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Chaffee Winter 2013 CHAPTER 2 Psychology 100: General Psychology WEEK 2 ASSIGNMENTS Read Chapter 2: The Biology of the Mind It is impossible to be successful in the field of psychology without understanding the basics of neuronal communication. Please contact me if you have difficulty with this chapter. When studying the material, and the parts of the brain outlined in this chapter, try to remember structure and function. Be able to name the structure and state its function. Chaffee Winter 2013 This chapter is much more complicated than the previous chapter, yet it provides a remarkable introduction to the nervous system CHAPTER 2: THE BIOLOGY OF MIND Neural Neurons How Neurons Communicate Neurotransmitters The Nervous System Peripheral Nervous System Central Nervous System The Endocrine System The Brain Older Brain Structures The Cerebral Cortex Our Divided Brain Right-Left Brain Differences Chaffee Winter 2013 Communication INTRODUCTION “Everything psychological is simultaneously biological” (Myers, 2010, p. 47). Phrenology was a popular theory in the 1800s, invented by Franz Gall Bumps on the skull could reveal brain functioning Although this theory was false, it did correctly assume the brain has regions with different functions NEURAL COMMUNICATION Neuron: a nerve cell, building block of the nervous system Myelin sheath: a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of the neural impulse Action Potential: a neural impulse; the brief electrical charge that travels down an axon Chaffee Winter 2013 Sensory neuron: carries information from the sensory receptors to the brain and spinal cord Motor neuron: carries outgoing information from the brain and spinal cord to the muscles and glands Interneuron: neurons within the brain and spinal cord that communication internally and intervene between the sensory inputs and motor outputs Dendrite: a branching extension of a neuron that receives information and conducts impulses toward the cell body of the neuron Axon: an extension of the neuron through which messages are passed to other neurons or muscles and glands NEURAL COMMUNICATION (FIGURE 2.2) THE ACTION POTENTIAL An action potential is a brief electrical charge that travels down the axon, which is triggered by chemical signals from neighboring neurons. The purpose of the action potential is to continue that signal down the axon to the axon terminal The axon terminal is located at the synapse, or the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic cleft. As the action potential reaches the synapse, it stimulates the release of neurotransmitter molecules. These molecules are released into the synaptic cleft and may bind to receptor sites at the next neuron. Chaffee Winter 2013 HOW NEURONS COMMUNICATE (FIG 2.4) Chaffee Winter 2013 HOW NEURONS COMMUNICATE CONTINUED Neurotransmitters: By binding the receiving neuron, neurotransmitters influence the likelihood that receiving neuron will generate a neural impulse. Excitatory neurotransmitters increase the likelihood the impulse Inhibitory neurotransmitters decrease the likelihood of the neural impulse Reuptake: Allows the sending neuron to reabsorb the excess neurotransmitter in the synaptic cleft. Chaffee Winter 2013 Chemical messengers that cross the synaptic gaps between neurons. Neurotransmitters travel across the synapse and bind to the receptor sites on the receiving neuron. RECAP: NEURONAL COMMUNICATION MATCH THE TERMS AND DEFINITIONS A. Axon 2. Dendrite 3. Myelin 4. Synapse 5. Neurotransmitter 6. Reuptake F. 7. Action Potential G. B. C. D. E. Chaffee Winter 2013 1. The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron an extension of the neuron through which messages are passed to other neurons or muscles and glands enables vastly greater transmission speed of the neural impulse branching extension of a neuron that receives information and conducts impulses toward the cell body of the neuron the brief electrical charge that travels down an axon chemical messengers that cross the synaptic gaps between neurons Reabsorbing of excess neurotransmitter molecules in the synaptic cleft HOW NEUROTRANSMITTERS INFLUENCE US Drugs and other chemicals can affect the brain at the synapse, acting like a neurotransmitter. Chaffee Winter 2013 The process by which neurotransmitters influence us is complex, involving pathways of neural activity within the brain. HOW NEUROTRANSMITTERS INFLUENCE US Chaffee Winter 2013 THE NERVOUS SYSTEM THE NERVOUS SYSTEM Chaffee Winter 2013 The Nervous System: The body’s electrochemical communication network, consisting of the nerve cells of the peripheral and central nervous systems. Central Nervous System (CNS): brain and spinal cord Peripheral Nervous System (PNS): sensory and motor neurons that connect the CNS to the rest of the body Nerves: bundles of axons that form neural “cables” connecting the central nervous system with muscles, glands, and sense organs THE PERIPHERAL NERVOUS SYSTEM The Autonomic Nervous System is divided into two subdivisions. The Sympathetic Nervous System The Parasympathetic Nervous System Chaffee Winter 2013 Our peripheral nervous system (the sensory and motor neurons that connect the