Term
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Definition
| synapses in which the signal is mediated by a neurotransmitter |
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Term
| Where are synapses with direct electric coupling most common? |
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Definition
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Term
| First in signal transfer at chemical synapses, an action potential reaches the nerve terminal & _____ it |
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Definition
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Term
| Depolarization opens _____, enabling Ca2+ to enter the nerve terminal |
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Definition
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Term
| Increase in intracellular Ca2+ concentration is a signal for release of _____ from vesicles by exocytosis |
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Definition
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Term
| The released transmitter binds briefly to _____ in the postsynaptic membrane |
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Definition
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Term
| Why must the transmitter be inactivated quickly after activation of the receptor? |
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Definition
| to reestablish a lot background activity of the receptors; to ensure a high signal-to-noise ratio at the synapse |
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Term
| 3 ways that inactivation occurs |
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Definition
1. diffusion of the transmitter
2. enzymatic degradation
3. specific uptake mechanisms (transporter proteins) |
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Term
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Definition
| parts of ion channels that influence the functional state of the channel directly |
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Term
| Are metabotropic receptors coupled directly or indirectly with ion channels? |
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Definition
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Term
| What do metabotropic receptors do? |
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Definition
| they adjust the excitability of the postsynaptic neuron so that it responds more or less vigorously to the precise effects of ionotropic receptors |
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Term
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Definition
| the change of the membrane potential arising as a result of synaptic influence |
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Term
| excitatory postsynaptic potential (EPSP) |
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Definition
| a synaptic effect that depolarizes the postsynaptic cell & therefore increases the probability that the cell will fire action potentials |
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Term
| excitatory synapse/excitatory transmitter |
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Definition
| when the transmitter produces an EPSP |
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Term
| inhibitory transmitter/inhibitory synapse |
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Definition
| when the transmitter produces an IPSP |
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Term
| Because the depolarization caused by one EPSP is small, _____ of many EPSPs is usually needed to reach a threshold for eliciting an action potential |
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Definition
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Term
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Definition
| the property of synapses that allows them to change their properties by use |
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Term
| Use-dependent synaptic plasticity is the neuronal basis for _____ and _____ |
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Definition
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Term
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Definition
| the kind of cell contact that consists of channels that span the synaptic cleft |
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Term
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Definition
| when electronic synapses provide electrical coupling between many neurons in a group |
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Term
| What is the opposite process of exocytosis? |
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Definition
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Term
| Why are endocytotic vesicles coated with proteins (particularly clathrin & dynamin)? |
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Definition
| they are thought to help in budding of the vesicles from the membrane & in selecting their content |
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Term
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Definition
| fill the vesicles with neurotransmitter; exist in the vesicle membrane |
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Term
| The movement of vesicles requires the presence of _____ |
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Definition
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Term
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Definition
| a group of proteins that bind vesicles to actin filaments |
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Term
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Definition
| regulate the activity of the synapsins |
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Term
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Definition
| packets of transmitters that are released corresponding to the transmitter content of one vesicle |
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Term
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Definition
| a tiny EPSP that is elicited by the release of one quantum |
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Term
| An action potential does not necessarily elicit transmitter release; it merely increases the _____ |
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Definition
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Term
| Synapses equipped with _____ receptors mediate fast & precise information - for example, about "when", "what", & "where" concerning a sensory stimulus |
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Definition
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Term
| How do metabotropic receptors act indirectly on ion channels? |
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Definition
| by way of G proteins & intracellular second messengers |
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Term
| 2 most abundant transmitters acting on ionotropic receptors |
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Definition
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Term
| Where do norepinephrine, dopamine, & serotonin exert their main actions? |
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Definition
| on metabotropic receptors |
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Term
| How are the majority of transmitters removed from the ECF? |
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Definition
| uptake into glial cells or neurons |
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Term
| 2 families of transporter proteins |
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Definition
1. driven by concentration gradients of Na+ & Cl-
2. driven by concentration gradients of Na+ & K+ |
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Term
| What are antidepressants selective for? |
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Definition
| serotonin reuptake inhibitors |
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Term
| What is cocaine selective for? |
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Definition
| inhibiting dopamine-reuptake transporters |
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Term
| Are synaptic potentials all-or-none like action potentials? |
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Definition
| no! they are considered "graded" potentials |
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Term
| What is the mechanism behind an IPSP (usually)? |
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Definition
| opening of transmitter-gated K+ or Cl- channels |
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Term
| What does the opening of chloride channels by an inhibitory transmitter do to the depolarizing currents at nearby excitatory synapses? |
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Definition
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Term
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Definition
| summation that occurs in time |
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Term
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Definition
| summation that occurs in space |
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Term
| modulatory transmitter actions |
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Definition
| when the slow effects of receptors modulate the effects of the fast ones |
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Term
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Definition
| the frequency of action potentials |
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Term
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Definition
| the sum of both excitatory & inhibitory synaptic influences |
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Term
| Synapses close to the _____ of the axon are expected to have a greater chance of eliciting (or preventing) an action potential than synapses far out on the dendrites |
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Definition
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Term
| Spines are implicated in the processes of _____ & _____ |
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Definition
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Term
| What is an important function of inhibition? |
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Definition
| to suppress irrelevant sensory information & therefore allowing us to concentrate on certain events & leave others out |
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Term
| What is the cause of epileptic seizures? |
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Definition
| uncontrolled firing of groups of neurons |
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Term
| Excitatory neurons can limit their firing by way of an _____ |
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Definition
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Term
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Definition
| when an inhibitory neuron inhibits a different inhibitory neuron |
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Term
| 2 reasons a change of synaptic efficacy may arise |
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Definition
1. the presynaptic terminal releases more or less neurotransmitter in response to an action potential
2. the postsynaptic neuron has increased or reduced its response to the transmitter |
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Term
| Increased intracellular _____ appears as a rule to initiate the process of induction/maintenance of synaptic plasticity |
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Definition
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Term
| What undergoes changes in size & form & are therefore correlated with altered synaptic efficacy? |
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Definition
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Term
| Does the formation of new synapses/elimination of old ones stop as we age? |
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Definition
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Term
| Enduring changes in neurons - at either a molecular or a structural level - require altered _____ |
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Definition
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Term
| Long-term change in neurons would require long-term alteration of _____ |
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Definition
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Term
| How long does short-term plasticity last? |
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Definition
| less than a second to some minutes |
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Term
| How long does long-term plasticity last? |
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Definition
|
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Term
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Definition
| the fact that the ability of synapses to express plastic changes is subject to regulation by various signal substances |
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Term
| How does metaplasticity serve homeostatic purposes? |
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Definition
| it keeps plastic changes within certain limits |
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Term
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Definition
| when action potential reach the nerve terminal at relatively brief intervals & the amplitude of the ensuing postsynaptic potentials increases greatly; due to increased transmitter release by each presynaptic action potential |
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Term
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Definition
| when a series of presynaptic action potentials produce increased synaptic efficacy for minutes after the stimulation ends; due to increased transmitter release from the nerve terminal |
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