Editing Chemical synapse (section)

== Integration of synaptic inputs ==<!-- This section is linked from [[Summation]] -->
{{Main|Summation (neurophysiology)}}
In general, if an [[excitatory synapse]] is strong enough, an [[action potential]] in the presynaptic neuron will trigger an action potential in the postsynaptic cell. In many cases the [[excitatory postsynaptic potential]] (EPSP) will not reach the [[action potential|threshold]] for eliciting an action potential. When action potentials from multiple presynaptic neurons fire simultaneously, or if a single presynaptic neuron fires at a high enough frequency, the EPSPs can overlap and summate. If enough EPSPs overlap, the summated EPSP can reach the threshold for initiating an action potential. This process is known as summation, and can serve as a high pass filter for neurons.<ref>{{cite book |editor1=Bruce Alberts |editor2=Alexander Johnson |editor3=Julian Lewis |editor4=Martin Raff |editor5=Keith Roberts |editor6=Peter Walter |chapter=Ch. 11. Section: Single Neurons Are Complex Computation Devices
 |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK26910/#A2067
 |title=Molecular Biology of the Cell
 |publisher=Garland Science |isbn=978-0-8153-3218-3 |year=2002 |edition=4th
 |url=https://www.ncbi.nlm.nih.gov/books/NBK21054/
}} 
</ref>

On the other hand, a presynaptic neuron releasing an inhibitory neurotransmitter, such as [[GABA]], can cause an [[inhibitory postsynaptic potential]] (IPSP) in the postsynaptic neuron, bringing the [[membrane potential]] farther away from the threshold, decreasing its excitability and making it more difficult for the neuron to initiate an action potential. If an IPSP overlaps with an EPSP, the IPSP can in many cases prevent the neuron from firing an action potential. In this way, the output of a neuron may depend on the input of many different neurons, each of which may have a different degree of influence, depending on the strength and type of synapse with that neuron. [[John Carew Eccles]] performed some of the important early experiments on synaptic integration, for which he received the [[Nobel Prize for Physiology or Medicine]] in 1963.