Activity in cortical cells after stimulation of tooth pulp afferents in the cat. Extracellular analysis

The cortical projection of tooth pulp afferents has been investigated by extracellular recordings in lightly chloralose anaesthetized cats. The results indicate two different projection systems from the tooth pulp afferents terminating on the cortical cells. One system appears to be specific with topographical distribution and activates cells mainly in lamina IV in a restricted region of the coronal gyrus. The cells in this area receive excitation also from restricted cutaneous fields. At stimulation of the tooth pulps with single electrical pulses cells are activated with high discharge probability and with a stable latency. The other system projects mainly to cells in the superficial cortical laminae in a much larger area. These cells receive input from large bilateral cutaneous fields but show less discharge probability and require often temporal summation to discharge at tooth pulp stimulation.