Topic
Nervous system
About: Nervous system is a research topic. Over the lifetime, 16729 publications have been published within this topic receiving 847181 citations.
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TL;DR: Recent comparative analyses of extant species that are uncovering new evidence for evolutionary changes in the size and the number of neurons in the human nervous system, as well as the cellular and molecular reorganization of its neural circuits are considered.
271 citations
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TL;DR: A working hypothesis on the pathogenetic mechanism of mercury on the nervous system is proposed and it was found that the sensory neurons in the spinal ganglia and granule cells in the cerebellum were most vulnerable to mercury poisoning.
271 citations
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TL;DR: In most cases this ongoing DRG activity can be augmented by tetanic stimulation of the axons of neighboring neurons, where the active neuron itself has not been stimulated, and some previously silent DRG neurons can be cross-excited by neighbors.
Abstract: 1. Experiments based on teased fiber recording from rat sciatic nerve have shown that a small proportion of primary afferent neurons in intact dorsal root ganglia (DRGs) fire spontaneously. The prevalence of this discharge is substantially increased if the sciatic nerve has been chronically injured. 2. We now show that in most cases this ongoing DRG activity can be augmented by tetanic stimulation of the axons of neighboring neurons, where the active neuron itself has not been stimulated. In addition, some previously silent DRG neurons can be cross-excited by neighbors. This novel form of neuron-to-neuron communication is termed "DRG crossed afterdischarge." Cross-excitation never occurred at fixed latency in response to single stimulus pulses and is therefore not a case of ephaptic cross talk. 3. Crossed afterdischarge occurred only if the spontaneously active neuron and the stimulated neighbors shared the same DRG. It occurred in 83.5% of the spontaneously active neurons sampled that had myelinated (A) axons, but in only 4.4% of spontaneously active neurons with unmyelinated (C) axons. Among initially silent neurons, stimulation of neighbors evoked firing in 3.1% of A-fibers but in no C-fibers. 4. Crossed afterdischarge responses began within 500 ms of stimulation onset (with the use of 50-Hz tetani) and increased in magnitude for about the first 30 s of stimulation, declining thereafter. Intense excitations were often followed by a short period of depression until the original rate of ongoing discharge was restored. 5. The magnitude of crossed afterdischarge responses increased with increasing stimulation frequency until saturation. Minimal responses occurred with the use of tetani of as little as 1 Hz. Maximal responses occurred with the use of 100-200 Hz tetani. 6. The inclusion of C-fibers in the afferent volley produced little if any augmentation of responses. 7. Cross-excitation was demonstrated in DRGs in which many or all peripheral afferent axons were intact and continued to innervate hind limb skin. In these preparations natural cutaneous stimulation was shown to be capable of evoking crossed afterdischarge responses. The most effective stimuli were gentle or firm rubbing of the foot. Noxious pinch, heat, cold, and chemical stimulation was ineffective. 8. DRG crossed afterdischarge is a mechanism whereby sensation in response to peripheral stimulation may be distorted in time, space, and modality. Because its prevalence is much increased after axotomy, it might contribute to neuropathic sensory abnormalities, including pain, in patients with nerve injury.
271 citations
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TL;DR: Results clearly indicate a wide area- and cell-specific variation of cation chloride cotransporters, emphasizing the central role of anionic homeostasis in neuronal function and communication.
271 citations
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TL;DR: Findings show that cadherin provide a molecular system reflecting both early embryonic and mature nervous system architecture, and the possible roles of cadherins in the formation and maintenance of segmental and functional nervous system structures are discussed.
270 citations