Which set of properties correctly describes an excitatory postsynaptic potential (EPSP) recorded at the soma of a neuron?

• A All-or-none, non-decremental, refractory period present
• B Graded, decremental with distance, capable of temporal and spatial summation ✓
• C Graded, self-propagating, obeys the all-or-none law
• D Fixed amplitude, long duration, transmitted without decay along the dendrite

Explanation

An EPSP is a graded local depolarization produced by opening ligand-gated cation channels, chiefly sodium and potassium. It decays passively with distance along the membrane (electrotonic conduction) and its amplitude sums when inputs arrive together in time or across synapses in space. Action potentials, not EPSPs, are all-or-none, non-decremental, and self-propagating, which eliminates options A, C and D.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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