Fig 1.
fNIRS montage and representation of one channel.
(A) Sources and detectors were arrayed in a 10–10 system. (B) Illustrative demonstration of near-infrared diffuse reflection path between source and detector.
Fig 2.
Timeline assessments. CPM-test: condition pain modulation test; fNIRS: functional near-infrared spectroscopy. Pain VAS: Pain visual-analog scale. NPS: numeric pain scale. QST: Quantitative Sensory Testing. T0: mean temperature (three measurements per individual) at which the subjects reported a pain score of 6/10 on the NPS (0–10) during the QST before the heterotopic stimulus. T1: temperature equivalent to T0 but applied during hand water cold immersion. NPS(T0): NPS pain score during application of T0. NPS(T1): NPS pain score during application of T1.
Table 1.
Demographic and clinical characteristics of the study sample (n = 37).
Table 2.
Relationship of the outcomes and the main interest factor according to the spectrum of responders and nonresponders to CPM-test (n = 37).
Table 3.
MANCOVA analysis of the relationship between the FC according to the spectrum of responders or nonresponders according to change in NPS (0–10) during the CPM-test (n = 37).
Fig 3.
Heatmap visualization of FC across regions of interest in Z-values.
Nonresponders presented higher connectivity than responders between LMC and bilateral PFC. Blue color edges represent significantly lower values and red color edges represent significantly higher values, relative to the comparison between groups. A. Mean FC by region of interest in CPM-test responders. B. Mean FC by region of interest in CPM-test nonresponders. FC: functional connectivity; CPM-test: conditioned pain modulation test. LPFC: Left prefrontal cortex; LMC: Left motor cortex; RPFC: Right prefrontal cortex; RMC: Right motor cortex. *p<0.05. † FC between regions of interest that were associated with CPM-test groups despite the interaction effect of multiple psychiatric diagnoses.
Table 4.
MANCOVA analysis of the relationship between the FC according to the interaction analysis between the spectrum of responders or nonresponders on the CPM-test by psychiatric disorders according to the MINI (n = 37).