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Summation, which includes both spatial summation and temporal summation, is the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs (temporal summation).
The definition above is spatial summation (which they pictured as having multiple synapses placed close together, so that the effect of their firing sums up). By "temporal summation" they meant that the total incoming signal is = = () for some .
Temporal summation refers to successive excitatory stimuli on the same location of the postsynaptic neuron. Both types of summation are the result of adding together many excitatory potentials; the difference being whether the multiple stimuli are coming from different locations at the same time (spatial) or at different times from the same ...
Spatial summation occurs when postsynaptic potentials from adjacent synapses on the cell occur simultaneously and add together. An action potential occurs when the summated EPSPs, minus the summated IPSPs, in an area of membrane reach the cell's threshold potential.
Fig. 1: Spatial and temporal summation.Two EPSPs innervated in rapid succession sum to produce a larger EPSP, or an action potential in the postsynaptic cell. Coincidence detection relies on separate inputs converging on a common target.
For example, the left half of a receptive field can be the activating region, while the antagonistic region lies on the right. Accordingly, the hypercomplex cell will respond, with spatial summation, to stimuli on the left side (within the activating region) insofar as it does not extend further into the right side (antagonistic region).
Spatial summation means that the effects of impulses received at different places on the neuron add up, so that the neuron may fire when such impulses are received ...
Electrotonic potentials can sum spatially or temporally. Spatial summation is the combination of multiple sources of ion influx (multiple channels within a dendrite, or channels within multiple dendrites), whereas temporal summation is a gradual increase in overall charge due to repeated influxes in the same location. Because the ionic charge ...