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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Feeding state-dependent neuropeptidergic modulation of reciprocally interconnected inhibitory neurons biases sensorimotor decisions in Drosophila

Abstract An animal’s feeding state changes its behavioral priorities and thus influences even nonfeeding-related decisions. How the feeding state information is transmitted to nonfeeding-related circuits and what circuit mechanisms are involved in biasing nonfeeding-related decisions remain open questions. By combining calcium imaging, neuronal manipulations, behavioral analysis and computational modeling, we determined that the competition between different aversive responses to mechanical cues is biased by changes in the feeding state. We found that this effect is achieved by the differential modulation of two different types of reciprocally connected inhibitory neurons promoting opposing actions. This modulation results in a more frequent active type of response and, less frequently, a protective type of response if larvae are fed sugar than when they are fed a balanced diet. Information about the internal state is conveyed to inhibitory neurons through homologs of the vertebrate neuropeptide Y, which is known to be involved in regulating feeding behavior.

Science & Technology - Other Topics↗
DOE OSTI2025

Motor neurons in the tunicate caudal central nervous system reveal homology to the vertebrate spinal cord

ABSTRACT Invertebrate chordates, such as the tunicate Ciona, can offer insight into the evolution of the chordate phylum. Anatomical features shared between invertebrate chordates and vertebrates may be taken as evidence of their presence in a common chordate ancestor. The central nervous systems (CNSs) of Ciona larvae and vertebrates share a similar anatomy despite the Ciona CNS having only ∼180 neurons. However, the depth of conservation between the Ciona CNS and those of vertebrates is not resolved. The Ciona caudal CNS, while appearing spinal cord-like, has hitherto been thought to lack motor neurons, bringing into question its homology with the vertebrate spinal cord. We show here that the Ciona larval caudal CNS does, in fact, have functional motor neurons along its length, pointing to the presence of a functional spinal cord-like structure at the base of the chordates.

Kourakis, Matthew J.↗
DOE OSTI2026

From IMT Device Measurements to Network-Level Consequences: When Learning Suppresses Beyond-LIF Neuron Dynamics

Emerging neuromorphic devices such as insulator--metal transition (IMT) devices exhibit complex temporal dynamics, including slow internal state memory, hysteresis, and burst-like firing, which are poorly captured by conventional leaky integrate-and-fire (LIF) neurons. However, it remains unclear when such dynamics influence learning and inference at the network level, particularly under commonly used unsupervised plasticity rules. We present a controlled, full-stack co-design study spanning experimental characterization of individual IMT devices, compact neuron model development, and large-scale spiking network simulations with identical architectures and learning rules. Rather than optimizing benchmark accuracy, our goal is to diagnose when neuron-level dynamics survive learning and competition, and when they are suppressed, to inform the co-design of devices, networks, and learning rules that can exploit beyond-LIF complexity.

42 ENGINEERING↗
NASA NTRS1987

Possible role of brain stem respiratory neurons in mediating vomiting during space motion sickness

The object of this study was to determine if brain stem expiratory neurons control abdominal muscle activity during vomiting. The activity of 27 ventral respiratory group expiratory neurons, which are known to be of primary importance for control of abdominal muscle activity during respiration, was recorded. It is concluded that abdominal muscle activity during vomiting must be controlled not only by some brain stem expiratory neurons but also by other input(s).

Miller, A. D.↗
NASA NTRS1985

Sympathetic preganglionic efferent and afferent neurons mediated by the greater splanchnic nerve in rabbit

As a part of the study of the vestibular-autonomic pathways involved in motion sickness, the location and the morphology of preganglionic sympathetic neurons (PSNs) projecting via the greater splanchnic nerve were examined. Retrograde labeling of neurons was obtained by application of horseradish peroxidase to the cut end of the greater splanchnic nerve. Labeled PSNs were found, ipsilaterally, within the T1 to T11 spinal cord segments, with the highest density of neurons in T6. Most PSNs were located within the intermediolateral column, but a significant portion also occurred within the lateral funiculus, the intercalated region, and the central autonomic area; the proportion of labeling between the four regions depended on the spinal cord segment.

Torigoe, Yasuhiro↗
NASA NTRS1989

Associative memory - An optimum binary neuron representation

Convergence mechanism of vectors in the Hopfield's neural network is studied in terms of both weights (i.e., inner products) and Hamming distance. It is shown that Hamming distance should not always be used in determining the convergence of vectors. Instead, weights (which in turn depend on the neuron representation) are found to play a more dominant role in the convergence mechanism. Consequently, a new binary neuron representation for associative memory is proposed. With the new neuron representation, the associative memory responds unambiguously to the partial input in retrieving the stored information.

