another general aspect of the scratch response is that the response continues even after afferent input from the stimulated zone ceases. for a few seconds after the cessation of the scratch, the neural networks involved in the generation of the scratch reflex remain in a state of heightened sensitivity. during this period of increased excitability, stimuli normally too weak to trigger a scratch response are capable of eliciting a scratch response in a site specific manner. that is, stimuli, too weak to elicit the scratch response when applied in a rested preparation, are capable of eliciting the scratch response during the period of increased excitability just following a scratch response. this excitability is due, in part, to the long time constant of nmda receptors. research has also shown that voltage-gated calcium channels have a role in the increased excitability of spinal neurons.