Neuroscience
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Dendrite-targeting somatostatin-expressing interneurons (SST-INs) powerfully control signal integration and synaptic plasticity in pyramidal dendrites during cortical development. We previously showed that synaptic transmission from SST-INs to pyramidal cells (PCs) (SST-IN → PC) in the mouse visual cortex suddenly declined at around the second postnatal week. However, it is unclear what specific postsynaptic mechanisms underlie this developmental change. ⋯ Apart from pharmacological test, we observed that SST-IN → PC synapses did indeed contain α5-GABAARs by immunogold labeling for electron microscopy. More importantly, coinciding with the weakening of SST-IN → PC synaptic transmission, the number of α5-GABAAR particles in SST-IN → PC synapses significantly decreased at around the second postnatal week. Together, these data indicate that α5-GABAARs are involved in synaptic transmission from SST-INs to PCs in the neocortex, and are significantly diminished around the second postnatal week.
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The incidence of mild cognitive impairment in Parkinson's disease (PDMCI) is as high as 18-55%. However, the pathological mechanism of PDMCI is not yet clear. Our previous research showed that microvascular pathology and chronic cerebral hypoperfusion participated in the occurrence and development of PDMCI. ⋯ When Nogo-A expression was downregulated, the cognitive and microvascular impairments were alleviated, and the expression of sphingosine-1-phosphate receptor 2 (S1PR2) and the RhoA/ROCK signaling pathway were inhibited. These findings suggested that Nogo-A could bind to S1PR2, activate related signaling pathways, and lead to the inhibition of vascular remodeling in PDMCI mice. This study indicated that Nogo-A downregulation could mediate microvascular remodeling and provide further insights into the pathogenesis of PDMCI.
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Dopamine loss in Parkinson's disease (PD) is associated with abnormal oscillatory activity in the cortico-basal ganglia network. However, the oscillatory pattern of striatal neurons in PD remains poorly defined. Here, we analyzed the local field potentials in one untreated and five MPTP-treated non-human primates (NHP) with chronic, advanced parkinsonism. ⋯ Both alpha and low-beta frequency band oscillations of the striatum were highly coherent with the cortical and pallidal oscillations, confirming the presence of abnormal 8-20 Hz oscillatory activity in the cortico-basal ganglia network in parkinsonian NHPs. The reversal of parkinsonism induced by acute levodopa administration was associated with reduced 8-20 Hz oscillations in the striatum. These findings indicate that pathological oscillations at alpha and low-beta bands are also present in the striatum concordant with basal ganglia network changes in the primate model of PD.
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Rats are a popular animal model for vision research and for investigating disorders of the visual system. The study aimed to quantify the spatiotemporal contrast sensitivity function (CSF) of healthy adult Brown-Norway rats under scotopic and photopic illumination. Animals were trained to jump onto the one of two adjacent platforms behind which was displayed a sinewave grating pattern. ⋯ CSFs were also measured via the visual head-tracking reflex. Photopic contrast sensitivity, spatial acuity, and temporal acuity were all markedly below that of the grating detection task and optomotor findings for other rat strains. The CSF data provide a comprehensive and quantitative description of rat spatial and temporal vision and a benchmark for evaluating effects of ocular diseases on their ability to see.
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Alterations in the functional organization of motor cortex and interictal motor deficits are observed in people with epilepsy. While seizures in the rat lead to more cortical area devoted to simple cortical forelimb movement representations (motor maps) assessed using short-duration intracortical microstimulation (ICMS), the effect of seizures on complex movements derived with long-duration ICMS is unknown. Further, the relationship between motor map expression and motor impairment is not well understood. ⋯ Bicuculline also significantly expanded forelimb motor maps (108%) but without increasing representational overlap. Moreover, expanded map areas in bicuculline rats evoked qualitatively distinct forelimb movements to long-duration, but not short-duration (n = 5), ICMS that were truncated. Our evidence indicates that motor map expansion following repeated experimental seizures is associated with reduced segregation between cortical movement representations that is not entirely due to reduced cortical inhibition but may contribute to interictal motor deficits in some individuals with epilepsy.