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Plastic change often results from the alteration of the number of neurotransmitter receptors located on a synapse.There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity of neurotransmitters released into a synapse and changes in how effectively cells respond to those neurotransmitters.

Since memories are postulated to be represented by vastly interconnected networks of synapses in the brain, synaptic plasticity is one of the important neurochemical foundations of learning and memory (see Hebbian theory).

As the rising phase reaches its peak, voltage-gated Na channels are inactivated whereas voltage-gated K channels are activated, resulting in a net outward movement of K ions, which repolarizes the membrane potential towards the resting membrane potential.

Repolarization of the membrane potential continues, resulting in an undershoot phase or absolute refractory period.

Some neurons such as photoreceptor cells, for example, do not have myelinated axons that conduct action potentials.

Other unipolar neurons found in invertebrates do not even have distinguishing processes such as dendrites.Neurons are cells that are specialized to receive, propagate, and transmit electrochemical impulses.