Biological Psychology Chapter 1: The Cellular Foundation of Behavior PDF

Chapter 1 The Cellular Foundation of Behavior © Cengage Learning 2016 © Cengage Learning 2016  What is Biological Psychology Biology is the study of: Psychology is the study of: Ce...

Chapter 1 The Cellular Foundation of Behavior © Cengage Learning 2016 © Cengage Learning 2016  What is Biological Psychology Biology is the study of: Psychology is the study of: Cells, Brains, Walking, Talking, Physiology, CNS, Eating, Sleeping, Body, Neuroanatomy, etc.. (Biological Basis) (Behavior) Biological psychology is the study of the biological basis of behavior 2 Chapter Introduction, 1 + 2 © Cengage Learning 2016  Biological psychology is the study of the biological basis of behavior (the study of the physiological, evolutionary and developmental mechanisms of behavior and experiences). Chapter Introduction, 1 + 2 3 © Cengage Learning 2016  Biological Explanations of Behavior Physiological Explanation relates a behavior to the activity of the brain and other organs (the pigeons drink with their heads down, because of their neck muscle structure) Ontogenetic Explanation describes the development of a structure or a behavior (at early stage of its development the pigeons learn to drink this way from their parents) Chapter Introduction, 1 + 2 4 © Cengage Learning 2016  Evolutionary Explanation examines a structure or a behavior in terms of evolutionary history (doves drinks with their heads down too, thus, pigeons and doves have a common ancestor) Functional explanation describes why a structure or behavior evolved as it did (when pigeons drink this way the drink faster, thus spend less time on land, fly back and avoid predators like cats ) Chapter Introduction, 1 + 2 5 © Cengage Learning 2016  The Mind-Brain Relationship Mind-Body or Mind-Brain problem. 1. Dualism: the belief that mind and body are different kinds of substance (thought substance and physical substance) that exist independently but somehow interact. Chapter Introduction, 1 + 2 6 © Cengage Learning 2016  2. Monism: the belief that the universe consists of only one kind of existence. i. Materialism: everything that exists is material, or physical. ii. Mentalism: only the mind really exists. iii. Identity position: mental processes and brain processes are the same, but described differently. Chapter Introduction, 1 + 2 7 © Cengage Learning 2016  3. Solipsism: I alone exist, I alone am conscious Problem of other minds: The difficulty of knowing whether other people (or animals) have conscious experiences. Solipsism is sometimes expressed as the view that "I am the only mind which exists," or "My mental states are the only mental states." However, the sole survivor of a nuclear holocaust might truly come to believe in either of these propositions without thereby being a solipsist. Solipsism is therefore more properly regarded as the doctrine that, in principle, "existence" means for me my existence and that of my mental states. Chapter Introduction, 1 + 2 8 © Cengage Learning 2016  1.1 The Cells of the Nervous System Your mental experiences depend on the activity of a huge number of separate but interconnected cells We can begin to understand how this works by looking at the cells of the nervous system Chapter Introduction, 1 + 2 9 © Cengage Learning 2016  How Many Neurons Do We Have? Chapter Introduction, 1 + 2 10 © Cengage Learning 2016  Neurons and Glia, Part 1 The human nervous system comprises two kinds of cells – Neurons: receive information and transmit it to other cells. – Glia: serve many functions A supportive cell in the central nervous system. Unlike neurons, glial cells do not conduct electrical impulses. The glial cells surround neurons and provide support for and insulation between them. Glial cells are the most abundant cell types in the central nervous system. Types of glial cells include oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells. The human brain contains approximately 100 billion individual neurons Chapter Introduction, 1 + 2 11 © Cengage Learning 2016  The Structures of an Animal Cell, Part 1 Like other cells in the body, neurons contain the following structures – Membrane – Nucleus – Mitochondria – Ribosomes – Endoplasmic reticulum – Golgi bodies Chapter Introduction, 1 + 2 12 © Cengage Learning 2016  An Electron Micrograph of the Parts of a Neuron Chapter Introduction, 1 + 2 13 © Cengage Learning 2016  https://www.youtube.com/watch?v=URUJ D5NEXC8 Chapter Introduction, 1 + 2 14 © Cengage Learning 2016  The Structures of an Animal Cell, Part 2 Membrane: separates the inside of the cell from the outside environment Nucleus: contains the chromosomes Mitochondrion: performs metabolic activities and provides energy that the cells requires Chapter Introduction, 1 + 2 15 © Cengage Learning 2016  The Structures of an Animal Cell, Part 3 Ribosomes: sites at which the cell synthesizes new protein molecules Endoplasmic reticulum: network of thin tubes that transport newly synthesized proteins to their location Golgi bodies: Package newly synthesized proteins. Chapter Introduction, 1 + 2 16 © Cengage Learning 2016  The Structure of a Neuron Neuron cells are similar to other cells of the body but have a distinctive shape Chapter Introduction, 1 + 2 17 © Cengage Learning 2016  Neurons Human brain consists of 100 billion neurons and 100 trillion synapses. Another estimate is 86 billion neurons of which 16.3 are in the cerebral cortex and 69 in the cerebellum. © Cengage Learning 2016  Types of Neurons Sensory neurons or Bipolar neurons carry messages from the body's sense receptors (eyes, ears, etc.) to the CNS. These neurons have two processes. Sensory neuron account for 0.9% of all neurons. (Examples are retinal cells, olfactory epithelium cells.) Motoneurons or Multipolar neurons carry signals from the CNS to the muscles and glands. These neurons have many processes originating from the cell body. Motoneurons account for 9% of all neurons. (Examples are spinal motor neurons, pyramidal neurons, Purkinje cells.) Interneurons or Pseudopolare (Spelling) cells form all the neural wiring within the CNS (brain and spinal cord). These have two axons (instead of an axon and a dendrite). One axon communicates with the spinal cord; one with either the skin or muscle. These neurons have two processes. (Examples are dorsal root ganglia cells.) An interneuron acts as a “middle-man” between afferent, or sensory, neurons, which receive signals from the peripheral nervous system, and efferent, or motor, neurons, which transmit signals from the brain. It also connects to other interneurons, allowing them to communicate with one another. http://study.com/academy/lesson/interneurons-definition-function- quiz.html © Cengage Learning 2016  Neurotransmitters Neurotransmitters are chemicals located and released in the brain to allow an impulse from one nerve cell to pass to another nerve cell. © Cengage Learning 2016  Types of Neurotransmitters. Excitatory and inhibitory Some neurotransmitters are commonly described as "excitatory" or "inhibitory". The only thing that a neurotransmitter does directly is to activate one or more types of receptors. The effect on the postsynaptic cell depends entirely on the properties of the receptors. © Cengage Learning 2016  Glutamate - is used at the great majority of fast excitatory synapses in the brain and spinal cord. It is also used at most synapses that are "modifiable", i.e. capable of increasing or decreasing in strength. Modifiable synapses are thought to be the main memory-storage elements in the brain. GABA - is used at the great majority of fast inhibitory synapses in virtually every part of the brain. Many sedative/tranquilizing drugs act by enhancing the effects of GABA. Correspondingly glycine is the inhibitory transmitter in the spinal cord. Acetylcholine - is distinguished as the transmitter at the neuromuscular junction connecting motor nerves to muscles. The paralytic arrow-poison curare acts by blocking transmission at these synapses. Acetylcholine also operates in many regions of the brain, but using different types of receptors. Dopamine - has a number of important functions in the brain. It plays a critical role in the reward system, but dysfunction of the dopamine system is also implicated in Parkinson's Disease and schizophrenia. Serotonin - has a number of important functions that are difficult to describe in a unified way, including regulation of mood, sleep/wake cycles, and body temperature. It is released during sunny weather, and also when eating chocolate or taking Ecstasy. Substance P - undecapeptide responsible for transmission of pain from certain sensory neurons to the central nervous system. © Cengage Learning 2016  Neuronal Firing Action Potential. Sodium and potassium pump. © Cengage Learning 2016  Components of All Neurons Dendrites Soma/cell body Axon Presynaptic terminals Chapter Introduction, 1 + 2 24 © Cengage Learning 2016  https://www.youtube.com/watch?v=NsBaP temAjs Chapter Introduction, 1 + 2 25 © Cengage Learning 2016  Dendrites Branching fibers with a surface lined with synaptic receptors responsible for bringing information into the neuron Some also contain dendritic spines that further branch out and increase the surface area of the dendrite The greater the surface area of the dendrite, the more information it can receive Chapter Introduction, 1 + 2 26 © Cengage Learning 2016  Dendritic Spines Chapter Introduction, 1 + 2 27 © Cengage Learning 2016  CELL BODY/SOMA Contains the nucleus, mitochondria, and ribosomes Responsible