Background: Neuropathic pain remains difficult to treat because current analgesics often provide insufficient efficacy or dose-limiting adverse effects. Nav1.7 is genetically validated as a key regulator of human pain sensation, but the development of selective small-molecule Nav1.7 inhibitors has been limited by the high similarity among voltage-gated sodium channel subtypes. Methods: We generated monoclonal antibodies selectively targeting Nav1.7, humanized them for therapeutic development, and evaluated their binding, selectivity, functional channel inhibition, systemic analgesic efficacy, and effects on neuronal activity in a rat model of partial sciatic nerve ligation-induced neuropathic pain. Results: The humanized antibodies showed high-affinity and selective binding to Nav1.7 and functionally inhibited the channel in cellular assays. After systemic administration to neuropathic pain model rats, the lead antibody produced robust analgesia lasting at least 96 h. Electrophysiological analyses demonstrated reduced mechanically evoked and spontaneous neuronal activity, and immunohistochemistry showed decreased mechanical stimulus-induced phosphorylation of extracellular signal-regulated kinase in dorsal root ganglion neurons. The antibodies did not impair physiological nociception or motor function under the tested conditions. Conclusions: These findings provide preclinical proof of concept that humanized anti-Nav1.7 antibodies can act as systemically administered, long-acting biologic analgesics for neuropathic pain while preserving normal nociceptive and motor functions. The clinical advancement of S-151128 further supports the translational potential of this modality.

Paclitaxel is widely used in chemotherapy for common cancers. However, its administration is frequently associated with chronic pain and subsequent depression, anxiety, and lack of motivation, all of which lead to difficulties in the social lives of patients. In mouse models of paclitaxel-induced neuropathy, mechanical allodynia emerges within several days after intraperitoneal injections of paclitaxel, followed by depression- and anxiety-like behaviors. However, whether they show deficits in motivated behavior during this period and whether the time course of their symptoms is related to pain behavior remain unclear. Here, we investigated changes in locomotor-based behavioral performance. Before paclitaxel injection, the mice were trained to perform an operant conditioning task. In this task, they were water-restricted and head-fixed on a polystyrene disc, and spontaneous running was initiated to trigger a trial. After paclitaxel injection, changes in task performance were examined for 4 weeks. These mice exhibited mechanical hypersensitivity within the first week; however, a decline in the task success rate became evident after the second week. Subsequently, from the third week, the number of trials, the lick rate of anticipatory licking and the locomotor speed toward the reward decreased in the paclitaxel-treated mice compared with those in the vehicle-treated mice. Moreover, in paclitaxel-treated mice, resting-state c-Fos level during the behavioral impairment period was increased in the amygdala, which is implicated in emotion and motivated behaviors. These results demonstrate that in paclitaxel-treated mice, reduced reward expectation and impaired goal-directed behavior can be observed one week after the onset of pain-related behavior.

Cysteinyl leukotrienes (cysLTs) are secreted by mast cells and represent key lipid mediators in allergic airway inflammation. We recently reported that biotinylated heptapeptides containing D-amino acids suppress mast cell degranulation and exhibit pronounced anti-allergic effects. In this study, we aimed to investigate the effects of these peptides on the production of cysLTs by immunoglobulin E (IgE)/antigen-activated mast cells, as well as on in vivo allergic airway inflammation. CysLT release from IgE/antigen-activated RBL-2H3 cells was quantified using an enzyme-linked immunosorbent assay. The effects of biotinylated peptides on ovalbumin-induced allergic airway inflammation were assessed using bronchoalveolar lavage fluid (BALF) analysis. The effects of biotinylated peptides on the bioactivity of leukotriene C₄ (LTC4) were evaluated using a mouse hind paw edema model. Among the biotinylated peptides, Peptide 2 (D-Lys(Biotinyl)-Trp-Tyr-Lys-Asp-Gly-Asp) markedly inhibited cysLT release from RBL-2H3 cells and LTC4-induced paw edema in mice. The intranasal administration of high-dose (30–100 nmol/mouse) Peptide 2 caused significantly larger reduction in the counts of total inflammatory cells, lymphocytes, and eosinophils in BALF than did low-dose (0–10 nmol/mouse) Peptide 2. The systemic administration of Peptide 2 had slight effects at all doses. Peptide 2 is a promising candidate as a novel anti-allergic agent targeting IgE/antigen-activated mast cell-derived cysLTs for the treatment of allergic diseases.