Awwal, A. A.↗
NASA NTRS1991

Vector-averaged gravity alters myocyte and neuron properties in cell culture

The effect of changes in the gravitational field of developing neurons and myocytes on the development of these cells was investigated using observations of rotated cultures of embryonic spinal neurons and myocytes in a horizontal clinostat, in which rotation produces, from the cells' perspective, a 'vector-free' gravity environment by continous averaging of the vector, thus simulating the microgravity of space. It was found that, at rotation rates between 1 and 50 rpm, cellular and nuclear areas of myocytes become significantly enlarged and the number of presumptive nucleoli increase; in neurons, frequent and large swellings appeared along neuritic shafts. Some of these changes were reversible after the cessation of rotation.

Gruener, Raphael↗
NASA NTRS1992

GaAs Optoelectronic Integrated-Circuit Neurons

Monolithic GaAs optoelectronic integrated circuits developed for use as artificial neurons. Neural-network computer contains planar arrays of optoelectronic neurons, and variable synaptic connections between neurons effected by diffraction of light from volume hologram in photorefractive material. Basic principles of neural-network computers explained more fully in "Optoelectronic Integrated Circuits For Neural Networks" (NPO-17652). In present circuits, devices replaced by metal/semiconductor field effect transistors (MESFET's), which consume less power.

Lin, Steven H.↗
NASA NTRS1993

Automated system for analyzing the activity of individual neurons

This paper presents a signal processing system that: (1) provides an efficient and reliable instrument for investigating the activity of neuronal assemblies in the brain; and (2) demonstrates the feasibility of generating the command signals of prostheses using the activity of relevant neurons in disabled subjects. The system operates online, in a fully automated manner and can recognize the transient waveforms of several neurons in extracellular neurophysiological recordings. Optimal algorithms for detection, classification, and resolution of overlapping waveforms are developed and evaluated. Full automation is made possible by an algorithm that can set appropriate decision thresholds and an algorithm that can generate templates on-line. The system is implemented with a fast IBM PC compatible processor board that allows on-line operation.

Bankman, Isaac N.↗
NASA NTRS2003

Cell output, cell cycle duration and neuronal specification: a model of integrated mechanisms of the neocortical proliferative process

The neurons of the neocortex are generated over a 6 day neuronogenetic interval that comprises 11 cell cycles. During these 11 cell cycles, the length of cell cycle increases and the proportion of cells that exits (Q) versus re-enters (P) the cell cycle changes systematically. At the same time, the fate of the neurons produced at each of the 11 cell cycles appears to be specified at least in terms of their laminar destination. As a first step towards determining the causal interrelationships of the proliferative process with the process of laminar specification, we present a two-pronged approach. This consists of (i) a mathematical model that integrates the output of the proliferative process with the laminar fate of the output and predicts the effects of induced changes in Q and P during the neuronogenetic interval on the developing and mature cortex and (ii) an experimental system that allows the manipulation of Q and P in vivo. Here we show that the predictions of the model and the results of the experiments agree. The results indicate that events affecting the output of the proliferative population affect both the number of neurons produced and their specification with regard to their laminar fate.

Evaluation Studies↗
NASA NTRS2000

Independent controls for neocortical neuron production and histogenetic cell death

We estimated the proportion of cells eliminated by histogenetic cell death during the first 2 postnatal weeks in areas 1, 3 and 40 of the mouse parietal neocortex. For each layer and for the subcortical white matter in each neocortical area, the number of dying cells per mm(2) was calculated and the proportionate cell death for each day of the 2-week interval was estimated. The data show that cell death proceeds essentially uniformly across the neocortical areas and layers and that it does not follow either the spatiotemporal gradient of cell cycle progression in the pseudostratified ventricular epithelium of the cerebral wall, the source of neocortical neurons, or the 'inside-out' neocortical neuronogenetic sequence. Therefore, we infer that the control mechanisms of neocortical histogenetic cell death are independent of mechanisms controlling neuronogenesis or neuronal migration but may be associated with the ingrowth, expansion and a system-wide matching of neuronal connectivity. Copyright 2000 S. Karger AG, Basel.

