Tempo-spatial discrimination to non-noxious stimuli is better than for noxious stimuli

Tempo-spatial discrimination to non-noxious stimuli is better than for noxious stimuli Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188(p < 0.01). Increasing systolic blood pressure in the control group.Diastolic blood pressure decrease in tramadol and placebo groups.In the tramadol group, we saw more frequently mild side effects.Conclusions: Tramadol gave no reduction in postoperative painbut an increased frequency of desaturation and side effects. Otherdrugs or other doses ought to be tried for this kind of postoperativepain management.http://dx.doi.org/10.1016/j.sjpain.2017.04.020Tempo-spatial discrimination to non-noxiousstimuli is better than for noxious stimuliKen Steffen Frahm ∗ , Carsten Dahl Mørch, OleKæseler AndersenIntegrative Neuroscience Group, Center for®Neuroplasticity and Pain (CNAP), SMI , Departmentof Health Science & Technology, Aalborg University,9220 Aalborg, DenmarkE-mail address: ksf@hst.aau.dk (K.S. Frahm).Aims: The exteroceptive sensory system is responsible forsensing external stimuli in relation to time and space. The aim ofthe study was to investigate the tempo-spatial properties of theexteroceptive system using laser heat and mechanical touch stimulation.Methods: 13 healthy subjects were stimulated in the volarforearm. Each subject was stimulated using two paradigms, acontinuous stimulation along a continuous line on the skin, anda simultaneous 2-point stimulation. The line stimulations weredelivered in both a distal and proximal direction with lengths of25, 50, 75, and 100 mm. The 2-point stimulations were deliveredwith a point-to-point distance ranging from 10 to 100 mm, in stepsof 10 mm. Both paradigms were delivered using painful heat (laser)stimulation and mechanical (touch) stimulation. Following eachstimulation, subjects had to report the intensity (0–10 NRS, 3 beingpain threshold) and either direction (line stimuli) or number ofperceived points (2-point stimuli).Results: All four line lengths and both directions were reportedcorrectly for all mechanical line stimulation (an accuracy of 100%).For laser line stimulation the directional discrimination thresholdwas 68.5 mm and 70.2 mm for distal and proximal directed stimuli,respectively. The 2-point discrimination threshold for heat stimulation (67.9 mm) was higher than for the mechanical stimulation(34.5 mm). NRS was significant higher for laser stimulations thanfor the mechanical stimulation for both line and 2-point stimulations. NRS increased both with line length and distance between thetwo points (ANOVA, p < 0.001). The average NRS was 3.15 and 0.91for laser line and mechanical line stimulations, respectively. For 2point stimulation the average NRS was 3.72 and 1.06 for laser andmechanical stimulations, respectively.Conclusions: The findings indicate that the tempo-spatial acuityof the exteroceptive system is lower for noxious stimuli than forinnoxious stimuli. This is possible due to the larger receptive fieldsof nociceptive neurons and/or less lateral inhibition.http://dx.doi.org/10.1016/j.sjpain.2017.04.021171The encoding of the thermal grill illusion in thehuman spinal cordF. Fardo a,b,∗ , N. Finnerup a , P. Haggard baDanish Pain Research Center, Aarhus University,Aarhus, Denmarkb Institute of Cognitive Neuroscience, UniversityCollege London, London, UKE-mail address: francesca@clin.au.dk (F. Fardo).Aims: The spatial alternation of innocuous cold and warmstimuli on the skin can paradoxically provoke a hot, burning sensation, known as the thermal-grill illusion (TGI). Whether the TGIdepends on spinal or supraspinal integration mechanisms is stilldebated. To assess whether the TGI can be accounted by integrationof cold and warm afferent signals in the spinal cord, we leveragedanatomical knowledge on the spatial arrangement of dermatomesand spinal segmental projections.Methods: We stimulated a series of skin locations on the rightarm using one cold (∼20 ◦ C) and one warm thermode (∼40 ◦ C). Thetwo stimulus locations had identical physical distance on the skin.However, the distance between the cold and heat projection signals in the spinal cord varied across three conditions. Cold andwarm inputs were delivered (1) within the same dermatome (e.g.,C5–C5); (2) across the dermatome boundary of two adjacent spinalsegments (e.g., C5–C6); (3) across the dermatome boundary of twonon-adjacent spinal segments (e.g., C5–T1). In two experiments, weobtained an estimate of the strength of the TGI by asking 32 healthyparticipants to complete a temperature matching task.Results: Participants overestimated the actual average temperature of the two thermodes (Exp. 1) and the cold temperature of oneof the two thermodes (Exp. 2). However, this effect was significantlylarger when cold and heat stimuli were delivered within the samedermatome (+6.57 ± 3.99 ◦ C and +9.88 ± 5.60 ◦ C) or between dermatomes projecting to adjacent spinal segments (+6.26 ± 4.44 ◦ Cand +9.48 ± 5.83 ◦ C), compared to when cold and heat stimuliprojected to non-adjacent spinal segments (+3.46 ± 4.46 ◦ C and+4.80 ± 3.21 ◦ C).Conclusions: These results demonstrate that the strength of theillusion is modulated by the segmental distance between cold andheat spinal signals, and show that the perceived quality and intensity of thermal stimuli depends upon low-level spatial summationmechanisms in the spinal cord.http://dx.doi.org/10.1016/j.sjpain.2017.04.022Effect of cocoa on endorphin levels andcraniofacial muscle sensitivity in healthyindividualsA.H. Simoni, A. Randers, K. Jønsson, S. Arpe, J.N.Poulsen, P. Gazerani ∗Department of Health Science and Technology,Aalborg University, Aalborg, DenmarkE-mail address: gazerani@hst.aau.dk (P. Gazerani).Aims: Migraine headache is a recurrent incapacitating neurovascular disorder. A combination of events occurring within thetrigeminovascular system has been suggested to underlie migrainepathogenesis, including release of inflammatory neuropeptideswith subsequent effects on meningeal vessels and sensory transmission. Increased craniofacial muscle tenderness is also presentin patients with migraine and a lower ␤-endorphin concentrationhas been observed in these patients. Several external factors havebeen identified, which can modulate migraine. One such factoris cocoa, though controversies still exist whether this substanceexerts pro-algesic or analgesic effects. The present study evaluated http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Scandinavian Journal of Pain de Gruyter