CNS to the rest of the body) has two components: 1. Somatic Nervous System: the division of the PNS that controls the body’s skeletal muscles 2. Autonomic Nervous System: the part of the PNS that controls the glands and the muscles of the internal organs. THE NERVOUS SYSTEM Chaffee Winter 2013 SYMPATHETIC AND PARASYMPATHETIC DIVISIONS OF THE AUTONOMIC NERVOUS SYSTEM Sympathetic nervous system: division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations (fight or flight) Parasympathetic nervous system: division of the autonomic nervous system that calms the body, conserving its energy THE ENDOCRINE SYSTEM The Hormones: chemical messengers that are manufactured by the endocrine glands, travel through the blood stream, and affect other tissues including the brain The endocrine system and nervous system both produce molecules that act on receptors elsewhere. The nervous system sends fast messages while the endocrine system sends slower messages, but their effects can last longer. Brain Pituitary other glands Hormones Brain Chaffee Winter 2013 body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream THE ENDOCRINE SYSTEM Chaffee Winter 2013 THE ENDOCRINE SYSTEM CONTINUED The pituitary gland is a pea-sized structure located in the core of the brain The pituitary gland is controlled by the hypothalamus, an area of the brain located directly above the pituitary. The pituitary secretes hormones that influence the release of hormones by other endocrine glands E.g. the hypothalamus stimulates the pituitary to trigger the sex glands to release sex hormones. These hormones then influence the brain and behavior. Brain Pituitary other glands Hormones Brain Chaffee Winter 2013 The adrenal glands are a pair of endocrine glands that sit above the kidney. They secrete epinephrine and norepinephrine that help around the body in times of stress THE BRAIN: THE TOOLS OF DISCOVERY Types Electroencephalogram (EEG): a technique for the study of electrical current, or activity, within the brain. Positron emission tomography (PET): A highly specialized imaging technique that uses short-lived radioactive glucose to produce three-dimensional colored images of those substances functioning within the brain, such as during a task Magnetic Resonance Imaging (MRI): a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue Functional MRI (fMRI): a technique for revealing blood flow, and thus brain activity, by comparing successive MRI scans Chaffee Winter 2013 of Imaging THE BRAIN: OLDER STRUCTURES These structures are called “older” by the book as they are present in primitive animals, such as the shark, with a much longer history on earth than homo sapiens. The older brain structures control more basic functions, such as breathing. The brainstem is the oldest part of the brain, beginning where the spinal cord enters the skull. It is responsible for automatic survival functions The medulla is located at the base of the brainstem. It controls heartbeat and breathing. The pons is another area of the brainstem that helps coordinate movements. Within the brainstem is a neural network known as the reticular formation. These neurons control arousal, or alertness. Chaffee Winter 2013 THE BRAIN: OLDER STRUCTURES OLDER STRUCTURES CONTINUED The thalamus is located on top of the brainstem; it directs sensory information and motor signals from the brainstem to the cerebral cortex; also, it transmits information from the cortex to the cerebellum and medulla The cerebellum processes sensory input, coordinates motor output, and assists in balance THE LIMBIC SYSTEM Chaffee Winter 2013 The limbic system is a neural network located underneath the cerebral hemispheres, associated with emotions, motives, and drives AMYGDALA The amygdala, composed of two structures shaped like almonds (one in each hemisphere), functions to regulate aggression, fear, and emotion Kluver-Bucy syndrome: Remove amygdala in primates Result: mellow, difficulty recognizing objects, hypersexual, and displayed hyperorality THE HYPOTHALAMUS Hypothalamus: a neural structure lying below the thalamus helps govern the endocrine system via the pituitary directs maintenance activities: eating, drinking, temperature regulation Neural networks for emotion and reward The four Fs (fight, flight, feeding, sex) HIPPOCAMPUS The hippocampus is the third area of the limbic system, as defined by this book. Functions: Formation of new memory (first part affected by Alzheimer’s disease) Emotions, vulnerable to stress Spatial memory and navigation Chaffee Winter 2013 THE CEREBRAL CORTEX THE CEREBRAL CORTEX: STRUCTURE The The folds of the cortex increase surface area, thus allowing more neurons to fit within the skull. If you were to flatten the cerebral cortex, the brain would require triple the area. The degree of cortical folding indicates the complexity of cortical functions that are possible. Consider the differences in cortical folds in different animals, see next slide. Chaffee Winter 2013 cerebral cortex is the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center. Cortical Folds: THE CEREBRAL CORTEX: COMPARATIVE NEUROANATOMY STRUCTURE OF THE CORTEX The 2. 3. 