk&feature=related Reduction in production of dopamine Symptoms Tremor, Rigidity, Freezing, General slowing of gait, Facial mask Treatment: Surgery and Deep-brain stimulation Levadopa - small enough to pass through the blood-brain barrier Modules 4-7 and 18-20 How How do drugs interact with the communication of neurons? communication Drugs interfere with naturally occurring neurotransmitters Stimulate or Mimic the effects – AGONIST Inhibit the effects - ANTAGONIST Modules 4-7 and 18-20 Basic Mechanisms of Drugs What is a drug? Exogenous substance, not necessary for normal function, which alters the functions of cells Drugs cause changes in physiology and behavior ie… Ritalin blocks reuptake of dopamine - increased attention What is a psychoactive drug? A chemical substance that alters perceptions and mood Methylphenidate is psychoactive - Tylenol is not Modules 4-7 and 18-20 Therapeutic Index Effect of drug D ep ress ive e ffec t (he c eff Drugs often have more than one effect Therapeutic and Toxic Compare these when deciding on dosage high How does this happen? Site of action Affinity with site high affinity = low dose low affinity = high dose low Ana lges i ect art) low high Dose of drug Margin of safety Modules 4-7 and 18-20 Important Terms… Tolerance - decreased effectiveness Body compensates for effects of drug Alcohol – with time, need more to get as drunk May occur for some effects more than others Also true for pharmaceutical drugs … ie - Levadopa Withdrawal - symptoms produced when person stops using Usually opposite of drug effect Includes distress Dependence Physical and psychological (cravings) Modules 4-7 and 18-20 Depressants Depressants - Opiates Opium, Morphine, Heroin Also called narcotic analgesics or narcotics Mimics the naturally occurring Endorphins Physiological Effects Block incoming sensory information – pain information Constriction of the pupils Disrupts coordination of digestive activity Slow digestion constipation Reduces sex hormones / sex drive Extremely addictive Modules 4-7 and 18-20 Stimulants Generally speed up the body functions Increase heart rate and breathing, energy, self-confidence Withdrawal can include: fatigue, headache, irritability Modules 4-7 and 18-20 Hallucinogens: Marijuana Serves as a depressant AND hallucinogenic Depressant: disinhibition, euphoria Hallucinogenic: amplifies sensitivity to colours, sounds, tastes, smells Impairs perceptual skills, motor skills and reaction time Can intensify feelings experienced at the moment If you are feeling anxious, it may lead to a panic attack Therapeutic uses: Chronic pain – serves as analgesic Treats nausea (e.g., from chemotherapy) Increases appetite Modules 4-7 and 18-20 Review So Far… How does the mind “talk” to the body? What biological structures allow this conversation? Neurons Neurotransmitters In what ways can this be interfered with? Diseases – Multiple Sclerosis, Parkinson’s Disease Drugs – Agonists, Antagonists Mechanisms and Types Modules 4-7 and 18-20 The The Brain – Module 5 How do we study the brain? How is the brain organized? Modules 4-7 and 18-20 Observation & Manipulation Observation Monitor the behavioral effects of brain diseases and injuries Lesion studies Manipulation Transcranial Magnetic Stimulation Magnet stimulus disrupts functioning Modules 4-7 and 18-20 The The Electroencephalogram (EEG) (EEG) Breakthrough when they realized the brain also emits weak electrical signals… generated by the firing of neurons Measured and amplified by an EEG Records and amplifies the weak electrical signals Modules 4-7 and 18-20 Recording EEG Several small electrodes are placed against the scalp Neuronal activity from one brain area is subtracted from activity at a reference location Modules 4-7 and 18-20 EEG Traces Modules 4-7 and 18-20 Imaging Brain Activity Computerized Axial Tomography (CAT scan, CT scan) Series of X-Rays at slightly different angles Combine X-rays into 3-D image of the brain Poor resolution Modules 4-7 and 18-20 Imaging Brain Activity Positron Emission Topography (PET) Radioactive liquid injected into bloodstream that detects glucose consumption Disadvantages: Invasive Poor spatial resolution Poor temporal resolution Modules 4-7 and 18-20 Imaging Brain Activity Magnetic Resonance Imaging (MRI) Magnet forces water molecules to align Pulse disrupt them, and time to realignment is measured Better resolution than CT Modules 4-7 and 18-20 Imaging Brain Activity Functional Magnetic Resonance Imaging (fMRI) Increased activity = increased blood flow = increased oxygen (more than needed) Good spatial resolution Poor temporal resolution Expensive Modules 4-7 and 18-20 The Structures of the Brain Hindbrain Brainstem, Medulla, Cerebellum Forebrain