Journal of Neurology Research, ISSN 1923-2845 print, 1923-2853 online, Open Access
Article copyright, the authors; Journal compilation copyright, J Neurol Res and Elmer Press Inc
Journal website http://www.neurores.org

Original Article

Volume 6, Number 1, February 2016, pages 1-7

Selective Laser Stimulation of Aδ- or C-Fibers Through Application of a Spatial Filter: A Study in Healthy Volunteers

Figures

Figure 1.
Figure 1. Probability of Aδ- or C-fiber activation at varying laser beam diameters (D), (Equation (1)), derived for the average spatial distribution of Aδ- and C-fibers (ρAδ = 0.5/mm2 and ρC = 5/mm2 [2]. The error bars represent the probability for the upper and lower limit of the fiber density Aδ-fibers 0.1 - 1/mm2 and of C-fibers 2 - 8/mm2 [5]. When the density of the nerve fibers changes due to disease, the curve is expected to shift (e.g., response rates drop).
Figure 2.
Figure 2. Schematic display of the grid design and measurement set-up.
Figure 3.
Figure 3. Histogram of all response times (Aδ-protocol and C-protocol).
Figure 4.
Figure 4. The theoretically (Equation (1)) and experimentally determined response rate at varying grid diameters. (Top) Aδ and (bottom) C-fibers. Aδ response rates are determined for the Aδ-protocol, and C response rates are for the C-protocol. Ccor stands for Ccorrected (Aδ responses are excluded). The median response rates are shown, and the error bars represent the quartiles.

Tables

Table 1. Ratio Between Aδ- and C-Fiber Stimulation at Different Grid Diameters per Stimulation Protocol
 
Grid diameterProtocol
AδC
Ratio Aδ:CStimulations perceivedRatio Aδ:CStimulations perceived
In total 440 stimulations were given per protocol per diameter.
0.40.08:1.048%0.05:1.062%
0.60.16:1.062%0.12:1.070%
1.00.47:1.074%0.30:1.081%
2.01.17:1.083%0.49:1.089%

 

Table 2. Derived Density of Aδ- and C-Fibers From the Median Response Rate to Stimulation at Different Grid Diameters
 
Grid diameterDensity of Aδ-fibers, /mm2Density of C-fibers, /mm2
CCcorrected
0.4-7.297.29
0.60.374.264.75
1.00.281.342.80
2.00.160.320.73