Organization of the Thermal Grill Illusion by Spinal Segments

The thermal grill illusion (TGI) is a paradoxical perception of burning heat and pain resulting from the simultaneous application of interlaced warm and cold stimuli to the skin. The TGI is considered a type of chronic centralized pain and has been used to apply nociceptive stimuli without inflicting harm to human participants in the study of pain mechanisms. In addition, the TGI is an interesting phenomenon for researchers, and various topics related to the TGI have been investigated in several studies, which we will review here. According to previous studies, the TGI is generated by supraspinal interactions. To evoke the TGI, cold and warm cutaneous stimuli should be applied within the same dermatome or across dermatomes corresponding to adjacent spinal segments, and a significant difference between cold and warm temperatures is necessary. In addition, due the presence of chronic pain, genetic factors, and sexual differences, the intensity of the TGI can differ. In addition, cold noxious stimulation, topical capsaicin, analgesics, self-touch, and the presence of psychological diseases can decrease the intensity of the TGI. Because the TGI corresponds to chronic centralized pain, we believe that the findings of previous studies can be applied to future studies to identify chronic pain mechanisms and clinical practice for pain management.

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The encoding of the thermal grill illusion in the human spinal cord

Scandinavian Journal of Pain ◽

10.1016/j.sjpain.2017.04.022 ◽

2017 ◽

Vol 16 (1) ◽

pp. 171-171

Author(s):

F. Fardo ◽

N. Finnerup ◽

P. Haggard

Keyword(s):

Spinal Cord ◽

Spatial Summation ◽

Spatial Arrangement ◽

Physical Distance ◽

Matching Task ◽

Human Spinal Cord ◽

Thermal Grill Illusion ◽

Spinal Segments ◽

Integration Mechanisms ◽

The Right

Abstract Aims The spatial alternation of innocuous cold and warm stimuli on the skin can paradoxically provoke a hot, burning sensation, known as the thermal-grill illusion (TGI). Whether the TGI depends on spinal or supraspinal integration mechanisms is still debated. To assess whether the TGI can be accounted by integration of cold and warm afferent signals in the spinal cord, we leveraged anatomical knowledge on the spatial arrangement of dermatomes and spinal segmental projections. Methods We stimulated a series of skin locations on the right arm using one cold (∼20 °C) and one warm thermode (∼40°C). The two 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 and warm inputs were delivered (1) within the same dermatome (e.g., C5–C5); (2) across the dermatome boundary of two adjacent spinal segments (e.g., C5–C6); (3) across the dermatome boundary of two non-adjacent spinal segments (e.g., C5–T1). In two experiments, we obtained an estimate of the strength of the TGI by asking 32 healthy participants to complete a temperature matching task. Results Participants overestimated the actual average temperature of the two thermodes (Exp. 1) and the cold temperature of one of the two thermodes (Exp. 2). However, this effect was significantly larger when cold and heat stimuli were delivered within the same dermatome (+6.57 ± 3.99°C and +9.88 ± 5.60 °C) or between dermatomes projecting to adjacent spinal segments (+6.26 ±4.44°C and +9.48 ± 5.83 °C), compared to when cold and heat stimuli projected to non-adjacent spinal segments (+3.46 ± 4.46 °C and +4.80 ± 3.21 °C). Conclusions These results demonstrate that the strength of the illusion is modulated by the segmental distance between cold and heat spinal signals, and show that the perceived quality and intensity of thermal stimuli depends upon low-level spatial summation mechanisms in the spinal cord.

