Article Figures & Data
Figures
- Fig 1.
A, Average numbers of voxels for the 2 g and 15 g stimuli across 8 healthy volunteers. Regions of interest include areas in the brain stem and cervical spinal cord. The only significance was found in the thalamus where there were more active voxels with the 15 g than 2 g stimulus. B, A box and whiskers plot of mean pain intensity and unpleasantness scores with SD across 8 healthy volunteers. Also included in the plot are the range of values for intensity and unpleasantness. The diamond corresponds to the median for the range of data and is indicated as a numeric value to the right of bars. The pain intensity and unpleasantness ratings for the 15 g filament were significantly higher than for the 2 g filament. Significance (*) was determined by using a 2-tailed, paired, Student t test (P < .05).
- Fig 2.
Combined data showing location of neuronal activity in touch (2 g and 15 g filament) and brush stimuli from 8 healthy volunteers superimposed onto transverse anatomic drawings. The figure shows significant areas of activity (T > 2.5) across the group. The T-value correlation map on the right indicates the corresponding color for each T-value. The asterisks indicate specific areas referred to in the text.
- Fig 3.
Positive and negative signal intensity responses with 2 g or 15 g von Frey filaments. Each row shows 8 consecutive transverse sections spanning the C6 level of the cord. Respective T-values (−7.0 < T < 7.0) are represented with colors as indicated at the bottom of the figure.
- Fig 4.
Schematic diagram showing ascending and descending pathways. Ascending touch pathways include the dorsal column–medial lemniscus. Touch sensation transmits via heavily myelinated Aβ fibers that ascend in the ipsilateral dorsal columns to the gracile or cuneate nuclei in the brain stem. Ascending pain pathways include the anterolateral pathway, which is a combination of the spinothalamic, spinoreticular, and spinomesencephalic pathways. Pain sensation transmits via thinly myelinated Aδ fibers and unmyelinated C primary afferent fibers. Descending fibers modulate touch and pain sensation.54 Red highlights descending pathways from the cortex, blue shows descending modulation from the reticular formation, and green highlights descending modulation from the raphe nuclei. PRF = pontine reticular formation; NRM = nucleus raphe magnus, RVM = rostral ventromedial medulla, MRF = medullary reticular formation. Pathways are drawn according to selected publications.34,53–55
