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Cunha M, Tavares I, Costa-Pereira JT. Centralizing the Knowledge and Interpretation of Pain in Chemotherapy-Induced Peripheral Neuropathy: A Paradigm Shift towards Brain-Centric Approaches. Brain Sci 2024; 14:659. [PMID: 39061400 PMCID: PMC11274822 DOI: 10.3390/brainsci14070659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 06/17/2024] [Accepted: 06/24/2024] [Indexed: 07/28/2024] Open
Abstract
Chemotherapy-induced peripheral neuropathy (CIPN) is a side effect of cancer treatment, often linked with pain complaints. Patients report mechanical and thermal hypersensitivity that may emerge during chemotherapy treatment and may persist after cancer remission. Whereas the latter situation disturbs the quality of life, life itself may be endangered by the appearance of CIPN during cancer treatment. The causes of CIPN have almost entirely been ascribed to the neurotoxicity of chemotherapeutic drugs in the peripheral nervous system. However, the central consequences of peripheral neuropathy are starting to be unraveled, namely in the supraspinal pain modulatory system. Based on our interests and experience in the field, we undertook a review of the brain-centered alterations that may underpin pain in CIPN. The changes in the descending pain modulation in CIPN models along with the functional and connectivity abnormalities in the brain of CIPN patients are analyzed. A translational analysis of preclinical findings about descending pain regulation during CIPN is reviewed considering the main neurochemical systems (serotoninergic and noradrenergic) targeted in CIPN management in patients, namely by antidepressants. In conclusion, this review highlights the importance of studying supraspinal areas involved in descending pain modulation to understand the pathophysiology of CIPN, which will probably allow a more personalized and effective CIPN treatment in the future.
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Affiliation(s)
- Mário Cunha
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; (M.C.); (J.T.C.-P.)
| | - Isaura Tavares
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; (M.C.); (J.T.C.-P.)
- I3S—Institute of Investigation and Innovation in Health, University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
| | - José Tiago Costa-Pereira
- Department of Biomedicine, Unit of Experimental Biology, Faculty of Medicine, University of Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; (M.C.); (J.T.C.-P.)
- I3S—Institute of Investigation and Innovation in Health, University of Porto, Rua Alfredo Allen 208, 4200-135 Porto, Portugal
- Faculty of Nutrition and Food Sciences, University of Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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Jiang S, Zheng C, Wen G, Bu B, Zhao S, Xu X. Down-regulation of NR2B receptors contributes to the analgesic and antianxiety effects of enriched environment mediated by endocannabinoid system in the inflammatory pain mice. Behav Brain Res 2022; 435:114062. [PMID: 35985400 DOI: 10.1016/j.bbr.2022.114062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 08/05/2022] [Accepted: 08/15/2022] [Indexed: 11/28/2022]
Abstract
Chronic pain states are highly prevalent and yet poorly controlled by currently available analgesics. It has been reported that enriched environment (EE), as a new way of endogenous pharmacotherapy, is effective in attenuating chronic inflammatory pain. However, the underlying molecular mechanisms are still not fully understood. NMDA NR2B receptor plays a critical role in pain transmission and modulation. Thus, in this study, we aimed at the effect of EE on the NR2B receptors expression in the prefrontal cortex, hippocampus and thalamus in the inflammatory pain mice. The results showed a significant increase of NR2B receptors in the thalamus of mice at 7 d following injection of CFA in the subcutaneous of the bottom of the left hind paw. EE significantly reduced the duration of mechanical hypersensitivity and anxiety-related behavior and the expression of NR2B receptors as compared to the standard condition. Furthermore, EE significantly increased 2-arachidonoylglycero (2-AG) levels at 7 d in the inflammatory pain mice as compared to the standard condition, and the effect of EE on the behavior and the expression of NR2B receptors was abolished by intraperitoneal injection of AM281 (a selective antagonist of CB1 receptor). Elevated 2-AG levels by intraperitoneal injection of JZL184 (a selective inhibitor of MAGL, the enzyme responsible for 2-AG hydrolysis) produced the same effect as EE. Results from this study provide the evidence that EE mimics endocannabinoids to take analgesic and anti-anxiety activities by decreasing the expression of the NR2B receptors via the CB1 receptor in the thalamus, pending further studies.