NASA Discipline Cell Biology↗
NASA NTRS1999

Adenovirus-mediated gene delivery to hypothalamic magnocellular neurons in mice

Vasopressin is synthesized by magnocellular neurons in supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei and released by their axon terminals in the neurohypophysis (NH). With its actions as an antidiuretic hormone and vasoactive agent, vasopressin plays a pivotal role in the control of body fluids and cardiovascular homeostasis. Because of its well-defined neurobiology and functional importance, the SON/PVN-NH system is ideal to establish methods for gene transfer of genetic material into specific pathways in the mouse central nervous system. In these studies, we compared the efficiency of transferring the gene lacZ, encoding for beta-galactosidase (beta-gal), versus a gene encoding for green fluorescent protein by using replication-deficient adenovirus (Ad) vectors in adult mice. Transfection with viral concentrations up to 2 x 10(7) plaque-forming units per coverslip of NH, PVN, and SON in dissociated, cultured cells caused efficient transfection without cytotoxicity. However, over an extended period of time, higher levels (50% to 75% of the cells) of beta-gal expression were detected in comparison with green fluorescent protein (5% to 50% of the cells). With the use of a stereotaxic approach, the pituitary glands of mice were injected with Ad (4 x 10(6) plaque-forming units). In material from these animals, we were able to visualize the expression of the beta-gal gene in the NH and in magnocellular neurons of both the PVN and SON. The results of these experiments indicate that Ad-Rous sarcoma virus promoter-beta-gal is taken up by nerve terminals at the injection site (NH) and retrogradely transported to the soma of the neurons projecting to the NH. We conclude that the application of these experimental approaches will provide powerful tools for physiological studies and potential approaches to deliver therapeutic genes to treat diseases.

Non-NASA Center↗
NASA NTRS1997

Preserved number of entorhinal cortex layer II neurons in aged macaque monkeys

The perforant path, which consists of the projection from the layer II neurons of the entorhinal cortex to the outer molecular layer of the dentate gyrus, is a critical circuit involved in learning and memory formation. Accordingly, disturbances in this circuit may contribute to age-related cognitive deficits. In a previous study, we demonstrated a decrease in N-methyl-D-aspartate receptor subunit 1 immunofluorescence intensity in the outer molecular layer of aged macaque monkeys. In this study, we used the optical fractionator, a stereological method, to determine if a loss of layer II neurons occurred in the same animals in which the N-methyl-D-aspartate receptor subunit 1 alteration was observed. Our results revealed no significant differences in the number of layer II neurons between juvenile, young adult, and aged macaque monkeys. These results suggest that the circuit-specific decrease in N-methyl-D-aspartate receptor subunit 1 reported previously occurs in the absence of structural compromise of the perforant path, and thus may be linked to an age-related change in the physiological properties of this circuit.

Non-NASA Center↗
NASA NTRS1993

The reducing agent dithiothreitol (DTT) does not abolish the inhibitory nicotinic response recorded from rat dorsolateral septal neurons

Previous intracellular recordings have demonstrated that dorsolateral septal nucleus (DLSN) neurons express a novel nicotinic receptor which produces a direct membrane hyperpolarization when activated by nicotinic agonists. Activation of the classical excitatory nicotinic receptors has been shown to require a disulfide bond involving the cysteines at positions 192 and 193 of the alpha subunits of the receptor. Reduction of this cystine bond with dithiothreitol (DTT) abolishes agonist activation of excitatory nicotinic receptors. We have now examined whether DTT treatment of the inhibitory nicotinic receptor on DLSN neurons also abolishes the inhibitory nicotinic response. We find that the inhibitory response persists after treatment of the neurons with 1 mM DTT, even if the reduction is followed by alkylation of the receptor with bromoacetylcholine to prevent possible reformation of disulfide bonds. This result suggests that the agonist binding site on the inhibitory nicotinic receptor does not require an intact disulfide bond, similar to the bond on the alpha subunit of the excitatory nicotinic receptor, for agonist activation of the receptor. Some of these results have been previously reported in abstract form.

NASA Discipline Number 16-10↗
NASA NTRS2005

Properties of cerebellar fastigial neurons during translation, rotation, and eye movements

