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Chapter 3

Chapter 3. Neuroscience And Behavior. Schacter Gilbert Wegner. PSYCHOLOGY. Slides prepared by: Melissa S. Terlecki, Cabrini College. 3.1. Neurons: The Origin of Behavior. PSYCHOLOGY. Schacter Gilbert Wegner. Parts of a Neuron.

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Chapter 3

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  1. Chapter 3 Neuroscience And Behavior Schacter Gilbert Wegner PSYCHOLOGY • Slides prepared by: • Melissa S. Terlecki, Cabrini College

  2. 3.1 Neurons: The Origin of Behavior PSYCHOLOGY Schacter Gilbert Wegner

  3. Parts of a Neuron • Neuron: cells in the nervous system that communicate with one another to perform information-processing tasks (approx. 100 billion neurons in the brain). • cell body: coordinates information-processing tasks and keeps the cell alive. • dendrites: receives information from other neurons and relays it to the cell body. • axon: transmits information to other neurons, muscles, or glands. • myelin sheath: insulating layer of fatty material. • nodes of Ranvier • synapse: the junction or region between the axon of one neuron and the dendrites or cell body of another.

  4. Figure 3.1: Components of a Neuron (p. 56)

  5. Types of Neurons and Cells • Glial cells: support cells found in the nervous system. • Sensory neurons: neurons that receive information from the external world and convey this information to the brain via the spinal cord. • Motor neurons: neurons that carry signals from the spinal cord to the muscles to induce movement. • Interneurons: neurons that connect sensory neurons, motor neurons, or other interneurons.

  6. Questions • How do the three types of neurons work together to transmit information?

  7. Electric Signaling: Communicating Information Within a Neuron • The communication of information within and between neurons proceeds in two stages: • conduction of an electric signal within a neuron from dendrite to cell body and axon. • transmission of electric signals between neurons over the synapse. • Ions: small electrically charged molecules that flow in and out of the cell.

  8. Figure 3.2: The Synapse (p. 58)

  9. Electric Signaling: Communicating Information Within a Neuron • Resting potential: the difference in electric charge between the inside and outside of a neuron’s cell membrane. • When the neuron is at rest, positively charged potassium ions (K+) flow out. • Cell is negatively charged (-70 millivolts). • Action potential: an electric signal that is conducted along an axon to a synapse. • Occurs only when threshold for stimulation is reached; all-or-none. • During action potential, positively charged sodium ions (Na+) flow in. • Cell is positively charged (+40 millivolts). • Refractory period: the time following an action potential during which a new action potential cannot be initiated.

  10. Figure 3.3: The Action Potential (p. 59)

  11. Figure 3.4: Myelin and Nodes of Ranvier (p. 60)

  12. Questions • Why is an action potential an all-or-nothing event?

  13. Chemical Signaling: Synaptic Transmission Between Neurons • An action potential reaches the end of an axon at the terminal button and a neurotransmitter is released into the synapse, collected at the receptor of the receiving neuron. • terminal buttons: knoblike structures that branch out from an axon. • neurotransmitters: chemicals that transmit information across the synapse to a receiving neuron’s dendrites. • receptors: parts of the cell membrane that receive the neurotransmitter and initiate a new electric signal. • postsynaptic neuron: the receiving neuron. • presynaptic neuron: the sending neuron.

  14. Chemical Signaling: Synaptic Transmission Between Neurons • Neurotransmitters leave the synapse. • Reuptake: neurotransmitter reabsorbed by terminal button of presynaptic neuron. • Enzyme deactivation: neurotransmitters destroyed by enzymes in synapse. • Autoreceptors: neurotransmitters bind to receptor sites on presynaptic neurons.

  15. Figure 3.5: Synaptic Transmission (p. 61)

  16. Questions • How does a neuron communicate with another neuron?

  17. Types of Neurotransmitters • Acetylcholine (Ach): involved in voluntary motor control, memory, regulation of attention, learning, sleeping, and dreaming. • Dopamine (DA): regulates motor behavior, motivation, pleasure, and emotional arousal. • Glutamate: involved in information transmission throughout the brain (major excitatory neurotransmitter). • GABA: involved in stopping firing of neurons in the brain (major inhibitory neurotransmitter). • Norepinephrine (NE): influences mood and arousal. • Serotonin (5-HT): regulates sleep and wakefulness, eating, and aggressive behavior. • Endorphins: chemicals that act within pain pathways and emotion centers of the brain.

  18. Ach DA Glutamate GABA NE Dopamine Endorphins Mood disorders Seizures “Runner’s high” Alzheimer’s disease Schizophrenia Parkinson’s disease Match the Neurotransmitter With Its Related Disorder or Behavior

  19. Questions • How do neurotransmitters create the feeling of a “runner’s high”?

  20. How Drugs Mimic Neurotransmitters • Many drugs affect the nervous system by increasing, interfering with, or mimicking the manufacture or function of neurotransmitters. • Agonists: drugs that increase the action of a neurotransmitter. • Antagonists: drugs that block the function of a neurotransmitter.

  21. Questions • How does giving L-dopa alleviate symptoms of Parkinson’s disease?

  22. 3.2 The Organization of the Nervous System PSYCHOLOGY Schacter Gilbert Wegner

  23. The Nervous System • Nervous system: an interacting network of neurons that conveys electrochemical information throughout the body. • Nerves: bundles of axons and glial cells that support neurons.

