Tooth pulp-evoked potentials in the monkey: Cortical surface and intracortical distribution

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Abstract
The distribution of tooth pulp-evoked potentials (TPEP) was characterized in the primary motor (MI), primary somatosensory (SI) and secondary somatosensory (SII) cortices of the monkey. Bipolar electrical tooth pulp stimulation elicited TPEP components P23 and N44 over SI, P26 and N72 over MI, and P27, N161, P280, N420, P561 and N662 over SII. Muscular artifacts and extradental input did not affect the TPEP as demonstrated by experiments using a neuromuscular blocking agent and removal of the pulp, respectively. The short latency TPEP recorded over SI and MI were evoked by low stimulus intensities and activation of A.beta. nerve fibers, whereas the long latency TPEP recorded over SII required higher stimulus intensities and the additional recruitment of A.delta. nerve fibers. Intracortical recordings revealed polarity reversals of components P23 and N44 in area, 3b, P26 and N72 in area 4, and P72, N161, P280, N420, P561 and N662 in the upper bank of the lateral sulcus (SII). Apparently, TPEP recorded from SI and MI relate to non-nociceptive mechanisms while TPEP recorded from SII relate to nociceptive mechanisms.