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PSY209 Exam 1
| Question | Answer |
|---|---|
| Behavioral neuroscience | the study of biological bases of psychological processes and behavior |
| neuroscience | the study of the nervous system |
| neurons | nerve cells, the basic unit of the nervous system |
| synapses | areas where billions of neurons make contacts with each other |
| axons and dendrites | specialized extensions of neurons that send and receive information, respectively, from neurons |
| how many neurons does the human brain have? | 86 billion |
| how thick is the human cerebral cortex? | less than 4 millimeters (a stack of four credit cards) |
| what is the area of an unfolded cortex? | 2500cm^2 (a newspaper unfolded) |
| how many capillaries? | 400 miles worth |
| What is nature's largest brain volume? | 8 liters (a sperm whale brain) |
| how many axons? | 100,000 miles worth (4 trips around the Earth) |
| How many calculations per second? | 10^16 |
| How many synapses? | More than 10 trillion (the number of cells in the rest of the entire body) |
| Longest axons on land? | 15 feet (giraffes) |
| how much of the body's oxygen does the brain need? | 20% |
| how many people suffer from strokes? | 15 million |
| how many people have Alzheimer's? | 35 million |
| how many people have epilepsy? | 50 million |
| How many pain receptors does the brain have? | 0 |
| How many neurons does the c. elegans have? | 302 |
| What happens if you delete the RMG neuron? | turns social c. elegans (left) into solitary c. elegans (right) |
| What behavior does administering a hormone affect? | strength of mating behavior |
| What behavior does stimulating the brain region electrically affect? | movement toward goal object |
| What behavior does cutting connections between parts of nervous system affect? | recognition of stimulus |
| What somatic effect occurs when a male is put in the presence of a female? | changes in hormone levels |
| What somatic effect occurs when a visual stimulus is presented? | changes in electrical activity of the brain |
| What somatic effect occurs when given training? | anatomical changes in nerve cells |
| What is brain size correlated to? | Learning scores |
| What are hormone levels correlated to? | strength of mating behavior |
| What are enlarged cerebral ventricles correlated to? | schizophrenic symptoms |
| What relationships does behavioral neuroscience seek to understand? | somatic variables and behavioral variables |
| social level | individuals behaving in social interactions |
| organ level | brain, spinal cord, peripheral nerves, and eyes |
| neural systems level | eyes and vision brain regions |
| brain region level | visual cortex |
| circuit level | local neural circuit |
| cellular level | single neuron |
| what ratio of people suffer from neurological or psychological disorders? | 1 out of 5 |
| What is the prevalence of epilepsy in the U.S. and what type of condition is it? | 2,000,000 and neurological |
| What is the prevalence of strokes in the U.S. and what type of condition is it? | 3,000,000 and neurological |
| What is the prevalence of Alzheimer's disease in the U.S. and what type of condition is it? | 2,500,000 and neurological |
| What is the prevalence of head and spinal cord trauma in the U.S. and what type of condition is it? | 1,000,000 and neurological |
| What is the prevalence of cerebral palsy in the U.S. and what type of condition is it? | 500,000 and neurological |
| What is the prevalence of Parkinson's disease and Huntington's disease in the U.S. and what type of condition is it? | 500,000 and neurological |
| What is the prevalence of anxiety disorders in the U.S. and what type of condition is it? | 85,000,000 and psychiatric |
| What is the prevalence of impulse control disorders and attention deficit disorder in the U.S. and what type of condition is it? | 75,000,000 and psychiatric |
| What is the prevalence of mood disorders in the U.S. and what type of condition is it? | 60,000,000 and psychiatric |
| What is the prevalence of alcohol and drug abuse in the U.S. and what type of condition is it? | 45,000,000 and psychiatric |
| What is the prevalence of schizophrenia in the U.S. and what type of condition is it? | 1,500,000 and psychiatric |