Peripheral nerve ischemia-reperfusion injury is considered to contribute to sensory disturbances that impair quality of life in patients with diabetic neuropathy and chemotherapy-induced neuropathy. However, the spinal mechanisms underlying these disturbances remain unclear, partly due to the lack of established animal models and evaluation systems. In the present study, we used a rat hindlimb ischemia-reperfusion model and in vivo extracellular recording to examine bidirectional changes in neuronal activity in the spinal dorsal horn. Ischemia was induced by tightly binding the rat ankle with a rubber band, followed by reperfusion. Behavioral analysis showed a significant increase in hindlimb licking behavior after reperfusion, indicating the development of sensory disturbance-like responses. Extracellular recordings from superficial dorsal horn neurons showed diverse patterns of spontaneous firing and responses to mechanical stimulation, with both hypersensitive and desensitized responses. Furthermore, mRNA expression levels of immediate early genes (Egr1, Egr3, and Fos) were upregulated in the spinal cord after reperfusion. These results suggest that this ischemia-reperfusion model reproduces complex neuronal responses relevant to peripheral neuropathy and provides a useful evaluation system for evaluating both increased and decreased neural activity. This approach may contribute to elucidating the mechanisms of sensory disturbances and to the development of new treatments for neuropathic conditions.

Itch is described as an unpleasant sensation, and chronic itch, such as that in atopic dermatitis (AD), often decreases a patient's QOL. There are few effective treatments for various chronic pruritic disorders that are not limited to inflammation. Selective serotonin reuptake inhibitors (SSRIs) are antidepressants used to treat some chronic pruritus disorders. However, there is little evidence from clinical and basic studies using animal models. In this study, we found that paroxetine suppressed acute and chronic itch in mouse models. Single administration of paroxetine (10 mg/kg) inhibited scratching behavior caused by histamine-dependent or histamine-independent itch. Moreover, paroxetine (10 mg/kg) inhibited spontaneous scratching behavior in AD model using NC/Nga mice without affecting locomotor function. These results suggest that paroxetine suppresses chronic itch caused by AD via histamine-dependent and -independent pathways. This study provides one of the few pieces of evidence that SSRIs suppress itch.

The expression of hormonal receptors in pain-processing regions complicates understanding the hormonal effects on pain mechanisms. This study investigates androgen receptor (AR) involvement in pain sensitivity and sex differences in pain perception. Mechanical pain thresholds were higher in normal male mice compared to gonadectomized (GDX) male and normal female mice, correlating with serum testosterone levels. In the dorsal root ganglia (DRG), AR was expressed in normal males but undetectable in GDX males and normal females. Androgen receptor overlapped with NeuN, a neuronal nuclei marker, indicating androgen signaling activation in sensory neurons. In male sensory neuron–selective AR conditional knockout (AR-cKO) mice, mechanical pain thresholds were significantly lower than in wild-type males, with the greatest AR depletion in calcitonin gene–related peptide (CGRP) + neurons. Electrophysiological analyses revealed increased excitability of spinal dorsal horn neurons in both GDX males and AR-cKO males. In female mice, administration of testosterone propionate or dihydrotestosterone significantly raised mechanical pain thresholds, accompanied by increased AR expression in the DRG. This effect was abolished in AR-cKO females, where AR depletion was most prominent in CGRP + neurons, consistent with male findings. These results indicate that primary sensory neurons, particularly CGRP + neurons, are critical targets of androgen in regulating mechanical pain sensitivity. Therefore, manipulating androgen signaling in sensory neurons may offer a promising approach to managing mechanical pain.

Background/Objectives: Chronic pain is a significant global health challenge and is associated with diverse conditions, such as diabetic neuropathic pain and spinal stenosis. Understanding the mechanisms of pain transmission is crucial, for both the peripheral and central pathways. However, there are limitations in spinal electrophysiological techniques in terms of the injection method. Traditional methods such as spinal injections may differ in the distributions and concentrations of drugs compared with intrathecal administration during the behavior test. So, we developed a new intrathecal administration method for electrophysiological recordings. Methods: Sprague–Dawley rats were injected with lidocaine intrathecally, and the analgesic effect was evaluated by the von Frey test. In vivo extracellular single-unit recordings of the superficial dorsal horn neurons were performed following a newly developed technique. Lidocaine was intrathecally injected into the arachnoid membrane after laminectomy. After that, the neural responses in the superficial dorsal horn were measured. Results: Newly developed intrathecally administered dye reached the spinal cord and the cauda equina. Intrathecally administrated lidocaine increased the paw withdrawal threshold and suppressed spinal neuronal firing. This suppression correlated with increases in paw withdrawal thresholds. Conclusions: This innovative method provides insights into the central effects of analgesics, which will help the development of therapies for chronic pain.