  24. Divisions of the Nervous System • Central nervous system (CNS): the part of the nervous system that is composed of the brain and spinal cord. • Peripheral nervous system (PNS): the part of the nervous system that connects the central nervous system to the body’s organs and muscles. • Somatic nervous system: a set of nerves that conveys information into and out of the CNS. • Autonomic nervous system (ANS): a set of nerves that carries involuntary and automatic commands that control blood vessels, body organs, and glands. • Sympathetic nervous system: a set of nerves that prepares the body for action in threatening situations. • Parasympathetic nervous system: a set of nerves that helps the body return to a normal resting state.

  25. Figure 3.6: The Human Nervous System (p. 65)

  26. Figure 3.7: Sympathetic and Parasympathetic Systems (p. 66)

  27. Questions • What triggers the increase in your heart rate when you feel threatened?

  28. Components of the Central Nervous System • The CNS is comprised of the brain and the spinal cord, which communicate and collaborate on a variety of complex tasks. • Spinal reflexes: simple pathways in the nervous system that rapidly generate muscle contractions.

  29. Figure 3.8: The Pain Withdrawal Reflex (p. 67)

  30. Questions • What important functions does the spinal cord perform on its own?

  31. The Human Brain (p. 68)

  32. Figure 3.9: The Major Divisions of the Brain (p. 68)

  33. Exploring the Brain • The brain is divided into 3 sections, though all interact as part of a whole. • Hindbrain (brain stem): an area of the brain that coordinates information coming into and out of the spinal cord, and controls the basic functions of life. • medulla: coordinates heart rate, circulation, and respiration (extension of the spinal cord into the skull). • reticular formation: regulates sleep, wakefulness, and arousal level (inside medulla). • cerebellum: controls fine motor skills (large part of hindbrain). • pons: relays information from the cerebellum to the rest of the brain (part of hindbrain).

  34. Figure 3.10: The Hindbrain (p. 69)

  35. Questions • Which part of the brain helps to orchestrate movements that keep you steady on your bike?

  36. Exploring the Brain • Midbrain: small, midsection of the brain that is important for orientation and movement, and also is the central location of DA and 5-HT that are involved in arousal, mood, and motivation. • tectum: orients an organism in the environment (part of midbrain). • tegmentum: involved in movement and arousal (part of midbrain).

  37. Figure 3.11: The Midbrain (p. 69)

  38. Exploring the Brain • Forebrain: the highest level of the brain, critical for complex cognitive, emotional, sensory, and motor function. It is divided into two parts. • cerebral cortex: the outermost layer of the brain, visible to the naked eye and divided into 2 hemispheres. • subcortical structures: areas of the forebrain housed under the cerebral cortex near the very center of the brain.

  39. Figure 3.12: The Forebrain (p. 70)

  40. Subcortical Structures in the Forebrain • Thalamus: relays and filters information from the senses and transmits the information to the cerebral cortex. • Hypothalamus: regulates body temperature, hunger, thirst, and sexual behavior. • Pituitary gland: the “master-gland” of the body’s hormone-producing system, releases hormones that direct the functions of many other glands in the body. • Hippocampus: critical for creating new memories and integrating them into a network of knowledge so that they can be stored in other parts of the cerebral cortex. • Amygdala: plays a central role in many emotional processes, particularly the formation of emotional memories.

  41. The Cerebral Cortex • The cerebral cortex can be divided into two symmetrical hemispheres, the left and right, connected by commisures. • corpus callosum: a thick band of nerve fibers that connects large areas of the cerebral cortex on each side of the brain and supports communication of information across the hemispheres. • contralteral representation in the brain.

  42. Figure 3.13: Cerebral Hemispheres (p. 70)

  43. The Cerebral Cortex • Two hemispheres divided into 4 lobes each. • occipital lobe: processes visual information. • parietal lobe: processes information about touch. • temporal lobe: responsible for hearing and language. • frontal lobe: has specialized areas for movement, abstract thinking, planning, memory, and judgment. • Association areas: areas of the cerebral cortex that are composed of neurons that help provide sense and meaning to information registered in the cortex. • plasticity: the ability of the association areas to be molded by experience.

  44. Figure 3.14: Cerebral Cortex and Lobes (p. 71)

  45. Questions • What types of thinking occur in the frontal lobe?

  46. Figure 3.15: Somatosensory and Motor Cortices (p. 72)

  47. The Homunculus (p. 72)

  48. 3.3 The Evolution of the Nervous System PSYCHOLOGY Schacter Gilbert Wegner

  49. Evolutionary Development of the Central Nervous System • The first neurons appeared in simple invertebrates, such as jellyfish. • The first CNS appeared in flatworms. • ganglia: small collections of neurons that integrate information and coordinate motor behavior in the body region near each ganglion. • In vertebrates, the CNS is organized in a hierarchy (the lower levels of the brain and spinal cord execute simpler functions; the higher levels perform more complex functions). • The forebrain is much larger in higher vertebrates (with some unique abilities in humans). • Mammals have a highly developed cerebral cortex; reptiles and birds have almost no cerebral cortex.

  50. Questions • Are our brains still evolving?

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