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Chapter 2

Chapter 2 Review- Psych 290.docx

7 Pages
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Department
Psychology
Course Code
PSYC 3250
Professor
Gerry Goldberg

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Chapter 2 - Cortical electrical-stimulation mapping: developed mid-20 century by wilder Penfield, neurosurgeon (mapping locations of functions in brain allowed for removal of diseased brain tissue w/o harming other brain regions The Nervous System is Composed of Cells - Nervous system composed of mostly nerve cells, also called neurons arranged into neural circuits - Neuron receives input from other neurons, integrates input and distributes processed info to others - Brain integrates info by assembling 100-150 billion of info units into array of circuits - Glial cells less impt than neuron, b/c neuron produce readily measured electrical signals - Camillo Golgi- continuous neurons: endless network of connected tubes through which info flowed - Ramon Cajal- contiguous neurons: neurons close together but gaps exist - Neuron doctrine: (1) brain composed of separate neurons and other cells that are independent structurally, metabolically and functionally (2) information is transmitted from cell to cell across tiny gaps (Charles Sherrington called these synapses, 10^15 of them in brain) The neuron has 4 structural divisions specialized for information processing - Neuron has mitochondria (energy), cell nucleus (contains genetic info), ribosomes (translate genetic info to proteins) 1. Dendrites: cellular extensions (input zone), receive info, elaborately branched to manage many synapses 2. Cell body: (soma), contains cell nucleus, receive additionally synaptic contact, most neuron input combined and transformed in cell body (integration zone) 3. Axon: leads away from cell body (conduction zone), transmits cell output info, in form of electrical impulses away from cell body 4. Axon terminal: swelling at end of axon, (output zone), transmit neuron activity to other cells Box 2.1- Neuroanatomical Methods provide ways to make sense of the brain - Clothes dye, make preserved nerve cells vivid (2 cell stains) 1. Golgi Stains: fills whole cell, dendritic spine too, but only some cells, useful for seeing the type & shape of cell; alternative to this is using fluorescent dye 2. Nissil Stains: outlines ALL cell bodies, dye is attracted to RNA distributed within cell, useful for measuring cell body size and density of cells - Light microscopes & electron microscopy 1. Autoradiography: cell manipulated to take photo of self (E.g. bathe brain tissue in radioactive drug solution, brain section put on slides, covered with photographic emulsion, when radioactivity is emitted by drug, emulsion produces dark grains where drug concentrated 2. Immunocytochemistry (ICC): Method for detecting particular protein in tissues in which an antibody recognizes and binds to the protein and then chemical methods used to leave visible reaction product around each antibody 3. In situ hybridization: Method for detecting particular RNA or DNA transcripts in tissue sections by providing a nucleotide probe, that is complementary to, and will therefore hybridize with, the transcript of interest 4. Immediate Early Genes (IEGs): A class of genes that show rapid but transient increases in expression in cells that have become activated 5. C-fos: An immediate early gene commonly used to identify activated neurons Tracing Pathways in Brain - Axon have smaller diameter than cell body, axon from different pathway look alike, brain has billion axon, fiber w/ different destination travel together, hard to disentangle - Usually: inject radioactive amino acids into cell body, cell take radioactive molecules and transport to axon, which then visualized through autoradiography - Horseradish peroxidase (HRP): Enzyme found in horseradish and other plants that is used to determine cells of origin of particular set of axons (retrograde labeling) (E.g. transynaptically: jump across synapse, work upstream to higher level of NS) Three types of nerve cells 1. Multipolar neurons: many dendrites, single axon, most common type 2. Bipolar neurons: single dendrite at one end of cell, single axon on other end, (common in sensory systems, like vision) 1 3. Unipolar neurons: also called monopolar, single extension (thought as axon), branches in two directions leaving cell body, one end input zone other output (transmit touch info from body to spinal cord) - All cells, dendrite input zone, in multi polar and bipolar, cell body also part of input zone 1. Montoneurons: motor neuron, govern movement, contract muscles after command from brain, some control glands and organs 2. Sensory neurons: carry messages from the periphery back to spinal cord & brain (diverse shapes) 3. Interneurons: make up most of brain, receives input from and sends output to other neurons (these axons short in comparison to other 2) - Adult size human brain 15 cm front to back The neuronal cell body and dendrites receive info across synapses - Aborization: The elaborate branching of dendrites of some neurons - Synapse has 3 principal components: 1. Presynaptic membrane of axon terminal of presynaptic neuron 2. Postsynaptic membrane on surface of dendrite or cell body of postsynaptic membrane 3. Synaptic cleft, separates pre and post synaptic membranes - Synaptic vesicle: in presynaptic neuron, contains molecule of neurotransmitter - Neurotransmitter: called synaptic, chemical or transmitter, chemical released from presynaptic axon terminal to communicate b/w neurons - Postsynaptic receptors: specialized protein molecules capture/ react to neurotransmitter molecule - Some neurons receive 100,000 synapse, usual 