Ch02 Biological Foundations of Behavior

CHAPTER 2 – BIOLOGICAL FOUNDATIONS OF BEHAVIOR MODULE 2.1 NEURONS: THE BODY'S WIRING After you have mastered the information in this unit, you will be able to: Define a neuron Identify the parts of a neuron Identify the types of neurons and the other types of cells in the nervous system Describe how a neural impulse is generated and transmitted from one neuron to another Discuss the roles of neurotransmitters in psychological functioning Key Terms and Concepts: Neurons Brain Soma Axon Terminal Buttons Neurotransmitters Synapse Dendrite Sensory Neurons Motor Neurons Glands Hormones Interneurons Nerve Glial Cells Myelin Sheath Nodes of Ranvier Multiple Sclerosis (MS) Ions Resting Potential Depolarization Action Potential All-or-None Principle Refractory Period Receptor Site Reuptake Enzymes Neuromodulators Antagonists Schizophrenia Hallucinations Delusions Parkinson’s Disease Agonists Stimulant Amphetamine Antidepressants Endorphins The Structure of the Neuron Basic building block of the nervous system Cells specialized for rapidly communicating information Neuron parts and functions Dendrites—receive information from adjoining neurons (or sensory receptors) Soma (cell body)—receives and stores information within the cell Nucleus—governs and directs action of the cell Axon—transmits neural impulse down length of cell Terminal buttons—branching at end of axon; contain neurotransmitters Types of neurons Sensory neurons—bring information from outside world to your brain Motor neurons—transmit responses from brain to muscles and glands Interneurons Connect neurons to other neurons Join sensory and motor neurons in spinal cord Synapses—chemical (neurotransmitter) connections between all neurons Glial Cells Most numerous cells within the nervous system “Glue” to help hold neurons together Assist and support activity of neurons Form myelin sheath Fatty, protective covering on many neuron axons Forms over time, usually by age of 12 Nodes of Ranvier (gaps in myelin sheath)—neural impulse may jump from node to node Multiple sclerosis (MS)—destruction of myelin sheath How Neurons Communicate Ions involved: sodium, potassium, and chloride Resting potential—neuron not activated; cell has slightly negative charge Depolarization—stimulation leads sodium to enter cell; electrical charge now changed from negative to positive Action potential—neuron fires down length of axon; called a neural impulse Neurotransmitters Synapse is tiny gap between one neuron and the next At synapse, the impulse changes from electrical to chemical Neurotransmitters are these chemical messengers across synapse Chemicals from adjacent neurons may either excite or inhibit cell firing Some important neurotransmitters Acetylcholine—for muscle contractions, and learning and memory Dopamine—related to muscle activity, also involved in emotional functioning Glutamate—keeps central nervous system aroused Serotonin—regulates emotion, satiety, and sleep Endorphins—body’s natural painkillers; similar chemically to narcotic drugs MODULE 2.2 THE PERIPHERAL NERVOUS SYSTEM: YOUR BODY'S INFORMATION SUPERHIGHWAY After you have mastered the information in this unit, you will be able to: Detail the organization of the nervous system Describe spinal reflexes Describe the autonomic nervous system Explain the relationship between the sympathetic and parasympathetic divisions of the autonomic nervous system Key Terms and Concepts: Nervous System Central Nervous System Spinal Cord Spine Reflex Spinal Reflex Peripheral Nervous System Somatic Nervous System Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System Central Nervous System Consists of brain and spinal cord Spinal cord is a column of nerves about as thick as one’s thumb, encased in the spine Transmits information between brain and peripheral nervous system Spinal reflexes are the quickest possible response to stimuli, bypassing the brain and involving only two or three neurons Peripheral nervous system—components of nervous system other than brain and spinal cord Peripheral Nervous System: Somatic nervous system Comprised of sensory and motor neurons Links communication between central nervous system and sense organs, muscles Autonomic nervous system—two further divisions Sympathetic nervous system Prepares body to meet physical demands or stress Increases heart rate, breathing, blood sugar Parasympathetic nervous system Slows bodily activity, conserves energy Fosters bodily processes, such as digestion MODULE 2.3 THE BRAIN: YOUR CROWNING GLORY After you have mastered the information in this unit, you will be able to: Discuss how the brain is organized and how its various parts function Describe the organization of the cerebral cortex Identify the major function associated with each of the four lobes of the cerebral cortex Key Terms and Concepts: Hindbrain Medulla Pons Brainstem Cerebellum Midbrain Reticular Formation Forebrain Thalamus Basal Ganglia Hypothalamus Limbic System Amygdala Hippocampus Cerebral Cortex Cerebrum Cerebral Hemispheres Corpus Callosum Occipital Lobes Parietal Lobes Somatosensory Cortex Frontal Lobes Motor Cortex Temporal Lobes Association Area The Brain Hindbrain—lowest part of brain Evolutionarily the “oldest” Medulla—breathing, heart rate, swallowing Pons—conducts information; influences wakefulness and sleep Cerebellum—controls balance and coordination Midbrain—above the hindbrain Connects hindbrain with forebrain Reticular formation Neural network that connects to thalamus Involved in attention, alertness and arousal Filters out irrelevant information Forebrain—largest part of the brain, located at top and front Thalamus—relay station, routes information to appropriate brain area Basal ganglia—control movement and coordination Hypothalamus Under the thalamus; size of a pea Regulates hunger, thirst, body temperature Involved in reproduction, emotional states Directs activity of the endocrine system Limbic system—memory and emotional processing Amygdala—aggression, rage and fear Hippocampus—important role in formation of memories Cerebral cortex Part of the forebrain Thin outer layer of cerebrum Two cerebral hemispheres (connected by corpus callosum) Each hemisphere—four lobes Occipital lobes—vision Parietal lobes Includes somatosensory cortex Touch, pressure, pain, temperature Area proportional to sensitivity of skin tissue Frontal lobes “Executive center” Accesses stored memories Used to solve problems, reason, carry out coordinated activities Involved in emotional states Motor cortex—voluntary movement Temporal lobes—hearing Consists largely of association areas—higher mental functions MODULE 2.4 METHODS OF STUDYING THE BRAIN After you have mastered the information in this unit, you will be able to: Describe the various recording and imaging techniques used to study brain functioning Discuss the experimental methods used to study brain functioning Key Terms and Concepts: Lesioning Electrical Recording Methods of Studying the Brain Recording and imaging techniques EEG (electroencephalograph)—records electrical activity in the brain CT (computed tomography) scan—measures reflection of an X-ray beam passing through body PET (positron emission tomography) scan—radioactive isotope reveals more active parts of brain MRI (magnetic resonance imaging)—gives picture of body’s soft matter; disrupted atoms give signals as they realign Experimental methods Lesioning Part of experimental animal’s brain is destroyed Researcher investigates effects of the brain tissue loss Electrical recording—electrodes in neurons/brain tissue reveal changes Electrical stimulation—observe results of mild electric current passed through brain MODULE 2.5 THE DIVIDED BRAIN: SPECIALIZATION OF FUNCTION After you have mastered the information in this unit, you will be able to: Discuss the major differences between the left and right hemispheres Describe how handedness is determined Discuss the main causes of brain damage and the effects of such damage on psychological functioning Explain the use of 'split-brain? patients to learn about brain lateralization Key Terms and Concepts: Lateralization Broca’s Area Wernicke’s Area Aphasia Plasticity Stroke Prefrontal Cortex Laceration Concussion Epilepsy Split-Brain Patients The Brain at Work: Lateralization and Integration Lateralization Division of functions between left and right hemispheres Left brain: language, logical analysis, mathematical computations Broca’s area: production of speech Wernicke’s area: understanding meaning in language Aphasia: loss or impairment in language communication Right brain: spatial relations, recognizing faces, emotional expression Integration: Both hemispheres share work in performing most tasks Handedness—hand dominance related to hemispheric specialization Left-handers may not follow typical pattern Genetic factors seem to play a role Prenatal hormones may also influence Twice as many males as females left-handed Brain Damage and Psychological Functioning Head trauma—laceration or concussion Stroke Flow of blood to brain is blocked Cerebral hemorrhage—bleeding into the brain Brain plasticity—healthy part of brain may take over lost function Exploring Psychology: Research on Split-Brain Patients: Does the Left Hand Know What the Right Hand is Doing? Corpus callosum may be severed as a treatment for severe epilepsy Patient holds a familiar object in the left hand—can use it but not name it The left hand connects to the right hemisphere, which lacks language capabilities Perception studies—researchers flash pictures to either left or right visual field Patients can only describe the picture if flashed to the right visual field (which connects to the left hemisphere) Split-brain patients appear quite normal in everyday behavior MODULE 2.6 THE ENDOCRINE SYSTEM: THE BODY'S OTHER COMMUNICATION SYSTEM After you have mastered the information in this unit, you will be able to: Identify the major endocrine glands Explain the role of hormones in behavior Key Terms and Concepts: Endocrine System Pancreas Diabetes Homeostasis Pituitary Gland Pineal Gland Adrenal Gland Gonads Ovaries Testes Germ Cells Thyroid Gland Premenstrual Syndrome (PMS) The Endocrine System A grouping of glands Glands release secretions called hormones Regulates bodily processes such as growth, reproduction, and metabolism Maintains homeostasis—an internally balanced state Important Glands Hypothalamus—secretes releasing factors that act on pituitary gland Pituitary gland “Master gland”—influences hormone activity of other glands Also promotes physical growth via GH (growth hormone) Pancreas Produces the hormone insulin Regulates amount of glucose in the blood Pineal gland Secretes melatonin Regulates sleep-wake cycles Adrenal glands Lie above the kidneys Adrenal cortex Secretes hormones that promote muscle development Stimulates liver to release sugar in times of stress Adrenal medulla—releases epinephrine and norepinephrine to deal with stress Gonads—sex glands Ovaries in women Produce egg cells for reproduction Secrete female hormones estrogen and progesterone Testes in men Produce sperm Secrete male sex hormone testosterone Hormones and Behavior Testosterone is linked to aggressive behavior Thyroid hormones—influence metabolism; related to behavior PMS—hormone sensitivity appears to play a role MODULE 2.7 GENES AND BEHAVIOR: A CASE OF NATURE AND NURTURE After you have mastered the information in this unit, you will be able to: Discuss the role of genetic factors in human behavior Describe the methods used to study genetic influences on behavior Key Terms and Concepts: Genotype Genes Deoxyribonucleic Acid (DNA) Chromosomes Phenotype Polygenic Traits Familial Association Studies Identical Twins Zygote Fraternal Twins Twin Studies Concordance Rates Adoptee Studies Genes Composed of deoxyribonucleic acid (DNA) Linked together on long strands called chromosomes Found in cell nucleus A child receives 23 chromosomes from each parent Human genome mapped in year 2000 Only twins share identical genetic code Genetic Influences on Behavior Genotype is the genetic code; phenotype is the gene’s physical or behavioral expression Phenotype depends on complex interaction of genes and environment Many psychological characteristics may be polygenic traits Genetic factors establish a predisposition; characteristics may not necessarily appear Kinship Studies Familial association studies Closer genetic links related to more similar traits and behaviors Higher incidence of schizophrenia as genetic commonality increases Limitation: people sharing close genetic links often share similar environment Twin studies Monozygotic (identical) twins—identical genetic inheritance Dizygotic (fraternal) twins—genetic commonality like siblings Concordance rates suggest genetic contribution Identical twins more similar than fraternals on sociability, some psychological disorders Limitation: identical twins may share greater environmental similarity Adoptee studies Adopted children compared to biological and adoptive parents Shyness in children more likely to resemble biological parent Genetically identical (monozygotic) twins, reared apart Rare event, but a natural experiment Heredity seems to play major role in personality development MODULE 2.8 APPLICATION: LOOKING UNDER THE HOOD: SCANNING THE HUMAN BRAIN After you have mastered the information in this unit, you will be able to: Describe some cutting-edge applications of brain scanning Memory and Cognitive Research Specific brain circuits may relate to specific memories Personality Research Different patterns of brain activity in people who are more or less extraverted or neurotic Personnel Selection Scans may indicate suitability for particular types of tasks Diagnosing Psychological Disorders Scans may be used to detect signs of schizophrenia, bipolar disorder, and ADHD