| Localization of function | a measure of where peak activity occurs, rather than a suggestion of a single region involved in a particular task |
| What do specialized cells do? | They make up the nervous system |
| What divisions does the nervous system consist of? | central and peripheral |
| What does the brain show? | regional specialization of functions |
| What protects and nourishes the brain? | specialized support systems |
| glial cells | provide support for and contribute to information processing neurons |
| What does the neuron doctrine state? | the brain is composed of independent cells and information is transmitted from cell to cell across synapses |
| Input zone | receives information from other cells through dendrites; where neurons collect and integrate information, either from the environment or from other cells |
| Integration zone | where the decision to produce a neural signal is made; cell body (soma) region where inputs are combined and transformed |
| Conduction zone | where information can be transmitted over great distances; single axon leads away from the cell body and transmits the electrical impulse |
| Output zone | where the neuron transfers information to other cells; axon terminals at the end of the axon communicate activity to other cells |
| How are neurons classified? | by shape, size, and function |
| Multipolar neurons | one axon, many dendrites (most common type) |
| Bipolar neurons | one axon, one dendrite |
| Unipolar neurons | a single extension branches in two directions, forming a receptive pole and an output zone |
| what do motor neurons do? | stimulate muscles or glands |
| what do sensory neurons do? | respond to environmental stimuli, such as light, odor, or touch |
| What do interneurons do? | receive input from and send input to other neurons |
| What do the neuronal cell body and dendrites? | receive information across synapses |
| What is the synaptic cleft? | a small space between a presynaptic neuron and a postsynaptic neuron |
| What does the membrane of the postsynaptic neuron contain? | ion channels that facilitate electrical activity |
| Where is information transmitted from and to? | from the axon of a presynaptic neuron to dendrites of a postsynaptic neuron |
| Why do dendrites have many dendritic spines? | to form synapses in order to facilitate contacts with many axons |
| synaptic vesicles | small spheres in presynaptic axon terminals that contain a neurotransmitter, a specialized chemical substance |
| Why are neurotransmitters released? | in response to electrical activity in the axon |
| Which direction does the anterograde transport travel? | from the cell body to the axon terminals |
| Which direction does the retrograde transport travel? | from the axon terminals to the cell body |
| Axonal transport | movement of materials within an axon via motor proteins |
| Axons number | usually one per neuron, with many terminal branches |
| Dendrites number | usually many per neuron |
| Axons diameter | uniform until start of terminal branching |
| Dendrites diameter | tapering progressively toward ending |
| Axons axon hillock | has axon hillock |
| Dendrites axon hillock | no axon hillock |
| Axons sheathing | usually covered with myelin |
| Dendrites sheathing | no myelin sheath |
| Axons length | ranging from practically nonexistent to several meters long |
| Dendrites length | often much shorter than axons |
| Astrocytes | a type of glial cell, star-shaped cells with many processes that receive neuronal input and monitor activity |
| Microglia | a type of glial cell, small cells that remove debris from injured cells |
| Oligodendrocytes | a type of glial cell, form myelin sheath in the brain and spinal cord |
| Schwann cells | a type of glial cell, provide myelin to cells outside the brain and spinal cord |
| myelin | a fatty sheath glial cells wrap around axons to insulate and speed conduction |
| nodes of Ranvier | gaps between myelin sections where the axon is exposed |
| multiple sclerosis | demyelinating disease |
| the central nervous system (CNS) | consists of the brain and spinal cord |
| the peripheral nervous system | consists of all parts of the nervous system that are not the brain and spinal cord |
| Somatic nervous system | voluntary movement; nerves that interconnect the brain and the skeletal muscles and sensory systems |
