scholarly journals A quantification of the relationship between neuronal responses in the rat rostral ventromedial medulla and noxious stimulation-evoked withdrawal reflexes

2015 ◽  
Vol 42 (1) ◽  
pp. 1726-1737 ◽  
Author(s):  
I. M. Devonshire ◽  
C. H. T. Kwok ◽  
A. Suvik ◽  
A. R. Haywood ◽  
A. H. Cooper ◽  
...  
Keyword(s):  
Rostral Ventromedial Medulla ◽  
Noxious Stimulation ◽  
Neuronal Responses ◽  
Ventromedial Medulla ◽  
Withdrawal Reflexes ◽  
The Relationship

Activity of most rostral ventromedial medulla neurons reflect EEG/EMG pattern changes

1989 ◽  
Vol 257 (6) ◽  
pp. R1496-R1505 ◽  
Author(s):  
D. A. Grahn ◽  
H. C. Heller
Keyword(s):  
Single Unit ◽  
Cortical Activation ◽  
Rostral Ventromedial Medulla ◽  
Emg Activity ◽  
Single Unit Activity ◽  
Neuronal Responses ◽  
Peripheral Stimulation ◽  
Ventromedial Medulla ◽  
Emg Patterns ◽  
Eeg Pattern

Studies in lightly anesthetized animals have demonstrated neurons in the rostral ventromedial medulla (RVM) that respond to specific modalities of peripheral stimulation. We initiated this study to investigate putative thermoafferent processing in such RVM neurons. Our results indicate that most RVM neuronal responses are not specific for the applied stimulus but reflect changes in cortical activation. Electroencephalogram/electromyogram (EEG/EMG) and RVM single unit activity was recorded in lightly urethan-anesthetized rats. Five distinct EEG/EMG patterns were observed. Their expression was a function of skin and core temperatures. Pinches and strong thermal manipulations caused a desynchronization of a synchronized EEG pattern and an increase in EMG activity. The activity of 38 of the 51 RVM neurons sampled correlated with changes in EEG/EMG activity. Thirteen neurons were not affected by changes in EEG/EMG activity. One unit responded to temperature manipulations within an EEG/EMG state, suggesting that a small portion of RVM neurons may transmit thermoafferent information.

scholarly journals Supraspinal Opioid Circuits Differentially Modulate Spinal Neuronal Responses in Neuropathic Rats

2020 ◽  
Vol 132 (4) ◽  
pp. 881-894 ◽  
Author(s):  
Anthony H. Dickenson ◽  
Edita Navratilova ◽  
Ryan Patel ◽  
Frank Porreca ◽  
Kirsty Bannister
Keyword(s):  
Anterior Cingulate Cortex ◽  
Cingulate Cortex ◽  
Neuronal Firing ◽  
Anterior Cingulate ◽  
Central Nucleus ◽  
Rostral Ventromedial Medulla ◽  
Evoked Responses ◽  
Neuronal Responses ◽  
Ventromedial Medulla ◽  
Control Response

Abstract Background The anterior cingulate cortex and central nucleus of the amygdala connect widely with brainstem nuclei involved in descending modulation, including the rostral ventromedial medulla. Endogenous opioids in these circuits participate in pain modulation. The hypothesis was that a differential opioidergic role for the brain nuclei listed in regulation of spinal neuronal responses because separable effects on pain behaviors in awake animals were previously observed. Methods This study utilized in vivo electrophysiology to determine the effects of morphine microinjection into the anterior cingulate cortex, right or left central nucleus of the amygdala, or the rostral ventromedial medulla on spinal wide dynamic range neuronal responses in isoflurane-anesthetized, male Sprague–Dawley rats. Ongoing activity in the ventrobasal thalamus was also measured. In total, 33 spinal nerve ligated and 26 control age- and weight-matched control rats were used. Results Brainstem morphine reduced neuronal firing to 60-g von Frey stimulation in control rats (to 65 ± 12% of control response (means ± 95% CI), P < 0.001) with a greater inhibition in neuropathic rats (to 53 ± 17% of control response, P < 0.001). Contrasting anterior cingulate cortex morphine had only marginal modulatory effects on spinal neuronal responses with limited variance in effect between control and neuropathic rats. The inhibitory effects of morphine in the central nucleus of the amygdala were dependent on pain state and laterality; only right-side morphine reduced neuronal firing to 60-g stimulation in neuropathic rats (to 65 ± 14% of control response, P = 0.001). In addition, in neuropathic rats elevated ongoing neuronal activity in the ventral posterolateral thalamus was not inhibited by anterior cingulate cortex morphine, in contrast to evoked responses. Conclusions Cumulatively the data support opioid modulation of evoked responses predominately through a lateralized output from the right amygdala, as well as from the brainstem that is enhanced in injured conditions. Minimal modulation of dorsal horn responses was observed after anterior cingulate cortex opioid administration regardless of injury state. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

scholarly journals Activation of rostral ventromedial medulla neurons by noxious stimulation of cutaneous and deep craniofacial tissues