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Commissural Interneurons in Rhythm Generation and Intersegmental Coupling in the Lamprey Spinal Cord

Journal of Neurophysiology ◽

10.1152/jn.1999.81.5.2037 ◽

1999 ◽

Vol 81 (5) ◽

pp. 2037-2045 ◽

Cited By ~ 44

Author(s):

James T. Buchanan

Keyword(s):

Spinal Cord ◽

Amino Acid ◽

Excitatory Amino Acid ◽

Rhythmic Activity ◽

Ventral Root ◽

Rhythm Generation ◽

Spinal Segment ◽

Spinal Segments ◽

Autocorrelation Method

Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord. To test the necessity of spinal commissural interneurons in the generation of the swim rhythm in lamprey, longitudinal midline cuts of the isolated spinal cord preparation were made. Fictive swimming was then induced by bath perfusion with an excitatory amino acid while recording ventral root activity. When the spinal cord preparation was cut completely along the midline into two lateral hemicords, the rhythmic activity of fictive swimming was lost, usually replaced with continuous ventral root spiking. The loss of the fictive swim rhythm was not due to nonspecific damage produced by the cut because rhythmic activity was present in split regions of spinal cord when the split region was still attached to intact cord. The quality of this persistent rhythmic activity, quantified with an autocorrelation method, declined with the distance of the split spinal segment from the remaining intact spinal cord. The deterioration of the rhythm was characterized by a lengthening of burst durations and a shortening of the interburst silent phases. This pattern of deterioration suggests a loss of rhythmic inhibitory inputs. The same pattern of rhythm deterioration was seen in preparations with the rostral end of the spinal cord cut compared with those with the caudal end cut. The results of this study indicate that commissural interneurons are necessary for the generation of the swimming rhythm in the lamprey spinal cord, and the characteristic loss of the silent interburst phases of the swimming rhythm is consistent with a loss of inhibitory commissural interneurons. The results also suggest that both descending and ascending commissural interneurons are important in the generation of the swimming rhythm. The swim rhythm that persists in the split cord while still attached to an intact portion of spinal cord is thus imposed by interneurons projecting from the intact region of cord into the split region. These projections are functionally short because rhythmic activity was lost within approximately five spinal segments from the intact region of spinal cord.

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Central neuropathic pain in multiple sclerosis is associated with impaired innocuous thermal pathways and neuronal hyperexcitability

Pain Medicine ◽

10.1093/pm/pnab103 ◽

2021 ◽

Author(s):

Michal Rivel ◽

Anat Achiron ◽

Mark Dolev ◽

Yael Stern ◽

Gaby Zeilig ◽

...

Keyword(s):

Multiple Sclerosis ◽

Neuropathic Pain ◽

Cross Sectional Study ◽

Healthy Controls ◽

Sectional Study ◽

Sensory Testing ◽

Cross Sectional ◽

Central Neuropathic Pain ◽

Body Regions ◽

Thermal Grill Illusion

Abstract Objective About a third of patients with multiple sclerosis (MS) suffer from chronic and excruciating central neuropathic pain (CNP). The mechanism underlying CNP in MS is not clear, since previous studies are scarce and their results are inconsistent. Our aim was to determine whether CNP in MS is associated with impairment of the spinothalamic-thalamocortical pathways (STTCs) and/or increased excitability of the pain system. Design Cross sectional study Setting General hospital Subjects 47 MS patients with CNP, 42 MS patients without CNP, and 32 healthy controls. Methods Sensory testing included the measurement of temperature, pain, and touch thresholds and the thermal grill illusion (TGI) for evaluating STTCs function, and hyperpathia and allodynia as indicators of hyperexcitability. CNP was characterized using interviews and questionnaires. Results The CNP group had higher cold and warm thresholds (p < 0.01), as well as higher TGI perception thresholds (p < 0.05), especially in painful body regions compared to controls, whereas touch and pain thresholds values were normal. The CNP group also had a significantly greater prevalence of hyperpathia and allodynia. Regression analysis revealed that whereas presence of CNP was associated with a higher cold threshold, CNP intensity, and the number of painful body regions were associated with allodynia and hyperpathia, respectively. Conclusions CNP in MS is characterized by a specific impairment of STTC function; the innocuous thermal pathways, and by pain hyperexcitability. Whereas CNP presence is associated with STTC impairment, its severity and extent are associated with pain hyperexcitability. Interventions that reduce excitability level may therefore mitigate CNP severity.