| Autonomic nervous system | largely unconscious regulation of bodily functions; nerves that primarily control the viscera (internal organs: kidneys, liver, lungs, heart, etc) |
| cranial nerves | (12 pairs) connecting brain with body without going through the spinal cord |
| What are the three sensory pathways? | Olfactory, optic, vestibulocochlear |
| What are the five motor pathways? | Oculomotor, trochlear, abducens, spinal accessory, hypoglossal |
| What are the four sensory and motor pathways? | Trigeminal, facial, glossopharyngeal, vagus |
| How many roots do spinal nerves have and how many pairs? | 31 pairs and 2 roots |
| Dorsal (back) root | carries sensory information from the body to the spinal cord |
| Ventral (front) root | carries motor information from the spinal cord to the muscles |
| How are nerves named? | for the segment of spinal cord they are connected to |
| cervical | neck 8 |
| thoracic | trunk 12 |
| lumbar | lower back 5 |
| sacral | pelvic 5 |
| coccygeal | bottom 1 |
| What spans CNS and PNS and has two major divisions? | Autonomic nervous system |
| Sympathetic nervous system | a division of the autonomic nervous system; prepares the body for action, has preganglionic neurons in the thoracic and lumbar regions of the spinal cord |
| What do preganglionic neurons do? | innervate the sympathetic chain, which runs along each side of the spinal cord |
| Parasympathetic nervous system | a division of the autonomic nervous system; conserves energy, has preganglionic neurons in the cranial nerves and the sacral spinal cord |
| preganglionic neurons | run from the central nervous system to the autonomic ganglia |
| postganglionic neurons | run from the autonomic ganglia to targets in the body |
| preganglionic neuron transmitters and parasympathetic transmitters | acetylcholine (ACh) |
| postganglionic neuron transmitters and sympathetic transmitters | norepinephrine (noradrenaline) (NE) |
| sagittal plane | divides into right and left |
| coronal plane | divides into front and back |
| horizontal plane | divides into up and down |
| medial | towards the middle |
| lateral | towards the side |
| anterior or rostral | head end |
| posterior or caudal | tail end |
| dorsal | toward the back |
| ventral | toward the belly, or front |
| What is the largest region of the brain? | cerebral cortex |
| frontal lobe | in cerebral cortex; anterior region, role in cognitive and emotional processing |
| parietal lobe | in cerebral cortex; between frontal and occipital lobes, role in linguistic processing |
| occipital lobe | in cerebral cortex; posterior region, role in visual processing |
| temporal lobe | in cerebral cortex; lateral region, role in auditory processing |
| Gray matter | contains mostly cell bodies and dendrites |
| white matter | consists mostly of axons with white myelin sheaths |
| corpus callosum | a bundle of axons and myelin sheaths that connects the two cerebral hemispheres |
| subdivisions of neural tube | forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon) |
| subdivisions of forebrain | telencephalon, diencephalon |
| subdivisions of hindbrain | metencephalon (cerebellum and pons), myelencephalon (medulla) |
| cortex | 6 layers, distinguished by type of neurons, pattern of dendrites, and pattern of axons |
| What is the most prominent type of neuron? | pyramidal neuron |
| Nuclei in motor control | caudate nucleus, putamen, globus pallidus, substantia nigra (in midbrain) |
| Collection of brain regions involved in emotion | amygdala, hippocampus, septum, mammillary bodies |
| Thalamus | in the diencephalon in the forebrain relays sensory information to amygdala to cortex |
| hypothalamus | in the diencephalon in the forebrain regulates vital functions (hunger, thirst, temperature, sex) output to midbrain/hindbrain (autonomic function) and pituitary (neuroendocrine gland) |
| Tectum (roof) | in the mesencephalon in the midbrain; superior colliculi and inferior colliculi |
| superior colliculi | processes visual information |
| inferior colliculi | processes auditory information |
| substantia nigra | in the cerebral peduncle in the mesencephalon; synthesizes dopamine, part of basal ganglia, motor control |
| tegmentum | in the mesencephalon; synthesizes dopamine, projections to cortex and striatum, and involved in reward/aversion |
