Neuroscience
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This study examined how semantic transparency modulated the processing of spoken Chinese compound words with event-related potential (ERP) recording. A reverse-block passive oddball paradigm was adopted to elicit mismatch negativity (MMN), which responds to holistic and combinatorial processing in opposite directions. Specifically, linguistic inputs that are processed as holistic lexical representations will elicit stronger MMNs (lexical enhancement) than those that do not have such representations. ⋯ Opaque words did not differ from pseudocompounds, which was interpreted as parallel employment of the holistic and combinatorial processing routes. Overall, the results are consistent with the idea that native Chinese speakers routinely attempt to process Chinese compound words by retrieving and combining morphemes. However, because the meanings of opaque words are irrelevant to their constituent morphemes, Chinese speakers must construct and retrieve their holistic representations to ensure accurate processing.
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Computations on the dendritic trees of neurons have important constraints. Voltage dependent conductances in dendrites are not similar to arbitrary direct-current generation, they are the basis for dendritic nonlinearities and they do not allow converting positive currents into negative currents. ⋯ We find that dendritic model performance on interesting machine learning tasks is not hurt by these constraints but may benefit from them. Our results suggest that single real dendritic trees may be able to learn a surprisingly broad range of tasks.
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Our previous studies revealed that miR-34a suppresses autophagy in the ageing cochlea, which correlates with cochlear hair cell loss and age-related hearing loss (AHL). However, the mechanisms underlying miR-34a regulation of autophagy in the cochlea remain unclear. Here, we show that nuclear translocation of transcription factor EB (TFEB), a master regulator of autophagy, was regulated by miR-34a in HEI-OC1 cells. ⋯ Long-term supplementation with rapamycin attenuated outer hair cells (OHCs) and inner hair cell synaptic ribbons, and delayed AHL in C57BL/6 mice. Most importantly, rapamycin partially restored TFEB's nuclear localization and autophagic flux in OHCs of the ageing cochlea. These findings open new avenues for protection against AHL through miR-34a/ATG9a/TFEB modulation of autophagy.
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Review
Cholinergic Modulation of Dendritic Signaling in Hippocampal GABAergic Inhibitory Interneurons.
Dendrites represent the "reception hub" of the neuron as they collect thousands of different inputs and send a coherent response to the cell body. A considerable portion of these signals, especially in vivo, arises from neuromodulatory sources, which affect dendritic computations and cellular activity. In this context, acetylcholine (ACh) exerts a coordinating role of different brain structures, contributing to goal-driven behaviors and sleep-wake cycles. ⋯ We consider the distribution of cholinergic receptors on these interneurons, including information about their specific somatodendritic location, and discuss how the action of these receptors can modulate dendritic Ca2+ signaling and activity of interneurons. The implications of ACh-dependent Ca2+ signaling for dendritic plasticity are also discussed. We propose that cholinergic modulation can shape the dendritic integration and plasticity in interneurons in a cell type-specific manner, and the elucidation of these mechanisms will be required to understand the contribution of each cell type to large-scale network activity.
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Decades of experimental and theoretical work support a now well-established theory that active dendritic processing contributes to the computational power of individual neurons. This theory is based on the high degree of electrical compartmentalization observed in the dendrites of single neurons in ex vivo preparations. ⋯ In this review, we contextualize these new findings and discuss their impact on the future of the field. Specifically, we consider how highly coordinated, and thus less compartmentalized, activity in soma and dendrites can contribute to cortical computations including nonlinear mixed selectivity, prediction/expectation, multiplexing, and credit assignment.