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Natural History and Clinical Outcomes of Paravertebral Arteriovenous Shunts

Stroke ◽

10.1161/strokeaha.120.033963 ◽

2021 ◽

Author(s):

Yueshan Feng ◽

Jiaxing Yu ◽

Jiankun Xu ◽

Chuan He ◽

Lisong Bian ◽

...

Keyword(s):

Natural History ◽

Clinical Outcomes ◽

Clinical Intervention ◽

Type A ◽

Neurological Deficits ◽

Type B ◽

Deterioration Rate ◽

Arteriovenous Shunts ◽

Spinal Segments

Background and Purpose: Paravertebral arteriovenous shunts (PVAVSs) are rare. Whether the intradural venous system is involved in drainage may lead to differences in clinical characteristics through specific pathophysiological mechanisms. This study aims to comprehensively evaluate the natural history and clinical outcomes of PVAVSs with or without intradural drainage. Methods: Sixty-four consecutive patients with PVAVSs from 2 institutes were retrospectively reviewed. Lesions were classified as type A (n=28) if the intradural veins were involved in drainage; otherwise, they were classified as type B (n=36). The clinical course from initial presentation to the last follow-up was analyzed. Results: The patients with type A shunts were older at presentation (52.5 versus 35.5 years, P <0.0001) and more likely to have lower spinal segments affected than patients with type B PVAVSs (67.8% versus 13.9%, P =0.00006). After presentation, the deterioration rates related to gait and sphincter dysfunction were significantly higher in patients with type A than type B shunts (gait dysfunction: 71.8%/y versus 17.0%/y, P =0.0006; sphincter dysfunction: 63.7%/y versus 11.3%/y, P =0.0002). According to the angiogram at the end of the latest treatment, 79% of type A and 75% of type B PVAVSs were completely obliterated. If the lesions were partially obliterated, a significantly higher clinical deterioration rate was observed in patients with type A shunts than those with type B shunts (69.9%/y versus 3.2%/y, P =0.0253). Conclusions: Type A PVAVSs feature rapid progressive neurological deficits; therefore, early clinical intervention is necessary. For complex lesions that cannot be completely obliterated, surgical disconnection of all refluxed radicular veins is suggested.

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Load-Displacement Characteristics of an Implanted Nuclear Pouch in the Lumbar Spine

10.1115/imece1999-0441 ◽

1999 ◽

Author(s):

Andrew P. Dooris ◽

Nicole M. Grosland ◽

Vijay K. Goel ◽

John S. Drake ◽

James W. Ahern ◽

...

Keyword(s):

Lumbar Spine ◽

Nuclear Space ◽

Patient Exposure ◽

Active Joint ◽

Surgical Morbidity ◽

Bone Chip ◽

Spinal Segments ◽

Load Displacement ◽

Graft Implantation

Abstract Fusion of the spinal segments is typically done to prevent or correct deformity, stabilize the spine after trauma or pathologic destruction, or eliminate painful movement of the spinal segments. Spinal interbody arthrodesis typically requires considerable patient exposure, necessary for discectomy and graft implantation, and resultant morbidity. Some researchers suggest nuclear replacements as active joint mobilizers, while others suggest full disc replacements, and although some biomechanical consideration has been given, results are unclear. We consider here a device which proposes to reduce surgical morbidity while promoting stability by fusion. The device investigated here is a bone-chip pouch, which fills the nuclear space. We present here initial findings of this device in lumbar cadaveric specimens.

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Synchronization of cardiac-related discharges of sympathetic nerves with inputs from widely separated spinal segments

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1995.268.6.r1472 ◽

1995 ◽

Vol 268 (6) ◽

pp. R1472-R1483 ◽

Cited By ~ 3

Author(s):

G. L. Gebber ◽

S. Zhong ◽

S. M. Barman

Keyword(s):

