What is the Difference Between Spatial and Temporal Summation?

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The difference between spatial and temporal summation lies in the number of presynaptic neurons involved in dispatching signals to the synapses of a postsynaptic neuron.

  • Spatial summation occurs when multiple presynaptic neurons release neurotransmitters simultaneously to generate a sufficient postsynaptic potential. This process involves signals coming from multiple simultaneous inputs. In spatial summation, multiple presynaptic terminals release neurotransmitters to generate a postsynaptic action potential.
  • Temporal summation, on the other hand, involves a single presynaptic neuron releasing multiple action potentials over a period of time. This process comes from repeated inputs and involves one presynaptic neuron releasing neurotransmitters many times. In temporal summation, multiple neurotransmitters are released from one presynaptic terminal.

In summary, spatial summation involves multiple presynaptic neurons, while temporal summation involves a single presynaptic neuron firing multiple times. Both processes contribute to the generation of action potentials in the nervous system, but they differ in the way they accumulate excitatory or inhibitory signals.

Comparative Table: Spatial vs Temporal Summation

The main difference between spatial and temporal summation lies in the type of multiple stimuli involved and their timing. Here is a table comparing the two types of summation:

Feature Spatial Summation Temporal Summation
Definition Spatial summation involves simultaneous signals coming from multiple presynaptic neurons. Temporal summation occurs when one presynaptic neuron releases neurotransmitters several times over a specific period.
Location Multiple synaptic inputs from different locations on a neuron's dendrites combine to generate an action potential. A single presynaptic neuron is responsible for generating the action potential.
Subthreshold Spatial summation involves the addition of single stimuli over separate locations on the neuron, each of which is subthreshold, to form a suprathreshold. One presynaptic neuron generates subthresholds over a certain period of time.
Efficiency Spatial summation is a type of simultaneous stimulation. Temporal summation is a type of high-frequency stimulation.

In summary, spatial summation is the process where multiple simultaneous signals from different presynaptic neurons combine to generate an action potential, while temporal summation involves the release of neurotransmitters from a single presynaptic neuron over time to create an action potential.