for the metabolic work of the neuron Covered with synapses on its surface in many neurons Chapter Introduction, 1 + 2 28 © Cengage Learning 2016  Axons Thin fiber of a neuron responsible for transmitting nerve impulses toward other neurons, organs, or muscles Maybe have a myelin sheath, an insulating material that contains interruptions in the sheath known as nodes of Ranvier Presynaptic terminals at the end points of an axon release chemicals to communicate with other neurons Chapter Introduction, 1 + 2 29 © Cengage Learning 2016  Chapter Introduction, 1 + 2 30 © Cengage Learning 2016  Afferent, Efferent and Intrinsic Afferent axon: refers to bringing information into a structure Efferent axon: refers to carrying information away from a structure Interneurons or intrinsic neurons: are those whose dendrites and axons are completely contained within a single structure Chapter Introduction, 1 + 2 31 © Cengage Learning 2016  Variations Among Neurons Neurons vary in size, shape, and function The shape of a neuron determines it connection with other neurons and its contribution to the nervous system The function is closely related to the shape of a neuron Example: Pukinje cells of the cerebellum branch extremely widely within a single plane Chapter Introduction, 1 + 2 32 © Cengage Learning 2016  The Diverse Shape of Neurons Chapter Introduction, 1 + 2 33 © Cengage Learning 2016  A Vertebrate Motor Neuron Chapter Introduction, 1 + 2 34 © Cengage Learning 2016  A Vertebrate Sensory Neuron Chapter Introduction, 1 + 2 35 © Cengage Learning 2016  https://www.youtube.com/watch?v=cUGuWh 2UeMk Chapter Introduction, 1 + 2 36 © Cengage Learning 2016  Action potential http://www.sumanasinc.com/webcontent/animations/content/action_potential.html http://www.sumanasinc.com/webcontent/animations/content/actionpotential.html http://webspace.ship.edu/cgboer/actionpot.html © Cengage Learning 2016  The Action Potential https://www.youtube.com/watch?v=iBDXOt _uHTQ https://www.youtube.com/watch?v=fHRC8 SlLcH0 Chapter Introduction, 1 + 2 38 © Cengage Learning 2016  To understand how a membrane potential is generated, first consider a hypothetical cell in which K+ is the only ion across the membrane other than the large negatively charged proteins inside of the cell. Because the cell has potassium channels through which K+ can move in and out of the cell, K+ diffuses down its chemical gradient (out of the cell) because its concentration is much higher inside the cell than outside. As K+ (a positively charged ion) diffuses out of the cell, it leaves behind negatively charged proteins. This leads to a separation of charges across the membrane and therefore a potential difference across the membrane. Experimentally it is possible to prevent the K+ from diffusing out of the cell. This can be achieved by applying a negative charge to the inside of the cell that prevents the positively charged K+ from leaving the cell. The negative charge across the membrane that would be necessary to oppose the movement of K+ down its concentration gradient is termed the equilibrium potential for K+ (EK; Nernst potential). © Cengage Learning 2016  1.2 The Nerve Impulse The electrical message that is transmitted down the axon of a neuron – Does not travel directly down the axon, but is regenerated at points along the axon so that it is not weakened The speed of nerve impulses ranges from less than 1 meter/second to 100 meters/second – A touch on the shoulder reaches the brain more quickly than a touch on the foot Chapter Introduction, 1 + 2 40 © Cengage Learning 2016  The Nerve Impulse The brain is not set up to register small differences in the time of arrival of touch messages However, in vision, movements must be detected as accurately as possible The properties of impulse control are well adapted to the exact needs for information transfer in the nervous system Chapter Introduction, 1 + 2 41 © Cengage Learning 2016 The Resting Potential of the Neuron, Part 1 Messages in a neuron develop from disturbances of the resting potential At rest, the membrane maintains an electrical gradient known as polarization – A difference in the electrical charge inside and outside of the cell Chapter Introduction, 1 + 2 42 © Cengage Learning 2016 The Resting Potential of the Neuron, Part 2 The inside of the membrane is slightly negative with respect to the outside (approximately -70 millivolts) The resting potential of a neuron refers to the state of the neuron prior to the sending of a nerve impulse Chapter Introduction, 1 + 2 43 © Cengage Learning 2016  The Membrane of a Neuron Chapter Introduction, 1 + 2 44 © Cengage Learning 2016  Forces Acting on Sodium and Potassium Ions The membrane is selectively permeable, allowing some chemicals to pass more freely than others Sodium, potassium, calcium, and chloride pass through channels in the membrane When the membrane is at rest: – Sodium channels are closed – Potassium channels are partially closed allowing the slow passage of potassium Chapter Introduction, 1 + 2 45 © Cengage Learning 2016 Ion Channels in the Membrane of a Neuron Chapter Introduction, 1 + 2 46 © Cengage Learning 2016  Ion Channels The sodium-potassium pump is a protein complex – Continually pumps three sodium ions out of the cells while drawing two potassium ions into the cell – Helps to maintain the electrical gradient Chapter Introduction, 1 + 2 47 © Cengage Learning 2016  Electrical and Concentration Gradients (Resting potential) The electrical gradient and the concentration gradient – the difference in distributions of ions – work to pull sodium ions out of the cell The electrical gradient tends to pull potassium ions into the cells – However, they slowly leak out, carrying a positive charge with them Chapter Introduction, 1 + 2 48 © Cengage Learning 2016  Sodium and Potassium Gradients for a Resting Membrane Chapter Introduction, 1 + 2 49 © Cengage Learning 2016  The Action Potential, Part 1 The resting potential remains stable until the neuron is stimulated – Hyperpolarization: increasing the polarization or the difference between the electrical charge of two places – Depolarization: decreasing the polarization towards zero – The threshold of excitation: a level above which any stimulation produces a massive depolarization Chapter Introduction, 1 + 2 50 © Cengage Learning 2016  Voltage-Activated Channels Membrane channels whose permeability depends upon the voltage difference across the membrane – Sodium and potassium channels When sodium channels are opened, positively charged sodium ions rush in and a subsequent nerve impulse occurs Chapter Introduction, 1 + 2 51 © Cengage Learning 2016  The Movement of Sodium and Potassium Ions During an Action Potential Chapter Introduction, 1 + 2 52 © Cengage Learning 2016  The Movement of Sodium and Potassium After an action potential occurs, sodium channels are quickly closed The neuron is returned to its resting state by the opening of potassium channels – Potassium ions flow out due to the concentration gradient and take with them their positive charge The sodium-potassium pump later restores the original distribution of ions Chapter Introduction, 1 + 2 53 © Cengage Learning 2016  Restoring the Sodium-Potassium Pump The process of restoring the sodium- potassium pump to its original distribution of ions takes time An unusually rapid series of action potentials can lead to a buildup of sodium within the axon – Can be toxic to a cell, but only in rare instances such as stroke and after the use of certain drugs Chapter Introduction, 1 + 2 54 © Cengage Learning 2016  Blocking Sodium Channels Local anesthetic drugs block sodium channels and therefore prevent action potentials from occurring – Example: Novocain and Xylocaine Chapter Introduction, 1 + 2 55 © Cengage Learning 2016  The All-or-None Law, Part 1 Action potentials back-propagate into the cell body and dendrites – Dendrites become more susceptible to structural changes responsible for learning The all-or-none law – States that the amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it – Action potentials are equal in intensity and speed within a given neuron Chapter Introduction, 1 + 2 56 © Cengage Learning 2016  The All-or-None Law, Part 2 Action potentials vary from one neuron to another in terms of amplitude, velocity, and shape Studies of mammalian axons show that there is much variation in the types of protein channels and therefore in the characteristics of the action potentials Chapter Introduction, 1 + 2 57 © Cengage Learning 2016  Refractory Periods After an action potential, a neuron has a refractory period during which time the neuron resists the production of another action potential – The absolute refractory period: the first part of the period in which the membrane cannot produce an action potential – The relative refractory period: the second part, in which it takes a stronger than usual stimulus to trigger an action potential https://www.youtube.com/watch?v=Gsf9IB- © Cengage Learning 2016 Chapter Introduction, 1 + 2 58  Propagation of an Action Potential, Part 1 In a motor neuron, the action potential begins at the axon hillock (a swelling where the axon exits the soma) Propagation of the action potential: the transmission of the action potential down the axon – The action potential does not directly travel down the axon Chapter Introduction, 1 + 2 59 © Cengage Learning 2016  Propagation of an Action Potential, Part 2 Chapter Introduction, 1 + 2 60 © Cengage Learning 2016  The Myelin Sheath The myelin sheath of axons are interrupted by short unmyelinated sections called nodes of Ranvier – Myelin is an insulating material composed of fats and proteins – At each node of Ranvier, the action potential is regenerated by a chain of positively charged ions pushed along by the previous segment Chapter Introduction, 1 + 2 61 © Cengage Learning 2016  An Axon Surrounded by a Myelin Sheath Chapter Introduction, 1 + 2 62 © Cengage Learning 2016  Saltatory Conduction The “jumping” of the action potential from node to node – Provides rapid conduction of impulses – Conserves energy for the cell Multiple sclerosis: disease in which the myelin sheath is destroyed – Associated with poor muscle coordination and sometimes visual impairments Chapter Introduction, 1 + 2 63 © Cengage Learning 2016  Saltatory Conduction in a Myelinated Axon Chapter Introduction, 1 + 2 64 © Cengage Learning 2016  Local Neurons, Part 1 Have short axons, exchange information with only close neighbors, and do not produce action potentials When stimulated, produce graded potentials – membrane potentials that vary in magnitude and do not follow the all-or- none law Depolarize or hyperpolarize in proportion to the stimulation https://www.youtube.com/watch? © Cengage Learning 2016 Chapter Introduction, 1 + 2 65  Local Neurons, Part 2 Difficult to study due to their small size Most of our knowledge has come from the study of large neurons Myth – Only 10 percent of neurons are active at any given moment Truth – You use all of your brain, even at times when you might not be using it very well Chapter Introduction, 1 + 2 66 © Cengage Learning 2016  Santiago Ramón y Cajal, a Pioneer of Neuroscience In the late 1800s, the Spanish investigator Santiago Ramon y Cajal (1852-1934) was the first to demonstrate that the individual cells comprising the nervous system remained separate – He showed that they did not merge into each other as previously believed Chapter Introduction, 1 + 2 67 © Cengage Learning 2016  Neurons and Glia, Part 2 Types of Glia Astrocytes – Help synchronize the activity of the axon by wrapping around the presynaptic terminal and taking up chemicals released by the axon Microglia – Remove waste material, viruses, and fungi from the brain Chapter Introduction, 1 + 2 68 © Cengage Learning 2016  Neurons and Glia, Part 2 Oligodendrocytes (in the brain and spinal cord) and Schwann cells (in the periphery of the body) – build the myelin sheath that surrounds and insulates certain vertebrate axons Radial glia – Guide the migration of neurons and the growth of their axons and dendrites during embryonic development Chapter Introduction, 1 + 2 69 © Cengage Learning 2016  Neurons and Glia, Part 3 When embryonic development finishes, most radial glia differentiate into neurons and a smaller number differentiate into astrocytes and oligodendrocytes Chapter Introduction, 1 + 2 70 © Cengage Learning 2016  Shapes of Various Glia Cells Chapter Introduction, 1 + 2 71 © Cengage Learning 2016 How An Astrocyte Synchronizes Associated Axons Chapter Introduction, 1 + 2 72 © Cengage Learning 2016  Glia cells video https://www.youtube.com/watch?v=52NVc 9Lku4o Chapter Introduction, 1 + 2 73 © Cengage Learning 2016  The Blood-Brain Barrier A mechanism that surrounds the brain and blocks most chemicals from entering – The immune system destroys damaged or infected cells throughout the body – Because neurons in the brain generally do not regenerate, it is vitally important for the blood brain barrier to block incoming viruses, bacteria, or other harmful material from entering Chapter Introduction, 1 + 2 74 © Cengage Learning 2016  How the Blood-Brain Barrier Works Chapter Introduction, 1 + 2 75 © Cengage Learning 2016  The Blood-Brain Barrier and the Active Transport The blood-brain barrier is essential to health, but can pose a difficulty in allowing chemicals such as chemotherapy for brain cancer to pass the barrier The Active transport: the protein-mediated process that expends energy to pump chemicals from the blood into the brain – Glucose, certain hormones, amino acids, and a few vitamins are brought into the brain via active transport Chapter Introduction, 1 + 2 76 © Cengage Learning 2016  Nourishment of Vertebrate Neurons Vertebrate neurons depend almost entirely on glucose – A sugar that is one of the few nutrients that can pass through the blood-brain barrier Neurons need a steady supply of oxygen – 20% of all oxygen consumed by the body is used by the brain Chapter Introduction, 1 + 2 77 © Cengage Learning 2016  Nourishment in Vertebrate Neurons The body needs a vitamin, thiamine, to use glucose Prolonged thiamine deficiency leads to death of neurons as seen in Korsakoff’s syndrome, a result of chronic alcoholism – Korsakoff’s syndrome is marked by severe memory impairment Chapter Introduction, 1 + 2 78 © Cengage Learning 2016