Papers of the Week

C-nociceptors are generally assumed to have a low maximum discharge frequency of 10 – 30 Hz. However, only mechano-insensitive "silent" C-nociceptors cannot follow electrical stimulation at 5 Hz (75 pulses) whereas polymodal C-nociceptors in the pig follow even 100 Hz without conduction failure. Sensitization by nerve growth factor increases the maximum following frequency of "silent" nociceptors in pig skin and might thereby contribute in particular to intense pain sensations in chronic inflammation. A distinct class of C-nociceptors with mechanical thresholds >150 mN resembles "silent" nociceptors at low stimulation frequencies in pig and human, but is capable of 100 Hz discharge and thus, is suited to encode painfulness of noxious mechanical stimuli.