scholarly journals An inexpensive air stream temperature controller and its use to facilitate temperature controlled behavior in livingDrosophila

2018 ◽  
Author(s):  
Ryan Sangston ◽  
Jay Hirsh
Keyword(s):  
Dopaminergic Neurons ◽  
Neural Circuits ◽  
Locomotor Behavior ◽  
Signaling Cascades ◽  
Temperature Dependent ◽  
Temperature Controller ◽  
Biologically Relevant ◽  
Air Stream ◽  
Temperature Controlled ◽  
Enclosed Chamber

AbstractControlling the environment of an organism has many biologically relevant applications. Temperature-dependent inducible biological reagents have proven invaluable for elucidating signaling cascades and dissection of neural circuits. Here we develop a simple and affordable system for rapidly changing temperature in a chamber housing adultDrosophilamelanogaster. Utilizing flies expressing the temperature inducible channel dTrpA1 in dopaminergic neurons, we show rapid and reproducible changes in locomotor behavior. This device should have wide application to temperature modulated biological reagents.Method SummaryWe develop widely applicable and affordable solution to rapidly changing temperature within an enclosed chamber using commercially available components.

Failure Analysis Case Study of a 1.5 Meter Space Flex Harness

2017 ◽  
Author(s):  
Erick Kim ◽  
Kamjou Mansour ◽  
Gil Garteiz ◽  
Javeck Verdugo ◽  
Ryan Ross ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Failure Modes ◽  
Field Of View ◽  
Area Of Interest ◽  
Air Stream ◽  
Novel Method ◽  
Temperature Controlled ◽  
Non Destructive ◽  
Failure Site

Abstract This paper presents the failure analysis on a 1.5m flex harness for a space flight instrument that exhibited two failure modes: global isolation resistances between all adjacent traces measured tens of milliohm and lower resistance on the order of 1 kiloohm was observed on several pins. It shows a novel method using a temperature controlled air stream while monitoring isolation resistance to identify a general area of interest of a low isolation resistance failure. The paper explains how isolation resistance measurements were taken and details the steps taken in both destructive and non-destructive analyses. In theory, infrared hotspot could have been completed along the length of the flex harness to locate the failure site. However, with a field of view of approximately 5 x 5 cm, this technique would have been time prohibitive.

scholarly journals MicroRNAs Regulate Multiple Aspects of Locomotor Behavior in Drosophila

2019 ◽  
Vol 10 (1) ◽  
pp. 43-55
Author(s):  
Nathan C. Donelson ◽  
Richa Dixit ◽  
Israel Pichardo-Casas ◽  
Eva Y. Chiu ◽  
Robert T. Ohman ◽  
...  
Keyword(s):  
Nervous System ◽  
Neural Development ◽  
Locomotor Behavior ◽  
Temperature Dependent ◽  
Motor Circuits ◽  
The Many ◽  
And Function ◽  
Post Transcriptional Regulation ◽  
Movement Tracking

Locomotion is an ancient and fundamental output of the nervous system required for animals to perform many other complex behaviors. Although the formation of motor circuits is known to be under developmental control of transcriptional mechanisms that define the fates and connectivity of the many neurons, glia and muscle constituents of these circuits, relatively little is known about the role of post-transcriptional regulation of locomotor behavior. MicroRNAs have emerged as a potentially rich source of modulators for neural development and function. In order to define the microRNAs required for normal locomotion in Drosophila melanogaster, we utilized a set of transgenic Gal4-dependent competitive inhibitors (microRNA sponges, or miR-SPs) to functionally assess ca. 140 high-confidence Drosophila microRNAs using automated quantitative movement tracking systems followed by multiparametric analysis. Using ubiquitous expression of miR-SP constructs, we identified a large number of microRNAs that modulate aspects of normal baseline adult locomotion. Addition of temperature-dependent Gal80 to identify microRNAs that act during adulthood revealed that the majority of these microRNAs play developmental roles. Comparison of ubiquitous and neural-specific miR-SP expression suggests that most of these microRNAs function within the nervous system. Parallel analyses of spontaneous locomotion in adults and in larvae also reveal that very few of the microRNAs required in the adult overlap with those that control the behavior of larval motor circuits. These screens suggest that a rich regulatory landscape underlies the formation and function of motor circuits and that many of these mechanisms are stage and/or parameter-specific.

scholarly journals Effects of vapor exposure to Δ9-tetrahydrocannabinol (THC) in the Maine Lobster (Homarus americanus)

2021 ◽  
Author(s):  
Arnold Gutierrez ◽  
Kevin M Creehan ◽  
Mitchell Turner ◽  
Rachelle N Tran ◽  
Tony M Kerr ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Homarus Americanus ◽  
Locomotor Behavior ◽  
Hot Water ◽  
Marginal Effect ◽  
Temperature Dependent ◽  
Tissue Samples ◽  
Thermal Nociception ◽  
Nociceptive Responses ◽  
History Of Use

