Article Figures & Data
Figures
- Figure 1.
Schematic of the psychophysical experiment. A, A von Frey filament is applied to the skin until it bends to deliver the target force. B, The shaded skin regions indicate the innervation area of the radial and superficial peroneal nerves. The circled regions within this represent the stimulation sites where the monofilaments were applied. Images created with BioRender.com. C, The two-alternative forced choice (2AFC) paradigm used for participants to judge which of the stimuli in the pair was perceived as “more intense” (with the innocuous forces) or “more painful” (with the noxious forces).
- Figure 2.
Psychometric function curves for mechanical force discrimination in the noxious force range (100–3,000 mN) obtained from the psychophysical 2AFC task in the hand and foot of each participant (n = 20). Each data point was computed from 10 trials. Note the logarithmic scale on the x-axis.
- Figure 3.
Psychometric function curves for mechanical force discrimination in the innocuous force range (6–80 mN) obtained from the psychophysical 2AFC task in the hand and foot of each participant (n = 20). Each data point was computed from 10 trials. Note the logarithmic scale on the x-axis.
- Figure 4.
Within-participant comparison of Weber fraction between the hand and foot dorsa in both ranges of stimulation forces. A, The foot is better at discriminating noxious mechanical forces than the hand. B, The hand is better at discriminating innocuous mechanical forces than the foot. Each pair of circles connected by a line represents an individual participant (n = 20 each for innocuous and noxious force range experiments).
- Figure 5.
Responses of nociceptors during the dynamic phase (500 ms onset) of von Frey stimulation with different forces. A, Recording traces of A and C nociceptors from the hand during the onset period at three different stimulation forces. B, Comparison of mean firing rates of hand and foot A nociceptors (n = 10 units each site). C, Comparison of mean firing rates of hand and foot C nociceptors (n = 10 units each site). Error bars represent SEM. Note the logarithmic scale on the x-axis.
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