Tempo-spatial discrimination to non-noxious stimuli is better than for noxious stimuli

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© 2017 Scandinavian Association for the Study of Pain
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Abstract

Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188(p < 0.01). Increasing systolic blood pressure in the control group.Diastolic blood pressure decrease in tramadol and placebo groups.In the tramadol group, we saw more frequently mild side effects.Conclusions: Tramadol gave no reduction in postoperative painbut an increased frequency of desaturation and side effects. Otherdrugs or other doses ought to be tried for this kind of postoperativepain management.http://dx.doi.org/10.1016/j.sjpain.2017.04.020Tempo-spatial discrimination to non-noxiousstimuli is better than for noxious stimuliKen Steffen Frahm ∗ , Carsten Dahl Mørch, OleKæseler AndersenIntegrative Neuroscience Group, Center for®Neuroplasticity and Pain (CNAP), SMI , Departmentof Health Science & Technology, Aalborg University,9220 Aalborg, DenmarkE-mail address: ksf@hst.aau.dk (K.S. Frahm).Aims: The exteroceptive sensory system is responsible forsensing external stimuli in relation to time and space. The aim ofthe study was to investigate the tempo-spatial properties of theexteroceptive system using laser heat and mechanical touch stimulation.Methods: 13 healthy subjects were stimulated in the volarforearm. Each subject was stimulated using two paradigms, acontinuous stimulation along a continuous line on the skin, anda simultaneous 2-point stimulation. The line stimulations weredelivered in both a distal and proximal direction with lengths of25, 50, 75, and 100 mm. The 2-point stimulations were deliveredwith a point-to-point distance ranging from 10 to 100 mm, in stepsof 10 mm. Both paradigms were delivered using painful heat (laser)stimulation and mechanical (touch) stimulation. Following eachstimulation, subjects had to report the intensity (0–10 NRS, 3 beingpain threshold) and either direction (line stimuli) or number ofperceived points (2-point stimuli).Results: All four line lengths and both directions were reportedcorrectly for all mechanical line stimulation (an accuracy of 100%).For laser line stimulation the directional discrimination thresholdwas 68.5 mm and 70.2 mm for distal and proximal directed stimuli,respectively. The 2-point discrimination threshold for heat stimulation (67.9 mm) was higher than for the mechanical stimulation(34.5 mm). NRS was significant higher for laser stimulations thanfor the mechanical stimulation for both line and 2-point stimulations. NRS increased both with line length and distance between thetwo points (ANOVA, p < 0.001). The average NRS was 3.15 and 0.91for laser line and mechanical line stimulations, respectively. For 2point stimulation the average NRS was 3.72 and 1.06 for laser andmechanical stimulations, respectively.Conclusions: The findings indicate that the tempo-spatial acuityof the exteroceptive system is lower for noxious stimuli than forinnoxious stimuli. This is possible due to the larger receptive fieldsof nociceptive neurons and/or less lateral inhibition.http://dx.doi.org/10.1016/j.sjpain.2017.04.021171The encoding of the thermal grill illusion in thehuman spinal cordF. Fardo a,b,∗ , N. Finnerup a , P. Haggard baDanish Pain Research