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Affiliation(s)
- Shukun Jiang
- Department of Forensic Clinical Medicine, School of Forensic Medicine, China Medical University, Shenyang, PR China; Key Laboratory of Forensic Bio-evidence Sciences, Liaoning Province, PR China; China Medical University Center of Forensic Investigation, Shenyang, PR China
| | - Chuanfei Zheng
- Department of Forensic Clinical Medicine, School of Forensic Medicine, China Medical University, Shenyang, PR China; Key Laboratory of Forensic Bio-evidence Sciences, Liaoning Province, PR China; China Medical University Center of Forensic Investigation, Shenyang, PR China
| | - Gehua Wen
- Department of Forensic Clinical Medicine, School of Forensic Medicine, China Medical University, Shenyang, PR China; Key Laboratory of Forensic Bio-evidence Sciences, Liaoning Province, PR China; China Medical University Center of Forensic Investigation, Shenyang, PR China
| | - Bin Bu
- Department of Forensic Clinical Medicine, School of Forensic Medicine, China Medical University, Shenyang, PR China; Key Laboratory of Forensic Bio-evidence Sciences, Liaoning Province, PR China; China Medical University Center of Forensic Investigation, Shenyang, PR China
| | - Shuang Zhao
- China Medical University Center of Forensic Investigation, Shenyang, PR China
| | - Xiaoming Xu
- Department of Forensic Clinical Medicine, School of Forensic Medicine, China Medical University, Shenyang, PR China; Key Laboratory of Forensic Bio-evidence Sciences, Liaoning Province, PR China; China Medical University Center of Forensic Investigation, Shenyang, PR China.
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Xing XX, Ma ZZ, Wu JJ, Ma J, Duan YJ, Hua XY, Zheng MX, Xu JG. Dysfunction in the Interaction of Information Between and Within the Bilateral Primary Sensory Cortex. Front Aging Neurosci 2022; 14:862107. [PMID: 35462694 PMCID: PMC9029819 DOI: 10.3389/fnagi.2022.862107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 02/09/2022] [Indexed: 11/18/2022] Open
Abstract
Background Interhemispheric and intrahemispheric long-range synchronization and information communication are crucial features of functional integration between the bilateral hemispheres. Previous studies have demonstrated that disrupted functional connectivity (FC) exists in the bilateral hemispheres of patients with carpal tunnel syndrome (CTS), but they did not clearly clarify the phenomenon of central dysfunctional connectivity. This study aimed to further investigate the potential mechanism of the weakened connectivity of primary somatosensory cortex (S1) based on a precise template. Methods Patients with CTS (n = 53) and healthy control subjects (HCs) (n = 23) participated and underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. We used FC to investigate the statistical dependency of the whole brain, effective connectivity (EC) to analyze time-dependent effects, and voxel-mirrored homotopic connectivity (VMHC) to examine the coordination of FC, all of which were adopted to explore the change in interhemispheric and intrahemispheric S1. Results Compared to the healthy controls, we significantly found a decreased strength of the two connectivities in the interhemispheric S1hand, and the results of EC and VMHC were basically consistent with FC in the CTS. The EC revealed that the information output from the dominant hemisphere to the contralateral hemisphere was weakened. Conclusion This study found that maladjusted connections between and within the bilateral S1 revealed by these methods are present in patients with CTS. The dominant hemisphere with deafferentation weakens its effect on the contralateral hemisphere. The disturbance in the bilateral S1 provides reliable evidence to understand the neuropathophysiological mechanisms of decreased functional integration in the brains of patients with CTS.
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Affiliation(s)
- Xiang-Xin Xing
- Department of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai, China
| | - Zhen-Zhen Ma
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Department of Rehabilitation Medicine, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jia-Jia Wu
- Department of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai, China
| | - Jie Ma
- Department of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yu-Jie Duan
- Department of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xu-Yun Hua
- Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai, China
- Department of Traumatology and Orthopedics, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Xu-Yun Hua,
| | - Mou-Xiong Zheng
- Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai, China
- Department of Traumatology and Orthopedics, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Mou-Xiong Zheng,
| | - Jian-Guang Xu
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation, Ministry of Education, Shanghai, China
- *Correspondence: Jian-Guang Xu,
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Tøttrup L, Diaz-Valencia G, Kamavuako EN, Jensen W. Modulation of SI and ACC response to noxious and non-noxious electrical stimuli after the spared nerve injury model of neuropathic pain. Eur J Pain 2020; 25:612-623. [PMID: 33166003 DOI: 10.1002/ejp.1697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 10/14/2020] [Indexed: 11/07/2022]
Abstract
BACKGROUND The current knowledge on the role of SI and ACC in acute pain processing and how these contribute to the development of chronic pain is limited. Our objective was to investigate differences in and modulation of intracortical responses from SI and ACC in response to different intensities of peripheral presumed noxious and non-noxious stimuli in the acute time frame of a peripheral nerve injury in rats. METHODS We applied non-noxious and noxious electrical stimulation pulses through a cuff electrode placed around the sciatic nerve and measured the cortical responses (six electrodes in each cortical area) before and after the spared nerve injury model. RESULTS We found that the peak response correlated with the stimulation intensity and that SI and ACC differed in both amplitude and latency of cortical response. The cortical response to both noxious and non-noxious stimulation showed a trend towards faster processing of non-noxious stimuli in ACC and increased cortical processing of non-noxious stimuli in SI after SNI. CONCLUSIONS We found different responses in SI and ACC to different intensity electrical stimulations based on two features and changes in these features following peripheral nerve injury. We believe that these features may be able to assist to track cortical changes during the chronification of pain in future animal studies. SIGNIFICANCE This study showed distinct cortical processing of noxious and non-noxious peripheral stimuli in SI and ACC. The processing latency in ACC and accumulated spiking activity in SI appeared to be modulated by peripheral nerve injury, which elaborated on the function of these two areas in the processing of nociception.