| cerebellum | in the metencephalon, involved in motor coordination and basic learning |
| granule cell layer | innermost layer in cerebellum, composed of small neurons |
| purkinje cell layer | middle layer in cerebellum, its large cells form a single row |
| molecular layer | outermost layer in cerebellum, made up of parallel fibers of granular cells and dendritic trees of Purkinje cells |
| Pons | in the metencephalon, attached to the cerebellum and relays signals from the forebrain to the cerebellum, contains motor nuclei and sensory nuclei, important for regulatory (sleep, breathing, facial sensation) |
| Medulla | in the myelencephalon; marks the transition from brain to spinal cord, all axons from the brain to the spinal cord pass through the medulla, contains nuclei that regulate autonomic functions (breathing, heart rate, sneezing) |
| meninges | protective membranes that surround the brain and spinal cord |
| Dura mater | a meninge, tough outermost sheet |
| Pia mater | a meninge, delicate innermost layer |
| Arachnoid | a meninge, substance between the dura mater and Pia mater that cushions the brain in cerebrospinal fluid (CSF) |
| cerebrospinal fluid | acts as a shock absorber and provides an exchange medium between blood and brain |
| Ventricular system of the brain | series of four chambers filled with CSF and lined with choroid plexus |
| choroid plexus | a membrane of cells that produces CSF |
| two lateral ventricles | in telencephalon, one in each hemisphere, extends into all four lobes |
| third ventricle | in diencephalon, at the midline, between the lateral ventricles |
| fourth ventricle | in hindbrain, CSF can exit here into the subarachnoid space, connects with the central canal in the spinal cord |
| Blood-brain-barrier (BBB) | dynamic physical and metabolic barrier between blood and CSF/brain consisting of specialized endothelial cells that protects the brain from blood-borne compounds, and maintains brain homeostasis |
| Intercellular pathway | passage of water-soluble molecules |
| Transcellular lipophilic pathway | passive diffusion of lipid-soluble molecules across the barrier |
| Transport protein pathway | active transport of large molecules across the barrier by specific proteins |
| Protein pumps | active transport back into the bloodstream of some lipophilic molecules |
| carotid arteries | major arteries to the brain (anterior, middle, posterior cerebral arteries) |
| anterior and middle arteries | originate from the internal carotid artery |
| posterior artery | originates from the basilar artery that itself arises from the vertebral arteries |
| circle of Willis | where the basilar and internal carotid arteries form a circle at the base of the brain |
| what do synapses cause? | graded, local changes in the postsynaptic membrane potential |
| what does synaptic transmission require? | a sequence of events |
| what do neurons and synapses make when they combine? | circuits |
| action potential | rapid electrical signal that travels along the axon of a neuron, produced by the movement of Na+ ions into the cell, brief and large change in membrane potential, originates in axon hillock, propagates along the axon |
| neurotransmitter | chemical messenger between neurons |
| what is a neuron at rest? | a balance of electrochemical forces |
| ions | electrically charged molecules |
| anions | negatively charged ions |
| cations | positively charged ions |
| what are ions dissolved in? | intracellular fluid |
| what separates ions from the extracellular fluid? | the cell membrane |
| how can one measure the membrane potential? | micro electrodes |
| In a resting cell, which fluid is more negative? | the intracellular fluid |
| what is a resting membrane potential? | -50 to -80 millivolts (mV) |
| what is the cell membrane also called? | lipid bilayer |
| ion channels | proteins that span the membrane and allow ions to pass, open and close in response to voltage changes, chemicals, or mechanical action, some channels are open all the time and allow only potassium ions to cross |
| selective permeability | K+ enters or leaves the cell freely with restriction on the flow of other ions |
| Diffusion | causes ions to flow from areas of high to low concentration, along their concentration gradient |