Rationale: Despite a long history of use in synaptic physiology, the lobster has been a neglected model for behavioral pharmacology. A restauranteur proposed that exposing lobster to cannabis smoke reduces anxiety and pain during the cooking process. It is unknown if lobster gill respiration in air would result in significant Δ9-tetrahydrocannabinol (THC) uptake and whether this would have any detectable behavioral effects. Objective: The primary goal was to determine tissue THC levels in the lobster after exposure to THC vapor. Secondary goals were to determine if THC vapor altered locomotor behavior or nociception. Methods: Tissue samples were collected from muscle, brain and hemolymph of Homarus americanus (N=3 per group) following 30 or 60 minutes of exposure to vapor generated by an e-cigarette device using THC (100 mg/mL in a propylene glycol vehicle). Separate experiments assessed locomotor behavior and hot water nociceptive responses following THC vapor exposure. Results: THC vapor produced duration-related THC levels in all tissues examined. Locomotor activity was decreased (distance, speed, time-mobile) by 30 min inhalation of THC. Lobsters exhibit a temperature-dependent withdrawal response to immersion of tail, antennae or claws in warm water; this is novel evidence of thermal nociception for this species. THC exposure for 60 minutes had only marginal effect on nociception under the conditions assessed. Conclusions: Vapor exposure of lobsters, using an e-cigarette based model, produces dose-dependent THC levels in all tissues and reduces locomotor activity. Hot water nociception is temperature dependent in the lobster, but no clear effects of THC inhalation were confirmed.

scholarly journals Fundamental bounds on learning performance in neural circuits

2018 ◽  
Author(s):  
Dhruva V. Raman ◽  
Timothy O’Leary
Keyword(s):  
Neural Circuits ◽  
Neural Circuit ◽  
Brain Size ◽  
Intrinsic Noise ◽  
Network Size ◽  
Learning Ability ◽  
Learning Performance ◽  
Optimal Size ◽  
Biologically Relevant ◽  
Learning Capacity

AbstractHow does the size of a neural circuit influence its learning performance? Intuitively, we expect the learning capacity of a neural circuit to grow with the number of neurons and synapses. Larger brains tend to be found in species with higher cognitive function and learning ability. Similarly, adding connections and units to artificial neural networks can allow them to solve more complex tasks. However, we show that in a biologically relevant setting where synapses introduce an unavoidable amount of noise, there is an optimal size of network for a given task. Beneath this optimal size, our analysis shows how adding apparently redundant neurons and connections can make tasks more learnable. Therefore large neural circuits can either devote connectivity to generating complex behaviors, or exploit this connectivity to achieve faster and more precise learning of simpler behaviors. Above the optimal network size, the addition of neurons and synaptic connections starts to impede learning performance. This suggests that overall brain size may be constrained by the need to learn efficiently with unreliable synapses, and may explain why some neurological learning deficits are associated with hyperconnectivity. Our analysis is independent of specific learning rules and uncovers fundamental relationships between learning rate, task performance, network size and intrinsic noise in neural circuits.

scholarly journals Theory of reinforcement learning and motivation in the basal ganglia

2017 ◽  
Author(s):  
Rafal Bogacz
Keyword(s):  
Synaptic Plasticity ◽  
Reinforcement Learning ◽  
Basal Ganglia ◽  
Dopaminergic Neurons ◽  
Neural Circuits ◽  
Negative Consequences ◽  
Striatal Neurons ◽  
Motivational State ◽  
Level Of Activity ◽  
Dopaminergic Modulation

AbstractThis paper proposes how the neural circuits in vertebrates select actions on the basis of past experience and the current motivational state. According to the presented theory, the basal ganglia evaluate the utility of considered actions by combining the positive consequences (e.g. nutrition) scaled by the motivational state (e.g. hunger) with the negative consequences (e.g. effort). The theory suggests how the basal ganglia compute utility by combining the positive and negative consequences encoded in the synaptic weights of striatal Go and No-Go neurons, and the motivational state carried by neuromodulators including dopamine. Furthermore, the theory suggests how the striatal neurons to learn separately about consequences of actions, and how the dopaminergic neurons themselves learn what level of activity they need to produce to optimize behaviour. The theory accounts for the effects of dopaminergic modulation on behaviour, patterns of synaptic plasticity in striatum, and responses of dopaminergic neurons in diverse situations.