2015 ◽  
Vol 113 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Sergey G. Khasabov ◽  
Patrick Malecha ◽  
Joseph Noack ◽  
Janneta Tabakov ◽  
Keiichiro Okamoto ◽  
...  
Keyword(s):  
Ocular Surface ◽  
Dose Effect ◽  
Male Rats ◽  
Rostral Ventromedial Medulla ◽  
Noxious Stimulation ◽  
Nociceptive Transmission ◽  
Ventromedial Medulla ◽  
On And Off Cells ◽  
Stimulation Of

The rostral ventromedial medulla (RVM) projects to the medullary and spinal dorsal horns and is a major source of descending modulation of nociceptive transmission. Traditionally, neurons in the RVM are classified functionally as ON, OFF, and NEUTRAL cells on the basis of responses to noxious cutaneous stimulation of the tail or hind paw. ON cells facilitate nociceptive transmission, OFF cells are inhibitory, whereas NEUTRAL cells are unresponsive to noxious stimuli and their role in pain modulation is unclear. Classification of RVM neurons with respect to stimulation of craniofacial tissues is not well defined. In isoflurane-anesthetized male rats, RVM neurons first were classified as ON (25.5%), OFF (25.5%), or NEUTRAL (49%) cells by noxious pinch applied to the hind paw. Pinching the skin overlying the temporomandibular joint (TMJ) altered the proportions of ON (39.2%), OFF (42.2%), and NEUTRAL (19.6%) cells. To assess the response of RVM cells to specialized craniofacial inputs, adenosine triphosphate (ATP; 0.01–1 mM) was injected into the TMJ and capsaicin (0.1%) was applied to the ocular surface. TMJ and ocular surface stimulation also resulted in a reduced proportion of NEUTRAL cells compared with hind paw pinch. Dose-effect analyses revealed that ON and OFF cells encoded the intra-TMJ concentration of ATP. These results suggest that somatotopy plays a significant role in the functional classification of RVM cells and support the notion that NEUTRAL cells likely are subgroups of ON and OFF cells. It is suggested that a portion of RVM neurons serve different functions in modulating craniofacial and spinal pain conditions.

Responses of neurons in rostral ventromedial medulla to nociceptive stimulation of craniofacial region and tail in rats

2021 ◽  
pp. 147539
Author(s):  
Jing-Shi Tang ◽  
Chen Yu Chiang ◽  
Jonathan O. Dostrovsky ◽  
Dongyuan Yao ◽  
Barry J. Sessle
Keyword(s):  
Rostral Ventromedial Medulla ◽  
Nociceptive Stimulation ◽  
Ventromedial Medulla ◽  
Stimulation Of

Current understanding of premonitory networks in migraine: A window to attack generation

Cephalalgia ◽  
2019 ◽  
Vol 39 (13) ◽  
pp. 1720-1727 ◽  
Author(s):  
Laura H Schulte ◽  
Kuan-Po Peng
Keyword(s):  
Sleep Disturbances ◽  
Integration Site ◽  
Basic Research ◽  
Rostral Ventromedial Medulla ◽  
Spinal Trigeminal Nucleus ◽  
Migraine Headaches ◽  
Migraine Pain ◽  
Ventromedial Medulla ◽  
External Stimuli ◽  
Premonitory Symptoms

Aim To describe neuronal networks underlying commonly reported migraine premonitory symptoms and to discuss how these might precipitate migraine pain. Background Migraine headache is frequently preceded by a distinct and well characterized premonitory phase including symptoms like yawning, sleep disturbances, alterations in appetite and food intake and hypersensitivity to certain external stimuli. Recent neuroimaging studies strongly suggest the hypothalamus as the key mediator of the premonitory phase and also suggested alterations in hypothalamic networks as a mechanism of migraine attack generation. When looking at the vast evidence from basic research within the last decades, hypothalamic and thalamic networks are most likely to integrate peripheral influences with central mechanisms, facilitating the precipitation of migraine headaches. These networks include sleep, feeding and stress modulating centers within the hypothalamus, thalamic pathways and brainstem centers closely involved in trigeminal pain processing such as the spinal trigeminal nucleus and the rostral ventromedial medulla, all of which are closely interconnected. Conclusion Taken together, these networks represent the pathophysiological basis for migraine premonitory symptoms as well as a possible integration site of peripheral so-called “triggers” with central attack facilitating processes.

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