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Invitation To Psychology Carol Wade and Carol Tavris PowerPoint Presentation by H. Lynn Bradman Metropolitan Community College-Omaha Wade and Tavris © 2005 Prentice Hall 4-1 Neurons, Hormones, and the Brain Chapter 4 Wade and Tavris © 2005 Prentice Hall 4-2 Neurons, Hormones, and the Brain • • • • • • The Nervous System: A Basic Blueprint Communication in the Nervous System Mapping the Brain A Tour Through the Brain The Two Hemispheres of the Brain Two Stubborn Issues in Brain Research Wade and Tavris © 2005 Prentice Hall 4-3 The Nervous System: A Basic Blueprint The Central Nervous System The Peripheral Nervous System Wade and Tavris © 2005 Prentice Hall 4-4 Divisions of the Nervous System • Central Nervous System – Brain – Spinal cord • Peripheral Nervous System – Somatic – Autonomic Wade and Tavris © 2005 Prentice Hall 4-5 Nervous System Organization Wade and Tavris © 2005 Prentice Hall 4-6 The Central Nervous System • Central Nervous System: The portion of the nervous system consisting of the brain and spinal cord. • Spinal Cord: A collection of neurons and supportive tissue running from the base of the brain down the center of the back, protected by a column of bones (the spinal column). Wade and Tavris © 2005 Prentice Hall 4-7 The Peripheral Nervous System • Somatic Nervous System: The subdivision of the PNS that connects to sensory receptors and to skeletal muscles; sometimes called the skeletal nervous system. • Autonomic Nervous System: The subdivision of the PNS that regulates the internal organs and glands. Wade and Tavris © 2005 Prentice Hall 4-8 Sympathetic and Parasympathetic Wade and Tavris © 2005 Prentice Hall 4-9 Communication in the Nervous System The Structure of the Neuron How Neurons Communicate Chemical Messengers in the Nervous System Wade and Tavris © 2005 Prentice Hall 4-10 Different Kinds of Neurons • Neurons vary in size and shape, depending on their location and function. More than 200 types have been identified in mammals. Wade and Tavris © 2005 Prentice Hall 4-11 The Structure of the Neuron • Dendrite: Branches that receive signals and transmit to cell body • Cell Body: Controls cell metabolism and determines firing • Axon: Carries impulses away from cell body • Myelin Sheath: Fatty insulation Wade and Tavris © 2005 Prentice Hall 4-12 How Neurons Communicate • Synapse: Site where a nerve impulse is transmitted from one neuron to another; includes the axon terminal, synaptic cleft, and receptor sites on receiving cell. • Neurotransmitter: Chemical substance that is released by transmitting neuron at the synapse and alters the activity of the receiving neuron. Wade and Tavris © 2005 Prentice Hall 4-13 Plasticity in Brain & Behavior • Some rats are housed alone in empty cages • Their littermate twins are group-housed in cages with toys, which are changed frequently • Richer environments led to heavier, thicker brains, more synapses, and better learning Wade and Tavris © 2005 Prentice Hall 4-14 Getting Connected • Neurons in a newborn’s brain are widely spaced, but form connections quickly. Wade and Tavris © 2005 Prentice Hall 4-15 Chemical Messengers in the Nervous System • Neurotransmitters are released into synaptic cleft • Bind to receptor site on receiving neuron • Electrical state of receiving neuron changes, becoming more (or less) likely to fire Wade and Tavris © 2005 Prentice Hall 4-16 Major Neurotransmitters • • • • • Acetylcholine (ACh) Dopamine Serotonin Norepinephrine Gamma amino butryic acid (GABA) Wade and Tavris © 2005 Prentice Hall 4-17 Endorphins • Chemical substances in the nervous system that are similar in structure and action to opiates; they are involved in pain reduction, pleasure, and memory, and are known technically as endogenous opioid peptides. Wade and Tavris © 2005 Prentice Hall 4-18 Hormones • Hormones: Chemical substances, secreted by organs called glands, that affect the functioning of other organs. • Endocrine Glands: Internal organs that produce hormones and release them into the bloodstream. Wade and Tavris © 2005 Prentice Hall 4-19 Mapping the Brain Wade and Tavris © 2005 Prentice Hall 4-20 Electroencephalogram Wade and Tavris © 2005 Prentice Hall 4-21 Positron Emission Tomography • Active areas have increased blood flow • Radioactive isotopes (small amounts) are placed in the blood • Sensors detect radioactivity • Different tasks show distinct activity patterns Wade and Tavris © 2005 Prentice Hall 4-22 Magnetic Resonance Imaging • Magnetic fields align certain ions and compounds • When field is removed, these molecules release energy as radio waves • Computer calculates tissue density from radio waves • Provides clear, 3D images Wade and Tavris © 2005 Prentice Hall 4-23 A Tour Through the Brain The Brain Stem The Cerebellum The Thalamus The Hypothalamus and the Pituitary Gland The Limbic System The Cerebrum Wade and Tavris © 2005 Prentice Hall 4-24 The Human Brain • This view shows the brain as if split in half front-to-back – Inside surface of right half of brain – Eyes on the left, near the word “hypothalamus” Wade and Tavris © 2005 Prentice Hall 4-25 The Brain Stem • Brain Stem: At the top of the spinal cord, consisting of medulla and pons – Medulla: Responsible for some automatic functions, such as breathing and heart rate – Pons: Involved in sleep, waking, and dreaming. – Reticular Activating System: A dense network of neurons found in the core of the brain stem; it arouses the cortex and screens incoming information. Wade and Tavris © 2005 Prentice Hall 4-26 The Cerebellum • Cerebellum: Regulates movement and balance, and is involved in learning some simple responses. Wade and Tavris © 2005 Prentice Hall 4-27 Thalamus and Hypothalamus • Thalamus: Relays sensory messages to the cerebral cortex. • Hypothalamus: Involved in emotions and drives vital to survival (e.g., fear, hunger, thirst, and reproduction); it regulates the autonomic nervous system. • Pituitary Gland: Small endocrine gland at the base of the brain, which releases many hormones and regulates other endocrine glands. Wade and Tavris © 2005 Prentice Hall 4-28 The Limbic System • Limbic System: A group of brain areas involved in emotional reactions and motivated behavior. • Amygdala: Involved in the arousal and regulation of emotion and the initial emotional response to sensory information. • Hippocampus: Involved in the storage of new information in memory. Wade and Tavris © 2005 Prentice Hall 4-29 The Cerebrum • Occipital Lobes: Vision • Parietal Lobes: body sensation • Temporal Lobes: Hearing, language • Frontal Lobes: Thinking, planning, movement Wade and Tavris © 2005 Prentice Hall 4-30 The Case of Phineas Gage • Gage was a railroad construction foreman • An 1848 explosion forced a steel tamping rod through his head • Others said he was “…no longer Gage…” • Lost his job, worked as a sideshow exhibit Wade and Tavris © 2005 Prentice Hall 4-31 The Two Hemispheres of the Brain Split Brains: A House Divided A Question of Dominance Wade and Tavris © 2005 Prentice Hall 4-32 Visual Pathways • Each hemisphere receives information about the opposite side of the visual field. • Objects to your left put images on right side of each retina; goes to right side of brain • Half of optic nerve fibers cross at the optic chiasm Wade and Tavris © 2005 Prentice Hall 4-33 Split Brains: A House Divided • Hemispheres of brain sometimes separated to treat severe epilepsy • Split brain operation includes the optic chiasm – Optic nerve no longer crosses – Visual information goes only to one hemisphere • Different sides of brain see different information Wade and Tavris © 2005 Prentice Hall 4-34 Divided Brain, Divided View Wade and Tavris © 2005 Prentice Hall 4-35 Two Stubborn Issues in Brain Research Why Do We Dream? Are There “His” and “Hers” Brains? Wade and Tavris © 2005 Prentice Hall 4-36 Why Do We Dream? • Rapid Eye Movement (REM) Sleep: Sleep periods characterized by fast eye movement behind closed eyelids, loss of muscle tone, and dreaming. • Activation-Synthesis Theory: Theory that dreaming results from cortical synthesis and interpretation of neural signals triggered by activity in the lower part of the brain. Wade and Tavris © 2005 Prentice Hall 4-37 Are There “His” & “Hers” Brains? • Sex differences in the brain have been studied for many years. – Many findings seem to reflect cultural bias, and change with cultural changes • Reliable differences have been found in activity of certain brain areas during some tasks – Example: MRI of language task, right Wade and Tavris © 2005 Prentice Hall ♂ ♀ 4-38