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NEUROSCIENCE & BIOLOGICAL PSYCHOLOGY AP Psychology Ms. Brown Myers - Ch. 2 Everything psychological is also biological. The Mystery of the Human Brain • The brain is not completely understood. How does our brain organize and communicate with itself? • How do our heredity and our experiences work together to wire our brain? • How do memories work in the brain? • • Scientists have discovered partial answers to these questions but much is left to discover! • Biological psychology – a branch of psychology concerned with the links between biology and, mental processes, and behavior. Early Brain Research • Phrenology – theory that the shape of and bumps on the skull could reveal mental abilities and character traits. Early 1800s – mid-20th century (used to justify racism and discrimination) • Quackery (fraudulent medical practice) • • Correctly focused attention on the idea that various brain regions have certain functions Contemporary Brain Research • In the last century, scientists have discovered that the body is made of cells. • Nerve cells (neurons) conduct electricity to “talk” to one another by sending chemical messages across a tiny gap that separates them. NEURONS Neuron • Nerve cell • Building block of the nervous system • Found all over the body Brain • Legs • Eyes • Anywhere there are nerves – We will mainly focus on the basic neuron (below) • Dendrites • The bushy extensions of a neuron that receive messages Soma • Cell body • Contains nucleus – DNA, genetics, etc Axon • The extension of a neuron through which electrical messages pass • Like the “backbone” of a neuron, if broken, the neuron dies. A X O N DENDRITES LISTEN… … AXONS SPEAK The dendrites can receive messages to make the neuron fire or not fire. If the message is to “fire,” the axon will send the message to the axon terminals. Myelin Sheath • Layer of fatty tissue on the axon that… Protects axon • Speeds neural impulse (the message) • Multiple sclerosis – a disease in which the myelin sheath degenerates resulting in a slowing of all communication to muscles and the eventual loss of muscle control • Made of glial cells, which also bind neurons together. Axon Terminals • Branches at the end of an axon that send messages to the dendrites of another neuron. • End in axon terminal buttons – contain vesicles that hold neurotransmitters Action Potential • A neural impulse in the form of a brief electrical charge that travels down the axon • A neuron fires an impulse when it receives a signal from sense receptors or by the neurotransmitters from another neuron. Direction of ACTION POTENTIAL Synapse • The junction between neurons. Synaptic gap, synaptic cleft, etc • Less than a millionth of an inch wide • I need 5 volunteers… • Stand next to each other facing the class. • Hold hands. • The person farthest to the RIGHT wants to send a message to the person farthest to the LEFT (without actually talking)– how will we do this? • When you feel the squeeze of your right hand, squeeze the right hand of the person beside you. • Right hand and arm • DENDRITES • Chest • SOMA • Left arm • AXON • Left hand • AXON TERMINALS How Nerve Impulses Work • Threshold - the level of stimulation required to trigger a neural impulse. • “all-or-none/nothing” principle It either fires… … or it doesn’t. How Nerve Impulses Work • Resting potential – the electrical charge of a neuron at rest. • Ions – electrically charged molecules Inside axon: overall • Outside axon: overall + • “I’m so HAPPY (+) that I’m OUTSIDE playing!” How Nerve Impulses Work Neuron receives chemical message. 2. Axon’s ion channels (holes in the axon membrane) open, allowing Na+ ions inside. 3. Ion channels open like a domino effect, traveling from the soma to the axon terminal. 4. After the impulse passes, the neuron dips below resting potential and cannot fire. The “ion pump” flushes out positive ions as it releases K+ ions outside. Less than 1/100 of a second. 1. How Neurons Communicate • Neurotransmitters - chemical messengers that travel across the synaptic gap between neurons 1. Action potential reaches the axon’s terminal buttons. 