Neuroscience
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Standard treatment for Parkinson's disease (PD) is L-DOPA, but with chronic administration the majority of patients develop L-DOPA-induced dyskinesia (LID). Emerging evidence implicates the cholinergic system in PD and LID. Muscarinic acetylcholine receptors (mAChR) are known to modulate movement and of late have been implicated as possible targets for LID. ⋯ Finally, we evaluated effects of striatum- or PPN-targeted tropicamide microinfusion on LID and motor performance. Despite prior evidence, M4R blockade in either site alone did not affect the severity of LID via local striatal or PPN infusions. Taken together, these data suggest M4R as a promising therapeutic target for reducing LID using more selective compounds.
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We established hypoglycemic rat models and divided them into three groups (the sham group, the acute hypoglycemia group and the recovery group). The brain water diffusion was examined using DWI. Thereafter, neuropathologic examinations were performed in order to evaluate the distribution of brain damage. ⋯ Our work revealed that hypoglycemia significantly influenced the water diffusion of the brain. The decrease of AQP4 was associated with the formation of cytotoxic edema in acute hypoglycemia. Hypoglycemia primarily tends to damage the cerebral cortex, hippocampus and hypothalamus and may result in permanent injury to the brain.
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Injection of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHAL) into the rat rostral and caudal supramammillary nucleus (SUM) provided expected patterns of projections into the hippocampus and the septal region. In addition, unexpectedly intense projections were observed into the claustrum defined by parvalbumin expression. ⋯ The SUM is usually involved in control of hippocampal theta activity, but the observation of intense projections into the claustrum indicates that it may also influence isocortical processes. Therefore, the SUM may coordinate sensory processing in the isocortex with memory formation in the hippocampus.
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Axonopathy manifested by axon swellings might constitute one of the earliest pathological features of Alzheimer's disease. It has been proposed that axonopathy might be associated with the origin of Aβ plaques. However, how axonopathy leads to Aβ plaque pathogenesis remains elusive. ⋯ Importantly, they colocalized with Aβ plaques in either the white matter or gray matter of the spinal cord at later stages, suggesting that these axonal swellings might represent the initial stages of Aβ plaque formation, and could play a role in Aβ plaque pathogenesis. Furthermore, using ultrastructural analysis we demonstrated that intracellular contents in the axonal dystrophies such as various dense vesicles leaked out into the extracellular matrix under a condition of axon swelling rupture in CST pathways of spinal cord. This provided precise structural evidence that how the Aβ leaks out from the axonal dystrophies into extracellular matrix and how an axonal swelling might serve as a nidus of amyloid plaque formation.
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Functional maps play crucial roles in the neural representations of the sensory cortices, although such representations occasionally extend beyond these maps. For example, the auditory cortex exhibits distinct tonotopic activation at the onset of tone, which is followed by rapid decays in the majority of neuronal signals and ongoing activities in only a small number of neurons. Such ongoing activity should be maintained by the cortical states. ⋯ Informative features were widely distributed over the auditory cortex and across multiple frequency bands. Furthermore, acoustic trauma disrupted tonotopic representation at the onset but did not affect neural representations by the correlation of ongoing activities. These results suggest that cross-correlations of LFP within the auditory cortex represent frequencies of sustained auditory stimuli, and that these representations are made beyond direct tonotopic activation at stimulus onset.