| Expression of tetanus toxin is known to reduce the frequency of spontaneous quantal release. |
| In this case, the quantal amplitude of postsynaptic response strongly depends on the number of accessible postsynaptic receptors in the vicinity of the release sites. |
| If the random number was smaller, a release event took place, the site was set to the empty state, and the size of the quantal response was determined as described below. |
| The number of receptors opened following quantal release may vary directly with the total number of receptors at the synapse, but other, more complex, interactions may occur. |
| Although these results do not definitively pinpoint the source of the steps, they confirm the earlier hypothesis that shortening is quantal. |
| Furthermore, it allows one to calculate the apparent quantal size for each response in a sequence of stimuli. |
