Publications by authors named "Nicholas F Hardy"

Brain-computer interfaces (BCIs) enable control of assistive devices in individuals with severe motor impairments. A limitation of BCIs that has hindered real-world adoption is poor long-term reliability and lengthy daily recalibration times. To develop methods that allow stable performance without recalibration, we used a 128-channel chronic electrocorticography (ECoG) implant in a paralyzed individual, which allowed stable monitoring of signals.

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Timing is fundamental to complex motor behaviors: from tying a knot to playing the piano. A general feature of motor timing is temporal scaling: the ability to produce motor patterns at different speeds. One theory of temporal processing proposes that the brain encodes time in dynamic patterns of neural activity (population clocks), here we first examine whether recurrent neural network (RNN) models can account for temporal scaling.

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Signaling of brain-derived neurotrophic factor (BDNF) via tropomyosin receptor kinase B (TrkB) plays a critical role in the maturation of cortical inhibition and controls expression of inhibitory interneuron markers, including the neuropeptide cortistatin (CST). CST is expressed exclusively in a subset of cortical and hippocampal GABAergic interneurons, where it has anticonvulsant effects and controls sleep slow-wave activity (SWA). We hypothesized that CST-expressing interneurons play a critical role in regulating excitatory/inhibitory balance, and that BDNF, signaling through TrkB receptors on CST-expressing interneurons, is required for this function.

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Most of the computations and tasks performed by the brain require the ability to tell time, and process and generate temporal patterns. Thus, there is a diverse set of neural mechanisms in place to allow the brain to tell time across a wide range of scales: from interaural delays on the order of microseconds to circadian rhythms and beyond. Temporal processing is most sophisticated on the scale of tens of milliseconds to a few seconds, because it is within this range that the brain must recognize and produce complex temporal patterns-such as those that characterize speech and music.

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Background: Neurogenesis continues throughout life in the hippocampal dentate gyrus. Chronic treatment with monoaminergic antidepressant drugs stimulates hippocampal neurogenesis, and new neurons are required for some antidepressant-like behaviors. Electroconvulsive seizures (ECS), a laboratory model of electroconvulsive therapy (ECT), robustly stimulate hippocampal neurogenesis.

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In recent years, optical sensors for tracking neural activity have been developed and offer great utility. However, developing microscopy techniques that have several kHz bandwidth necessary to reliably capture optically reported action potentials (APs) at multiple locations in parallel remains a significant challenge. To our knowledge, we describe a novel microscope optimized to measure spatially distributed optical signals with submillisecond and near diffraction-limit resolution.

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Following their birth in the adult hippocampal dentate gyrus, newborn progenitor cells migrate into the granule cell layer where they differentiate, mature, and functionally integrate into existing circuitry. The hypothesis that adult hippocampal neurogenesis is physiologically important has gained traction, but the precise role of newborn neurons in hippocampal function remains unclear. We investigated whether loss of new neurons impacts dendrite morphology and glutamate levels in area CA3 of the hippocampus by utilizing a human GFAP promoter-driven thymidine kinase genetic mouse model to conditionally suppress adult neurogenesis.

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