| electrostatic pressure | causes ions to flow towards oppositely charged areas |
| sodium-potassium pump | maintains resting potential and pumps out 3 sodium ions for every 2 potassium ions that are pumped in |
| electrostatic pressure | causes potassium ions to move into the negative interior of the cell when at rest |
| what happens when potassium builds up inside the cell? | it diffuses out through the membrane, along the concentration gradient |
| when does K+ reach equilibrium? | when movement out equals movement in |
| equilibrium | corresponds to resting membrane potential |
| Nernst equation | predicts the voltage needed to counterbalance the diffusion force pushing an ion across a membrane, predicts the equilibrium potential of only K+, resulting in a predicted potential of -80mV |
| Goldman equation | predicts voltage potentials similar to resting potentials, takes into account the intracellular and extracellular concentrations of several ions and the degree of membrane permeability to each |
| What is mostly found inside the cell? | K+ ions and proteins |
| What is mostly found outside the cell? | Na+ ions, Cl- ions, and Ca2+ ions |
| How are outside ions exchanged? | through specialized channels in the cell membrane |
| hyper polarization | increase in membrane potential, the interior of the cell becomes more negative |
| depolarization | decrease in membrane potential, the interior of the cell becomes less negative |
| the greater the hyper polarizing stimulus... | the greater the hyper polarization response |
| graded response | a change in potential |
| what happens to the hyper polarization response when the amplifier is farther away from the stimulator? | it occurs at the same time, but is lower |
| the greater the depolarizing stimulus... | the greater the depolarization response until a threshold (-40mV) is reached and action potential is triggered |
| all-or-none property of action potentials | neurons fire at full amplitude or not at all |
| what happens to the action potential when the amplifier is farther away from the stimulator? | it occurs later, but is of the same size |
| What does membrane potential depend on? | how many and which ion channels are open |
| when K+ channel is open and Na+ channel is closed... | K+ creates resting potential |
| when K+ channel is closed... | at threshold, voltage-gated Na+ channels open |
| after Na+ channels open and action potential is reached... | Na+ channels close automatically, K+ open, disbalance causes after potential |
| after after potential... | all channels close, cell returns to resting potential |
| Refractory period | time when only some stimuli can produce an action potential |
| Absolute refractory phase | time when no action potentials are produced |
| Relative refractory phase | time when only strong simulation can produce an action potential |
| refractory state | of the membrane, make action potentials travel in one direction after a depolarization |
| conduction velocity | the speed of propagation of action potentials which varies with the diameter of the axon |
| What is the speed of conduction in unmyelinated axons (invertebrates)? | slow |
| saltatory conduction | the axon potential travels inside the axon and jumps from node to node |
| What is the speed of conduction in myelinated axons (vertebrates)? | fast |
| Channelopathy | genetic abnormality of ion channels often causing a disorder (23 disorders currently identified) |
| Na+ channelopathy | various seizure disorders, muscle disorders, cardiac disorders |
| Cl- channelopathy | associated with deafness, kidney problems, movement disorders, epilepsy |
| How do animal toxins work? | they block specific ion channels |
| Tetrodotoxin (TTX) | produced in ovaries of puffer fish, block voltage-gated Na+ channels |
| Saxitoxin (STX) | produced by algae, block voltage-gated Na+ channels |
| Batrachotoxin | produced by poison dart frogs, force voltage-gated Na+ channels to stay open |
| postsynaptic potential | brief change in resting potential |
| excitatory postsynaptic potential (ESP) | produces small local depolarization, pushing the cell closer to threshold |
| synaptic delay | delay between an action potential reaching the axon terminal and creating a postsynaptic potential |
