Slide 1

Chapter 2 The Biological Perspective Slide 2 What is Biological Psychology? Neuroscience science that deals with the structure and functioning of the brain and the neurons, nerves, and nervous tissue that form the nervous system Biological Psychology or Behavioral Neuroscience branch of neuroscience that focuses on the biological bases of psychological processes, behavior, and learning How the nervous system works provides information about what is going on inside the body when you engage in a specific behavior, feel an emotion, or have an abstract thought Slide 3 Nervous system Central nervous system (CNS) BrainSpinal cord Peripheral nervous system (PNS) Autonomic nervous system Parasympathetic division Sympathetic division Somatic nervous system Slide 4 Overview of the Nervous System Nervous system a network of cells that carries information to and from all parts of the body (4 levels) Central nervous system (CNS) brain and spinal cord Brain interprets and stores information and sends orders to muscles, glands, and organs Spinal cord pathway connecting the brain and the peripheral nervous system Peripheral nervous system transmits information to and from the CNS Autonomic nervous system automatically regulates glands, internal organs and blood vessels, pupil dilation, digestion, and blood pressure Parasympathetic division maintains body functions under ordinary conditions; saves energy Sympathetic division prepares the body to react and expend energy in times of stress Somatic nervous system carries sensory information and controls movement of the skeletal muscles Slide 5 Structure of the Neuron: The Nervous Systems Building Block Neuron the specialized cell in the nervous system that receives and sends messages within that system One of the bodys messengers, therefore it has a very special structure 3 main parts of a neuron Dendrites branchlike structures that receive messages from other neurons Soma the cell body of the neuron responsible for maintaining the life of the cell Axon tube-like structure that carries the neural messages out to other cells Slide 6 Structure of the Neuron Axon Dendrites Soma Slide 7 Structure of the Neuron Neurons only make up 10% of cells in the brain Other 90% is glial cells Glial cells cells that provide structure for the neurons to grow on and around, deliver nutrients to neurons, and produce myelin Myelin fatty substances produced by glial cells that coat the axons of neurons to insulate, protect, and speed up the neural impulse Slide 8 Structure of the Neuron 2 types of glial cells produce myelin for the neurons in the nervous system Oligodendrocytes produce myelin for the neurons in the brain and spinal cord (CNS) Schwann cells produce myelin for the neurons of the body (PNS) Axons travel all over the body like cables, carrying messages Myelin wraps around the axon forming a protective sheath (myelin sheath) Nerves bundles of axons coated in myelin that travel together through the body Slide 9 Slide 10 Structure of the Neuron How do neurons send messages? When a neuron is at rest (not firing an impulse or message) it is actually electrically charged Inside and outside the cell, charged particles called ions are in a semi-liquid (jelly-like) solution The relative charge of ions inside the cell is mostly negative The relative charge of ions outside the cell is mostly positive Slide 11 Structure of the Neuron Cell membrane is semipermeable meaning that tiny substances inside and outside the cell can pass through channels in the membrane Inside the cell, there are smaller positively charged potassium ions and larger negatively charged protein ions Negatively charged protein ions are too big to go through the channels when the cell is at rest, leaving the inside of the cell with a mostly negative charge Outside the cell, there are lots of positively charged sodium ions and negatively charged chloride ions Unable to go into the cell when it is at rest because the channels are closed Slide 12 Slide 13 Structure of the Neuron Positively charged sodium ions cluster around the outside of the cell because the inside of the resting cell is mostly negatively charged and opposite charges attract This difference in charges creates an electrical potential Resting potential the state of the neuron when not firing a neural impulse http://www.youtube.com/watch?v=YP_P6bYvEjE Slide 14 Structure of the Neuron When the cell receives a strong enough stimulation from another cell (meaning the dendrites are activated) the channels in the cell membrane open up all down the cell and allow the sodium ions (positively charged) to rush into the cell Causes reversal in electrical charge - the inside of the cell becomes mostly positive and the outside becomes mostly negative (because many of the positive sodium ions are now inside the cell) Sodium ions begin entering the cell through the first channel that opens up, the channel closest to the soma The rest of the ion channels open up all down the axon in a kind of chain reaction Change in electrical