Stimulus-response relation of tooth pulp units in rat trigeminal nucleus

Electrical stimulation of the rat tooth pulp evokes a slow mass potential (SMP) in the trigeminal spinal nucleus. Single units in the SMP field were examined for their stimulus-response relation. The response profile of most single units differed from that of background SMPs in that the former tended to give a greater gradient or exponent when they were approximated by linear or power function, respectively. Most of single units with a short and stable latency could be described rather well by power function, while a majority of units with a longer and unstable latency had a relatively wide dynamic range to varied stimulus intensities and could be approximated more closely by linear function.