Microsaccades are involuntary eyemovements with small amplitude and fast velocity during attempted visual fixation. While microsaccadic rate and direction during fixation exhibit distinct modulation by attention, the ...
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Microsaccades are involuntary eyemovements with small amplitude and fast velocity during attempted visual fixation. While microsaccadic rate and direction during fixation exhibit distinct modulation by attention, the mechanisms for these modulations are still debated. To better understand the physiological and mechanistic processes underlying microsaccade generation, we examined the effects of task difficulty on microsaccadic parameters during the performance of a visual attention task with two levels of color detection difficulty. Our results indicate that high task difficulty can decrease microsaccadic rate and enhance the direction bias towards the orienting of the spatial attention induced by an endogenous attentional cue. Furthermore, we show that task difficulty make a trend of prolonged microsaccadic inhibition. Finally, we also found the proportion of large amplitude microsaccades increasement after the appearance of peripheral stimulus during the hard task. Taken together, our findings further support the idea that microsaccades are modulated by the attentional load.
Emerging evidence has implicated dysfunctional autophagy in a growing number of neurodegenerative diseases, including Parkinson's disease(PD). The identification of PD genetic risk factors provides unprecedented o...
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Emerging evidence has implicated dysfunctional autophagy in a growing number of neurodegenerative diseases, including Parkinson's disease(PD). The identification of PD genetic risk factors provides unprecedented opportunities for the dissection of the pathogenic mechanisms of PD and the development of therapeutics. Mutations in many PD associated genes are associated with the disruption of autophagy and increasing autophagy offers protection to neurons by maintaining neuronal protein homeostasis and prevention of toxic accumulation of lpha-synuclein. We have examined the role of autophagy essential genes in dopaminergic neurons using genetic animal models and our results implicate dysfunctional autophagy as one of the failing cellular mechanisms involved in the pathogenesis of idiopathic PD. Furthermore, our study of LRRK2, which is linked to the most common familial form of PD as well as sporadic cases, reveals LRRK2-mediated cellular pathways that regulate synaptic activity(plasticity) and is expected to assist in elucidating the pathogenic mechanisms of the familial PD and identifying better therapeutic targets.
New neurons are generated continuously in the dentate gyrus(DG) of hippocampus throughout adulthood in rodents and most other mammals. Newly generated neurons can integrate into the preexisting synaptic circuitry and ...
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New neurons are generated continuously in the dentate gyrus(DG) of hippocampus throughout adulthood in rodents and most other mammals. Newly generated neurons can integrate into the preexisting synaptic circuitry and are associated with learning and memory and other cognitive functions such as mood regulation. Previous studies showed that adult hippocampal neurogenesis was impaired in several lines of animal models of AD, and amyloid β(Aβ) was believed to be the major culprit. In the present study, we compared the effects of amyloid protein precursor(hA PP) and Aβ on the neurogenesis in adult hippocampus by using two different lines of mice which express similar amount of h APP but very different levels of Aβ. We found that while neurogenesis was impaired in both lines of mice, the degree of neurogenesis reduction was more prominent in the hippocampus of mice expressing h APP with much lower levels of Aβ. Our data suggested that APP but not Aβ might be the major factor affecting neurogeneis in the adult hippocampus.
Noonan syndrome(NS) is a neurodevelopmental disorder associated with congenital heart disease, short stature, facial abnormalities and cognitive deficits such as learning disabilities. Mutations in Ptpn11 which enco...
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Noonan syndrome(NS) is a neurodevelopmental disorder associated with congenital heart disease, short stature, facial abnormalities and cognitive deficits such as learning disabilities. Mutations in Ptpn11 which encodes SHP-2, a positive regulator for Ras-Erk signaling are responsible for ~ 50% of NS cases. We found that the mutant mice harboring NS-associated mutant Ptpn11 show increase in Erk signaling and enhanced excitatory synaptic function, suggesting that the imbalance between excitatory and inhibitory synaptic transmission could be the cellular mechanism underlying learning and memory deficits in the NS mouse models. Importantly, the behavioral and cellular deficits could be reversed in the adult by a FDA-approved drug lovastatin. We also examined the effect of cell type-specific ectopic expression of a NS-associated mutant SHP-2 on LTP and spatial memory in adult mice. Our results show that SHP-2 in the excitatory neuron is critically involved in hippocampus-dependent learning and memory.
Objective Glycosyltransferases are enzymes that catalyze the formation of a variety of Glycoconjugates. The role of β-1,3-galactosyltransferase 2(b3galt2)in inflammation of nervous system is unknown. Dental pulp infl...
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Objective Glycosyltransferases are enzymes that catalyze the formation of a variety of Glycoconjugates. The role of β-1,3-galactosyltransferase 2(b3galt2)in inflammation of nervous system is unknown. Dental pulp inflammation can be used as an inflammatory model of peripheral nervous system. In present study, we investigate the role of b3galt2 in neuroinflammation. Methods Expression of b3galt2 is examined by RT-PCR and western blot, NFk B signaling pathway is determined by immunohistochemistry. Results Inflammation induced upregulation of b3galt2, and b3galt2 has a pro-inflammatory role in dental pulp inflammation. Conclusion b3galt2 may play an important role in mediating peripheral neuroinflammation.
