The Hodgkin–Huxley model of an action potential in the squid giant axon has been the basis for much of the current understanding of the ionic bases of action potentials.
Briefly, the model states that the generation of an action potential is determined by two ions: Na and K .
Synaptic plasticity in both excitatory and inhibitory synapses has been found to be dependent upon postsynaptic calcium release Two molecular mechanisms for synaptic plasticity (researched by the Eric Kandel laboratories) involve the NMDA and AMPA glutamate receptors.
When ionotropic receptors are activated, certain ion species such as Na to enter the postsynaptic neuron, which depolarizes the postsynaptic membrane.
If more of the same type of postsynaptic receptors are activated, then more Na will enter the postsynaptic membrane and depolarize cell.
As Na ions enter the cell, the membrane potential is further depolarized, and more voltage-gated sodium channels are activated.
Such a process is also known as a positive feedback loop.
After neurotransmitters are synthesized, they are packaged and stored in vesicles.