Chemotherapy-induced peripheral neuropathy (CIPN) is a significant adverse event with unclear mechanisms and limited treatment alternatives. This study aimed to investigate the efficacy of two alkalizing agents, a mixture of potassium citrate and sodium citrate (K/Na citrate) or sodium bicarbonate (NaHCO3), in preventing and treating paclitaxel (PTX)-induced mechanical allodynia in rodents. The results from rodent models demonstrated that repeated prophylactic administration of K/Na citrate or NaHCO3 could inhibit the development of PTX-induced mechanical allodynia. Moreover, K/Na citrate was effective in preventing the PTX-induced exacerbation of mechanical allodynia, even when treatment was initiated immediately after the onset of allodynia. K/Na citrate also reduced the levels of the plasma complement component anaphylatoxin C3a in a PTX-induced CIPN rat model. Complement activation, resulting in the production of C3a, has been implicated in the pathogenesis of this model. Additionally, pretreatment with Na citrate significantly prevented the reduction in neurite outgrowth caused by PTX. Furthermore, K/Na citrate inhibited spontaneous and mechanical stimuli-induced firing in spinal dorsal horn neurons. These findings indicate that K/Na citrate may regulate the development of PTX-induced mechanical allodynia by modulating complement activation and providing neuroprotection against PTX-induced peripheral nerve injury. This study implies that alkalization could help prevent PTX-induced peripheral neuropathy and mitigate its exacerbation.

Neuropathic pain represents a critical challenge in medical research and clinical practice. Enhanced peripheral nerve activity and spinal dorsal horn neuronal firing are thought to contribute to the nociceptive hypersensitivities that are observed in chronic pain conditions, including those modeled by partial sciatic nerve ligation (PSNL). However, the detailed in vivo neuronal response dynamics and underlying mechanisms in the PSNL model remain to be fully clarified. To better understand these mechanisms, we evaluated dorsal root ganglion (DRG) and spinal dorsal horn neuronal activity in the PSNL model using in vivo approaches. Von Frey testing revealed sustained mechanical allodynia in PSNL animals; withdrawal thresholds were significantly reduced up to day 14 post-surgery. Immunohistochemistry revealed a stimulation-dependent increase in phosphorylated extracellular signal-regulated kinase (pERK)-positive neurons in the DRG, thereby indicating heightened peripheral nerve activity. Additionally, electrophysiological recordings demonstrated the enhanced firing of spinal dorsal horn neurons in response to the same stimuli. Notably, DRG pERK expression changes correlated with spinal neuronal firing frequency. Together, these findings suggest that peripheral nerve activity drives spinal neuronal sensitization, thus elucidating both pain mechanisms in the PSNL model and activity-dependent signaling in neuropathic pain.