2. Buttons release neurotransmitters (chemicals) 3. Travel across the synapse 4. Bind/connect to receptor sites on the next neuron’s dendrites Neurotransmitters • Lock-and-key relationship between the neurotransmitter and the receptor site. • When the neuron receives neurotransmitters, it will fire/not fire Dopamine Serotonin Chart on pg. 58 • Neurotransmitters Many types of neurotransmitters that affect us differently and are found in different parts of the brain Neurotransmitter Function Examples of Malfunction Acetylcholine (ACh) Movement Learning Memory Too little - Alzheimer’s disease Dopamine Movement Learning Attention Reward/Pleasure Too little – Parkinson’s disease Mood Hunger Sleep Too little – depression Norepinephrine Alertness Arousal Too little – depressed mood Too much – mania (linked to bipolar disorder) GABA (gammaaminobutyric acid) Inhibitory properties Too little – seizures, tremors, and insomnia (calms neural activity) Alcohol increases GABA activity and slows brain activity Glutamate Excitatory properties (stimulates neural activity) Serotonin Too much – schizophrenia •“Too much dopamine can make you ‘dopey.’” •“Sarah’s tone is sad.” Too much – migraines, seizures Alcohol decreases glutamate activity and slows brain activity Endorphins “Happy people don’t kill their husbands!” • Natural, opiate-like neurotransmitters linked to pain control and pleasure • Inhibit (block) pain signals Ex: Runner’s high • One of the top suggested remedies for depression is exercise naturally produce chemicals that will stimulate pleasure and happiness • • Too little – hypersensitivity to pain • Too much – insensitivity to pain INTERACTIVE NEURON Brain, Neurotransmitters, and Other Chemicals • Cocaine, heroin, morphine, anti-depressants, anti- psychotics, etc manipulate the production of neurotransmitters. • Too much manipulation brain may stop naturally producing similar transmitters. • When the medication or drug is withdrawn, the brain may be deprived of the neurotransmitters until the it can naturally start producing its own again. • Explains the uncomfortable withdrawal period when a drug addict ceases using the drug. Brain, Neurotransmitters, and Other Chemicals • Various drugs and substances can effect communication at the synapse, by exciting or inhibiting a neuron to fire. • Agonist – molecules that are similar to neurotransmitters and can mimic their effects. • Eg: the venom of a black widow spider floods the brain with agonists similar to ACh which results in muscle contractions, convulsions, and even death. • Antagonist – a molecule that block a neurotransmitter’s release • Eg: Botulin (a poison in improperly canned food), causes paralysis by blocking the release of ACh from the sending neuron. Neural Networks • Interconnected neural cells; with experience, networks can learn and strengthen • Neurons can receive and send information from and to many neurons at the same time. • Neurons cluster to work in groups to produce shorter, faster connections (bound together by glial cells). • Experience causes neural networks to grow and strengthen eg: practicing the piano builds neural connections that help this behavior. IMPORTANT •Communication WITHIN a neuron… • ELECTRICAL – action potential •Communication BETWEEN neurons… • CHEMICAL - neurotransmitters NERVOUS SYSTEM Central Nervous System (CNS) • The brain and the spinal cord Peripheral Nervous System (PNS) • the sensory and motor neurons that connect the CNS to the rest of the body. • Everything but the brain and spinal cord Nerves • In the PNS • Neural cables • Connect the CNS to muscles, glands, and sense organs • Ex: optic nerve connects the eye to the brain Eye = sense organ • Optic nerve = PNS • Brain = CNS • Nervous System Neurons • Information travels through the nervous system in 3 type of neurons. 1. Sensory neurons – (aka afferent neurons) carry incoming information from the senses to the CNS 2. Interneurons – CNS neurons that internally communicate between sensory inputs and motor outputs 3. Motor Neurons – (aka efferent neurons) carry out going information from the CNS to muscles and glands Sensory feel… Inter interpret… Motor move The Spinal Cord and Reflexes • CNS is the highway between the brain and the PNS. However, sometimes the body can react without the message reaching the brain. • Reflex – simple, autonomic, inborn response to a sensory stimulus, such as the knee-jerk response. • Reflex pathway = 1 sensory neuron + 1 communication interneuron + 1 motor neuron • Ex: simple pain reflex, simple knee-jerk reflex The Spinal Cord and Reflexes • Simple pain “reflex” – hand jerks away when touching a hot surface. • The movement is initiated in the spinal cord. • Later, the pain is perceived in the brain. • Short delay between movement and sensation. What happens if the Spinal Cord is severed? • Paralysis because sensory messages cannot reach brain and motor messages cannot