Final answer:
Long-term potentiation (LTP) is a mechanism for learning and memory in the brain. It involves synaptic strengthening and the insertion of additional receptors, increasing the likelihood of neuron firing. Long-term depression (LTD) is the weakening of a synaptic connection.
Step-by-step explanation:
Long-term potentiation (LTP) is a mechanism for learning and memory in the brain. It is a persistent strengthening of a synaptic connection based on the Hebbian principle: cells that fire together wire together. LTP involves the activation of NMDA receptors, which allows calcium ions to enter the postsynaptic cell. This triggers a signaling cascade that results in the insertion of additional AMPA receptors, strengthening the synapse and increasing the likelihood of the postsynaptic neuron firing in response to neurotransmitter release. Long-term depression (LTD) is the opposite of LTP and involves the weakening of a synaptic connection.