Table 1.
Numbers of neurons recorded, adjustments to offset known recording bias and estimated percentages of neuron types after adjustment
| C-neurons |
Aδ-neurons |
Aαβ-neurons |
ALL CVs | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| n | n x 16.074 |
As % of all C |
As % of ALL |
n | As % of all Aδ |
As % of ALL |
n | Aαβ | As % of all Aαβ |
As % of All DRG |
As % of All DRG |
|
| Nociceptors | 113 | 1816.36 | 69.3 | 48.521C | 72 | 62.07 | 1.921Aδ | 211 | 211 | 20.95 | 5.661Aαβ | 56.1 |
| LTMRs | 7 | 112.52 | 4.29 | 3.01 | 20 | 17.24 | 0.53 | 568 | 775 | 76.96 | 20.7 | 24.2 |
| Unresponsive | 38 | 610.81 | 23.3 | 16.32 | 19 | 16.38 | 0.51 | 21 | 21 | 2.09 | 0.56 | 17.4 |
| Cooling | 5 | 80.37 | 3.07 | 2.15 | 5 | 4.31 | 0.13 | 0 | 0 | 0 | 0 | 2.3 |
| Totals | 163 | 2620.06 | 100 | 70 | 116 | 100 | 3.10 | 800 | 1007 | 100 | 26.9 | 100 |
| All CVs Total n recorded | 1079 | All Cs | 2620 | All As | 1123 | Total Cs+As | 3743.3 | |||||
Intracellular recordings made by X. Fang and L. Djouhri of neurons in normal (untreated) rat L4 and L5 DRGs n = 1079. Nociceptors are included in this table regardless of whether they were thermally tested. Numbers in bold are raw numbers of recorded neurons without adjustment.
There are two main sources of bias for which adjustments were made. Underlined numbers in the Table and below are those after adjustment.
Adjustment 1) for Rejection of Aαβ-LTMRs during recording to avoid their domination of the data set. To determine the extent of this bias, X. Fang carried out a series of experiments accepting all neurons encountered regardless of sensory properties. This determined the unbiased/expected percentage ratio of Aαβ-nociceptors to Aαβ-LTMRs to be 21.4%:78.6%. The number of Aαβ-LTMRs recorded (568, Table 1) was therefore multiplied by 1.364, increasing it to 775, to achieve a ratio of 211:775, equivalent to the unbiased 21.4%:78.6% ratio. This compensated for Aαβ-LTMRs rejected during experiments.
Adjustment 2) for Underestimation of C-neurons due to greater difficulties in recording from them. After making Adjustment 1, the number of recorded C-neurons was adjusted upwards (X16.07) to 2620 to reach 70% of the total neurons, which was the percentage that the small neuron population in rat L5 DRGs contributed to the whole DRG, determined with unbiased counting methods [1••]. We assumed that rat L4 and L5 DRGs are similar, as they innervate similar tissues and both run predominantly in the sciatic nerve.
These corrections were applied to Figure 1a data to generate Figure 1b. The total adjusted neuron number including both adjusted A-neurons and C-neurons is 3743 (Table 1).
Superscripts C, Aδ and Aαβ refer to neurons with CVs in these ranges. Numerals 1-3 refer to the order in which values are used in examples of calculations to determine totals of a nociceptor subtype, in this case polymodal nociceptors (PMNs), (see Table 3, and Legend) and for generating other percentages used in Figure 3. 1 or 2 decimal places are used to enable easier tracking of calculations.