4. Chaffee Winter 2013 1. brain is divided into four areas called lobes Frontal Lobes: Portion of the cerebral cortex lying just behind the forehead; involved in speech, motor functioning, and higher order thought such as planning, judgment, decision making Parietal Lobes: receives sensory input Temporal Lobes: auditory processing, speech Occipital Lobes: receives input from visual fields FUNCTIONS OF THE CORTEX: MOTOR Chaffee Winter 2013 The motor cortex is located at the rear (posterior) portion of the frontal lobes and it controls voluntary movements The motor cortex controls contralateral movement, meaning the movement on the opposite site of the body. MOTOR CORTEX: NEURAL PROSTHESIS As you can see from the figure on the previous slide, the motor cortex has been mapped Guided by a 100-electrode brain implant, this monkey learned to control a mechanical arm that can grab snacks and put them in his mouth (Velliste et al., 2008). This research raises hope for the use of neural prosthetics in people with paralyzed limbs. FUNCTIONS OF THE CORTEX: SENSORY The sensory cortex is located at the front of the parietal love. It registers and processes body touch, movement, and position information. The visual cortex of the occipital lobe receives visual input from your eyes. The auditory cortex of the temporal lobes receives auditory information from your ears. FUNCTIONS OF THE CORTEX: ASSOCIATION Chaffee Winter 2013 The areas of the cerebral cortex that are not involved in primary motor or sensory functions, but rather in higher mental functions such as learning, remembering, thinking and speaking, are known as association areas. More “intelligent” animals have more association areas of their cortex. These areas are responsible for integrating and acting on information received and processed by sensory areas. ASSOCIATION AREAS CONTINUED The association areas of the frontal lobe enable judgment, planning, and processing of new memories. Damage to the frontal lobe can alter the capacity to make plans and can even change personality. Read the story of Phineas Gage, starting on page 72. THE BRAIN Chaffee Winter 2013 THE BRAIN’S PLASTICITY Severed neurons do not regenerate, but some neural tissue can reorganize in response to damage. In the case of blind or hearing impaired individuals, the unused brain areas are available for other uses. For example, when a blind person reads Braille, the brain area dedicated to that finger expands as areas of the visual cortex are activated (Baringa, 1992; Sadato et al., 1996). Neurogenesis, or the formation of new neurons, can also occur after damage. However, new neurons are only formed deep within the brain and must migrate elsewhere and form connections (Gould, 2007). Chaffee Winter 2013 The brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience, is known as plasticity. OUR DIVIDED BRAIN The left and right hemisphere of the brain are largely separate. Chaffee Winter 2013 The corpus callosum is a large band of neural fibers connecting the two brain hemispheres and carrying messages between them RIGHT-LEFT DIFFERENCES IN THE INTACT BRAIN Lateralization: the specialization of certain functions by each side of the brain One side tends to be dominant in each activity The Whole Brain Left brain Right side of body Serial processor (Linear thought) Logical reasoning, detailed analysis, basics of language Right brain Left side of body Parallel processor (Conscious, complex thought) Emotional and creative processes VIDEO: STROKE OF INSIGHT Each time one of these short talks is assigned, your goal is to find a “take-home” message from the information presented. On exams, you will be asked what your “take-home” message was from the talk, and I expect you to provide a short paragraph (more than 1 sentence) that reflect your knowledge of the material presented by the speaker and your opinion on the topic. Watch this 18 minute presentation: http://www.ted.com/ talks/jill_bolte_taylor_s_powerful_stroke_of_insight.html Jill Bolte-Taylor, the speaker, is a renowned neuroscientist. The video describes her experience of a cerebral hemorrhage, or stroke, and her recovery. Chaffee Winter 2013 Throughout the course, we will watch several Ted Talks, short lectures, from leading researchers. Visit http:// www.ted.org and note the purpose of this organization to provide “Riveting talks by remarkable people, free to the world.” CHAPTER 2 LEARNING OBJECTIVES Chaffee Winter 2013 Neural Communication 1. Describe a neuron, including its major parts. 2. Describe an action potential, synapse, and neurotransmitter. The Nervous System 1. Distinguish the central and peripheral nervous system. 2. Distinguish the subdivisions of the peripheral nervous system. 3. Distinguish the sympathetic and parasympathetic divisions of the autonomic nervous system. The Endocrine System: What are hormones? Describe their path from the brain to the body, and back. Describe the major divisions of the brain as discussed in your text: 1. Older structures: Brainstem 2. Limbic System: Hypothalamus, Amygdala, Hippocampus 3. Know the four main divisions of the cortex. 4. Describe plasticity and neurogenesis 5. What is the corpus callosum? How are the left and right hemispheres different? Take-home message from Jill Bolte-Taylor presentation.