Neuroscience
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Neuroinflammation is proposed to be an important component in the development of several central nervous system (CNS) disorders including depression, Alzheimer's disease, Parkinson's disease, and traumatic brain injury. However, exactly how neuroinflammation leads to, or contributes to, these central disorders is unclear. The objective of the study was to examine and compare the expression of mRNAs for interleukin-6 (IL-6), IL-7, IL-10 and the receptors for IL-6 (IL-6R) and IL-7 (IL-7R) using in situ hybridization in discrete brain regions and in the spleen after multiple injections of 3mg/kg lipopolysaccharide (LPS), a model of neuroinflammation. ⋯ These studies indicate that LPS-induced neuroinflammation has substantial but variable effects on the regional and cellular patterns of CNS IL-6, IL-7 and IL-10, and for IL-6R and IL-7R mRNA expression. It is apparent that administration of LPS can affect non-neuronal and neuronal cells in the brain. Further research is required to determine how CNS inflammatory changes associated with IL-6, IL-10 and IL-6R could in turn contribute to the development of CNS neurological disorders.
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The somatosensory information from the orofacial region, including the periodontal ligament (PDL), is processed in a manner that differs from that used for other body somatosensory information in the related cortices. It was reported that electrical stimulation to rat PDL elicited activation of the insular oral region (IOR) and the primary (S1) and secondary (S2) somatosensory cortices. However, the physiological relationship between S1 and S2/IOR is not well understood. ⋯ An injection of FluoroGold™ (FG) to the initial response area in S1 or the S2/IOR showed that FG-positive cells were scattered in the non-injected cortical counterpart. This morphological result demonstrated the presence of a bi-directional intracortical connection between the initial response areas in S1 and the S2/IOR. These findings suggest the presence of a mutual connection between S1 and the S2/IOR as an intracortical signal processing network for orofacial nociception.
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Perineuronal nets (PNNs) are structures of extracellular matrix molecules surrounding the cell bodies and proximal dendrites of certain neurons. While PNNs are present throughout the mouse cerebral cortex, recent studies have shown that the components differ among cortical sub-regions and layers, suggesting region-specific functions. Parvalbumin-expressing interneurons (PV neurons) may be important regulators of cortical plasticity during the early "critical period" that is sensitive to sensory input. ⋯ These WFA(+) PNNs changed from granular-like to reticular-like structures during normal cortical development, while this transition was delayed by sensory deprivation. This study indicates that the formation of reticular-like WFA(+) PNNs is dependent on sensory experience in the mouse somatosensory cortex. We suggest that Cat-315(+) molecules and WFA expression in PNNs are involved in the early critical period of input-dependent cortical plasticity.
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Microglia are critical for developmental pruning and immune response to injury, and are implicated in facilitating neural plasticity. The rodent gustatory system is highly plastic, particularly during development, and outcomes following nerve injury are more severe in developing animals. The mechanisms underlying developmental plasticity in the taste system are largely unknown, making microglia an attractive candidate. ⋯ Our results show that microglia density is highest during times of normal gustatory afferent pruning. Furthermore, the quantity of the microglia response is higher in the mature system than in neonates. These findings link increased microglia presence with instances of normal developmental and injury induced alterations in the rNTS.
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The subthalamic nucleus (STN) shapes motor behavior and is important for the initiation and termination of movements. Here we ask whether the STN takes aggregated sensory information into account, in order to exert this function. To this end, local field potentials (LFP) were recorded in eight patients suffering from Parkinson's disease and receiving deep-brain stimulation of the STN bilaterally. ⋯ The left and right STN LFPs similarly were modulated by stimulus deviance starting at about 100ms post-stimulus onset. The MMN has been viewed as an index of an automatic auditory change detection system, more recently phrased in terms of predictive coding theory, which prepares the organism for attention shifts and for action. The LFP-data from the STN clearly demonstrate that the STN receives information on stimulus deviance, possibly as a means to bias the system to interrupt ongoing and to allow alternative actions.