Neuroscience
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Objects play vital roles in scene categorization. Although a number of studies have researched on the neural responses during object and object-based scene recognition, few studies have investigated the neural mechanism underlying object-masked scene categorization. Here, we used functional magnetic resonance imaging (fMRI) to measure the changes in brain activations and functional connectivity (FC) while subjects performed a visual scene-categorization task with different numbers of 'signature objects' masked. ⋯ Another core hub was found in left middle temporal gyrus (MTG) and its connection with middle cingulate cortex (MCC), supramarginal gyrus (SMG) and insula might serve in the processing of motor response and the semantic relations between objects and scenes. Brain-behavior correlation analysis substantiated the contributions of the FC to the different processes in the object-masked scene-categorization tasks. Altogether, the results suggest that masking of objects significantly affected the object attention, cognitive demand, top-down modulation effect, and semantic judgment.
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Handedness effects with respect to regional corpus callosum (CC) anatomy remain open to question. Midsagittal CC tracings were obtained from structural MRIs in 21 female monozygotic twin pairs with discordant handedness (MZHd). The CC was divided into 99 percentile widths which were grouped into seven regions based on Denenberg's (1989, 1991b) factor analysis. ⋯ Results support a claim that CC region W22-39, interconnecting premotor cortex in females, provides for environmentally influenced components of handedness, given the difference within MZHd twin pairs. By contrast, CC W3-18, connecting prefrontal cortex, was sensitive to direction and consistency of handedness, both in twins and singletons, a result consistent with combined genetic and environmental effects. Findings highlight the significance of MZHd twin studies in elucidating the developmental mechanisms underpinning structure-function asymmetry, cortical interconnectivity and neurodevelopmental bases of left hand preference.
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Comparative Study
Age- and Expertise-Related Differences of Sensorimotor Network Dynamics during Force Control.
Age-related deterioration of force control is evident on behavioral and neural levels. Extensive and deliberate practice can decrease these changes. This study focused on detecting electrophysiological correlates of age- and expertise-related differences in force control. ⋯ Late middle-aged novices showed high values for both hands while late middle-aged experts showed higher values for the right than for their left hand. Activation of attentional networks was lower in late middle-aged experts compared to novices. These results may relate to different control strategies of the three groups.
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Excitatory amino acid transporter 2 (EAAT2) is primarily located in perisynaptic astrocytic processes (PAP) where it plays a critical role in synaptic glutamate homeostasis. Dysregulation of EAAT2 at the translational level has been implicated in a myriad of neurological diseases. We previously discovered that pyridazine analogs can activate EAAT2 translation. ⋯ This was not dependent upon compound-mediated local translation in neurons. This suggests that compound enhances the structural and functional capacity of the PAP which in turn facilitates enhanced plasticity of the tripartite synapse. Overall, this provides insight into the mechanism action site of pyridazine derivatives as well as the growing appreciation of the dynamic regulation and functional aspects of the PAP at the tripartite synapse.
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Retinal horizontal cells (HCs) are inhibitory neurons, which modulate the transmission of light-elicited signals from photoreceptors to bipolar cells in the outer retina. HCs of the same physiological type are extensively coupled via gap junctions. In the zebrafish retina, the population of HCs comprises up to four morphologically distinct subtypes. ⋯ The localization of Cx53.4 protein within the retina was analyzed using a specific antibody. Immunofluorescence analyses demonstrated that the expression of Cx53.4 is restricted to HCs of all four subtypes. Further, immunoelectron microscopy confirmed the presence of Cx53.4 in gap junctions between HC dendrites and between their axon terminals.