Human studies have repeatedly shown that conditioning pain modulation (CPM) exerts an overall descending inhibitory effect over spinal nociceptive activity. Previous studies have reported a reduction of the nociceptive withdrawal reflex (NWR) under CPM. Still, how descending control influences the muscle activation patterns involved in this protective behavior remains unknown. This study aimed to characterize the effects of CPM on the withdrawal pattern assessed by a muscle synergy analysis of several muscles involved in the lower limb NWR. To trigger descending inhibition, CPM paradigm was applied using the cold-pressor test (CPT) as conditioning stimulus. Sixteen healthy volunteers participated. The NWR was evoked by electrical stimulation on the arch of the foot before, during and after the CPT. Electromyographic (EMG) activity of two proximal (rectus femoris and biceps femoris) and two distal (tibialis anterior and soleus) muscles was recorded. A muscle synergy analysis was performed on the decomposition of the EMG signals, based on a non-negative matrix factorization algorithm. Results showed that two synergies (Module I and II) were sufficient to describe the NWR pattern. Under CPM, Module I activation amplitude was significantly reduced in a narrow time-window interval (118-156 ms) mainly affecting distal muscles, whereas Module II activation amplitude was significantly reduced in a wider time-window interval (150-250 ms), predominantly affecting proximal muscles. These findings suggest that proximal muscles are largely under supraspinal control. The descending inhibitory drive exerted onto the spinal cord may adjust the withdrawal pattern by differential recruitment of the muscles involved in the protective behavior.
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http://dx.doi.org/10.1016/j.neuroscience.2019.04.016 | DOI Listing |
Inflammopharmacology
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Department of Research and Development, First Floor, Molecules Biolabs Private Limited, Commercial Building Kinfra, 3/634Konoor Road, Muringur, Vadakkummuri, Koratty, Mukundapuram, Thrissur, Kerala, 680309, India.
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December 2024
Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine.
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Methods: The transethosomal system containing various caryophyllene concentrations was prepared.
Free Radic Biol Med
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Intervertebral disc degeneration (IDD) is intricately linked to the pathogenesis of low back pain (LBP). The balance of nucleus pulposus (NP) cell and intervertebral disc (IVD) integrity is significantly supported by amino acid metabolism within an avascular milieu. However, the specific metabolic demands during the progression of IDD are not fully understood.
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Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.
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Department of Medical Research and Development, Research Division, Chang Gung Memorial Hospital at Linkou, Taoyuan 33305, Taiwan. Electronic address:
Aims: Chronic pain is a critical public health issue that severely impacts quality of life and poses significant treatment challenges, particularly due to the risk of adverse effects associated with pharmacological therapies. The search for effective non-invasive treatment alternatives has become increasingly relevant. Low-intensity focused ultrasound (LIFU) has been identified as an effective non-invasive strategy for pain management, although the underlying mechanism remains unclear.
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