| Inhibitory postsynaptic potential (IPSP) | produces a small hyper polarization, pushing the cell further away from threshold |
| chloride ions (Cl-) | when they enter the cell, they make the inside more negative and result in IPSPs |
| What happens when the excitatory neuron is fired? | causes depolarization (EPSP) of the neuron |
| What happens when the inhibitory neuron is fired? | causes hyper polarization (IPSP) of the neuron |
| When will a postsynaptic neuron fire an action potential? | when the excitatory input is stronger than inhibitory input and the depolarization that exceeds the threshold reaches its axon hillock |
| spatial summation | summing of potentials that come from different parts of the cell |
| when will an action potential occur? | when the overall sum of EPSPs and IPSPs depolarizes the cell at the axon hillock |
| temporal summation | summing of potentials that arrive at the axon hillock at different times |
| the closer together in time they arrive... | the greater the summation and possibility of an action potential |
| where do action potentials occur? | the axon |
| Where do EPSPs occur? | the dendrites and soma |
| Where do IPSPs occur? | the dendrites and soma |
| What is an action potential's signaling role? | conduction along an axon |
| What is an EPSP's signaling role? | transmission between neurons |
| What is an IPSP's signaling role? | transmission between neurons |
| What is the typical duration of an action potential? | 1-2 ms |
| What is the typical duration of an EPSP? | 10-100 ms |
| What is the typical duration of an IPSP? | 10-100 ms |
| What is the character of an action potential? | all-or-none, digital |
| What is the character of an EPSP? | graded, analog |
| What is the character of an IPSP? | graded, analog |
| What is the amplitude of an action potential? | overshooting, 100mV |
| What is the amplitude of an EPSP? | depolarizing, from less than 1 to more than 20mV |
| What is the amplitude of an IPSP? | hyper polarizing, from less than 1 to about 15mV |
| What is an action potential's mode of propagation? | actively propagated, regenerative |
| What is an EPSP's mode of propagation? | local, passive spread |
| What is an IPSP's mode of propagation? | local, passive spread |
| What is the ion channel opening of an action potential? | First Na+, then K+, in different channels |
| What is the ion channel opening of an EPSP? | Na+-K+ |
| What is the ion channel opening of an IPSP? | Cl--K+ |
| What is the action potential channel sensitive to? | voltage (depolarization) |
| What is the EPSP channel sensitive to? | chemical (neurotransmitter) |
| What is the IPSP channel sensitive to? | chemical (neurotransmitter) |
| First step of synaptic transmission | action potential travels down the axon to the axon terminal |
| Second step of synaptic transmission | voltage-gated Ca2+ channels open and Ca2+ enters |
| Third step of synaptic transmission | synaptic vesicles fuse with membrane (exocytosis) and release neurotransmitters into the synaptic cleft |
| Fourth step of synaptic transmission | neurotransmitters cross the synaptic cleft and bind to postsynaptic receptors and cause an EPSP or IPSP |
| Fifth step of synaptic transmission | EPSPs or IPSPs spread toward the postsynaptic axon hillock |
| Sixth step of synaptic transmission | neurotransmitter action is brief, either inactivated by enzyme degradation or removed by transporters for reuptake and recycling |
| Seventh step of synaptic transmission | neurotransmitters may activate presynaptic auto receptors resulting in a decrease in its own release |
| SNARE | protein serving as tether |
| v-SNAREs | attach to vesicles |
| t-SNAREs | attach to presynaptic membrane |
| Synaptotagmin | protein attached to the vesicle, activated by Ca2+, triggers the fusion of the vesicle with the presynaptic membrane resulting in the release of neurotransmitters into synaptic cleft |
| What are receptors activated or inhibited by? | ligands |
| endogenous ligands | neurotransmitters and hormones |
| exogenous ligands | drugs and toxins from outside the body |
| Acetylcholine (ACh) | a neurotransmitter that can bind to the nicotinic receptor (a ligand-gated ion channel) to then allow Na+ ions to enter the cell (need 2 molecules) |
| What does nicotine mimic? | ACh (agonist) |
| What does curare do? | it is toxic, causes paralysis, and blocks nicotinic receptors (antagonist) |
| Nicotinic ACh receptors | ligand-gated ion channel on muscles and in autonomic ganglia |
| Muscarinic ACh receptors | G-protein-coupled receptor in the brain, on organs innervated by the parasympathetic division or the autonomic system, activated by ACh, and activated by muscarine (found in mushrooms) |
| Receptor numbers in cells are... | dynamic, daily changes in adulthood, changes during development, and changes with drug use |
| Up-regulation | increase in receptor number |
| Down-regulation | decrease in receptor number |
| Ionotropic receptors | ligand-gated ion channel activated by neurotransmitters, opening of ion channel, ion enters the cell |
| Metabotropic receptors | G-protein-coupled receptors activated by neurotransmitters, activation of G proteins, activation of second chemical (second messenger) or activation of nearby ion channel, ions enter the cell |
| What is the speed of ionotropic receptors? | fast, direct opening of ion channel |
| what is the speed of metabotropic receptors? | slow, indirect opening of ion channel |
| What percentage of ligands (neurotransmitters and hormones) bind to G-protein-coupled receptors? | 80% |
| Why is neurotransmitter action brief? | Degradation and reuptake |
| Degradation | rapid breakdown and inactivation of transmitter by an enzyme, e.g. acetylcholinesterase (AChE) breaks down ACh and recycles it |
| Reuptake | transmitter is taken up into the presynaptic cell by specialized transporters (SSRI) |
| What do neurotransmitters do when they do not cross the synaptic cleft? | they bind to auto receptors (auto=self) on the presynaptic cell to control its own release |
| Axo-dendritic | axon terminal synapses on a dendrite |
| Axo-somatic | axon terminal synapses on the cell body (soma) |
| Axo-axonic | synapse between two axons |
| Dendro-dendritic | synapse between two dendrites |
| Chemical synapse | chemical substance mediates synaptic transmission from pre to postsynaptic, synaptic cleft = 20-40nm |
| Electrical synapse | gap junctions, ions flow through large channels (connexons) into adjacent cells, synaptic cleft=2-4nm, no time delay |
| the axon potential jumps... | directly to the postsynaptic cell without first being transformed into a chemical signal |
| neural chain | circuit with neurons linearly attached allows for fast response (=reflex) |
| stretch reflect (knee-jerk reflex) | monosynaptic: sensory neuron-synapse-motor neuron |
| Withdrawal reflex (nociceptive/flexor withdrawal reflex) | polysynaptic: sensory neuron-synapse-interneuron-synapse-motor neuron |
| startle reflex (moro reflex in babies) | polysynaptic: sensory-neuron-synapse-brainstem-synapse-motor neuron |
| Fear reflex | polysynaptic: sensory neuron-synapse-thalamus-synapse-amygdala-synapse-motor-neuron, thalamus to amygdala pathway carries information rapidly to the amygdala |
| knee-jerk reflex | fast, axons are large and myelinated, sensory cells are synapse directly onto motor neurons, uses fast, ionotropic synapses |
| the thalamus to cortex to amygdala pathway... | is slower but allows the external stimuli to be cognitively appraised |
| synaptic transmission | a complex electrochemical process |
| complex array | formed by neurotransmitter systems in the brain |
| What do the effects of drugs depend on? | the site of action and dose |
| Drugs affect... | each stage of neural conduction and synaptic transmission |
| some neuroactive drugs... | ease the symptoms of injury or psychiatric illness and are used to alter conscious experiences |
| neurochemistry | focuses on the basis chemical composition and processes of the nervous system |
| neuropharmacology | the study of drugs that affect the nervous system |
| exogenous substances | substances from outside our own bodies, used throughout human history to affect our physiology and behavior |
| endogenous substances | substances that naturally occur within the body |
| the receptor will change shape if... | the receptor is ionotropic |
| the receptor will alter chemical reactions if... | the receptor is metabotropic |
| agonist drug | mimics effects of usual neurotransmitter |
| antagonist drug | binds receptor without activating it, thereby blocking the receptor from being activated (competitive vs non-competitive) |