Phase Angle ◽

Cervical Spinal Cord ◽

Sympathetic Nerves ◽

Time Interval ◽

Renal Nerve ◽

Cardiac Nerve ◽

Spinal Segments ◽

The Difference ◽

Decerebrate Cats ◽

Inferior Cardiac Nerve

We used phase spectral analysis to study the relationships between the cardiac-related discharges of pairs of postganglionic sympathetic nerves in urethan-anesthetized or decerebrate cats. Phase angle when converted to a time interval should equal the difference in conduction times from the brain to the nerves (i.e., transportation lag) if their cardiac-related discharges have a common central source. Transportation lag was estimated as the difference in the onset latencies of activation of the nerves by electrical stimulation of the medulla or cervical spinal cord. The phase angle for the cardiac-related discharges of two nerves was not always equivalent in time to the transportation lag. For example, in some cases the cardiac-related discharges of the renal nerve were coincident with or led those of the inferior cardiac nerve. In contrast, the electrically evoked responses of the renal nerve lagged those of the inferior cardiac nerve by > or = 32 ms. These observations are consistent with a model of multiple and dynamically coupled brain stem generators of the cardiac-related rhythm, each controlling a different sympathetic nerve or exerting nonuniform influences on different portions of the spinal sympathetic outflow.

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Spinal stimulation to locate preganglionic neurons controlling the kidney, spleen, or intestine

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1992.263.4.h1026 ◽

1992 ◽

Vol 263 (4) ◽

pp. H1026-H1033 ◽

Cited By ~ 3

Author(s):

R. B. Taylor ◽

L. C. Weaver

Keyword(s):

Spinal Cord ◽

Sympathetic Outflow ◽

Renal Nerve ◽

Homocysteic Acid ◽

Sympathetic Control ◽

The Third ◽

Preganglionic Neurons ◽

Spinal Segments ◽

Vascular Beds ◽

Nerve Discharge

The organization of sympathetic preganglionic neurons may be a substrate for selective control of sympathetic outflow to different vascular beds. This study was done to determine the spinal segments containing preganglionic neurons controlling discharge of renal, splenic, and mesenteric postganglionic nerves. In urethan-anesthetized rats, preganglionic neurons were stimulated by microinjecting D,L-homocysteic acid (3 nl, 0.17 M) into the lateral gray matter of the third thoracic (T3) to the fourth lumbar (L4) spinal segments. Responses from all three nerves could be elicited from segments T4-T13. The greatest increases in renal nerve discharge were evoked from segments T8-T12, the largest increase of 59 +/- 9% elicited from T10. Increases in splenic and mesenteric nerve discharge were smaller and were evoked more uniformly from T4-L3. The largest increases in discharge of splenic and mesenteric nerves were 19 +/- 5% (from T5) and 26 +/- 4% (from T10), respectively. The widely overlapping spinal cord segments controlling these three organs suggest that location of the preganglionic neurons in different spinal segments is not part of the mechanism for selective sympathetic control. However, the larger renal nerve responses demonstrate that sympathetic output to these organs can be differentiated at the level of the spinal cord.

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Experimental Spinal Cord Injury: Spatiotemporal Characterization of Elemental Concentrations and Water Contents in Axons and Neuroglia

Journal of Neurophysiology ◽

10.1152/jn.1999.82.5.2143 ◽

1999 ◽

Vol 82 (5) ◽

pp. 2143-2153 ◽

Cited By ~ 24

Author(s):

Richard M. LoPachin ◽

Christopher L. Gaughan ◽

Ellen J. Lehning ◽

Yoshiro Kaneko ◽

Thomas M. Kelly ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Water Content ◽

