Neuroscience
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Review
Neural plasticity during motor learning with motor imagery practice: Review and perspectives.
In the last decade, many studies confirmed the benefits of mental practice with motor imagery. In this review we first aimed to compile data issued from fundamental and clinical investigations and to provide the key-components for the optimization of motor imagery strategy. We focused on transcranial magnetic stimulation studies, supported by brain imaging research, that sustain the current hypothesis of a functional link between cortical reorganization and behavioral improvement. As perspectives, we suggest a model of neural adaptation following mental practice, in which synapse conductivity and inhibitory mechanisms at the spinal level may also play an important role.
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Stimulus exposure duration in emotion perception research is often chosen pragmatically; however, little work exists on the consequences of stimulus duration for the processing of emotional faces. We utilized the spatiotemporal resolution capabilities of magnetoencephalography (MEG) to characterize early implicit processing of emotional and neutral faces in response to stimuli presented for 80 and 150ms. ⋯ No effects on reaction time or accuracy were observed. Our findings caution that differences in stimulus duration may result in differential neural processing of emotional faces and challenge the idea that neutral faces constitute a neutral baseline.
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Although dopaminergic medication improves functional mobility in individuals with Parkinson's disease (PD), its effects on walking turns are uncertain. Our goals was to determine whether dopaminergic medication improves preplanned and unplanned walking turns in individuals with PD, compared to healthy controls. Nineteen older adults with mild-to-moderate PD and 17 healthy controls performed one of the following three tasks, presented randomly: walking straight, or walking and turning 180° to the right or left. ⋯ Compared to controls, turning impairments in subjects with PD remained while ON medication and problems regulating step width were the most prominent features of their walking pattern. Specifically, subjects with PD turned with narrower cross-over steps, i.e. when the external foot crossed over the line of progression of the internal leg. We conclude that turning impairments remained even after dopaminergic medication and problems modulating step width appears to be a critical feature for turning in PD.
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Glaucoma is an irreversible and blinding neurodegenerative disease of the eye, and is characterized by progressive loss of retinal ganglion cells (RGCs). Since endogenous hydrogen sulfide (H2S) was reported to be involved in neurodegeneration in the central nervous system, the authors aimed to develop a chronic ocular hypertension (COH) rat model simulating glaucoma and therein test the H2S level together with the retinal protein expressions of related synthases, and further investigated the effect of exogenous H2S supplement on RGC survival. COH rat model was induced by cross-linking hydrogel injection into anterior chamber, and the performance of the model was assessed by intraocular pressure (IOP) measurement, RGC counting and retinal morphological analysis. ⋯ The results showed that the COH model succeeded in simulating glaucoma features, and retinal H2S level decreased significantly when the retinal protein expressions of CBS, CSE and 3-MST were downregulated generally in the COH rats. Furthermore, the decrease of retinal H2S level and loss of RGCs were both improved by NaHS treatment in experimental glaucoma, without obvious variation of IOP. Our study revealed that the intracameral injection of cross-linking hydrogel worked efficiently in modeling glaucoma, and H2S had protective effect on RGCs and might be involved in the pathological mechanism of glaucomatous neuropathy.
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Depression is one of the most prevalent and life-threatening forms of mental illness. The heavy social burden imposed by this disorder calls for a better understanding of its pathogenesis. Light deficiency is an important factor potentially leading to depression. ⋯ These synaptological results indicate that the absolute synaptic strength of single L5PC connections was enhanced and the transmitter release probability was increased although the connections between L5PCs became sparse. Therefore, a compensation mechanism accompanied the negative changes that were consistent with the depressive behavioral phenotype. Our findings from the motor cortex of depression-like behavior mice may underlie the neural microcircuit mechanism of depression, providing insights into the pathogenesis of depression at a level of single neurons and synaptic connections.