The most medial of the deep cerebellar nuclei, the fastigial nucleus (FN), receives sensory vestibular information and direct inhibition from the cerebellar vermis. We investigated the signal processing in the primate FN by recording single-unit activities during translational motion, rotational motion, and eye movements. Firing rate modulation during horizontal plane translation in the absence of eye movements was observed in all non-eye-movement-sensitive cells and 26% of the pursuit eye-movement-sensitive neurons in the caudal FN. Many non-eye-movement-sensitive cells recorded in the rostral FN of three fascicularis monkeys exhibited convergence of signals from both the otolith organs and the semicircular canals. At low frequencies of translation, the majority of these rostral FN cells changed their firing rates in phase with head velocity rather than linear acceleration. As frequency increased, FN vestibular neurons exhibited a wide range of response dynamics with most cells being characterized by increasing phase leads as a function of frequency. Unlike cells in the vestibular nuclei, none of the rostral FN cells responded to rotational motion alone, without simultaneously exhibiting sensitivity to translational motion. Modulation during earth-horizontal axis rotation was observed in more than half (77%) of the neurons, although with smaller gains than during translation. In contrast, only 47% of the cells changed their firing rates during earth-vertical axis rotations in the absence of a dynamic linear acceleration stimulus. These response properties suggest that the rostral FN represents a main processing center of otolith-driven information for inertial motion detection and spatial orientation.

Non-NASA Center↗
NASA NTRS2004

CNS development under altered gravity: cerebellar glial and neuronal protein expression in rat neonates exposed to hypergravity

The future of space exploration depends on a solid understanding of the developmental process under microgravity, specifically in relation to the central nervous system (CNS). We have previously employed a hypergravity paradigm to assess the impact of altered gravity on the developing rat cerebellum. The present study addresses the molecular mechanisms involved in the cerebellar response to hypergravity. Specifically, the study focuses on the expression of selected glial and neuronal cerebellar proteins in rat neonates exposed to hypergravity (1.5 G) from embryonic day (E)11 to postnatal day (P)6 or P9 (the time of maximal cerebellar changes) comparing them against their expression in rat neonates developing under normal gravity. Proteins were analyzed by quantitative Western blots of cerebellar homogenates; RNA analysis was performed in the same samples using quantitative PCR. Densitometric analysis of Western blots suggested a reduction in glial (glial acidic protein, GFAP) and neuronal (neuronal cell adhesion molecule, NCAM-L1, synaptophysin) proteins, but the changes in individual cerebellar proteins in hypergravity-exposed neonates appeared both age- and gender-specific. RNA analysis suggested a reduction in GFAP and synaptophysin mRNAs on P6. These data suggest that exposure to hypergravity may interfere with the expression of selected cerebellar proteins. These changes in protein expression may be involved in mediating the effect of hypergravity on the developing rat cerebellum. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

NASA Program Fundamental Space Biology↗
NASA NTRS2008

Activating STAT3 Alpha for Promoting Healing of Neurons

A method of promoting healing of injured or diseased neurons involves pharmacological activation of the STAT3 alpha protein. Usually, injured or diseased neurons heal incompletely or not at all for two reasons: (1) they are susceptible to apoptosis (cell death); and (2) they fail to engage in axogenesis that is, they fail to re-extend their axons to their original targets (e.g., muscles or other neurons) because of insufficiency of compounds, denoted neurotrophic factors, needed to stimulate such extension. The present method (see figure) of treatment takes advantage of prior research findings to the effect that the STAT3 alpha protein has anti-apoptotic and pro-axogenic properties.

Conway, Greg↗
DOE OSTI2026

Material‐Driven Neuronal Oscillators and Filters via Active Reactance in CC‐NDR and VC‐NDR Electro‐Thermal Memristors

The continued scaling of artificial intelligence and telecommunications hardware is increasingly constrained by the power, bandwidth, and area limitations of transistor-based circuits. Neuromorphic processor units, analog oscillators, and active inductors and capacitors rely on complex multi-transistor architectures restricting material choices and incurring energy and footprint overhead. Here, we show that active reactance in electro-thermal memristors provides an intrinsic, material driven route to neuronal oscillator dynamics and signal processing. Using a physics-based compact modeling framework, we bridge negative differential resistance (NDR) and bias-tunable reactance, which underlies spiking dynamics in electro-thermal memristors. Memristors with negative temperature coefficients of resistance (TCR) manifest current-controlled (CC-) NDR and act as active inductors, thus generating spiking above a critical circuit capacitance; whereas memristors with positive TCR manifest voltage-controlled (VC-) NDR and active capacitance, leading to spiking above a critical inductance. By creating a compact model for La 0.7 Ca 0.3 MnO 3 as a representative VC-NDR material and comparing it with LaCoO 3 manifesting CC-NDR, we explain the physical origins of their distinct current-voltage characteristics, reactive phase shifts and consequent spiking behaviors. Finally, we demonstrate tunable filtering enabled by the active reactance of electro-thermal memristors, establishing them as a compact hardware platform for neuronal oscillator functionality and integrated filtering beyond conventional CMOS.

active reactance↗