Spinal cord injury(SCI) leads to irreversible neuronal loss and glial scar formation, which ultimately result in persistent neurological dysfunction. Cellular regeneration could be an ideal approach to replenish the l...
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Spinal cord injury(SCI) leads to irreversible neuronal loss and glial scar formation, which ultimately result in persistent neurological dysfunction. Cellular regeneration could be an ideal approach to replenish the lost cells and repair the damage. However, the adult spinal cord has limited ability to produce new neurons. Here we show that resident astrocytes can be converted to doublecortin(DCX)-positive neuroblasts by a single transcription factor, SOX2, in the injured adult spinal cord. Importantly, these induced neuroblasts can mature into synapse-forming neurons in vivo. Neuronal maturation is further promoted by treatment with a histone deacetylase inhibitor, valproic acid(VPA). The results of this study indicate that in situ reprogramming of endogenous astrocytes to neurons might be a potential strategy for cellular regeneration after SCI.
In adult rodentneocortex, somatostatin-expressing interneurons densely inhibit pyramidal neuorns, but the amplitudeof monosynaptic SST-Pyr is significantly smaller that that of *** this is developmently established is...
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In adult rodentneocortex, somatostatin-expressing interneurons densely inhibit pyramidal neuorns, but the amplitudeof monosynaptic SST-Pyr is significantly smaller that that of *** this is developmently established is poorly *** transgenic mouse lines and multi-channel patch-clamp, here we found that the amplitude of adult monosynaptic SST-Pyr synapse issignificantly smaller than that of juvenile micin layer2/3 of primaryvisual *** developmental transformation wasrapid and occuredjust one day after eye-opeing. The magnitude of SST-Pyr synapses in P14-15 wasone third that of P12-13. In contrast, the magnitude of SST-L1 IN remained constant between the second and third postnatal *** analysis suggestedthat this developmental transformation was *** results indicated that the SST-Pyr inhibitory circuit was rapidly regulated after eye-opening. More work should be done to explore the functional difference between juvenile and adult somatostatin-expressing interneurons.
Stress, acting through glucocorticoids(GC), has profound effects on brain physiology and pathology and is causally implicated in depressive illness. To date, the exact cellular and molecular mechanisms underlying the ...
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Stress, acting through glucocorticoids(GC), has profound effects on brain physiology and pathology and is causally implicated in depressive illness. To date, the exact cellular and molecular mechanisms underlying the pathophysiology of MDD have not been identified. Here we use RNA-seq profiling of PC-12 cell treated with or without Corticosterone and demonstrate significantly increased expression of mitogen activated protein kinase(MAPK) phosphatase-1(MKP-1) in the high concentration of Corticosterone subjects compared to matched controls. MKP-1, also known as DUSP1, is a member of a family of dual-specificity phosphatases(DUSP) that dephosphorylate both threonine and tyrosine residues and thereby serves as a key negative regulator of MAPK cascade, a major signaling pathway involved in neuronal plasticity, function and survival. These in vitro studies identify MKP-1 as a critical factor in MDD pathophysiology and as a novel target for therapeutic interventions.
AMPA-type glutamate receptors(AMPARs) mediate fast excitatory neurotransmission in brain. The subunit composition of the receptors determines their synaptic targeting and functional properties, and thus is a fundament...
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AMPA-type glutamate receptors(AMPARs) mediate fast excitatory neurotransmission in brain. The subunit composition of the receptors determines their synaptic targeting and functional properties, and thus is a fundamental parameter for neuronal computations. AMPARs in brain predominantly assemble as heterotetramers. However, the stoichiometry and assembly of heteromeric AMPARs remain unclear. Using the recently solved crystal structure of Glu A2 full-length AMPAR as a template, we performed cysteine mutant cross-linking experiments in full-length Glu A1/A2 to draw the picture of the heteromeric AMPAR architecture. Using non-reducing cross-linking assay, we demonstrate that the heterodimer formation has a preferred architecture. By swapping the critical domains, we further reveal the critical domains that control the heteromeric assembly pattern. Our study sheds light on the stoichiometry and assembly of an important type of glutamate receptor in brain.
Damage to orbitofrontal cortex(OFC) produces an unusual pattern of deficits. Patients have intact cognitive abilities but are impaired in making everyday decisions. Here we review anatomical, neuropsychological, and n...
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Damage to orbitofrontal cortex(OFC) produces an unusual pattern of deficits. Patients have intact cognitive abilities but are impaired in making everyday decisions. Here we review anatomical, neuropsychological, and neurophysiological evidence to determine the neuronal mechanisms that might underlie these impairments. We suggest that OFC plays a key role in processing reward: It integrates multiple sources of information regarding the reward outcome to derive a value signal. In effect, OFC calculates how rewarding a reward is. This value signal can then be held in working memory where it can be used by lateral prefrontal cortex to plan and organize behavior toward obtaining the outcome, and by medial prefrontal cortex to evaluate the overall action in terms of its success and the effort that was required. Thus, acting together, these prefrontal areas can ensure that our behavior is most efficiently directed towards satisfying our needs.
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