postszinaptikus

Postszinaptikus (postsynaptic) refers to the neuron or cell that receives signals at a chemical synapse. The postsynaptic element is typically a dendrite or soma of a neuron, though in some circuits it may be another cell type. Its function is to detect the neurotransmitter released by the presynaptic neuron and translate chemical signaling into electrical or biochemical responses.

When a neurotransmitter is released into the synaptic cleft, it binds to receptors on the postsynaptic membrane. This binding can open ligand-gated ion channels (ionotropic receptors), producing fast changes in membrane potential, or activate G-protein coupled pathways (metabotropic receptors), triggering slower, broader signaling cascades. The postsynaptic response depends on the receptor types present and their distribution on the membrane.

The immediate electrical outcome is a postsynaptic potential. An excitatory postsynaptic potential (EPSP) depolarizes the membrane toward the threshold for firing an action potential, while an inhibitory postsynaptic potential (IPSP) hyperpolarizes the membrane or stabilizes it against depolarization. PSPs integrate over time and across neighboring synapses, determining whether the postsynaptic neuron reaches firing threshold.

Plasticity at the postsynaptic side includes changes in receptor number, subunit composition, and receptor sensitivity, as well as trafficking of receptors to and from the membrane. Such postsynaptic plasticity contributes to learning and memory, with mechanisms including long-term potentiation and long-term depression.

Dysfunction of postsynaptic components or receptors can underlie neurological and psychiatric conditions, and many pharmacological treatments target postsynaptic receptors to modulate neural signaling.