Thalamus, Basal ganglia, Cerebral Cortex Cerebral Cortex Two Hemispheres separated by Corpus Callosum Four Lobes Frontal Temporal Parietal Occipital Modules 4-7 and 18-20 The Hindbrain The Brainstem Where spinal cord meets the skull All functions are automatic and related to survival Medulla – controls breathing, heartbeat etc… Cerebellum Coordinates voluntary movement Important for balance and gait Modules 4-7 and 18-20 The Forebrain Thalamus Sensory switchboard – relays sensory information to appropriate brain regions Hypothalamus Directly below the thalamus Responsible for body maintenance Thirst, hunger, sex drives, temperature Modules 4-7 and 18-20 The Forebrain Basal Ganglia 3 Structures: Caudate nucleus Putamen Globus Pallidus Involved in movement Provider of dopamine Modules 4-7 and 18-20 Cerebral Cortex Cerebral Patient 1: Does not recognize people he talks to until he sees their face Cannot visually identify objects Difficulty describing what he knows about objects Patient 3: Blinds spots in visual field Difficulty identifying colours Cannot recognize words Patient 2: Confuses steps involved in making simple things (ex. Coffee) Has difficulty carrying out actions Inability to focus Patient 4: Cannot attend to more than one thing at a time Difficulty telling left from right Cannot attend to left half of space Plasticity Most neurons don’t regenerate BUT they can reorganize Examples?? Plasticity of neurons is best early in life Still happens just to a lesser degree for older adults following trauma or stroke Modules 4-7 and 18-20 Left and Right Hemispheres Depending on the task these 2 hemispheres interact to different degrees All communication about tasks must pass through the Corpus Callosum Left and Right space… Modules 4-7 and 18-20 Split-Brain Patients Scientists believed that epileptic seizures resulted from amplification of brain functioning Can we reduce this by not allowing the hemispheres to “talk” to each other -- severed the corpus callosum Both hemispheres comprehend and follow instructions Do so independently of each other Modules 4-7 and 18-20 Hemispheric Differences Left-Hemisphere Left LeftSpeaking / Signing Complex movements Calculations Word Recognition Right side of body Right-Hemisphere Right RightPerceptual Tasks Picture Recognition Emotional content Geometry, mental rotation Direction and distance Non-language sounds Music Left side of body Modules 4-7 and 18-20 Review So Far… How are the mind’s functions tied to the brain? How do we study the brain? Observation, Manipulation, Imaging How is the brain organized? Hindbrain Forebrain Cerebral Cortex Other Plasticity, Lateralization Modules 4-7 and 18-20 What is Consciousness? Like life… Consciousness is difficult to define Psychology almost lost its study of consciousness altogether Defined as a science of behavior instead of as the study of “mental life” Advances in neuroscience = ability to relate brain activity to different mental states Study of mental processes regains importance Modules 4-7 and 18-20 Consciousness is… Our awareness of ourselves and our environment Relatively slow and has a limited capacity But highly skilled at handling new situations Most daily activities require little conscious awareness Frees up resources if novel challenges are encountered “Nature’s way of keeping us from thinking and doing everything at once” Modules 4-7 and 18-20 Daydreams and Fantasies “Nearly everyone has daydreams or waking fantasies everyday” (Singer, 1975) Most often involving mundane aspects of daily life For example: Rehearsing your favorite pick-up line and its success Replaying how you wish an argument had ended Daydreams can be adaptive May even substitute for impulsive behavior Modules 4-7 and 18-20 Biological Rhythms Circadian Rhythm Stages of Sleep Modules 4-7 and 18-20 Circadian Rhythm Body temperature rises as morning approaches, peaks during the day, dips in the early afternoon and gradually declines throughout the evening This biological cycle of body temperature reflects our sleeping and waking cycle °C 4 am 8 am 12 pm 4 pm 8 pm 12 am Modules 4-7 and 18-20 Circadian Rhythm & Productivity Thinking and memory performance are highest at peaks in circadian rhythm Most university students report themselves as “nightowls” Productivity and performance improves across the day Modules 4-7 and 18-20 Sunrise… Sunset… Light stimulates the circadian rhythm by activating lightsensing proteins in the retina Proteins signal the hypothalamus which triggers the circadian clock. This cycle has been extending beyond 24-hour because of our longer days “Artificial light delays sleep” Modules 4-7 and 18-20 Stages of Sleep In addition to a sleeping and waking cycle, there is also a