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47 Cards in this Set
- Front
- Back
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What are the 4 "model organisms"? What makes them unique from other organisms that are extensively studied?
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These 4 species have had their genomes completely sequenced, thus leading to their informal adoption as "model organisms" by neuroscientists.
1. Nematode (C. Elegans) 2. Fruit fly (D. Melanogaster) 3. Zebrafish (Danio rerio) 4. Mouse (Mus Musculus) |
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What did Italian pathologist Camillo Golgi do?
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1. Identified Golgi apparatus
2. Critically important Golgi cell staining technique 3. Articulated and championed "reticular theory," which stated that each nerve cell was connected to its neighbors by protoplasmic links, forming a continuous nerve cell network, or "reticulum (Latin for "net) |
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What is the "neuron doctrine"? Who were its major proponents?
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The theory championed by Spanish: Santiago Ramon Cajal and British: Charles Sherrington that eventually replaced the reticular theory.
-Cajal argued persusasively that nerve cells are discrete entitites, and that they communicate with one another by means of specialized contacts, which Sherrington called synapses. (pg. 4) |
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What are 2 broad categories are the cells of the nervous system divided into?
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Nerve cells "neurons" and their supporting cells called Neuroglia (or simplia glia)
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What do neurons do?
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Neurons are specialized for electrical signaling over long distances.
-Have all the functions of a typical cell (metabolic, synthetic, etc), plus... 1. Specific enzymatic pathways for neurotransmitters 2. Gene products to make proteins for ion pores/channels 3. Machinery for specialized vesicle secretion 4. Fancy cytoskeletal proteins 5. Enhanced intra-cellular transport mechanisms 6. Myelination (in some cases) |
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What do glial cells do?
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Supporting cells make various connective tissues (e.g. meningeal membranes) and include the glia.
-Glial functions: 1. Nutrition and screening of metabolites, inter-cell signaling chemicals 2. Ionic and osmotic regulation 3. Modulation of synaptic function 4. Immune system function 5. Enhancement of intra-neural signal conduction |
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Convergence vs. Divergence
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The "number of inputs" to a single neuron reflects the degree of "convergence" (i.e. lots of dendritic branches" while the "number of targets" innervated by any one neuron reflects its divergence.
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Synaptic Cleft
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In between the pre-and postsynaptic components, molecules must traverse an interval of extracellular space. It is not simply empty space, however, rather, it is the site of extracellular proteins that influence the diffusion, binding and degradation of molecules secreted by the presynaptic terminal.
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Axon
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The portion of a nerve cell specialized for relaying electrical signals. Here, the information conveyed by synapses on the neuronal dendrites is integrated and "read out."
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Local circuit neurons (interneurons) vs. Projection neurons
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Local circuit neurons (interneurons) are relatively short axons, while axons of projection neurons extend to distant targets. For example, axons that run from the human spinal cord to the foot are about a meter long.
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What is the axon hillock? What role does it play in relation to action potentials?
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The point where an action potential initiates, which carries signals over such distances in a self-regenerating wave of electrical activity propagating to the terminus of the axon, at which point synaptic contacts are made. The axon hillock is the anatomical part of a neuron that connects the cell body (the soma) to the axon. It is the location where the summation of inhibitory postsynaptic potentials (IPSPs) and excitatory postsynaptic potentials (EPSPs) from numerous synaptic inputs on the dendrites or cell body occurs.
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What is synaptic transmission?
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The chemical and electrical process by which the information encoded by action potentials is passed on at synaptic contacts to the next cell in a pathway.
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Chemical vs. Electrical synapses? Which is more common?
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Chemical is much more abundant in the nervous system. Electrical is more rare, and is facilitated by gap junctions.
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What are synaptic vesicles?
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They are secretory organelles in the presynaptic terminal of chemical synapses. These spherical structures are filled with neurotransmitter molecules. The positioning of synaptic vesicles at the presynaptic membrane and their fusion to initiate NT release is regulated by a # of proteins either within or associated with the vesicle. The NT's released form synaptic vesicles modify the electrical properties of the target cell by binding to NT receptors localized primarily at the post-synaptic specialization.
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What are the 3 types of glial cells in the mature CNS?
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1. Astrocytes- Starlike appearance that mainly serves to maintain an appropriate chemical environment for neuronal signaling.
2. Oligodendrocites- Lays down a laminated, lipid-rich wrapping called myelin around some axons. In the PNS, the cells that elaborate myelin are called Schwann cells. 3. Microglial- Derived primarily from hematopoietic precursor cells (very similar to macrophages, and serve as scavenger cells that remove cell debris). They also secrete signaling molecules, particularly a wide variety of cytokines that are also produced by cells of the immune system. |
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What is a neural circuit?
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Neurons are never found in isolation. They are organized into ensembles called neural circuits that process specific kinds of ino and provide the foundation of sensation, perception, and behavior.
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Neuropil
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The synaptic connections that define neural circuits are typically made in a dense tangle of dendrites, axon terminals, and glial cell processes that together constitute what is called neuropil. The neuropil constitutes the regions between nerve cell bodies where most synaptic connectivity occurs.
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CNS vs. PNS
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CNS = Brain and spinal cord
PNS = spinal and cranial nerves |
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Gray matter vs. White matter
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Gray = refers to any accumulation of cell bodies and neuropil in the brain and spinal cord
white = (named for its relatively light appearance, the result of lipid content of myelin) refers to axon tracts and commissures |
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Sympathetic vs. Parasympathetic Division Innervation
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In the sympathetic division of the autonomic motor system, the ganglia lie along or in front of the vertebral column and send their axons to a variety of peripheral targets. In the Parasympathetic division, the ganglia are found within or adjacent to the organs.