Severely Injured ◽

Channel Blockade ◽

Compression Injury ◽

Ion Distribution ◽

Elemental Concentrations ◽

Cord Injury ◽

Spinal Segments

To examine the role of axonal ion deregulation in acute spinal cord injury (SCI), white matter strips from guinea pig spinal cord were incubated in vitro and were subjected to graded focal compression injury. At several postinjury times, spinal segments were removed from incubation and rapidly frozen. X-ray microanalysis was used to measure percent water and dry weight elemental concentrations (mmol/kg) of Na, P, Cl, K, Ca, and Mg in selected morphological compartments of myelinated axons and neuroglia from spinal cord cryosections. As an index of axon function, compound action potentials (CAP) were measured before compression and at several times thereafter. Axons and mitochondria in epicenter of severely compressed spinal segments exhibited early (5 min) increases in mean Na and decreases in K and Mg concentrations. These elemental changes were correlated to a significant reduction in CAP amplitude. At later postcompression times (15 and 60 min), elemental changes progressed and were accompanied by alterations in compartmental water content and increases in mean Ca. Swollen axons were evident at all postinjury times and were characterized by marked element and water deregulation. Neuroglia and myelin in severely injured epicenter also exhibited significant disruptions. In shoulder areas (adjacent to epicenter) of severely injured spinal strips, axons and mitochondria exhibited modest increases in mean Na in conjunction with decreases in K, Mg, and water content. Following moderate compression injury to spinal strips, epicenter axons exhibited early (10 min postinjury) element and water deregulation that eventually recovered to near control values (60 min postinjury). Na+ channel blockade by tetrodotoxin (TTX, 1 μM) perfusion initiated 5 min after severe crush diminished both K loss and the accumulation of Na, Cl, and Ca in epicenter axons and neuroglia, whereas in shoulder regions TTX perfusion completely prevented subcellular elemental deregulation. TTX perfusion also reduced Na entry in swollen axons but did not affect K loss or Ca gain. Thus graded compression injury of spinal cord produced subcellular elemental deregulation in axons and neuroglia that correlated with the onset of impaired electrophysiological function and neuropathological alterations. This suggests that the mechanism of acute SCI-induced structural and functional deficits are mediated by disruption of subcellular ion distribution. The ability of TTX to reduce elemental deregulation in compression-injured axons and neuroglia implicates a significant pathophysiological role for Na+ influx in SCI and suggests Na+ channel blockade as a pharmacotherapeutic strategy.

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Degenerative axonopathy associated with copper deficiency in pigs

Pesquisa Veterinária Brasileira ◽

10.1590/s0100-736x2017000900002 ◽

2017 ◽

Vol 37 (9) ◽

pp. 911-915 ◽

Cited By ~ 1

Author(s):

Roberio G. Olinda ◽

Lisanka A. Maia ◽

Maria T.S. Frade ◽

Mauro P. Soares ◽

Severo S. Barros ◽

...

Keyword(s):

White Matter ◽

Purkinje Cells ◽

Copper Deficiency ◽

Clinical Signs ◽

Atomic Absorption Spectrophotometry ◽

Semiarid Region ◽

Spastic Paralysis ◽

Myelin Sheaths ◽

Cu Deficiency ◽

Spinal Segments

ABSTRACT: The epidemiological, clinic and morphological (pathological and ultrastructural) aspects of four outbreaks of copper deficiency affecting 21- to 90-day-old pigs in the Northeast region of Brazil are reported. Clinical signs began with paraparesis and ataxia and progressed to flaccid or spastic paralysis of the pelvic and thoracic limbs, followed by sternal and/or lateral recumbence. In addition, some animals showed dog-sitting position and intention tremors. The clinical manifestation period was 5-20 days. Significant gross lesions were not observed; however, microscopically, symmetrical degeneration of the white matter with ballooned myelin sheaths containing occasional macrophages was observed, mainly in the spinal cord. Two pigs presented with necrosis ad loss of Purkinje cells and ectopic Purkinje cells in the granular layer and cerebellar white matter. A ultrastructural analysis showed different degrees of damage of myelinated axons in the spinal segments, including an absence of the axoplasm structures with only axonal residues remaining. The myelin sheaths were degenerated and often collapsed into the space previously occupied by the axon. These results suggest that myelin degeneration is secondary to the axonal lesion. Finally, the concentration of copper in the liver was determined using atomic absorption spectrophotometry and was found to be low (ranging from 2.2 to 10.8 ppm). In conclusion, in the Brazilian semiarid region, Cu deficiency occurs in 21 to 90-day-old pigs that ingested different types of waste in their food.

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