Neuroscience letters
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Neuroscience letters · Jul 2003
Robust localization and lateralization of human language function: an optimized clinical functional magnetic resonance imaging protocol.
An optimized clinical functional magnetic resonance imaging (fMRI) protocol with a total scanning time of 8 min is presented that localizes Broca's and Wernicke's areas robustly and determines hemispheric dominance. Language function was visualized using two different sentence generation (SG) and word generation (WG) tasks. Block designed blood oxygenation level dependent (BOLD) fMRI was applied in 14 right-handed volunteers at 1.5 T during visual stimulation. ⋯ Mean BOLD-signals for Broca ranged from 1.53% (SG) to 2.56% (WG), and for Wernicke from 1.47% (SG) to 1.80% (WG). LI indicated left language dominance. The data provided further evidence for the high anatomical variability of language areas, which underlined the relevance of an individual language localization and lateralization prior to brain surgery.
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In humans, kappa agonist-antagonist opioids such as nalbuphine have been proposed to produce both analgesia and anti-analgesia by acting at distinct receptors. The anti-analgesia appears to be greater in men, which may contribute to the greater nalbuphine analgesia observed in women. Kappa agonist-antagonists are also known to produce sexually dimorphic antinociception in nonhuman species but are generally more potent in males; anti-analgesia has not been reported in animals. ⋯ Using the Randall-Selitto paw-withdrawal test, nalbuphine (0.5-10 mg/kg) induced dose-dependent antinociception in the rat. The antinociceptive effect of nalbuphine (0.5 or 1 mg/kg) was not enhanced by lower doses of naloxone but was antagonized by higher doses. These data do not support the hypothesis that the naloxone-sensitive anti-analgesic effect of nalbuphine observed in humans is present in the rat and could explain, at least in part, the opposite direction of the sex differences for kappa agonist-antagonist opioid analgesia observed in these two species.
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Neuroscience letters · Jul 2003
Periodic abstinence enhances nociception without significantly altering the antinociceptive efficacy of spinal morphine in the rat.
Naloxone administration in the opioid dependent rat is associated with spinal glutamate release and NMDA receptor activation which reportedly is also responsible for opioid tolerance. We hypothesized that episodic withdrawal during chronic infusion of spinal morphine might paradoxically enhance tolerance. Rats (24/group) infused with intrathecal morphine (M) for 4 days (20 nmol/microl per h) were given a daily subcutaneous (s.c.) injection of naloxone 0.6 mg/kg per 0.2 ml (MN) or saline 0.2 ml (MS). ⋯ The MN group showed a significantly greater decline in daily latencies compared with the MS group, but also had greater withdrawal hyperalgesia upon termination of the infusion. Dose response to spinal morphine was not significantly different in either MS or MN groups. Periodic abstinence thus enhanced nociception without significantly altering the antinociceptive effect of spinal morphine in this group.