Post-synaptic potentials

Definition

Graded, local changes in membrane potential of the postsynaptic cell following neurotransmitter binding at a chemical synapse. Unlike all-or-none action potentials, post-synaptic potentials vary in amplitude with stimulus strength and summate spatially and temporally. Excitatory post-synaptic potentials (EPSPs) depolarize the membrane toward threshold, while inhibitory post-synaptic potentials (IPSPs) hyperpolarize or stabilize it. In arthropods, these potentials govern synaptic integration in sensory processing, motor pattern generation, and learning circuits.

Etymology

Example

In the escape response circuit of the cockroach Periplaneta americana, a single giant interneuron EPSP can reach threshold and trigger an action potential, whereas in the honeybee mushroom body, summation of many small EPSPs from olfactory projection neurons enables odor discrimination and associative learning.

Synonyms

• postsynaptic potentials

Related Terms

• Action potential
• Synapse
• Neurotransmitter
• graded potential
• excitatory post-synaptic potential
• inhibitory post-synaptic potential
• neuromuscular junction
• synaptic integration

Usage Notes

Often abbreviated PSP in neurophysiology literature. The hyphenated spelling 'post-synaptic' predominates in British and some American biological texts, while 'postsynaptic' (closed) is common in American neuroscience. Specialists distinguish PSPs from receptor potentials (generator potentials in sensory receptors) and from end-plate potentials at neuromuscular junctions, though the latter are technically a subclass of PSP. In arthropod neurotoxicology, many insecticides (e.g., neonicotinoids) and spider venoms (e.g., α-latrotoxin from Latrodectus) act by disrupting post-synaptic receptor function or neurotransmitter clearance, altering PSP amplitude or duration.