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Affiliation(s)
- Lea Tøttrup
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Gabriela Diaz-Valencia
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Ernest N Kamavuako
- Department of Engineering, King's College London, London, UK.,Faculté de Médecine, Université de Kindu, Maniema, D.R Congo
| | - Winnie Jensen
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Xing XX, Hua XY, Zheng MX, Ma ZZ, Huo BB, Wu JJ, Ma SJ, Ma J, Xu JG. Intra and inter: Alterations in functional brain resting-state networks after peripheral nerve injury. Brain Behav 2020; 10:e01747. [PMID: 32657022 PMCID: PMC7507705 DOI: 10.1002/brb3.1747] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 05/18/2020] [Accepted: 06/04/2020] [Indexed: 12/16/2022] Open
Abstract
INTRODUCTION Numerous treatments suggest that brain plasticity changes after peripheral nerve injury (PNI), and most studies examining functional magnetic resonance imaging focused on abnormal changes in specific brain regions. However, it is the large-scale interaction of neuronal networks instead of isolated brain regions contributed to the functional recovery after PNI. In the present study, we examined the intra- and internetworks alterations between the related functional resting-state networks (RSNs) in a sciatic nerve injury rat model. METHODS Ninety-six female rats were divided into a control and model group. Unilateral sciatic nerve transection and direct anastomosis were performed in the latter group. We used an independent component analysis (ICA) algorithm to observe the changes in RSNs and assessed functional connectivity between different networks using the functional networks connectivity (FNC) toolbox. RESULTS Six RSNs related to PNI were identified, including the basal ganglia network (BGN), sensorimotor network (SMN), salience network (SN), interoceptive network (IN), cerebellar network (CN), and default mode network (DMN). The model group showed significant changes in whole-brain FC changes within these resting-state networks (RSNs), but four of these RSNs exhibited a conspicuous decrease. The interalterations performed that significantly decreased FNC existed between the BGN and SMN, BGN and IN, and BGN and DMN (p < .05, corrected). A significant increase in FNC existed between DMN and CN and between CN and SN (p < .05, corrected). CONCLUSION The results showed the large-scale functional reorganization at the network level after PNI. This evidence reveals new implications to the pathophysiological mechanisms in brain plasticity of PNI.
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Affiliation(s)
- Xiang-Xin Xing
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xu-Yun Hua
- Department of Traumatology and Orthopedics, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Yangzhi Rehabilitation Hospital, Tongji University, Shanghai, China
| | - Mou-Xiong Zheng
- Department of Traumatology and Orthopedics, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Zhen-Zhen Ma
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Bei-Bei Huo
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jia-Jia Wu
- Center of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Shu-Jie Ma
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jie Ma
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jian-Guang Xu
- School of Rehabilitation Science, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Center of Rehabilitation Medicine, Yueyang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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Wang Z, Huang S, Yu X, Li L, Yang M, Liang S, Liu W, Tao J. Altered thalamic neurotransmitters metabolism and functional connectivity during the development of chronic constriction injury induced neuropathic pain. Biol Res 2020; 53:36. [PMID: 32843088 PMCID: PMC7448455 DOI: 10.1186/s40659-020-00303-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 08/08/2020] [Indexed: 11/17/2022] Open
Abstract
Background To investigate the thalamic neurotransmitters and functional connections in the development of chronic constriction injury (CCI)-induced neuropathic pain. Methods The paw withdrawal threshold was measured by mechanical stimulation the right hind paw with the von frey hair in the rats of CCI-induced neuropathic pain. The N-acetylaspartate (NAA) and Glutamate (Glu) in thalamus were detected by magnetic resonance spectrum (MRS) process. The thalamic functional connectivity with other brain regions was scanned by functional magnetic resonance image (fMRI). Results The paw withdrawal threshold of the ipsilateral side showed a noticeable decline during the pathological process. Increased concentrations of Glu and decreased levels of NAA in the thalamus were significantly correlated with mechanical allodynia in the neuropathic pain states. The thalamic regional homogeneity (ReHo) decreased during the process of neuropathic pain. The functional connectivity among the thalamus with the insula and somatosensory cortex were significantly increased at different time points (7, 14, 21 days) after CCI surgery. Conclusion Our study suggests that dynamic changes in thalamic NAA and Glu levels contribute to the thalamic functional connection hyper-excitation during CCI-induced neuropathic pain. Enhanced thalamus-insula functional connection might have a significant effect on the occurrence of neuropathic pain.
