Search results for "senso."
showing 10 items of 4746 documents
Characterization of blink reflex interneurons by activation of diffuse noxious inhibitory controls in man.
1998
The blink reflex consists of an early, pontine R1-component and a late, medullary R2-component. R1 and R2 can be evoked by innocuous stimuli, but only the R2 also by painful heat, suggesting that the R2 is mediated by wide dynamic range neurons (WDR) of the spinal trigeminal nucleus. Remote noxious stimuli suppress the activity in WDR neurons via activation of diffuse noxious inhibitory controls (DNIC), whereas low-threshold mechanoreceptive neurons (LTM) are unaffected. In order to characterize the trigeminal interneurons of R1 and R2 we investigated the modulation of the blink reflex by remote painful heat. The blink reflex was elicited in 11 healthy subjects by innocuous electrical pulse…
Left-hemisphere dominance in early nociceptive processing in the human parasylvian cortex.
2003
Pain perception comprises sensory and emotional dimensions. While the emotional experience is thought to be represented in the right hemisphere, we here report a left-hemisphere dominance for the early sensory component of pain perception using brain electrical source analysis of laser-evoked potentials. Ten right-handed subjects underwent several series of laser radiant heat stimuli to pairs of parallel lines on the dorsum of the left or right hand. Stimulus location and intensity were randomised independently. The sensory-discriminative aspects of pain were emphasised by asking the subjects to perform either a spatial or an intensity discrimination task and were contrasted with active dis…
Roles of capsaicin-insensitive nociceptors in cutaneous pain and secondary hyperalgesia.
2001
Polymodal nociceptors respond to mechanical, thermal and chemical stimuli. Whereas sensitivities to heat and to the irritant substance capsaicin have recently been linked via the properties of the vanilloid receptor type 1 receptor ion channel, sensitivity to noxious mechanical stimuli such as the pinpricks used in clinical neurology seems to be unrelated. We investigated the peripheral neural basis of pinprick pain using quantitative psychophysical techniques combined with selective conduction block by nerve compression and selective desensitization by topical capsaicin treatment. Complete A-fibre block by compression of the superficial radial nerve (criterion: loss of first pain sensation…
The impact of baroreflex function on endogenous pain control: a microneurography study.
2015
The interaction between sympathetic vasoconstrictor activity to muscles [muscle sympathetic nerve activity (MSNA), burst frequency (BF) and burst incidence (BI)] and different stress and somatosensory stimuli is still unclear. Eighteen healthy men (median age 28 years) underwent microneurography recordings from the peroneal nerve. MSNA was recorded during heat pain (HP) and cold pain (CP) alone as well as combined with different stress tasks (mental arithmetic, singing, giving a speech). An additional nine healthy men (median age 26 years) underwent the stimulation protocol with an additional control task (thermal pain combined with listening to music) to evaluate possible attentional confo…
Inward currents in primary nociceptive neurons of the rat and pain sensations in humans elicited by infrared diode laser pulses
2002
Radiant heat is often used to study nociception in vivo. We now used infrared radiation generated by a diode laser stimulator (wavelength 980 nm) to investigate transduction mechanisms for noxious heat stimuli in acutely dissociated dorsal root ganglion (DRG) neurons of rats in vitro. The laser stimulator offered the unique opportunity to test whether the same stimuli also elicit pain sensations in humans. A specific heat-induced current (I(heat)) was elicited in six of 13 small DRG neurons (diameteror =30 microm) tested in the whole-cell configuration of the patch-clamp mode. Current responses in the seven heat-insensitive neurons were within the range explainable by the temperature depend…
Hypnotic hypo- and hyperalgesia: divergent effects on pain ratings and pain-related cerebral potentials.
1993
Pain ratings and pain-related cerebral potentials in response to noxious stimuli were investigated under hypnotic hypo- or hyperalgesia. Out of a sample of 50 subjects the 10 most highly hypnotizable were selected using the Stanford Hypnotic Susceptibility Scale. Phasic pain was induced by brief electrical stimuli intracutaneously applied to the subject's left middle finger. The subjects took part in three experimental sessions. The first session was without hypnosis for familiarization with the experimental surroundings. In the two other sessions, the subjects were hypnotized and given a suggestion of analgesia or hyperalgesia with respect to pain sensation in the left hand. The sequence o…
Configural information in gender categorisation.
2006
International audience; The role of configural information in gender categorisation was Studied by aligning the top half of one face with the bottom half of another. The two faces had the same or different genders. Experiment I shows that participants were slower and made more errors in categorising the gender in either half of these composite faces when the two faces had a different gender, relative to control conditions where the two faces were nonaligned or had the same gender. This result parallels the composite effect for face recognition (Young et al. 1987 Perception 16 747 - 759) and facial-expression recognition (Calder et al. 2000 Journal of Experimental Psychology: Human Perceptio…
Epoch versus impulse models in the analysis of parametric fMRI studies
2013
Abstract Objective In parametric fMRI studies the relationship between the amplitude of the hemodynamic response and electrophysiological or behavioral parameters is commonly analyzed using the general linear model (GLM). We examined ways of using single-trial response time (RT) in the analysis of a decision-making task to better isolate task-specific activation. Methods fMRI and RT data were recorded in twenty-one subjects performing a visual-oddball-task. Four explanatory variables (EVs) were generated for the GLM-analysis: A conventional (constant impulse) EV, a constant epoch EV informed using subjects’ average RT, a variable impulse EV and a variable epoch EV both informed using single…
The efficacy of acupuncture in human pain models: A randomized, controlled, double-blinded study
2012
Acupuncture is frequently used to treat pain, although data supporting the analgesic efficacy from placebo-controlled studies is sparse. In order to get evidence for acupuncture analgesia we performed a study with 2 well-recognized experimental human pain models - the cold-pressor (CP) test and intradermal capsaicin injection. Fifty healthy men were included. Our study compared Traditional Chinese Medicine-based acupuncture to sham acupuncture with Streitberger placebo needles in a randomized, controlled, double-blinded trial. The primary endpoint was the reduction of mean pain intensity during 3minutes of CP test or of mean pain intensity within 10minutes after capsaicin injection. Seconda…
Intracortical inhibition and facilitation in human facial motor area: difference between upper and lower facial area.
2001
Objective: To investigate the intracortical inhibitory and excitatory systems in the motor cortical representation of upper and lower facial muscles. Methods: Paired-pulse transcranial magnetic stimulation (TMS) was applied to 7 healthy volunteers, with the interstimulus interval (ISI) between the conditioning stimulus (CS) and test stimulus, varied from 1 to 20 ms. CS was set at 90% of motor threshold. Muscle evoked potentials (MEPs) were recorded from first dorsal interosseus (FDI), orbicularis oculi (o. oculi) and mentalis muscles. Result: TMS evoked MEPs in o. oculi on both ipsi- and contralateral sides in all subjects. In the paired-pulse study, MEP amplitude in the mentalis decreased …