Postsynaptic potentials add together over space or time to reach the threshold for firing.
Temporal summation: rapid repeated inputs add; spatial summation: inputs from different synapses add. The axon hillock integrates the total.
Summation lets neurons act as integrators. The time constant and length constant of the membrane affect summation.
Key idea: neurons fire only when total input reaches threshold.
Postsynaptic potentials add together over space or time to reach the threshold for firing.
Summation is one of the 54 topics in Neuroscience. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Nervous System, Action Potential, Long-Term Potentiation.
A single EPSP is about 0.5 mV, so many are needed to reach threshold.
Work through the Beginner topics in Neuroscience first, such as Nervous System, Neuron, Central and Peripheral Nervous Systems, then return to Summation. Intermediate topics assume the Beginner vocabulary.
The closest topics to Summation are Nervous System, Action Potential, Long-Term Potentiation, Neuron. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Summation. To practise the whole of Neuroscience, use the Neuroscience quiz.
Summation: Postsynaptic potentials add together over space or time to reach the threshold for firing. Nervous System: The brain, spinal cord and nerves that sense, process and respond to information. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Nervous System and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.
The brain, spinal cord and nerves that sense, process and respond to information.
🧠 NeuroscienceA rapid, all-or-none reversal of membrane potential that travels along an axon.
🧠 NeuroscienceA lasting strengthening of synapses after repeated stimulation, a cellular basis for learning.
🧠 NeuroscienceA nerve cell with dendrites, a cell body and an axon that transmits electrical signals.
🧠 Neuroscience