charge is called the Action Potential because the electrical potential is now in action, rather than at rest (like in resting potential) Slide 15 http://www.youtube.com/watch?v=R0TdXkxBOkE&featu re=related http://www.youtube.com/watch?v=R0TdXkxBOkE&featu re=related Slide 16 Structure of the Neuron During action potential, the cell becomes positive inside and negative outside After the action potential passes, the cell has to return back to its resting potential, meaning it has to get the positively charged sodium ions out Ion channels close immediately after the action potential passes Then, the cell membrane literally pumps the positive sodium ions out Meanwhile, small positively charged potassium ions inside the neuron move out rapidly helping to restore the negative charge inside the cell http://www.youtube.com/watch?v=GTHWig1vOnY Slide 17 Structure of the Neuron To start an action potential, the neuron must receive a signal strong enough to break the threshold for firing Neurons are receiving Fire! and Dont Fire! messages from other neurons constantly When the Fire! messages are great enough to cancel out the Dont Fire! messages, the threshold is crossed and the neuron fires Neurons fire in a sort of all-or-none fashion, either firing at full strength or not firing at all Like a light switch, when its on, its on and when its off, its off. No dimmer switch Slide 18 Sending the Message to Other Cells: The Synapse The end of the axon fans out into several short fibers that have swellings or little knobs on the ends called synaptic knobs or axon terminals The synaptic knobs are filled with little saclike structures called synaptic vesicles Synaptic vesicles are filled with chemical substances called neurotransmitters (the message carriers) Slide 19 Sending the Message to Other Cells: The Synapse Next to the synaptic knob is the dendrite of another neuron, in between them is a fluid-filled space called the synapse or the synaptic gap Remember, in the synaptic knob are vesicles full of neurotransmitters The dendrite next to the synaptic knob contains ion channels that have receptor sites Receptor sites proteins that allow only particular molecules of a certain shape to fit into it Slide 20 Sending the Message to Other Cells: The Synapse When the action potential reaches the synaptic knob, it causes the vesicles to release their neurotransmitters into the synapse The neurotransmitters float across the synapse and many of them fit themselves into the receptor sites This opens the ion channels and allows sodium ions to rush in, activating the next cell The next cell may be another neuron, or a cell on a muscle or gland http://www.youtube.com/watch?v=HXx9qlJetSU Slide 21 Sending the Message to Other Cells: The Synapse When neurotransmitters bind to receptor sites they have one of two possible effects (remember the Fire! and Dont Fire! signals?) which depend on what kind of synapse they are release into Excitatory synapse ion channels open causing the next cell to fire Inhibitory synapse ion channels close causing the next neuron to stop firing http://www.youtube.com/watch?NR=1&v=LT3VKAr4roo Start a 1:07 Slide 22 Neurotransmitters: Messengers of the Network At least 50 100 different types of neurotransmitters in the human body Acetylcholine - 1 st neurotransmitter to be discovered Excitatory Causes muscles to contract Roles in cognition, particularly memory GABA (Gamma Amino Butyric Acid) Inhibitory Decreases the activity level of neurons in the brain Slide 23 Neurotransmitters: Messengers of the Network Serotonin Both excitatory and inhibitory Linked with sleep, mood, and appetite Dopamine Both excitatory or inhibitory Involved in control of movement and sensations of pleasure Low levels have been found to cause Parkinsons disease Increased levels linked to schizophrenia Endorphins Special type of neurotransmitter called a neural regulator Controls the release of other neurotransmitters When endorphins are released in the body, the neurons transmitting information about pain are not able to fire action potentials Slide 24 Neurotransmitters: Messengers of the Network Some chemicals not naturally found in the body can either enhance or block the effects of neurotransmitters on receptor sites Fit into receptor sites on target cells 2 types Agonists mimic or enhance the effects of a neurotransmitter Antagonists block or reduce a cells response to the action of a neurotransmitter Slide 25 Neurotransmitters: Messengers of the Network Antagonist Example: Acetylcholine neurotransmitter found at the synapses between neurons and muscle cells, causes muscles to contract If acetylcholine receptor sites on the muscle cells are blocked, then the acetylcholine cant get to the site and the muscle will be incapable of contracting (meaning the muscle is paralyzed) Curare a drug used on poison blow darts is just similar enough to fit into the receptor site without actually stimulating the cell This blocks acetylcholine from its receptor sites causing paralysis Slide 26 Neurotransmitters: Messengers of the Network Agonist Example: Acetylcholine causes most muscles to contract, but actually slows the contraction of the heart muscle Black widow spiders venom stimulates the release of excessive amounts of acetylcholine and causes convulsions and possible death Slide 27 Reuptake and Enzymes After neurotransmitters are released into the synapse they must be taken back into the axon they came from before the next stimulation can occur Reuptake process by which neurotransmitters are taken back into the synaptic vesicles However acetylcholine which simulates muscles must be cleared out of the synapse more quickly (no time for the sucking up process) A special enzyme specifically designed to break apart acetylcholine clears the synapse very quickly (called enzymatic degradation) Slide 28 The Central Nervous System: The Central Processing Unit CNS = brain and spinal cord Brain core of the nervous system Spinal cord long bundle of neurons Divided into 2 areas that serve 2 vital functions Outer area composed mainly of myelinated axons and nerves Message pipeline - Carries messages from the body up to the brain and from the brain down to the body Inner area mainly composed of cell bodies separated by glial cells Primitive brain responsible for certain reflexes, very fast, lifesaving reflexes Slide 29 Inside of the spinal cord contains 3 types of neurons that make up the reflex arc Afferent (sensory) neurons carry messages from the senses to the spinal cord Ex. If you burn your finger, afferent neurons relay information about the sharp pain in your finger Efferent (motor) neurons carry messages from the spinal cord to the muscles and glands Ex. Send command to pull your finger back from the painful stimulus Interneurons connect the afferent (sensory) neurons to the efferent (motor) neurons Help coordinate signals between sensory neurons and motor neurons The Central Nervous System: The Central Processing Unit Slide 30 Neuroplasticity the ability of the brain and spinal cord to change in structure and function Can change the structure and function of many cells in response to experience and trauma Stem cells cells that can become other cells (blood cells, nerve cells, and brain cells) Facilitate neuroplasticity If stem cells can be successfully implanted into damaged areas in the spinal cord, the newly developed neurons may be able to assume the roles that the damaged neurons can no longer perform The Central Nervous System: The Central Processing Unit Slide 31 The Peripheral Nervous System: Nerves on the Edge Peripheral nervous system (PNS) made up of all the nerves and neurons that are NOT in the brain and spinal cord Includes all the nerves that connect to your eyes, ears, skin, mouth, and muscles Allows the brain and spinal cord to communicate with these sensory systems Divided into 2 major systems Somantic nervous system controls the senses and voluntary muscles Autonomic nervous system controls organs, glands, and involuntary muscles Slide 32 The Somantic Nervous System 2 parts Sensory pathway all the nerves carrying messages from the senses to the CNS (nerves containing afferent neurons) Nerves from the body going to the CNS to relay information Motor pathway all the nerves carrying messages from the central nervous system to the skeletal muscles of the body (nerves containing efferent neurons) Nerves from the CNS going out to the body telling the body what to do Slide 33 The Autonomic Nervous System 2 systems Sympathetic division turns on the bodys fight-or-flight reactions, including increased heart rate, increased breathing, and dilation of your pupils fight-or flight system Active during times of stress Parasympathetic division controls the body when its in a state of rest to keep the heart beating regularly, to control normal breathing, and to coordinate digestion eat-drink-rest system Active most of the time Slide 34 Distant Connections: The Endocrine Glands Sort of the 2 nd messenger system in the body Endocrine glands have no ducts and secrete chemicals called hormones directly into the blood stream Hormones are carried by the blood stream to organs in the body Compared to communication between neurons, the hormonal system is slower, and has more widespread effects on the body and behavior Slide 35 The Pituitary: Master of the Hormonal Universe Pituitary Gland master gland, controls or influences all of the other endocrine glands located in the brain just below the hypothalamus Hypothalamus controls the glandular system by influencing the pituitary gland Secretes the hormones that control milk production and salt levels in the body and growth from infancy to adulthood Slide 36 The Pineal & Thyroid Glands Pineal gland Located in the brain, near the back, directly above the brain stem Secretes melatonin hormone that helps track day length and contributes to the regulation of the sleep-wake cycle in humans Thyroid gland Located in the neck Secretes a hormone that regulates metabolism (how fast the body burns its available energy) Slide 37 The Pancreas & Gonads Pancreas Controls the level of blood sugar in the body by secreting insulin and glucagons Too little insulin = diabetes Too much insulin = hypoglycemia Gonads Sex glands, secrete hormones that regulate sexual behavior and reproduction Called ovaries in females Called testes in males Slide 38 Adrenal Glands 2 Adrenal glands - located on the top of each kidney Critical role in regulating the bodys response to stress Adrenal glands are divided into 2 parts Adrenal medulla releases epinephrine and norepinephrine when people are under stress and aids in sympathetic arousal Adrenal cortex produces over 30 different hormones called corticoids Most important is cortisol released when the body feels both physical and psychological stress Slide 39 Looking Inside the Brain: Deep Lesioning How can psychologists find out about what parts of the brain do? In animals deliberately damage a part of the brain then test the animal to see what has happened to its abilities Deep lesioning - a thin wire, insulated everywhere except the tip, is surgically inserted into the brain. Then an electrical current strong enough to kill off the target neurons is sent through the tip of the wire In humans study and test people who already have brain damage Not ideal no 2 injuries are exactly the same Slide 40 Brain Stimulation Electrical stimulation of the brain (ESB) Less harmful than lesioning Temporarily disrupt or enhance the formal functioning of specific brain areas through electrical stimulation Invasive techniques deep brain stimulation (DBS) Surgically implant electrodes in specific deep-brain areas which are connected to an impulse generator that is surgically implanted under the collar bone Used in treatment for Parkinsons disease and seizure disorders Noninvasive techniques repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) rTMS magnetic pulses are applied to the cortex using special copper wire coils positioned over the head tDCS uses scalp electrodes to pass very low amplitude direct currents to the brain Slide 41 Mapping Brain Structure Computed Tomography (CT) series of brain x-rays Involves mapping slices of the brain using a computer Magnetic Resonance Imaging (MRI) uses a magnetic field to take pictures of the brain More detail than CT scans MRI scan CT scan Slide 42 Mapping Brain Function Electroencephalogram (EEG) provides a record of the electrical activity of groups of neurons just below the surface of the skull Functional Magnetic Resonance Image (fMRI) uses magnetic fields in the same way as an MRI, but goes a step further and pieces the pictures together to show changes over a short period of time Positron Emission Tomography (PET) involves injecting a person with a low dose of radioactive substance and then recording the activity of that substance in the persons brain Single Photon Emission Computed Tomography (SPECT) similar to PET but uses somewhat different radiotracer technique EEGfMRI PET SPECT Slide 43 From the Bottom Up: The Structures of the Brain The brain can be roughly divided into 3 sections Brainstem lowest part of the brain that connects to the spinal cord Cortex outer wrinkled covering of the brain Structures under the cortex (subcortical structures) includes everything between the brainstem and the cortex Slide 44 Brainstem 4 important structures Medulla controls life-sustaining functions such as heart beat, breathing, and swallowing Pons influences sleep, dreaming, and coordination of movements Reticular formation plays crucial role in attention and arousal, such as attending to certain kinds of information in the environment Cerebellum controls all involuntary, rapid, fine motor movement (ex. People can sit upright in a chair because the cerebellum controls all the little muscles that keep you from falling out of the chair) Slide 45 Structures Under the Cortex Limbic system involved in emotions, motivation, memory, and learning Thalamus round structure in the center of the brain Hypothalamus just below the front of the thalamus Hippocampus in the temporal lobes on each side of the brain Amygdala near the hippocampus Cingulate cortex in the cortex, right above the corpus callosum in the frontal and parietal lobes Slide 46 The Limbic System Thalamus receives input from sensory systems, processes it, and then passes it on to the appropriate area Every sensation passes through the thalamus except for smell Hypothalamus interacts with the endocrine system to regulate body temperature, thirst, hunger, sleeping, sexual activity, and mood Hippocampus critical in the formation of long-term memories and for memories of the locations of objects Amygdala involved in response to fear Cingulate cortex important role in emotion and cognition Slide 47 The Cortex Cortex outermost part of the brain (wrinkly part) Made up of tightly packed neurons and is actually only about 1/10 of an inch thick Corticalization refers to the fact that the cortex is wrinkled, allowing a much larger area of cortical cells to exist in the small space inside the skull Divided