| inverse agonist | binds receptor and initiates opposite effect of usual neurotransmitter |
| Neurotransmitter criteria | substance exists in presynaptic axon terminals, released when action potentials reach axon terminals, receptors for the substance exist on postsynaptic membrane, when experimentally applied substance induces changes in postsynaptic cells |
| glutamate | most prevalent excitatory neurotransmitter, plays role in cognition, learning and memory, binds to ionotropic (NMDA, AMPA, kainite) and metabotropic (mGLUR1-8) receptors |
| excitotoxicity | excess of glutamate release resulting in damage/loss of neurons, plays a role in Alzheimer's disease, brain trauma, seizure disorders, Parkinson's disease, stroke, Huntington's disease, autism, schizophrenia |
| GABA | gamma-Aminobutyric acid, most prevalent inhibitory neurotransmitter, binds to ionotropic (GABA_A, GABA_C) and metabotropic (GABA_B) receptors |
| Drugs based on enhancing GABA function | hypnotics, sedatives, tranquilizers, anticonvulsants (most well known=benzodiazepines, diazepam=valium), alcohol, cannabis, to treat pain, seizures, anxiety, migraine |
| Alzheimer's disease is associated with... | damage to cholinergic nerve cell bodies in the brain |
| monoamine neurotransmitters | catecholamines (dopamine, epinephrine/adrenaline) - not in the brain |
| Indoleamines | melatonin, serotonin |
| Mesostriatal pathway | originating in the substantial nigra and projecting to the striatum where dopamine is found (important in motor control, neuronal loss is causing Parkinson's disease) |
| Mesocorticolimbic pathway | originating in the ventral tegmental area (VTA) and projecting to the cortex and limbic areas, important for reward and aversion and learning, abnormalities associated with schizophrenia and depression |
| Norepinephrine (NE) | synthesized in the locus coeruleus (pons) and lateral segmental system (midbrain), binds to metabotropic (alpha 1, alpha 2; beta 1, beta 2, beta 3) receptors, modulates mood, arousal, attention, behavioral flexibility and sexual behavior |
| beta blocker (propranolol) | reduces performance anxiety |
| serotonin (5-hydroxytryptamine, 5-HT) | synthesized in 7 raphe nuclei, with dorsal raphe nucleus being the largest, role in sleep, mood, sexual behavior, depression and anxiety |
| selective serotonin reuptake inhibitors (SSRIs) | antidepressants (prozac) |
| How is serotonin deactivated? | in the synapse by reuptake (by a serotonin transporter) into the presynaptic neuron |
| What does Prozac block? | the serotonin transporter, increasing the availability of serotonin in the synapse |
| binding affinity | the degree of chemical attraction between a ligand and a receptor |
| when a drug has a high affinity for its receptor... | it is effective at very low doses |
| low-affinity ligands | neurotransmitters, rapidly dissociate from receptors |
| efficacy (intrinsic activity) | the ability of a bound ligand to activate the receptor |
| agonists have... | high efficacy |
| antagonists have... | low efficacy |
| drug-response curve (DRC) | relationship between drug doses and the effects, tool to understand pharmacodynamics (functional relationship between drugs and their targets) |
| ED_50 value | effective dose for 50% of people receiving the drug, allows comparison of potency of drugs |
| higher potency | comparable effects at lower doses |
| therapeutic index | separation between effective dose and toxic/lethal dose, determined by comparing ED_50 with TD_50 (toxic dose for 50% of individuals) or LD_50 (lethal dose for 50% of individuals) |
| antidepressants | class of drugs used to treat symptoms of depression |
| monoamine oxidase (MAO) inhibitors | prevent breakdown of monamines at synapses |
| tricyclic antidepressants | prevent the reuptake of serotonin and norepinephrine into presynaptic axon terminals |
| selective serotonin reuptake inhibitors (SSRIs) | same mechanism as tricyclic antidepressants but with fewer side effects |
| anxiolytics (tranquilizers) | class of drugs used to treat anxiety disorders |
| Benzodiazepine agonists | act on GABA_A receptors and enhance the inhibitory effects of GABA, safe and effective for short-term use, however long-term use is discouraged because of dependency and withdrawal effects |
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