Opiate microinjections into midbrain do not affect the aversiveness of caudal trigeminal stimulation but produce somatotopically organized peripheral hypoalgesia

Kasman, Glenn S.; Rosenfeld, J. Peter

doi:10.1016/0006-8993(86)90025-9

Cited by 7 publications

(3 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our study is the first to demonstrate such a somatotopic effect in key regions of the descending pain modulatory system. Although the PAG is an important downstream control area of the descending pain modulatory system (Bingel and Tracey, 2008;Heinricher et al, 2009) and animal data have previously suggested at least a coarse somatotopic representation of body quadrants (Soper and Melzack, 1982;Kasman and Rosenfeld, 1986), it did not allow for classification in our study. This is likely to be explained by the particularly small size, shape, and location around the aqueduct of the PAG that renders normalization procedures difficult and reduces the sensitivity of MVPA approaches.…”

Section: Discussionmentioning

confidence: 68%

Representation of Spatial Information in Key Areas of the Descending Pain Modulatory System

2014

View full text Add to dashboard Cite

Behavioral studies have demonstrated that descending pain modulation can be spatially specific, as is evident in placebo analgesia, which can be limited to the location at which pain relief is expected. This suggests that higher-order cortical structures of the descending pain modulatory system carry spatial information about the site of stimulation. Here, we used functional magnetic resonance imaging and multivariate pattern analysis in 15 healthy human volunteers to test whether spatial information of painful stimuli is represented in areas of the descending pain modulatory system. We show that the site of nociceptive stimulation (arm or leg) can be successfully decoded from local patterns of brain activity during the anticipation and receipt of painful stimulation in the rostral anterior cingulate cortex, the dorsolateral prefrontal cortices, and the contralateral parietal operculum. These results demonstrate that information regarding the site of nociceptive stimulation is represented in these brain regions. Attempts to predict arm and leg stimulation from the periaqueductal gray, control regions (e.g., white matter) or the control time interval in the intertrial phase did not allow for classifications above chance level. This finding represents an important conceptual advance in the understanding of endogenous pain control mechanisms by bridging the gap between previous behavioral and neuroimaging studies, suggesting a spatial specificity of endogenous pain control.

show abstract

Section: Discussionmentioning

confidence: 68%

Representation of Spatial Information in Key Areas of the Descending Pain Modulatory System

2014

View full text Add to dashboard Cite

show abstract

“…PAG stimulation has been shown to induce analgesia for several weeks that was naloxone reversible, and thus depended on opioid mechanisms 15. Furthermore, a rough somatotopy has been demonstrated that affected distinct extremities16 and upper versus lower body parts17 differently. Therefore, placebo analgesia that is specific for one foot and lasts throughout an experiment of 1 hour can possibly be mediated by this structure.…”

Section: Discussionmentioning

confidence: 99%

Somatotopy of placebo analgesia is independent of spatial attention

Domnick

Lorenz²,

Hauck³

2011

JPR

View full text Add to dashboard Cite

Placebo analgesia is being increasingly appraised as an effective support of pharmacological and surgical treatments of pain. The understanding of its neurobiological and psychological basis is therefore of high clinical relevance. It has been shown that placebo analgesia is somatotopically organized and relies on endogenous opioids. However, it is not clear whether temporal fluctuations of cue-dependent spatial attention account for the site specificity of placebo analgesia or whether a somatotopic placebo effect is possible without an attentional focus on the respective location. To address this issue we induced placebo expectations for one specific foot in healthy subjects, the other foot serving as a control location. The feet were stimulated in random order by painful laser stimuli. Half of the pulses were cued for stimulus location, whereas in the other half of trials the subjects were naïve about the location. We found that about half of the subjects exhibited a somatotopic placebo effect that was statistically independent of the spatial cue. We suggest that, after the induction of an initial expectation, placebo analgesia is spatially specific but does not necessarily depend on momentary fluctuations of spatial attention. This result rather suggests that the somatotopy of placebo analgesia relies on the creation of spatially guided expectations or conditioning, but can be maintained without ongoing monitoring of the affected body part.

show abstract

“…Morphine injection into the periaqueductal gray (PAG) elicited a dose-dependent, naloxone-reversible increase in body temperature (Widdowson et al 1983;Zhukov et al 1988). Injection sites producing hyperthermia were distributed mostly in the caudal ventral PAG, many of them also increasing TFL (Shen et al 1986), as already described for morphine (Guo and Tang 1990;Iwamoto et al 1978;Yaksh 1986, 1989;Kasman and Rosenfeld 1986;Levy and Proudfit 1979;Lewis and Gebhart 1977;Tortorici and Morgan 2002;Urban and Smith 1994;Yaksh et al 1976Yaksh et al , 1988Yeung et al 1977Yeung et al , 1978 and for DAMGO (Fang et al 1989, Smith et al 1988). Identical effects were reported with the hot-plate test (Bobeck et al 2012;Iwamoto et al 1978;Yaksh 1986, 1989;Lane et al 2005;Morgan et al 2006Morgan et al , 2014Yaksh et al 1976).…”

Section: Hyperthermia and Analgesia Elicited By Intracerebral Morphinementioning

confidence: 58%

Entanglement between thermoregulation and nociception in the rat: the case of morphine

Bitar

Pollin

Karroum

et al. 2016

Journal of Neurophysiology

View full text Add to dashboard Cite

In thermoneutral conditions, rats display cyclic variations of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Systemic morphine elicits their vasoconstriction followed by hyperthermia in a naloxone-reversible and dose-dependent fashion. The dose-response curves were steep with ED in the 0.5-1 mg/kg range. Given the pivotal functional role of the rostral ventromedial medulla (RVM) in nociception and the rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, the RVM/rMR was blocked by muscimol: it suppressed the effects of morphine. "On-" and "off-" neurons recorded in the RVM/rMR are activated and inhibited by thermal nociceptive stimuli, respectively. They are also implicated in regulating the cyclic variations of the vasomotion of the tail and paws seen in thermoneutral conditions. Morphine elicited abrupt inhibition and activation of the firing of on- and off-cells recorded in the RVM/rMR. By using a model that takes into account the power of the radiant heat source, initial skin temperature, core body temperature, and peripheral nerve conduction distance, one can argue that the morphine-induced increase of reaction time is mainly related to the morphine-induced vasoconstriction. This statement was confirmed by analyzing in psychophysical terms the tail-flick response to random variations of noxious radiant heat. Although the increase of a reaction time to radiant heat is generally interpreted in terms of analgesia, the present data question the validity of using such an approach to build a pain index.

show abstract

Opiate microinjections into midbrain do not affect the aversiveness of caudal trigeminal stimulation but produce somatotopically organized peripheral hypoalgesia

Cited by 7 publications

References 15 publications

Representation of Spatial Information in Key Areas of the Descending Pain Modulatory System

Representation of Spatial Information in Key Areas of the Descending Pain Modulatory System

Somatotopy of placebo analgesia is independent of spatial attention

Entanglement between thermoregulation and nociception in the rat: the case of morphine

Contact Info

Product

Resources

About