Prefrontal hemodynamic mapping by functional near-infrared spectroscopy in response to thermal stimulations over three body sites

Abstract

, "Prefrontal hemodynamic mapping by functional near-infrared spectroscopy in response to thermal stimulations over three body sites," Neurophoton. 3(4), 045008 (2016), doi: 10.1117/1.NPh.3.4.045008. Abstract. Functional near-infrared spectroscopy (fNIRS) was used to examine hemodynamic responses in the prefrontal cortex (PFC) during noxious thermal pain, induced by thermal stimulations over three different body sites over the right forearm, right temporomandibular joint, and left forearm. Functional NIRS measurements were obtained from three groups of healthy volunteers, one group for each body region. Each group was subjected to both low-pain stimulation (LPS) and high-pain stimulation (HPS) by a 16 × 16 mm 2 thermode of a temperature-controlled thermal stimulator over the respective three body sites. Our results showed that HPS given at three sites induced significant increases (p < 0.05) in oxy-hemoglobin concentration (ΔHbO) in the PFC with similar temporal patterns in relatively spread PFC areas. In contrast, LPS did not cause any significant ΔHbO in the PFC of any subject group. Our observed PFC activations induced by acute HPS were generally consistent with previous reports by fMRI studies. The study also found a peculiar global trend of postpain deactivation in the PFC, which is attributed to global vasoconstriction due to acute nocuous pain. Overall, these results indicate that hemodynamic activities in PFC exhibit consistent temporal and spatial patterns in response to acute thermal stimulation given across all three body sites.

Mapping cortical network effects of fatigue during a handgrip task by functional near-infrared spectroscopy in physically active and inactive subjects

“…General linear model (GLM) analysis was used to quantify time-dependent ΔHbO patterns elicited during the handgrip task, by using a series of consecutive stimulation-specific boxcar functions convolved with a hemodynamic response function as a regressor, as in prior studies. [26][27][28] Only ΔHbO values were analyzed and reported in this study, because ΔHbR values were found to have similar and opposite qualitative trends but with smaller amplitudes and lower signal-to-noise ratio, as previously reported in other studies for other motor activation tasks and as seen in Fig. 1(c).…”

Morphine Attenuates fNIRS Signal Associated With Painful Stimuli in the Medial Frontopolar Cortex (medial BA 10)

“…In this section, we focus on the HbO concentration changes to electrical stimuli. HbO response has often been observed to have a much higher SNR relative to HbR (Obrig et al, 2000 ; Yennu et al, 2016 ). In this study, an initial quality assurance analysis showed that the recorded HbO signals were more reliable in revealing the true shape of the hemodynamic response to external stimuli (results not shown).…”

Using prerecorded hemodynamic response functions in detecting prefrontal pain response: a functional near-infrared spectroscopy study

“…7 Several difficulties remain regarding using the defined feature of the aPFC response (viz., the amplitude of HbO decrease) to detect pain in individual cases including: (1) the hemodynamic response to pain seems to show habituation with repetitive painful stimuli, leading to an insignificant difference in the response amplitude between innocuous stimuli and repeated noxious stimuli; 6,7 (2) distinct patterns in the shape of the hemodynamic response function (HRF) to pain (in terms of e.g., activations or deactivations, the peak/nadir time, dispersion, and undershoot time) have also been observed across different subjects, brain regions, and types of pain. In addition to the deactivations, multiple studies using fNIRS also reported pain-induced activations in the aPFC, largely in the lateral portion; [16][17][18][19] and (3) while the aPFC hemodynamic changes associated with pain were shown to be bilateral in some studies, others observed predominantly left-lateralized responses. 9,10 These results suggest using personalized analysis in the detection of the brain response to pain to properly characterize the signal.…”