Summation

Definition

Summation is the process by which multiple synaptic potentials combine to produce a larger effect on a neuron. It can be either temporal, where signals are received in quick succession, or spatial, where signals are received simultaneously from different locations.

5 Must Know Facts For Your Next Test

1. Summation occurs at the axon hillock of a neuron.
2. Temporal summation involves multiple signals arriving at different times but close enough to each other to add up.
3. Spatial summation involves multiple signals coming from different synapses on the same neuron at the same time.
4. Both excitatory and inhibitory postsynaptic potentials can contribute to summation.
5. The combined effect of summation determines whether the neuron will reach the threshold potential to fire an action potential.

Review Questions

• What is the difference between temporal and spatial summation?
• Where does summation occur in a neuron?
• How do excitatory and inhibitory postsynaptic potentials influence summation?

Related terms

Synapse:

A junction between two neurons where neurotransmitters are released.

Action Potential: A rapid rise and fall in voltage across a cellular membrane that constitutes a nerve impulse.

Excitatory Postsynaptic Potential (EPSP): A postsynaptic potential that makes the neuron more likely to fire an action potential.