3. Synpatic Transmission Part 2 Flashcards
refers to the ability of the synapse to change its properties depending on its level of activity
synaptic plasticity
synaptic plasticity is thought to be the basis of:
learning and memory
when brief tetanic stimuli were given in the dendate gyrus, each tetanus caused an increase in the:
amplitude of the synaptic response (eventually lasting for hours)
only the combined tetanus of two distinct groups of presynaptic fibers in the _____ can produce long term potentiation
Schaffer collateral/ commissural pathway
part of the brain involved in aspects of spatial memory
the hippocampus
what is the major principle of the Hebbian synapse?
neurons that fire together, wire together; those that don’t, won’t
what are the three main phases of long-term potentiation (LTP)?
- early - induction phase
- medium - expression phase
- late - maintenance phase
how long does long term potentiation (LTP) last?
days to weeks
phase of LTP characterized by NMDA receptor activation and calcium dependence
early - induction phase
phase of LTP characterized by changes to receptors and release machinery as well as local protein synthesis
medium - expression phase
phase of LTP characterized by genomic involvement, is translation dependent, and has possible anatomical changes
late - maintenance phase
when measuring LTP, synaptic currents are larger in:
amplitude (after tetanic stimulation)
which receptor is critical for induction of LTP?
the NMDA receptor
describe the double-gated properties of the NMDA receptor
- ligand dependent (requires glutamate binding)
- voltage dependent (requires depolarization to remove Mg++ block of channel pore)
- activation requires BOTH elements
Ca++ entry through the NMDA channel is critical for the _____ of synaptic changes
induction and expression
large changes in intracellular [Ca++] induces:
long term potentiation (LTP)
acts as both an ion and a signalling molecule (intracellular second messenger)
Ca++
a large post synaptic increase in Ca++ triggers an increase in post-synaptic responsiveness via:
- an increase in AMPA receptors (postsynaptically)
- an increase in neurotransmitter release (presynaptically)
- an increase in synaptic contacts
Ca-MKII is a key enzyme in the:
induction of LTP
LTP is absent in mutant mice that do not express:
Ca++/calmodulin kinase
a synapse in which the postsynaptic membrane only expresses NMDA receptors; the NMDA receptors are not activated due to the Mg++ block
silent synapse
a type of receptor which is inserted into silent synapses during LTP
AMPA receptors
receptors can be inserted into the membrane, or retrieved, depending on the induction of:
long term potentiation (LTP) or long term depression (LTD)
for medium-term expression of LTP, local signalling mechanisms suffice, however, _____ may be necessary
local protein synthesis
for long-term maintenance of LTP, nuclear involvement is necessary via:
genomic translation
in long term depression (LTD), lower concentrations of calcium entry in the postsynaptic cell elicit:
changes which oppose synaptic enhancement
long term depression (LTD) is evoked by:
both NMDA receptors and voltage-dependent Ca++ channel activation
long term depression (LTD) is likely to include both pre and postsynaptic elements:
- a decrease in postsynaptic AMPA receptors
- a decrease in presynaptic release of glutamate
- a decrease in synaptic contacts