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Affiliation(s)
- Zhifu Wang
- College of Integrated Traditional Chinese and Western Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Sheng Huang
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, Fujian, China.,Fujian Collaborative Innovation Center for Rehabilitation Technology, Fuzhou, 350122, Fujian, China
| | - Xiangmei Yu
- College of Integrated Traditional Chinese and Western Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Long Li
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, Fujian, China.,Fujian Collaborative Innovation Center for Rehabilitation Technology, Fuzhou, 350122, Fujian, China
| | - Minguang Yang
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, Fujian, China.,Fujian Collaborative Innovation Center for Rehabilitation Technology, Fuzhou, 350122, Fujian, China
| | - Shengxiang Liang
- National-Local Joint Engineering Research Center of Rehabilitation Medicine Technology, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, Fujian, China.,Fujian Collaborative Innovation Center for Rehabilitation Technology, Fuzhou, 350122, Fujian, China
| | - Weilin Liu
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China
| | - Jing Tao
- College of Rehabilitation Medicine, Fujian University of Traditional Chinese Medicine, Fuzhou, 350122, China.
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Acupuncture Induces Reduction in Limbic-Cortical Feedback of a Neuralgia Rat Model: A Dynamic Causal Modeling Study. Neural Plast 2020; 2020:5052840. [PMID: 32148473 PMCID: PMC7023796 DOI: 10.1155/2020/5052840] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/02/2020] [Accepted: 01/10/2020] [Indexed: 11/17/2022] Open
Abstract
Background Neuropathic pain after brachial plexus avulsion remained prevalent and intractable currently. However, the neuroimaging study about neural mechanisms or etiology was limited and blurred. Objective This study is aimed at investigating the effect of electroacupuncture on effective connectivity and neural response in corticolimbic circuitries during implicit processing of nociceptive stimulus in rats with brachial plexus pain. Methods An fMRI scan was performed in a total of 16 rats with brachial plexus pain, which was equally distributed into the model group and the electroacupuncture group. The analysis of task-dependent data determined pain-related activation in each group. Based on those results, several regions including AMY, S1, and h were recruited as ROI in dynamic causal modeling (DCM) analysis comparing evidence for different neuronal hypotheses describing the propagation of noxious stimuli in regions of interest and horizontal comparison of effective connections between the model and electroacupuncture groups. Results In both groups, DCM revealed that noxious stimuli were most likely driven by the somatosensory cortex, with bidirectional propagation with the hypothalamus and amygdala and the interactions in them. Also, the 3-month intervention of acupuncture reduced effective connections of h-S1 and AMY-S1. Conclusions We showed an evidence that a full connection model within the brain network of brachial plexus pain and electroacupuncture intervention reduces effective connectivity from h and AMY to S1. Our study for the first time explored the relationship of involved brain regions with dynamic causal modeling. It provided novel evidence for the feature of the organization of the cortical-limbic network and the alteration caused by acupuncture.
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Neuroimaging of pain in animal models: a review of recent literature. Pain Rep 2019; 4:e732. [PMID: 31579844 PMCID: PMC6728006 DOI: 10.1097/pr9.0000000000000732] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 02/06/2019] [Accepted: 02/12/2019] [Indexed: 01/19/2023] Open
Abstract
Neuroimaging of pain in animals allows us to better understand mechanisms of pain processing and modulation. In this review, we discuss recently published brain imaging studies in rats, mice, and monkeys, including functional magnetic resonance imaging (MRI), manganese-enhanced MRI, positron emission tomography, and electroencephalography. We provide an overview of innovations and limitations in neuroimaging techniques, as well as results of functional brain imaging studies of pain from January 1, 2016, to October 10, 2018. We then discuss how future investigations can address some bias and gaps in the field. Despite the limitations of neuroimaging techniques, the 28 studies reinforced that transition from acute to chronic pain entails considerable changes in brain function. Brain activations in acute pain were in areas more related to the sensory aspect of noxious stimulation, including primary somatosensory cortex, insula, cingulate cortex, thalamus, retrosplenial cortex, and periaqueductal gray. Pharmacological and nonpharmacological treatments modulated these brain regions in several pain models. On the other hand, in chronic pain models, brain activity was observed in regions commonly associated with emotion and motivation, including prefrontal cortex, anterior cingulate cortex, hippocampus, amygdala, basal ganglia, and nucleus accumbens. Neuroimaging of pain in animals holds great promise for advancing our knowledge of brain function and allowing us to expand human subject research. Additional research is needed to address effects of anesthesia, analysis approaches, sex bias and omission, and potential effects of development and aging.
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