Abstract Numerous clinical studies have shown that chronic pain patients very often suffer from affective disorders, such as depression accompanied by decreased motivation. It has been proposed that they share a common neuronal mechanism since it has been reported that the rate of psychiatric disorders in chronic pain patients is approximately two to three times higher than in non-patients (McWilliams et al. Pain, 106:127-133, 2003). Central sensitization is one of the prominent hypotheses for the neuropathology of chronic pain of which pain information is abnormally amplified in the brain due to altered function of sensory-related regions which also affects emotion-related regions as well. Several preclinical studies have shown that deficit in motivated-behavior in animal persistent-pain models. However, the underlying neuronal mechanism remains largely unraveled. In rodents, locomotion is known to be essential for seeking and obtaining reward while licking behavior have been indicated as a crucial behavioral signal for expectation of reward. In this study, we examined these behavioral parameters in a paclitaxel-induced peripheral neuropathy (PIPN) mouse model. These mice exhibit mechanical allodynia and depression-like behavior for 2-3 weeks after intraperitoneal injection of paclitaxel (Toma et al. Neuropharmacology 17:305–315, 2017). We examined their changes of behavioral parameters during operant conditioning task that enabled us to quantitatively analyze licking and locomotion. Mice were water-restricted, placed on a polystyrene disc with their head fixed and trained to perform a locomotor operant task that required them to start running spontaneously to trigger the following trial. After running for 1 second, a drop of water was delivered from the spout as a reward, followed by a 2 second quiescence period. Trained mice achieved success rate over 80 % after 8-10 sessions were randomly assigned to PIPN group (n = 6) or control group (n = 7) and examined task performance for 4 weeks. PIPN mice showed altered performance during the second week after injection. During this period, the mean success rate in PIPN group significantly dropped (as low as 66%) but not in control group. In unsuccessful trials, mice typically stopped prematurely before reaching the goal. Moreover, the frequency of anticipatory licking significantly decreased in PIPN mouse. However, total running distance during the task remained unchanged. These results indicate that PIPN mice show deficits in motivational behavioral parameters during the period which they go through persistent pain. The behavioral paradigm in this study could be a useful to study mouse pain models to elucidate the neuronal mechanism of deficits in motivational behavior. This work was supported by JST SPRING, Grant Number, JPMJSP2145 (TO), Tamura Science &Technology Foundation (HN), Takeda Science Foundation (HN), KAKENHI No, 23H04673 (HN).

Fibromyalgia (FM) is a chronic disorder characterized by widespread pain and various accompanying symptoms, with complex mechanisms involving both peripheral and central nervous systems that remain unclear. Herein, we introduce a study employing a reserpine-induced rat model of FM, investigating the spinal dorsal horn in particular. In reserpine-induced FM model rats, we observed pronounced mechanical hypersensitivity of cutaneous and muscular C-fiber nociceptors. Moreover, increased expression of the ASIC3 (one of acid-sensing ion channel) in dorsal root ganglia implicated its role in peripheral sensitization. Within the spinal dorsal horn, enhanced microglial activation was evident; pharmacological inhibition with minocycline significantly attenuated mechanical hyperalgesia, indicating the critical involvement of microglial activity in central pain processing. Furthermore, patch-clamp recordings revealed altered synaptic transmission characterized by enhanced spontaneous excitatory postsynaptic currents (EPSCs) and reduced inhibitory postsynaptic currents (IPSCs), contributing to heightened pain signaling in the FM model. These findings suggest that an imbalance of intensified excitatory and diminished inhibitory neurotransmission in the spinal dorsal horn leads to impaired sensory gating and augmented nociceptive transmission to higher centers, a pivotal mechanism in the pathophysiology of FM.

Neuropathic pain remains difficult to treat effectively because of the limitations of current pain medications. The Nav1.7 sodium channel plays a crucial role in pain sensation. The development of selective inhibitors has been challenging because of the high similarity among Nav channel subtypes. To address this issue, we developed monoclonal antibodies that selectively target Nav1.7 and humanized them for clinical use for the first time. When administered systemically to neuropathic pain model rats, a potent analgesic effect was observed that lasted for at least 96 hours. Electrophysiological studies revealed that the antibody reduced mechanically-evoked and spontaneous neuronal activity in the model. Importantly, the antibodies did not impact physiological pain or motor function. Collectively, our findings suggest that these novel Nav1.7-targeting antibodies are potentially effective analgesic drugs for chronic pain, including neuropathic pain. Our novel humanized anti-Nav1.7 antibodies have the potential to be used for the development of new analgesic, and one such antibody, S-151128 is currently in clinical trial. ### Competing Interest Statement E.K., D.N., T.T., and M.Y. are inventors on patent WO2023/074888, which covers some of the material in this paper. D.U. received research funding from Shionogi & Co., Ltd. All authors except D.U. are employees of Shionogi & Co., Ltd.

