COVID-19 Journal Club
The COVID-19 Global Pandemic has posed significant challenges to the pain community. To reinforce the message that the we—those who do human pain research—are part of a community, I put together the COVID-19 Journal Club (or as some like to call it, the #PainStars Forum). It's an opportunity to connect, to remain intellectually stimulated, to learn, and to keep up with the literature.
We meet over Zoom every month. The specifics, papers, and link to the Zoom will be posted here. We look forward to seeing you all.
Tuesday, April 20, 2021, 3 pm EST
Title: A picture is worth a thousand words: linking fibromyalgia pain widespreadness from digital pain drawings with pain catastrophizing and brain cross-network connectivity
Presented by: Dr. Vitaly Napadow, Professor in Radiology, Harvard Medical School, USA
Abstract: Pain catastrophizing is prominent in chronic pain conditions such as fibromyalgia, and has been proposed to contribute to the development of pain widespreadness. However, the brain mechanisms responsible for this association are unknown. We hypothesized that increased resting Salience Network (SLN) connectivity to nodes of the Default Mode Network (DMN), representing previously reported pain-linked cross-network enmeshment, would be associated with increased pain catastrophizing and widespreadness across body sites.We applied functional Magnetic Resonance Imaging (fMRI) and digital pain drawings (free-hand drawing over a body outline, analyzed using conventional software for multivoxel fMRI analysis) to investigate precisely-quantified measures of pain widespreadness and the associations between pain catastrophizing (Pain Catastrophizing Scale, PCS), resting brain network connectivity (Dual-regression Independent Component Analysis, 6-minute multiband accelerated fMRI), and pain widespreadness in fibromyalgia patients (N=79).Fibromyalgia patients reported pain in multiple body areas (most frequently the spinal region, from the lower back to the neck), with moderately high pain widespreadness (mean±SD: 26.1±24.1 percent of total body area), and high PCS scores (27.0±21.9, scale range: 0-52), which were positively correlated (r=0.26,p=0.02). A whole-brain regression analysis focused on SLN connectivity indicated that pain widespreadness was also positively associated with SLN connectivity to the Posterior Cingulate Cortex (PCC), a key node of the DMN. Moreover, we found that SLN-PCC connectivity statistically mediated the association between pain catastrophizing and pain widespreadness (p=0.01).In conclusion, we identified a putative brain mechanism underpinning the association between greater pain catastrophizing and a larger spatial extent of body pain in fibromyalgia, implicating a role for brain SLN-DMN cross-network enmeshment in mediating this association.
Relevant Paper: https://pubmed.ncbi.nlm.nih.gov/33230008/
Meeting ID: 817 7935 5356
Tuesday, May 11, 2021, 1 pm EST
Title: Physiological and Chemical Properties of C-Tactile Afferents in Man and Their Distribution Across the Body
Presented by: Dr. Line Löken, Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Sweden
Abstract: Since the discovery that the skin of man is innervated with unmyelinated tactile (CT) afferents that convey social and emotional aspects of touch, extensive explorations of the physiology and function of these afferents have been made. In spite of this, aspects of the properties of CT afferents as well as their prevalence and density in different areas of the human body have remained elusive. Numerous microneurography studies in the human peroneal nerve, without reports of CT afferents, suggested that these afferents are lacking in the more distal parts of the limbs. Here we recorded from unmyelinated low-threshold mechanosensitive afferents in the peroneal, lateral antebrachial and radial nerves. The most distal receptive fields were located on the proximal phalanx of the third finger for the superficial branch of the radial nerve, and near the lateral malleolus for the peroneal nerve. We found that the physiological properties with regards to conduction velocity and mechanical threshold, as well as their tuning to brush velocity, was similar in CT units across the antebrachial, radial and peroneal nerves. Lastly, we explored the chemical sensitivity of these afferents and found that CT afferents were not activated by either the pruritogen histamine or the cooling agent menthol. In light of previous studies showing the combined effects that temperature and mechanical stimuli have on these neurons, including a lack of responsiveness to capsaicin, these findings add to the growing body of research suggesting that CT afferents constitute a unique sense organ with highly specialized mechanisms for transducing stimuli relevant to affective touch sensation.
