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Both the presynaptic and postsynaptic sites contain extensive arrays of molecular machinery that link the two membranes together and carry out the signaling process. In many synapses, the presynaptic part is located on the terminals of axons and the postsynaptic part is located on a dendrite or soma .
Axon terminals (also called terminal boutons, synaptic boutons, end-feet, or presynaptic terminals) are distal terminations of the branches of an axon. An axon, also called a nerve fiber, is a long, slender projection of a nerve cell that conducts electrical impulses called action potentials away from the neuron's cell body to transmit those ...
Here is a summary of the sequence of events that take place in synaptic transmission from a presynaptic neuron to a postsynaptic cell. Each step is explained in more detail below. Note that with the exception of the final step, the entire process may run only a few hundred microseconds, in the fastest synapses. [14]
This difference across the membrane is what the neuron uses to actually do the work of sending messages from the axon hillock of the neuron all the way down to the presynaptic terminal and then on to the postsynaptic terminal because of the release of neurotransmitter into the synaptic cleft. [3]
As it pertains to LTP, retrograde signaling is a hypothesis describing how events underlying LTP may begin in the postsynaptic neuron but be propagated to the presynaptic neuron, even though normal communication across a chemical synapse occurs in a presynaptic to postsynaptic direction. It is used most commonly by those who argue that ...
Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Postsynaptic potentials are graded potentials , and should not be confused with action potentials although their function is to initiate or inhibit action potentials.
The amount of attenuation of the signal is due to the membrane resistance of the presynaptic and postsynaptic neurons. Long-term changes can be seen in electrical synapses. For example, changes in electrical synapses in the retina are seen during light and dark adaptations of the retina. [16]
Basic ways that neurons can interact with each other when converting input to output. Summation, which includes both spatial summation and temporal summation, is the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs ...