Table 2.
Percentages of all nociceptors with RFs at different tissue depths and of PMNs at different depths
|
2a | |||
|---|---|---|---|
| % of mechanical nociceptors with RFs at different depths |
|||
| C | Aδ | Aβ | |
| Superficial | 17.72C | 36.12Aδ | 56.92Aβ |
| Dermal | 24.8 | 15.3 | 17.53 |
| Deep | 57.5 | 48.63 | 25.6 |
|
2b | |||
|---|---|---|---|
| % mechanical nociceptive RFs at different depths that are PMN/MH + MHC/MC |
|||
| C | Aδ | Aβ | |
| Superficial | 79/57.9/23.53C | 13.6/13.6/03Aδ | 3.1/2.1/1.03Aβ |
| Dermal | 25/8.3/13 | 0*/0*/0* | 0/0/0 |
| Deep | 0/0/0 | 0*/0*/0* | 0/0/0 |
The depths of nociceptive RFs were defined on the basis of noxious mechanical stimuli as follows: those with superficial RFs responded to needle pressure (not puncture) and fine pinch of superficial tissues with fine forceps, those with dermal RFs responded only to squeeze of a fold of skin tissue including dermis, and those with deep RFs responded only to pressure to tissues including deep fascia, muscle, and periosteum by squeezing across muscles, the foot or whole leg.
*indicates only 1-3 neurons tested with noxious thermal stimuli, so less weight should be placed on these calculations.
Table 2a Percentages of all nociceptors with RFs at different tissue depths regardless of whether they were tested with noxious thermal stimuli as for Table 1.
Table 2b Percentages of nociceptors with RFs that were PMN/MH + MHC/MC at the different tissue depths. MH + MC includes all such units of the PMN group. All nociceptors included had been tested for noxious mechanical and noxious heat, but not all were tested with noxious cold, thus percentages from which MC and MHC were calculated were smaller than numbers than for MH. Nociceptors included high-threshold mechanoreceptors (HTMs), and polymodal nociceptors (PMNs), either mechano-heat units (MH), mechano-cold (MC) or both (MHC). This data set had no neurons that responded only to noxious heat. PMNs include MH, MC and MHC. Non-noxious cooling-sensitive C-neurons (often showing ongoing firing) are not considered nociceptive, and are thus excluded from this Table, but included in Table 1, Figure 1f and Figure 3.
Superscripts as in Table 1; for example, 2C and 3C are the second and third numbers used to calculate C-fiber PMN contribution to the total number of DRG neurons. Note that 3C refers to 3 numbers 80/55/25. These are the percentages of C-nociceptors with superficial RFs that were PMNs/MH + MHC/MC respectively. These calculations were repeated for these three types of unit, and then for the different tissue depths (superficial, dermal or deep) of receptive fields.