Long-term Potentiation

Long-term potentiation, or LTP, is a process of synaptic strengthening that occurs over time between pre and post synaptic neuronal connections.

In one mechanism, when presynaptic neurons repeatedly fire and stimulate the postsynaptic cell, this action induces changes in the type and number of ion channels in the post synaptic membrane such as one class of glutamate receptors called N-methyl-D-aspartate, or NMDA.

NMDA receptors are usually inactivated by magnesium ions, however, with strong depolarization from repeated stimulation, the magnesium ions are displaced allowing calcium ions to enter.

This calcium influx initiates a signaling cascade that culminates in a second class of glutamate receptors. Alpha amino three hydroxy five methyl four isoxazolepropionic acid, or AMPA for short, inserting into the membrane. In this case, more positive ions flow into the neuron making a stronger postsynaptic response to the same presynaptic stimulation.

LTP is essential for learning, and is one way to explain the adage practice makes perfect since the newly strengthened response can last from minutes to weeks or longer if the presynaptic stimulation persists.