Long Term Potentiation (LTP) Flashcards
Hebbian synapse definition
Coordinated activity of a presynaptic terminal and a postsynaptic neuron strengthen the synaptic connections between them
What is the hippocampus involved in?
Spatial memory
Discuss relevance of LTP to aspects of learning and memory
There are different types of synapses and LTP
LTP varies in non-hippocampal areas (eg. cortex)
There are different types of memory
Morris water maze
LTP phenomenon
Usually CA3 -> CA1 synapses
High frequency stimulus produces long-lasting potentiation
Properties of LTP phenomenon
Shows input specificity (increased sensitivity is shown only in synapses which are tetanicly stimulated)
Shows co-operativity which does not need HFS
How does LTP occur?
Could occur by pre-synaptic changes
Evidence suggests it is often a post-synaptic event
Ca2+ has a critical role
How does LTP occur?
Could occur by pre-synaptic changes
Evidence suggests it is often a post-synaptic event
Ca2+ has a critical role
NMDA receptors
Blocked by magnesium
When depolarisation occurs and glutamate binds, Mg2+ leaves and channel opens
Needs tetanic stimulation
What is tetanic stimulation
High-frequency stimulation
Late stage LTP
Usually requires protein synthesis
Late stage LTP
Usually requires protein synthesis for long term storage
cAMP signalling may be critical
Phosphorylation _____ AMPA currents
Enhances
What is AMPAfication?
Increasing the number of AMPA receptors on the post-synaptic site
What is AMPAfication?
Increasing the number of AMPA receptors on the post-synaptic site
LTP overview
When neuron is active, glutamate released
Activates AMPA receptor
If AMPA activity large enough depolarises the membrane of post-synaptic neuron
Removes Mg2+ block from NMDA receptor
Ca2+ enters and activates calcium calmodulin
Calmodulin activates CaMKII and adenyl cyclase
Adenylyl cyclase activates PKA -> nucleus and triggers gene expression
CaMKII phosphorylates AMPA receptors, increases number of AMPA receptors