biological rhythm during our sleep. Every 90 to 100 minutes we cycle through 5 stages of sleep Stages are easily detected by an EEG Modules 4-7 and 18-20 The Study of Sleep Researchers apply physiological methods to study sleep Could directly measure bodily activity with mechanical devices Activity included: heart rate, muscle tension, breathing… Breakthrough when they realized the brain also emits weak electrical signals… generated by the firing of neurons Measured and amplified by an EEG Modules 4-7 and 18-20 Typical EEG Patterns Beta awake & alert Alpha awake but relaxed Modules 4-7 and 18-20 EEG and The Sleep Cycle Brain activity gradually slows as we drift into sleep The Stages of Sleep Begins as we relax (alpha) Sleep is marked by the slow and irregular brain waves of Stage 1 Hallucinations are likely here 20 min. of Stage 2 soon follows Sleep spindles – bursts of rapid, rhythmic brain activity Modules 4-7 and 18-20 EEG and The Sleep Cycle The Stages of Sleep Stages 3 & 4 feature increasingly larger, slower delta waves Last for about 30 minutes Difficult to wake at this point REM Sleep Almost all muscles relaxed… except the eyes Modules 4-7 and 18-20 REM Sleep Lasts for about 10 minutes Characterized by: Elevated heart rate Rapid and irregular breathing Momentary bursts of eye movement Paradoxical Sleep Genital arousal but almost complete muscle relaxation The body is internally aroused, but externally calm As the night progresses, Stage 4 sleep gets shorter and REM sleep lengthens Modules 4-7 and 18-20 The Purpose of Sleep Considering we will spend an average of 25 years sleeping… Is it worth all of our time??? Reduces energy expenditure so our bodies can focus on tissue growth and repair Important for the organization and consolidation of memories But… neuronal connections deteriorate quickly if not used We cycle between deep sleep and periods of intense activity – REM sleep Modules 4-7 and 18-20 Sleep Deprivation To be fully alert, most adults require 8 hours of uninterrupted sleep Average adult gets only 6.9 hours Suppresses disease fighting immune system Those who sleep 7-8 hour nights tend to live longer than those who are chronically sleep-deprived. Alters metabolic and hormonal functioning Mimics aging, leads to obesity, hypertension and memory impairment Modules 4-7 and 18-20 Are you a sleep-deprived student? Are T F I need an alarm clock to wake up at the appropriate time. It’s a struggle for me to get out of bed in the morning. Weekday mornings I hit snooze several times to get more sleep. I feel tired, irritable, and stressed out during the week. I have trouble concentrating and remembering. I feel slow with critical thinking, problem solving and being creative. I often fall asleep watching TV. Effects of Sleep Deprivation Daylight Savings Time Accidents increase after “loosing” one hour of sleep Canada: 7% higher the Monday after the change US: 17% more traffic-related death on the Monday after In Australia, 30% of highway deaths are the result of falling asleep behind the wheel (20% in the US) Modules 4-7 and 18-20 Sleep Sleep Disorders - Insomnia 10 – 15% of people complain of insomnia A persistent problem in falling and/or staying asleep Often excess stress is to blame Sleeping pills and alcohol only exacerbate the problem Some hints: - Relax before bedtime - Avoid caffeine and heavy foods before bedtime - Get regular exercise - Aim for a regular sleeping schedule Modules 4-7 and 18-20 Other Sleeping Disorders Narcolepsy Uncontrollable sleep attacks, may lapse directly into REM sleep Condition is quite rare – estimated 1 in 2000 people Sleep Apnea Intermittent cessation of breathing while sleeping Quickly arouses and snorts to regain oxygen levels Process can repeat over 400 times per night Night Terrors, Sleepwalking & Sleeptalking Most typical in children and young adults Modules 4-7 and 18-20 Review So Far Levels of Consciousness Daydreams and Fantasies Biological Rhythms Circadian Rhythm Studying Sleep with EEG and Sleep Stages The Function of Sleep and Sleep Deprivation Sleep Disorders Modules 4-7 and 18-20 Neuroscience & Consciousness How does the mind “talk” to the body? What biological structures allow this conversation? In what ways can this be interfered with? Diseases… Drugs… How are the mind’s functions tied to the brain? How is sleep important to the brain’s functioning? How do our environments and genetics influence who we are? Modules 4-7 and 18-20 Reminder!! Online Assignment One – Due this Friday by midnight Next Week: Modules 8, 9, 10 & 11 Developing Through the Life Span Prenatal Development Infancy and Childhood Adolescence Adulthood Modules 4-7 and 18-20 ...
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