Long Term Potentiation

Synaptic Plasticity

Ability of synapses to strengthen or weaken, in response to increases or decreases in their activity

Trisynaptic circuit of the hippocampus

Entorhinal cortex → dentate gyrus (perforant path) synapses; Dentate gyrus → CA3 (mossy fiber) synapses; CA3 → CA1 (Schaffer collateral) synapses

Long Term Potentiation

Long lasting increase in the strength of a synapse based on recent patterns of neuronal activity

Input Cooperativity

Enough synapses active simultaneously to cause spatial summation and LTP at multiple synapse

AMPA & NMDA in LTP

NMDA receptors are required for inducing LTP. It signals for AMPA receptors to be sensitized and to put more AMPA receptors into the membrane. AMPA receptors are required for the expression of LTP, as they are the receptors that have increased.

Post-synaptic changes in LTP

More AMPA receptors expressed; More AMPA receptors moved to post synapse and on edges of synaptic cleft; AMPA receptors phosphorylated → stay open longer → more depolarization from the same amount of glutamate release; More AMPA receptors with GluR1 subunit; BDNF involved in growth, dendrite makes branches, spines increase, dendritic branching

Pre-synaptic changes in LTP

Nitric Oxide; Decreased threshold for AP firing; Increased release of neurotransmitter (increased number of loaded vesicles primed for release); Axon expansion; Release of transmitter from additional sites

Long Term Depression

Long lasting decrease in the strength of a synapse based on recent patterns of neuronal activity.

Neurogenesis

The process by which neurons are produced