What is the Difference Between Action Potential and Synaptic Potential?

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The key difference between an action potential and a synaptic potential lies in their origin, function, and duration. Here are the main differences:

  • Origin: An action potential is a sudden, fast, transitory, and propagating change in the resting membrane potential of neurons, occurring when a neuron sends nerve impulses along the axon and depolarizes the cell body. In contrast, a synaptic potential is the potential difference across the postsynaptic membrane, resulting from the release of neurotransmitters from the presynaptic terminal.
  • Function: Action potentials are the means by which neurons communicate with each other, sending electrical signals down the axon to the synaptic terminals. Synaptic potentials, on the other hand, are the "incoming" signals that a neuron receives at its synapses, and they can be either excitatory or inhibitory, depending on the neurotransmitters released.
  • Duration: Action potentials are short-lasting events, with a typical duration of a few milliseconds. Synaptic potentials, however, degrade quickly as they move away from the synapse and are not static, changing over time as a result of synaptic plasticity.

To summarize, action potentials are the electrical signals generated by neurons to communicate with each other, while synaptic potentials are the incoming signals received by neurons at their synapses, which can either excite or inhibit the neuron's activity.

Comparative Table: Action Potential vs Synaptic Potential

Here is a table summarizing the differences between action potential and synaptic potential:

Feature Action Potential Synaptic Potential
Definition The sudden, fast, transitory, and propagating change of the resting membrane potential of neurons, which occurs when a neuron sends nerve impulses along the axon and depolarizes the cell body[^1^] The potential difference across the post-synaptic membrane, which depends on the release of neurotransmitters from the presynaptic terminal[^1^]
Direction Unidirectional, propagating along the axon Localized and often summed at the post-synaptic membrane
Ionic Basis Due to the flow of certain ions into and out of the neuron[^1^] Requires activation of ligand-gated ion channels located on the post-synaptic membrane[^3^]
Function Action potentials are the fundamental units of communication between neurons and are essential for information processing, propagation, and transmission[^1^] Synaptic potentials are the basis for synaptic transmission between neurons and can either excite or inhibit the postsynaptic neuron[^4^]
Examples Excitatory Post-Synaptic Potentials (EPSPs) and Inhibitory Post-Synaptic Potentials (IPSPs) Sodium and potassium ion exchanges

In summary, action potentials are rapid and long-range electrical events that transmit information along the axon, while synaptic potentials are localized electrical changes at the post-synaptic membrane that depend on neurotransmitter release and can either excite or inhibit the postsynaptic neuron[^2^].