Cannabinoids suppress nociceptive processing of acute stimuli, but little is known about their effects on processes that lead to hyperexcitability of nociceptive neurons following prolonged noxious stimulation. Wind-up, the increasingly strong response of spinal nociceptive neurons to repetitive noxious electrical stimuli, results from a fast-rising cumulative depolarization and increase in int...

The insula, particularly its posterior portion, is often regarded as a primary cortex for pain. However, this interpretation is largely based on reverse inference, and a specific involvement of the insula in pain has never been demonstrated. Taking advantage of the high spatiotemporal resolution of direct intracerebral recordings, we investigated whether the human insula exhibits local field po...

Introduction: Formalin injection induces nociceptive bahaviour in phase I and II, with a quiescent phase between them. While active inhibitory mechanisms are proposed to be responsible for initiation of interphase, the exact mechanisms which lead to termination of nociceptive response in phase II are not clear yet. Phase II is a consequence of peripheral and central sensitization processes, whi...

Functional neuroimaging studies in humans have shown that nociceptive stimuli elicit activity in a wide network of cortical areas commonly labeled as the "pain matrix" and thought to be preferentially involved in the perception of pain. Despite the fact that this "pain matrix" has been used extensively to build models of where and how nociception is processed in the human brain, convincing expe...

Although pain is traditionally assumed to be poorly localized, recent work indicates that spatial acuity for nociception is surprisingly high. Here we investigated whether the nervous system can also accurately estimate the distance between two nociceptive stimuli. Estimating distance implies a metric representation of spatial relations, a property that underlies abilities such as perceiving th...

Considering the importance of a deeper understanding of the effect throughout life of opioid analgesia at birth, our objective was to determine whether morphine administration in early life, once a day for 7 days in 8-day-old rats, alters the nociceptive response over the short (P16), medium (P30), and long term (P60) and to evaluate which system is involved in the altered nociceptive response....

Topographic maps of the receptive surface are a fundamental feature of neural organization in many sensory systems. While touch is finely mapped in the cerebral cortex, it remains controversial how precise any cortical nociceptive map may be. Given that nociceptive innervation density is relatively low on distal skin regions such as the digits, one might conclude that the nociceptive system lac...

Introduction: Some evidence demonstrates endogenous inhibitory pathways of pain involved in the interphase (phase between early and later phase) of the formalin test. We previously showed that swimming stress modulates the pain-related behaviors during the interphase of the formalin test. In this study, we evaluated the role of the endogenous opioid system in modulating nociceptive responses of...

abstract  introduction: diabetic rats display exaggerated hyperalgesic behavior in response to noxious stimuli that may resemble and model aspects of painful diabetic neuropathy in humans. this study was designed to investigate the effect of trigonella foenum-graecum (tfg) on formalin-induced nociceptive responses (standard formalin test) in streptozotocin (stz)-induced diabetic rats.  methods:...