leave brain • Paraplegia - patient can still move two limbs • Quadriplegia - all four limbs are paralyzed • Most famous case in recent times was the actor Christopher Reeves ( d. 2004) Speed of Neural Communication in the Body • Everyone stand up, turn to your right, and await further instructions… • Shoulder squeeze • Wrist squeeze Somatic and Autonomic Nervous Systems • Somatic – controls the body’s skeletal muscles • Running, dancing, etc • Autonomic – controls the glands and the muscles of internal organs • Heartbeat, digestion, sweating PNS Autonomic Somatic – Skeletal Somatic Autonomic - Automatic Sympathetic and Parasympathetic Nervous Systems • Sympathetic – arouses the body • When someone is in crisis, we feel sympathy for them • Parasympathetic – calms the body • Parasympathetic - paralyzing Autonomic Sympathetic Parasympathetic Let’s Put It All Together! Nervous System Peripheral Central (PNS) (CNS) Autonomic Sympathetic Parasympathetic Somatic THE ENDOCRINE SYSTEM Endocrine System • The body’s “slow” chemical communication system made of glands that secrete hormones into the bloodstream • Hormones – chemical messengers manufactured by glands Travel slowly in the bloodstream • When hormones act on the brain, they can trigger interest in sex, food, aggression, “flight or fight” • • Gland - An organ in the body that secretes a substance for use somewhere else in the body Hormones vs Neurotransmitters Hormones • • chemical messengers for the endocrine system Travel in the blood stream Neurotransmitters • Chemical messengers in the brain • Travel in the brain in the synapse between neurons The endocrine system tries to keep a balance in the body while we respond to feelings of stress, anger, fear, and exertion. Pituitary Gland • Small pea-shaped gland in the limbic system of the brain • Secretes growth hormone • Most influential gland – “master” gland (controls other glands) • Controlled by the hypothalamus • Liaison between the nervous system and the endocrine system • Acromegaly – caused by a tumor on the pituitary gland Adrenal Gland • Pair of glands above the kidneys that release adrenaline and noradrenalin which helps to arouse the body in times of stress Increase heart rate, blood pressure, and blood sugar for energy • Hormones can last in the bloodstream after the triggering event. • Daughter Lifts Car Off Dad THE BRAIN The Brain • Brain size ≠ Intelligence • Brain structure and complexity = Intelligence Older Brain Structures • Perform unconscious simple tasks necessary for survival… Breathing • Coordinating movement • Heartbeat • • Brainstem Medulla • Pons • Reticular formation • • Thalamus • Cerebellum Brainstem • Oldest part and central core of the brain • Beginning where the spinal cord swells as it enters the skull • Responsible for automatic survival functions Brainstem = area in the red box Medulla • The base of the brainstem • Controls heartbeat and breathing Pons • Above the medulla • Helps coordinate movement by relaying information to the cerebellum Reticular Formation • A nerve network in the brainstem • Helps control arousal and sleep When stimulated, it arouses your focus. • If severed, you could enter a coma. • Narcolepsy = malfunction of reticular formation • Thalamus • The brain’s sensory switchboard, located on top of the brainstem • Directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla Cerebellum • The “little brain” attached at the rear of the brainstem • Processes sensory input and coordinates movement output and balance • An injured cerebellum would cause difficultly walking and keeping balance jerky movements The Limbic System • A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres • Associated with EMOTIONS, MEMORIES, and SMELL Hippocampus • Amygdala • Hypothalamus • Hippocampus • In the temporal lobe • Processes/stores memories Amnesia can result from injury to the hippocampus • “You’d remember if you saw a hippo on campus!” • Amygdala • Two lima bean-sized structures above the hippocampus • Influences fear and aggression Larger in males more aggression • Emotional problems result from which part of the amygdala is stimulated/damaged (too much aggression, no fear, no emotions, etc) • Hypothalamus • Below the thalamus • Directs maintenance activities Eating • Drinking • Body temperature • • Controls the pituitary gland • Interprets emotions and tells the pituitary gland which glands need to secrete hormones • Reward/pleasure center The Cerebral Cortex • The intricate fabric of interconnected neural cells that covers the