Center, Aarhus University,Aarhus, Denmarkb Institute of Cognitive Neuroscience, UniversityCollege London, London, UKE-mail address: francesca@clin.au.dk (F. Fardo).Aims: The spatial alternation of innocuous cold and warmstimuli on the skin can paradoxically provoke a hot, burning sensation, known as the thermal-grill illusion (TGI). Whether the TGIdepends on spinal or supraspinal integration mechanisms is stilldebated. To assess whether the TGI can be accounted by integrationof cold and warm afferent signals in the spinal cord, we leveragedanatomical knowledge on the spatial arrangement of dermatomesand spinal segmental projections.Methods: We stimulated a series of skin locations on the rightarm using one cold (∼20 ◦ C) and one warm thermode (∼40 ◦ C). Thetwo stimulus locations had identical physical distance on the skin.However, the distance between the cold and heat projection signals in the spinal cord varied across three conditions. Cold andwarm inputs were delivered (1) within the same dermatome (e.g.,C5–C5); (2) across the dermatome boundary of two adjacent spinalsegments (e.g., C5–C6); (3) across the dermatome boundary of twonon-adjacent spinal segments (e.g., C5–T1). In two experiments, weobtained an estimate of the strength of the TGI by asking 32 healthyparticipants to complete a temperature matching task.Results: Participants overestimated the actual average temperature of the two thermodes (Exp. 1) and the cold temperature of oneof the two thermodes (Exp. 2). However, this effect was significantlylarger when cold and heat stimuli were delivered within the samedermatome (+6.57 ± 3.99 ◦ C and +9.88 ± 5.60 ◦ C) or between dermatomes projecting to adjacent spinal segments (+6.26 ± 4.44 ◦ Cand +9.48 ± 5.83 ◦ C), compared to when cold and heat stimuliprojected to non-adjacent spinal segments (+3.46 ± 4.46 ◦ C and+4.80 ± 3.21 ◦ C).Conclusions: These results demonstrate that the strength of theillusion is modulated by the segmental distance between cold andheat spinal signals, and show that the perceived quality and intensity of thermal stimuli depends upon low-level spatial summationmechanisms in the spinal cord.http://dx.doi.org/10.1016/j.sjpain.2017.04.022Effect of cocoa on endorphin levels andcraniofacial muscle sensitivity in healthyindividualsA.H. Simoni, A. Randers, K. Jønsson, S. Arpe, J.N.Poulsen, P. Gazerani ∗Department of Health Science and Technology,Aalborg University, Aalborg, DenmarkE-mail address: gazerani@hst.aau.dk (P. Gazerani).Aims: Migraine headache is a recurrent incapacitating neurovascular disorder. A combination of events occurring within thetrigeminovascular system has been suggested to underlie migrainepathogenesis, including release of inflammatory neuropeptideswith subsequent effects on meningeal vessels and sensory transmission. Increased craniofacial muscle tenderness is also presentin patients with migraine and a lower ␤-endorphin concentrationhas been observed in these patients. Several external factors havebeen identified, which can modulate migraine. One such factoris cocoa, though controversies still exist whether this substanceexerts pro-algesic or analgesic effects. The present study evaluated

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Scandinavian Journal of Painde Gruyter

Published: Dec 29, 2017

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