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Rapid eye movement (REM) sleep consists of a dreaming state in which there is activation of the cortical and hippocampal electroencephalogram (EEG), rapid eye movements, and loss of muscle tone. Although REM sleep was discovered more than 50 years ago, the neuronal circuits responsible for switching between REM and non-REM (NREM) sleep remain poorly(More)
We examined the relation between ectopic afferent firing and tactile allodynia in the Chung model of neuropathic pain. Transection of the L5 spinal nerve in rats triggered a sharp, four- to six-fold increase in the spontaneous ectopic discharge recorded in vivo in sensory axons in the ipsilateral L5 dorsal root (DR). The increase, which was not yet apparent(More)
It is generally acknowledged that humans display highly variable sensitivity to pain, including variable responses to identical injuries or pathologies. The possible contribution of genetic factors has, however, been largely overlooked. An emerging rodent literature documents the importance of genotype in mediating basal nociceptive sensitivity, in(More)
Primary sensory neurons with myelinated axons were examined in vitro in excised whole lumbar dorsal root ganglia (DRGs) taken from adult rats up to 9 days after tight ligation and transection of the L(5) spinal nerve (Chung model of neuropathic pain). Properties of subthreshold membrane potential oscillations, and of repetitive spike discharge, were(More)
Abnormal afferent discharge originating at ectopic sites in injured primary sensory neurons is thought to be an important generator of paraesthesias, dysaesthesias, and chronic neuropathic pain. We report here that the ability of these neurons to sustain repetitive discharge depends on intrinsic resonant properties of the cell membrane and that the(More)
UNLABELLED Na+ channels are large transmembrane proteins with a voltage-gated central pore capable of selectively passing Na+ ions. They are critical determinants of the electrical excitability of sensory neurons and play a key role in pain sensation by controlling afferent impulse discharge. Injury and disease affecting peripheral nerves induces axonopathy(More)
Clinical pain syndromes, and experimental assays of nociception, are differentially affected by manipulations such as drug administration and exposure to environmental stress. This suggests that there are different 'types' of pain. We exploited genetic differences among inbred strains of mice in an attempt to define these primary 'types'; that is, to(More)
1. We used the tested fiber method to record from single myelinated afferents axons ending in a chronic nerve injury site (neuroma) in the rat sciatic nerve or L4,5 dorsal root. Axons were chosen for study that fired spontaneously with a stable tonic or interrupted (bursty) autorhythmic firing pattern. 2. Agents that block voltage-sensitive Na+ channels(More)
In humans, trauma to a peripheral nerve may be followed by chronic pain syndromes which are only relieved by blockade of the effects of sympathetic impulse traffic. It is presumed that, after the lesion, noradrenaline released by activity of sympathetic postganglionic axons excites primary afferent neurons by activating alpha-adrenoceptors, generating(More)