Oxidative stress and neuroinflammation accompanied by microglial activation are increased in Alzheimer's disease (AD) and contribute to the pathogenesis of AD. Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) is a master transcription factor that acts as an endogenous defense mechanism against oxidative stress and inflammation and is a potential target for preventing AD. Psoraleae Semen (PS) reportedly has antioxidant and anti-inflammatory effects. This study aimed to examine the effects of PS extract (PSE) on Nrf2 activation and prevention of cognitive dysfunction in AppNL-P-F AD model mice. The effects of PSE on antioxidant response element (ARE) activity and cytoprotection in PC12 cells and on microglial activation in BV-2 cells were evaluated. PSE showed high ARE activity and prevented 6-hydroxydopamine-induced cytotoxicity in PC12 cells. Moreover, PSE suppressed lipopolysaccharide-induced nitric oxide production in BV-2 cells. Oral administration of PSE prevented cognitive dysfunction in AppNL-P-F mice without affecting motor function. Our results support that PSE can contribute to the development of new preventive and therapeutic agents for AD focusing on Nrf2 activation.

Introduction: Atopic dermatitis (AD) is one of the most prevalent intractable chronic itch diseases worldwide. In recent years, new molecular-targeted drugs have emerged, but side effects and economic challenges remain. Therefore, since it is important for AD patients to have a wider range of treatment options, it is important to explore new therapeutic agents. Gabapentinoids, gabapentin and pregabalin, have been shown to be effective for the clinical treatment of several chronic itch. Recently, mirogabalin (MGB) was developed as a novel gabapentinoid. MGB is a drug for neuropathic pain and has a margin of safety between its side effects and the analgesic effect for animal experiments. Herein, we showed that MGB exhibited an antipruritic effect in a mouse model of AD using NC/Nga mice.Methods and results: The oral administration of MGB (10 mg/kg) inhibited spontaneous scratching behavior in AD mice and its effect was dose dependently. Then, when MGB (10 mg/kg) was orally administrated to healthy mice, it did not affect motor function, including locomotor activity, wheel activity, and coordinated movement. Moreover, gabapentin (100 mg/kg) and pregabalin (30 mg/kg), inhibited spontaneous scratching behavior in AD mice and decreased motor function in healthy mice. Furthermore, intracisternal injection of MGB (10 μg/site) significantly suppressed spontaneous scratching behavior in AD mice.Discussion: In summary, our results suggest that MGB exerts an antipruritic effect via the spinal dorsal horn using NC/Nga mice. We hope that MGB is a candidate for a novel therapeutic agent for AD with relatively few side effects.

Remimazolam is an ultra-short benzodiazepine that acts on the benzodiazepine site of γ-aminobutyric acid (GABA) receptors in the brain and induces sedation. Although GABA receptors are found localized in the spinal dorsal horn, no previous studies have reported the analgesic effects or investigated the cellular mechanisms of remimazolam on the spinal dorsal horn. Behavioral measures, immunohistochemistry, and in vitro whole-cell patch-clamp recordings of dorsal horn neurons were used to assess synaptic transmission. Intrathecal injection of remimazolam induced behavioral analgesia in inflammatory pain-induced mechanical allodynia (six rats/dose; p < 0.05). Immunohistochemical staining revealed that remimazolam suppressed spinal phosphorylated extracellular signal-regulated kinase activation (five rats/group, p < 0.05). In vitro whole-cell patch-clamp analysis demonstrated that remimazolam increased the frequency of GABAergic miniature inhibitory post-synaptic currents, prolonged the decay time (six rats; p < 0.05), and enhanced GABA currents induced by exogenous GABA (seven rats; p < 0.01). However, remimazolam did not affect miniature excitatory post-synaptic currents or amplitude of monosynaptic excitatory post-synaptic currents evoked by Aδ- and C-fiber stimulation (seven rats; p > 0.05). This study suggests that remimazolam induces analgesia by enhancing GABAergic inhibitory transmission in the spinal dorsal horn, suggesting its potential utility as a spinal analgesic for inflammatory pain.

