W2.1 - synaptic transmission et al

packet 1.3

true or false: only one AP can arrive at a neuron at a time, resulting in no overlap of signals

false

the _____-_____ _____ channels are crucial for the start of the cascade that results in neurotransmitter release

voltage-gated calcium

what do SSRIs do?

try to keep serotonin in the cleft so it will activate more and create a better mood

myesthenia gravis causes a breakdown of what neurotransmitter?

acetycholine (Ach)

what does breakdown of Ach by myesthenia gravis result in?

weaker contractions

when an action potential arrives at the ______ terminal, it _____ the membrane and opens voltage-gated ___ channels

presynaptic, depolarizes, calcium

define exocytosis

when a synaptic vessel fuses with the presynaptic membrane to release its contents into the synaptic cleft

what generates the postsynaptic electrical response?

neurotransmitters binding to receptors on ion channels in the postsynaptic cell

what are 2 factors that determine whether postsynaptic actions are excitatory or inhibitory

which ion channel is opened and the electrochemical gradient for that ion

many drugs interfere with step 10 of the sequence of events at a synapse, which is:

removal of neurotransmitter by glial uptake or enzymatic degradation

what are the 2 types of receptor proteins?

ionotropic and metabotropic

what are ionotropic receptors

the receptor and the ion channel are the same structure

what are 3 characteristics of ionotropic receptors

essential for synaptic transmission and signaling; are less selective; move faster than metabotropic receptors

what are metabotropic receptors

“g-protein coupled receptors,” meaning they are separate from the ion channel and use G-proteins as intermediate molecules to communicate

what are 3 characteristics of metabotropic receptors

do not have ion channels; move slower than ionotropic receptors

what is a ligand

any molecule that binds to a specific site on a receptor

what does an excitatory postsynaptic potential (EPSP) do?

depolarizes the cell and increases likelihood of an AP

what does an inhibitory postsynaptic potential (IPSP) do?

hyperpolarizes the cell and decreases the likelihood of an AP

what are EPSPs and IPSPs measured in?

millivolts

whether the response is excitatory or inhibitory depends on _____ ___ ____ the receptor opens and the ____ ____ for those ions

which ion channel, concentration gradient

true or false: a single EPSP is typically strong enough to reach threshold on its own

false

define temporal summation

when repeated inputs from the same synapse arrive in quick succession and add up

define spatial summation

when inputs from different synapses arrive at the same time and add up

what decides whether a neuron will fire and EPSP or an IPSP?

which side has more charge (whichever side wins)

what is the primary excitatory neurotransmitter

glutamate

what is the primary inhibitory neurotransmitter

GABA

the _______ isn’t inherently excitatory/inhibitory, its the _____ and the _____ that determine the effect

neurotransmitter, receptor, ions

summation has to add up to _____ for an AP to occur

threshold

in what 3 locations does plasticity occur?

at synapses, within neurons, within glia

what does plasticity affect? (2)

the structure and function of neural circuits and systems; the cortical maps

why is early mobilization so important in terms of plasticity?

we want to preserve real estate in the brain for that body part (so nothing else moves in while you aren’t using that part)

define plasticity

the capacity of the nervous system to change

plasticity is the basis of what 4 things?

memory, gaining motor skills, gaining cognitive skills, adaptation to injury/disability

time spent focused on a body part creates (more.less) space dedicated to it in the brain

more

the sensory map is not ______, but remodels based on _____ and _____

fixed, experience, demand

what does short-term plasticity change

how much neurotransmitter is released

what does long-term plasticity lead to

changes in gene expression that permanently alter brain function

true or false: synaptic strength is not fixed

true

what does synaptic strength change in response to?

neural activity

what are the 2 mechanisms of short-term synaptic plasticity?

synaptic facilitation and synaptic depression

define synaptic facilitation

increase in neurotransmitter release, creating a stronger synaptic response

define synaptic depression

decrease in neurotransmitter release, creating a weaker synaptic response

what causes a synaptic depression?

when the presynaptic cell is firing too often and depletes the pool of available neurotransmitters, resulting in less of them released at each AP, causing a weaker synaptic response

what animal did the study on synaptic plasticity use because of its large neurons?

Aplysia (sea slug)

define habituation

repeated stimulus causes a progressively weaker response over time

define sensitization

generalization of an aversive response elicited by a noxious stimulus

the ____ of stimulus and its _____ determine which direction plasticity goes (sensitization or habituation)

type, consequences

_____ and _____ matter in the nervous system determining what to do in response to a stimulus

intensity, repetition

more ____ and _____ stimuli lead to _____ and _____ sensitization

frequent, repeated, stronger, longer

more ____ _____ stimuli leads to _____ habituation

frequent, harmless, more

sensitization includes synaptic ____ while habituation includes synaptic _____

facilitation, depression

sensitization of presynaptic neuron depends on the ____

interneuron

more _____ released into the synaptic cleft results in more neurotransmitter release

calcium

true or false: despite the amplification of the presynaptic neuron by the interneuron in sensitization, there is not enough activity to deplete the neurotransmitter pool as in synaptic depression

true

habituation is a change within the _____ ___-__ _____. sensitization involves an _____ ______ _____ acting on that same __ to strengthen it.

existing sensory-motor synapse, additional circuit element, synapse

long-term sensitization occurs with ___ __ ___

frequent noxious stimuli

what does long-term sensitization/habituation do to a presynaptic cell?

alters the gene expression to cause structural remodeling

in long-term sensitization, there is an (increase/decrease) in synaptic connections with the post-synaptic cell, while in long-term habituation, there is an (increase/decrease) in synaptic connections.

increase, decrease

define long-term potentiation (LTP)

long-lasting increase in synaptic strength

what leads to LTP? (list the sequence of 4 ending in LTP)

synaptic facilitation leading to sensitization becoming long-term sensitization causing LTP

define long-term depression (LTD)

long-lasting decrease in synaptic strength

what leads to LTD? (list the sequence of 4 ending in LTD)

synaptic depression leading to habituation becoming long-term habituation causing LTD

synaptic strength in the discussion of LTP and LTD means":

the same presynaptic input now produces a bigger postsynaptic response

what is the connection of interest in the trisynaptic circuit of the hippocampus

between Schaffer-Collateral and CA1 cells

define tetany

high frequency stimulation

LTP results in:

increase in the sensitivity of the post-synaptic neuron that lasts for a long time

define specificity