Table of Contents
Morphological Correlates of LTP
Changes in Synapse Number
Question: Generation of New Synapses
Morphological Correlates of LTP - Spine swelling, Neck widening
Morphological Correlates of LTP - Changes in Existing Synapse Structure
Question -
Modification of Existing synapses:
New synapses are continuously
generated in the brain.
LTP in Hippocampal Slices
LTP Within Slices
Adult Hippocampal Slices
LTP does NOT produce new synapses or modify existing synapses in mature hippocampus
Experiment to test for mature spine plasticity
Scoring Strategies
Mature Hippocampal Dendrite Tips
Mature Dendrites Become More Spiny Possibly to Compensate for Lost Synaptic Activity
LTP in Immature
Hippocampal Neurons
Hippocampal Dendritic Filopodia at PN6
Two dendritic filopodia synapse on 1 axon at PND6
Immature Dendrite
Spinogenesis during Development
Role of activity in filopodial outgrowth
Role of synaptically released glutamate in dendritic spine formation
On average 6 new spines/ 100 um dendrite are formed in the path of the glutamate - others remain unchanged
Subset of synapses change connectivity with LTP in organotypic slices
Transient increase in perforated PSDs
Blockade of LTP by KN93 prevents morphological correlates
Enduring increase in the frequency of multiple spine boutons where both spines arise from the same parent dendrite
Issue in all three of these
developmental LTP studies
Evidence that LTP might preserve newly formed synapses.
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