BackgroundPostherpetic pain (PHP) is difficult to control. Although Neurotropin® (NTP) and methylcobalamin (MCB) are often prescribed to treat the pain, the efficacy of combined treatment for PHP remains imcompletely understood.ObjectiveIn this study, we investigate the combined effects of NTP and MCB on PHP in mice.MethodsNTP and MCB were administered from day 10–29 after herpes simplex virus type-1 (HSV-1) infection. The pain-related responses were evaluated using a paint brush. The expression of neuropathy-related factor (ATF3) and nerve repair factors (GAP-43 and SPRR1A) in the dorsal root ganglion (DRG) and neurons in the skin were evaluated by immunohistochemical staining. Nerve growth factor (NGF) and neurotrophin-3 (NT3) mRNA expression levels were evaluated using real-time PCR.ResultsRepeated treatment with NTP and MCB after the acute phase inhibited PHP. Combined treatment with these drugs inhibited PHP at an earlier stage than either treatment alone. In the DRG of HSV-1-infected mice, MCB, but not NTP, decreased the number of cells expressing ATF3 and increased the number of cells expressing GAP-43- and SPRR1A. In addition, MCB, but not NTP, also increased and recovered non-myelinated neurons decreased in the lesional skin. NTP increased the mRNA levels of NTF3 in keratinocytes, while MCB increased that of NGF in Schwann cells.ConclusionThese results suggest that combined treatment with NTP and MCB is useful for the treatment of PHP. The combined effect may be attributed to the different analgesic mechanisms of these drugs.

The therapeutic benefits of photobiomodulation (PBM) in pain management, although well documented, are accompanied by concerns about potential risks, including pain, particularly at higher laser intensities. This study investigated the effects of laser intensity on pain perception using behavioral and electrophysiological evaluations in rats. Our results show that direct laser irradiation of 1000 mW/cm2 to the sciatic nerve transiently increases the frequency of spontaneous firing in the superficial layer without affecting the deep layer of the spinal dorsal horn, and this effect reverses to pre-irradiation levels after irradiation. Interestingly, laser irradiation at 1000 mW/cm2, which led to an increase in spontaneous firing, did not prompt escape behavior. Furthermore, a significant reduction in the time to initiate escape behavior was observed only at 9500 mW/cm2 compared to 15, 510, 1000, and 4300 mW/cm2. This suggests that 1000 mW/cm2, the laser intensity at which an increase in spontaneous firing was observed, corresponds to a stimulus that did not cause pain. It is expected that a detailed understanding of the risks and mechanisms of PBM from a neurophysiological perspective will lead to safer and more effective use of PBM.

Mast cells play an important role in allergic reactions by releasing potent mediators, including histamine and platelet-activating factor (PAF), upon activation. We recently reported that a biotinylated heptapeptide (peptide 2), D-Lys(Biotinyl)-Trp-Tyr-Lys-Asp-Gly-Asp, which is highly stable in the plasma, inhibits PAF bioactivity and anaphylactic hypothermia in vivo. However, the effects of this peptide on allergy induction by mast cells have not been investigated. Several biotinylated heptapeptides, including peptide 2, inhibited IgE/antigen-stimulated degranulation in RBL-2H3 cells. Peptide 2 also markedly inhibited the degranulation induced by calcium ionophore A23187. All peptides (peptide 1, 2 and 3) inhibited activating stimuli-induced increase in intracellular Ca2+ levels. The transforming growth factor-alpha shedding assay indicated that peptide 2 antagonized against the histamine H1 receptor. Furthermore, peptide 2 inhibited histamine-induced rat paw edema. These results highlight the potential of peptide 2 in the prevention and treatment of various allergic diseases mediated by mast cell activation.

The pain matrix, which includes several brain regions that respond to pain sensation, contribute to the development of chronic pain. Thus, it is essential to understand the mechanism of causing chronic pain in the pain matrix such as anterior cingulate (ACC), or primary somatosensory (S1) cortex. Recently, combined experiment with the behavior tests and in vivo calcium imaging using fiber photometry revealed the interaction between the neuronal function in deep brain regions of the pain matrix including ACC and the phenotype of chronic pain. However, it remains unclear whether this combined experiment can identify the interaction between neuronal activity in S1, which receive pain sensation, and pain behaviors such as hyperalgesia or allodynia. In this study, to examine whether the interaction between change of neuronal activity in S1 and hyperalgesia in hind paw before and after causing inflammatory pain was detected from same animal, the combined experiment of in vivo fiber photometry system and von Frey hairs test was applied. This combined experiment detected that amplitude of calcium responses in S1 neurons increased and the mechanical threshold of hind paw decreased from same animals which have an inflammatory pain. Moreover, we found that the values between amplitude of calcium responses and mechanical thresholds were shifted to negative correlation after causing inflammatory pain. Thus, the combined experiment with fiber photometry and the behavior tests has a possibility that can simultaneously consider the interaction between neuronal activity in pain matrix and pain induced behaviors and the effects of analgesics or pain treatments.