Differences Between Temporal and Spatial Summation

Temporal vs Spatial Summation

As much as possible, we don’t want to get involved in complicated matters. During our school days we have probably hated math and even the sciences. In math, you need to compute. We usually hate to deal with numbers. In science, there are too many technical terms, and we start to curse all the inventors and scientists who made us suffer in our studies. Even science has math! Have you heard of temporal and spatial summation? It isn’t the typical summation of “x” and “y.” It has something to do with science, especially neurons. Neurons are part of the nervous system. Without them, there will be no stimulus and reaction. To know more about the difference between temporal and spatial summation, we need to study these complicated terms. But no worries! This article will explain temporal and spatial summation in its simplest terms. I believe you will learn something from these explanations.

Before we dig deeper into the difference between temporal and spatial summation, let us define “summation” first. The other term for “summation” is “frequency summation.” It is a process wherein neurons communicate with each other in order to determine an action potential which is triggered by postsynaptic potentials. A presynaptic neuron emits neurotransmitters which fall into one of two categories: excitatory and inhibitory neurotransmitters. The postsynaptic cell becomes further depolarized due to the excitatory neurotransmitters. When the work of excitatory neurotransmitters increases, the inhibitory transmitters lessen their effects. The work of neurons can only revolve into two actions: exciting or inhibiting; thus only producing a limited response. There is temporal summation if the target neuron only receives a repeatedly short interval input from a lone axon terminal. There is spatial summation when the target neuron receives several inputs from several sources.

“Temporal summation” is the effect produced by a particular neuron to be able to achieve an action potential. “Summation” generally occurs depending on how long the time constant is and the frequent occurrence of action potentials. There is always another rise in the action potential just before the previous potential ends. The previous and second potential points will summate thus generating a larger potential. When this occurs, the potential can reach its threshold to begin another action potential. With regards to vision, temporal summation is involved. The Bunsen-Roscoe law is the inverse proportion of intensity and time. The vision’s frequency is related to the frequency of flashes. According to the law, the longer the stimulus, the better chance it can attain the number of quanta needed for vision.

Meanwhile, “spatial summation” is the method of achieving an action potential in a neuron which receives input from several cells. When you add or summate the potentials from the dendrites, you will have spatial summation. As mentioned earlier, when a potential reaches the threshold, it will generate another action potential. This is called the excitatory phase while the inhibitory phase prevents or neutralizes the cell from achieving such action potential. According to Ricco’s law, within the eye, the intensity and area are inversely variable due to the combination of signals from rods to bipolars which turn into ganglion cells.

Summary:

1. “Summation” is also known as “frequency summation.” It is a process wherein neurons communicate with each other in order to determine an action potential which is triggered by postsynaptic potentials.

2. Summation generally occurs depending on how long the time constant is and on the frequent occurrence of action potentials.

3. “Temporal summation” is the effect produced by a particular neuron to be able to achieve an action potential.

4. Meanwhile, “spatial summation” is the method of achieving an action potential in a neuron which receives input from several cells.

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