cerebral hemispheres • The body’s ultimate control and information-processing center higher level functions Like bark on a tree – a thin surface that covers the brain hemispheres • Contains billions of neurons and even more glial cells that bind together and nourish them. • Lobes of the Brain • Geographical subdivisions of the cerebral cortex separated by prominent fissures (folds) in the brain. LOBES OF THE BRAIN AND THEIR FUNCTIONS (FPOT) Lobe Frontal Where in Cerebral Cortex? Behind the forehead Parietal At the top of the head, towards the rear At the back of the head Occipital Temporal Roughly above the ears (near the “temples”) Function Involved in speaking, muscle movements, and making plans/judgments, “personality” Receives sensory input for touch and body position Includes the visual areas, which receive visual information from the opposite visual field Includes auditory areas, each of which receive auditory information primarily from the opposite ear Sensory and Motor Cortexes Sensory Cortex • An area at the front of the PARIETAL lobe that registers and processes body touch and movement sensations Parallel to the motor cortex, behind it • Stimulation – sensation of being touch depending on the area • Motor Cortex • An area at the rear of the FRONTAL lobe that controls voluntary movements Sends outgoing movements • Stimulation – movement in the body depending on the area • Motor and Sensory Cortexes • The more sensitive a body region, the larger the area in the sensory cortex Visual and Auditory Cortexes Visual Cortex • An area in the OCCIPITAL lobe that processes vision from the opposite eye Auditory Cortex • An area in the TEMPORAL lobe that processes sounds from the opposite ear Association Areas • Areas of the cerebral cortex that are involved in HIGHER MENTAL FUNCTIONS such as learning, remembering, thinking, and speaking. • Any area in the cerebral cortex that is not in the motor, sensory, visual, or auditory cortexes. • In all 4 lobes The Brain and Language • Aphasia – impairment of language, usually caused by left hemisphere damage either to… • Broca’s area – frontal lobe, left hemisphere, directs movement necessary for speech • Wernicke’s area – temporal lobe, left hemisphere, involved in language comprehension Brain Plasticity • The brain’s capacity for modification, as evident in the reorganization following damage to the brain and in experiments on the effects of the experience on brain development • SOME neural tissue can reorganize (not regenerate) as the brain repairs itself after damage. Blindness - when reading Braille, the brain area dedicated to that finger expands as the sense of touch invades the visual cortex, which normally helps people see • Deafness - the auditory cortex receives no information from sound, so it expands to new functions like visual tasks, which is why deaf people have been found to have enhanced peripheral vision. • Lateralization • The brain’s two hemispheres are not exactly alike and perform certain functions • Ex: left hemisphere contains speech/language areas Crash Course - Brain Split Brain • When the two brain hemispheres are not attached by the corpus callosum • Corpus callosum Band of neural fibers that connects the two brain hemispheres together and allows them to communicate • Possible to survive with a split brain, but may have difficultly integrating vision, speech, and motor skills. • Studying the Brain • Lesion – damage to brain tissue • Allows us to study the functions of the brain in circumstances that would be unethical to replicate • Ex: Phineas Gage • Gabrielle Giffords’ brain after attempted assassination • still has difficulty speaking, limited vision in both eyes and no peripheral in the right eye, and her right arm and leg are paralyzed. She continues to undergo speech and physical therapy. Electroencephalogram (EEG) • Records the waves of electrical activity that sweep across the brain’s surface; measured by electrodes placed on the scalp Positron emission tomography (PET) Scan Scan detects where a radioactive form of glucose goes while the brain performs a given task. Glucose = energy Red areas = glucose activity = most active (while performing that given task) Magnetic Resonance Imaging (MRI) • Uses magnetic fields and radio waves to images that distinguish among different types of soft tissue, allowing us to see structures within the brain. Functional MRI (fMRI) • A technique for revealing blood flow and therefore, brain activity by comparing successive MRI scans Crash Course – The Chemical Mind