Their work showed that spatial summation of excitatory and inhibitory postsynaptic potentials caused attenuation of the excitatory response during the inhibitory response most of the time.
12.
In his article, Denny-Brown alternately proposes that lesions of the parieto-occipital lobe cause errors in spatial summation, not spatial perception.
13.
"' Spatial summation "': If a cell is receiving input at two synapses that are near each other, their postsynaptic potentials add together.
14.
Spatial summation refers to several excitatory stimuli from different synapses converging on the same postsynaptic neuron at the same time to reach the threshold needed to reach an action potential.
15.
Regarding "'nociceptive stimulation "', spatial summation is the ability to integrate painful input from large areas while temporal summation refers to the ability of integrating repetitive nociceptive stimuli.
16.
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 ).
17.
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.
18.
This is called spatial summation and is complemented by temporal summation, wherein successive releases of transmitter from one synapse will cause progressive polarization change as long as the presynaptic changes occur faster than the decay rate of the membrane potential changes in the postsynaptic neuron.
19.
"' 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 simultaneously, even if each impulse on its own would not be sufficient to cause firing.
20.
Cells showing linear spatial summation are termed X cells ( also called parvocellular, P, or midget ganglion cells ), and those showing non-linear summation are Y cells ( also called magnocellular, M, or parasol retinal ganglion cells ), although the correspondence between X and Y cells ( in the cat retina ) and P and M cells ( in the primate retina ) is not as simple as it once seemed.