5000-10 000 - Neural plasticity: (neuroplasticity) NS ability to change in response to environment - Dendritic spines: increase surface are of dendrite, allowing extra synapse (rapidly alter or don’t due to training or sensory stimuli) The axon integrates then transmits information - Axon hillock: cone-shaped area from which axon originates out of cell body (Integration zone of neuron) - Axon collateral: Branch of an axon from a single neuron (many allow for influence of many postsynaptic cells) - Cell body manufactures enzymes & structural proteins under guidance of DNA (deoxyribonucleic acid), in cell nucleus - Axonal transport: The transportation of materials from the neural cell body to distant regions in the dendrites and axons and from the axon terminals back to cell body (both ways) - Axon Function: (1) rapid transmission of electrical signals along outside of axon (2) slower transportation of substances inside axon, to and from axon terminals - Axon covered in myelin sheath, usually one axon per neuron Glial cells support and enhance neural activity - Glial cells communicate with one another and provide neurons w/ raw materials and chemical signals that alter neuronal structure and excitability - 4 types 1. Astrocyte: Star shaped glial cells w/ numerous processes (extensions) that run in all directions  Regulate blood flow, when attached to blood vessels  Formulation of synapses 2. Microglial cells: extremely small glial cells that remove cellular debris from injured or dead cells  Imp for neural pain systems & synapses (interference cause Alzheimer’s or dementia) 3. Oligodendrocytes: glia cells that forms myelin in central nervous system (CNS); brain/spine 4. Schwann cell: glial cell that forms myelin in the peripheral nervous system (PNS) - Myelin: fatty insulation around axon formed by glial cells, improves speed of conduction of nerve impulses (myelination can continue 10-15 years in brain regions) - Node of Ranvier: gap b/w successive segments of myelin sheath where axon membrane expose - Edema: swelling of issue, especially in brain, response to injury - Multiple sclerosis: “many scars”, disorder characterized by degeneration of myelin The Nervous system consists of Central and Peripheral Divisions - Gross neuroanatomy: anatomical features of NS apparent to naked eye - Peripheral nervous system: portion of nervous system, all nerves and neurons outside brain and spinal cord - Central nervous system: Portion of NS that includes brain and spinal cord - Nerve: Collection of axons bundled together outside CNS 2 - Motor nerve: Nerve that conveys neural activity from brain& spine to muscle tissue and causes it to contract - Sensory nerves: Never that conveys sensory info from periphery into CNS - Three NERVE divisions of PNS 1. Cranial nerves: connected directly to brain (12 bundles of axons, serve sensory system and motor system of head & neck, face) 2. Spinal nerve: also called somatic nerve, emerges from spinal cord 3. Autonomic nervous system: nerve that control viscera (internal organs); supplies neural connections to gland and smooth muscles of internal organs Cranial nerve (12 types) LOOK AT DIAGRAM 1. Olfactory: Smell 2. Optic: Vision 3. Oculomotor: muscle that move eye 4. Trochlear: Muscle that move eye 5. Abducens: Muscle that move eye 6. Trigeminal: face sinuses, teeth, Jaw muscles 7. Facial: facial muscles, salivary glands, tear gland 8. Vestibulocochelar: Inner ear hearing and balance 9. Glossopharyngeal: Taste & other mouth sensations; Throat muscles 10. Vagus: Info from internal organs, Internal organs (helps control autonomic nervous system) 11. Spinal accessory: Neck muscles 12. Hypoglossal: Tongue muscles Spinal nerves (31 bundles of axons) - Dorsal root: Branch of spinal nerve, entering dorsal horn of spinal cord, that carries sensory info from the peripheral nervous system (body) to the spinal cord - Ventral root: Branch of spinal nerve arising from ventral horn of spinal cord, carries motor messages from spinal cord to PNS (body) - 8 cervical (ventral and dorsal NECK); 12 thoracic (trunk), 5 lumbar (lower back), 5 sacral (pelvic), 1 coccygeal (bottom) The Autonomic Nervous System (ANS) - Autonomic ganglia: collections of nerve cell bodies, belonging to autonomic division of peripheral nervous system that are found in various locations and innervate (provide neural input) the major organs - Preganglionic: Neurons in autonomic NS run from central nervous system to autonomic ganglia - Postganglionic: neurons in autonomic NS run from autonomic ganglia to various target in body - Parasympathetic postganglionic cells and preganglionic cells produce & release acetylcholine where we get cholinergic neuron - Sympathetic postganglionic produce & use norepinephrine where we get noradrenergic neuron ANS Three major division - Sympathetic, parasympathetic and the enteric nervous system - Sympathetic nervous system:  Component of autonomic nervous system that arises from thoracic and lumbar spinal cord  Sympathetic chain: Chain of ganglia that runs along each side of spinal column, part of sympathetic nervous system  Prepares body for action (widen pupils, increase blood pressure, heart quickens) “Fight or Flight”  Uses norepinephrine: accelerate organ activity - Parasympathetic nervous system  Rest and digest response, helps body relax  Arises from cranial nerves and sacral spinal chord (parasympathetic ganglia not chained, dispersed)  Uses acetylcholine: slow down activity - Enteric nervous system  Local network of sensory and motor neurons, regulate functioning of gut The Central nervous system consists of brain and spinal cord - Spinal cord funnels sensory info from body to brain & motor command from brain to bod
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