into right and left sections called cerebral hemispheres Cerebral hemispheres communicate with each other through the corpus callosum Corpus callosum thick bank of neurons (axons) Slide 48 The Cortex Each cerebral hemisphere can be roughly divided into 4 sections called lobes Occipital lobes Parietal lobes Temporal lobes Frontal lobes Slide 49 Occipital Lobes Visual information Primary visual cortex processes visual information from the eyes Visual association cortex helps identify and make sense of the visual information from the eyes Example: a patient who had a tumor in the right occipital lobe area in the visual association cortex could see and even describe objects in physical terms but couldnt identify them Described a rose as a red inflorescence with a green tubular projection Slide 50 Parietal Lobes Process information regarding touch, temperature, body position, and possibly taste Somatosensory cortex processes information from the skin and internal body receptors for touch, temperature, and body position Slide 51 Temporal Lobes Process auditory information Primary auditory cortex processes auditory information coming in from the ears Auditory association area - helps identify and make sense of the auditory information from the ears Slide 52 Frontal Lobes Responsible for higher mental functions such as planning, personality, and decision making, as well as language and motor movements Motor cortex band of neurons that control the movements of the bodys voluntary muscles by sending commands out to the somatic division of the peripheral nervous system Mirror neurons recent research: neurons that fire while an individual is performing an action as well as when an individual is watching someone else perform that same action Slide 53 The Association Areas of the Cortex Association areas made up of neurons in the cortex that are devoted to making connections between the sensory information coming into the brain and stored memories, images, and knowledge In other words, help people make sense of incoming sensory input 2 important association areas Brocas area left frontal lobe Wernickes area left temporal lobe Slide 54 Association Areas of the Cortex Brocas area responsible for speech production Allows people to speak smoothly and fluently Brocas aphasia - Damage to Brocas area causes a person not to be able to produce the words they want to speak Can understand what others say, but cannot speak fluently http://www.youtube.com/watch?v=1aplTvEQ6ew (teenage stroke) http://www.youtube.com/watch?v=1aplTvEQ6ew Wernickes area involved in understanding the meaning of words Wernickes aphasia damage to Wernickes area causes a person to use words that dont make sense and sometimes have trouble making sense of what others say Can still speak fluently, but will use the wrong words http://www.youtube.com/watch?v=aVhYN7NTIKU (dentist) http://www.youtube.com/watch?v=aVhYN7NTIKU Slide 55 Specialization of the Cerebral Hemispheres Roger Sperry discovered that the right and left hemispheres are not identical Split-brain research cut through the corpus callosum (the communication point between the hemispheres) Right and left hemispheres cannot communicate with each other This research has revealed that the right and left hemispheres are lateralized, meaning that they specialize in different things Slide 56 Left HemisphereRight Hemisphere Controls the right handControls the left hand Spoken languageNonverbal Written languageVisual-spatial perception Mathematical calculationsMusic and artistic processing Logical thought processesEmotional thought and recognition Analysis of detailProcesses the whole ReadingPattern recognition Facial recognition Left hemisphere processes information in a sequence and is good at breaking things down into smaller parts for analysis Right hemisphere processes information all at once and simultaneously, a more global or holistic style of processing Slide 57 Applying Psychology to Everyday Life Attention-deficit/hyperactivity disorder (ADHD) developmental disorder involving behavioral and cognitive aspects of inattention, impulsivity, and hyperactivity Brain areas involved in ADHD are typically divided: Areas responsible for regulating attention and cognitive control Areas responsible for alertness and motivation Neuroimaging studies: Cortical areas involved in attention and cognition are found to be smaller in people with ADHD Prefrontal cortex (primarily right side) Basal ganglia (involved in response control) Cerebellum Corpus callosum Slide 58 Applying Psychology to Everyday Life Most problematic aspects of attention and cognition in people with ADHD: Vigilance (being able to watch out for something important) Being able to effectively control ones own cognitive processes such as staying on task, maintaining effort, or engaging in self- control New research is examining the possibility that ADHD may have multiple causes Environmental factors (such as low-level lead exposure) Genetic influences The role of heredity and familial factors Personality factors