Meeting ID: 869 2562 7073
Tuesday, May 26, 2021, 12 pm EST
Title: Observation of others’ painful heat stimulation involves responses in the spinal cord
Presented by: Dr. Jan Haaker, Research Group Leader, Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf
Abstract: Observing others’ aversive experiences is central to know what is dangerous for ourselves. Hence, observation often elicits behavioral and physiological responses comparable to first-hand aversive experiences. However, it is unresolved if first-hand aversive experiences involves neural processes that are similar when we merely observe aversive stimulation in others. I will outline neural and neuropharmacological pathways that are involved in observation of others painful stimulation and overlap with neural systems that process first-hand aversive experiences. This includes responses in the brain, as well as neural responses in the spinal cord. Beside this common cerebro-spinal network, I will further propose a distinct processing of self and others’ pain that is based on activity in the spinal cord.
Meeting ID: 853 5248 6944
Friday, June 4, 2021, 11 am EST
Title: Pain-related modulations of ongoing oscillations recorded from the human insula using intracerebral EEG
Presented by: Dr. Giulia Liberati, Principal Investigator at the Institute of Neuroscience, UCLouvain, Belgium
Abstract: Pain is a very common experience in everyday life, as it enables us to develop adaptive behavior that is critical for survival. However, to this date, the exact mechanisms through which pain arises from brain activity are still debated. The complexity of studying pain is due to the fact that it is a highly flexible phenomenon that needs to continuously adjust to behavioral demands. This adjustment is evident, for instance, when a circumstance that would generally cause excruciating pain is barely noticed, such as when a soldier is wounded during a battle but keeps fighting, or in a case of an athlete during an important competition. To this end, pain might be better understood by focusing on dynamic features of pain-related activities.My main hypothesis is that pain arises from the modulation of spontaneous and dynamically fluctuating ongoing neural oscillations. To test this hypothesis, I rely on the recording of intracerebral electroencephalography (iEEG) acquired on patients undergoing a presurgical evaluation of focal epilepsy, and on a novel frequency analysis method, frequency tagging of ongoing oscillations (FT-OO).
Meeting ID: 885 9787 7994
Tuesday, June 14, 2021, 12 pm EST
Title: Endogenous opioids contribute to the feeling of pain relief in humans
Presented by: Laura Sirucek, PhD Student (Becker and Schweinhardt Labs), Balgrist University, Switzerland
Tuesday, July 6, 2021, 8:30 am
Title: A Neuroimaging Biomarker for Sustained Experimental and Clinical Pain
Presented by: Choog-Wan (Wani) Woo, Assistant Professor, IBS Center for Neuroscience Imaging Research, Department of Biomedical Engineering, Sungkyunkwan University, Korea
Abstract: Sustained pain is a major characteristic of clinical pain disorders, but it is difficult to assess in isolation from co-occurring cognitive and emotional features in patients. In this study, we developed a functional magnetic resonance imaging signature based on whole-brain functional connectivity that tracks experimentally induced tonic pain intensity and tested its sensitivity, specificity and generalizability to clinical pain across six studies (total n = 334). The signature displayed high sensitivity and specificity to tonic pain across three independent studies of orofacial tonic pain and aversive taste. It also predicted clinical pain severity and classified patients versus controls in two independent studies of clinical low back pain. Tonic and clinical pain showed similar network-level representations, particularly in somatomotor, frontoparietal and dorsal attention networks. These patterns were distinct from representations of experimental phasic pain. This study identified a brain biomarker for sustained pain with high potential for clinical translation.
Meeting ID: 886 4397 0504