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Enteric System
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A component of the visceral motor system, which is made up of small ganglia as well as individual neurons scattered throughout the wall of the gut. These neurons influence gastric motility and secretion.
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Neurofilaments
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Multi-helical (10 nm)
-Cytoskeletal elements found only in neurons -Totally polymerized in neuron, maintain cell shape -Disorganized in neurons of Alzheimer's patients |
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Microtubules vs. Microfilaments
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Microtubules (tubulin polymer): 20-25nm
-Scaffolding for transport motors: intracellular transport Microfilaments (actin + myosin): 3-7nm -Involved with dendritic spines and long-term changes in synaptic strength -In a dynamic pool in cell; polymerized and depolymerized as needed. |
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Anterograde tracing vs. Retrograde tracing
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Refers to the direction in which staining techniques are used.
-Anterograde: Traces neural connections from their source to their termination -Retrograde: from termination to source |
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What are the different types of Intracellular Transport?
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Fast Axonal Transport vs. Slow Axonal Transport.
Within Slow AT, there is fast-slow and slow-slow |
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What is the mechanism for fast-axonal transport? Specify which are anterograde vs. retrograde.
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Microtubule scaffolding attaches two types of motors (ATPases)
-Kinesin: organelles/vesicles moved at 400mm/day, anterograde only -Dynein: organelles/vesicles moved at 200-300 mm/day, retrograde only |
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What are the mechanisms for Slow axonal Transport?
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Both types are anterograde only.
1. "Fast-slow"- 5mm/day, transport of certain proteins, especially enzymes and actin 2. "Slow-slow"- 0.2-2.5 mm/day, transport of neurofilaments and microtubule subunits, other proteins. |
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What are the basic cell types of glia? And what do they do?
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1. Astrocytes: help maintain the blood-brain barrier. Selective nutrient transport
2. Oligodendrocytes: (CNS) and Schwann Cells (PNS): enhance electrical signal conduction along axons 3. Microglia: Immune system functions in CNS |
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What is single-cell, or single-unit, electrophysiological recording with microelectrodes?
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This method often records from several nearby cells in addition to the one selected, providing further useful info. The use of microelectrodes to record action potential activity provides a cell by cell analysis of the organization of topographic maps, and can give insight into the type of stimulus to which the nueron is "tuned" (i.e., the stimulus that elicits a maximal change in action potential activity from the baseline state).
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What is a neuron's receptive field?
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Single-unit analysis is often used to define a neuron's receptive field--the region in sensory space (eg the body surface, or a specialized structure such as the retina) within which a specific stimulus elicits the greatest action potential response.
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What is histological staining?
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Histology: The study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining a thin slice (section) of tissue under a light microscope or electron microscope.
-Specific cell biological features of neurons useful for histological identification -Can take advantage of neuronal intracellular transport: HRP, biocytin *(can stain for microtubules, microtubules, membranes, neurofilaments, mitochondria, NT's or their specific synthetic enzymes (e.g. CAT), myelin) |
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What is the Nissl stain technique?
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Exploits high metabolic activity of neurons; neurons typically packed with mitochondria and rER. Cresyl violet used to stain mitochondria (nissl bodies)
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What is Synthetic neurotransmitter enzyme stain?
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This technique works by coupling fluorescent dye to a synthetic substrate for a neuron-specific enzyme (like CAT- choline acetyl transferase, which converts): choline + acetyl CoA ---> CoA + Ach
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Histological staining- biocytin
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Intracellular injection of a tracer dye-- one common dye is the amino acid biocytin. Injected via intracellular glass micropipette.
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What was the beginning of "modern neuroscience" according to Professor Zelick?
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Cajal uses Golgi's technique to map structure of nervous system:
-Neurons have different cell morphologies, but can be categorized into types -Types are consistently found in the same parts of the nervous system, across vertebrate taxa -Neuron types make predictable connections to other neuron types -Neuron types have predictable trajectories form one part of the nervous system to another |
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What techniques constitute functional analysis?
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1. Lesion studies
2. Recording techniques 3. Functional imaging |
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What is Wernicke's area?
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Language comprehension and choosing which words are appropriate.
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What is Broca's area responsible for?
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-Motor pattern generation for words
-Planning motor actions for speech |
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What happens when you get a Wernicke lesion?
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"Word-salad" : Leads to plenty of nicely and easily made words but not necessarily meaningful or the correct response.
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What happens when you have a Broca lesion?
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It leads to frustration: you know what you want to say, but the motor generation is deficient and you can't out the words you want. Those words that are produced are appropriate.
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What is the myotatic reflex?
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Commonly known as "the knee-jerk reflex"
1. Hammer tap stretches tendon, which, in turn, stretches sensory receptors in leg extensor muscle. 2. A) Sensory neuron synapses with and excites motor neuron in the spinal cord. B) Sensory neuron also excites spinal interneuron C) Interneuron synapse inhibits motor neuron to flexor muscles. 3. A) Motor neuron conducts action potential to synapses on extensor muscle fibers, causing contraction B) Flexor muscle relaxes because the activity of its motor neurons has been inhibited. 4. Leg extends |
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Ipsilateral vs. Contralateral
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Ipsilateral = same side
contralateral = opposite side |
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What does it mean to decussate?
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It means to cross or intersect or as to form a cross.
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Does a large brain correlate with greater intelligence?
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Brain allometry is slippery
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Ipsilateral vs. Contralateral
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Ipsilateral = same side
contralateral = opposite side |
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What does it mean to decussate?
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It means to cross or intersect or as to form a cross.
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Does a large brain correlate with greater intelligence?
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Brain allometry is slippery
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