scholarly journals Fundamental bounds on learning performance in neural circuits

2019 ◽  
Vol 116 (21) ◽  
pp. 10537-10546 ◽  
Author(s):  
Dhruva Venkita Raman ◽  
Adriana Perez Rotondo ◽  
Timothy O’Leary
Keyword(s):  
Neural Circuits ◽  
Neural Circuit ◽  
Intrinsic Noise ◽  
Network Size ◽  
Learning Ability ◽  
Learning Performance ◽  
Optimal Size ◽  
Biologically Relevant ◽  
Learning Capacity ◽  
Optimal Network

How does the size of a neural circuit influence its learning performance? Larger brains tend to be found in species with higher cognitive function and learning ability. Intuitively, we expect the learning capacity of a neural circuit to grow with the number of neurons and synapses. We show how adding apparently redundant neurons and connections to a network can make a task more learnable. Consequently, large neural circuits can either devote connectivity to generating complex behaviors or exploit this connectivity to achieve faster and more precise learning of simpler behaviors. However, we show that in a biologically relevant setting where synapses introduce an unavoidable amount of noise, there is an optimal size of network for a given task. Above the optimal network size, the addition of neurons and synaptic connections starts to impede learning performance. This suggests that the size of brain circuits may be constrained by the need to learn efficiently with unreliable synapses and provides a hypothesis for why some neurological learning deficits are associated with hyperconnectivity. Our analysis is independent of specific learning rules and uncovers fundamental relationships between learning rate, task performance, network size, and intrinsic noise in neural circuits.

scholarly journals Temperature-dependent development and mortality of Australian cockroach, Periplaneta australasiae (Fabricius) (Blattodea: Blattidae

2010 ◽  
Vol 40 (No. 1) ◽  
pp. 11-15 ◽  
Author(s):  
V. Stejskal ◽  
J. Lukáš ◽  
R. Aulický
Keyword(s):  
Development Rate ◽  
Effect Of Temperature ◽  
Thermal Constant ◽  
Pest Species ◽  
Temperature Dependent ◽  
Thermal Threshold ◽  
Dependent Development ◽  
Thermal Constants ◽  
Temperature Controlled ◽  
Periplaneta Australasiae

The effect of temperature on the development of the 1<SUP>st</SUP> instar of <I>Periplaneta australasiae</I> (Fabr.) was studied at the four constant temperatures of 21°C, 24°C, 27°C and 30°C in temperature-controlled chambers. Mortality was 50% at 30°C, and 10% at 21°C, 24° and 27°C. Thermal constants were established by plotting linear regression to development rate. The thermal threshold for the development was 17.1°C and the thermal constant for 1<SUP>st</SUP> instar larvae was 147.1 day-degrees. As “safe temperature” (<I>t<SUB>s</SUB></I>) – the temperature to be maintained in stores or food premises to prevent the development of a pest species – we recommend 16°C.

scholarly journals The Functional and Neurobiological Properties of Bad Taste

2019 ◽  
Vol 99 (1) ◽  
pp. 605-663 ◽  
Author(s):  
Lindsey A. Schier ◽  
Alan C. Spector
Keyword(s):  
Neural Circuits ◽  
Mammalian Brain ◽  
Gustatory System ◽  
Biologically Relevant ◽  
Neural Architecture ◽  
Technological Advances ◽  
Close Relationship ◽  
The Brain ◽  
Experimental Strategies

The gustatory system serves as a critical line of defense against ingesting harmful substances. Technological advances have fostered the characterization of peripheral receptors and have created opportunities for more selective manipulations of the nervous system, yet the neurobiological mechanisms underlying taste-based avoidance and aversion remain poorly understood. One conceptual obstacle stems from a lack of recognition that taste signals subserve several behavioral and physiological functions which likely engage partially segregated neural circuits. Moreover, although the gustatory system evolved to respond expediently to broad classes of biologically relevant chemicals, innate repertoires are often not in register with the actual consequences of a food. The mammalian brain exhibits tremendous flexibility; responses to taste can be modified in a specific manner according to bodily needs and the learned consequences of ingestion. Therefore, experimental strategies that distinguish between the functional properties of various taste-guided behaviors and link them to specific neural circuits need to be applied. Given the close relationship between the gustatory and visceroceptive systems, a full reckoning of the neural architecture of bad taste requires an understanding of how these respective sensory signals are integrated in the brain.

scholarly journals Structural variability of CG-rich DNA 18-mers accommodating double T–T mismatches

2020 ◽  
Vol 76 (12) ◽  
pp. 1233-1243
Author(s):  
Petr Kolenko ◽  
Jakub Svoboda ◽  
Jiří Černý ◽  
Tatsiana Charnavets ◽  
Bohdan Schneider
Keyword(s):  
Crystal Structures ◽  
Bacterial Species ◽  
Crystal Data ◽  
Temperature Dependent ◽  
Base Pairs ◽  
Biologically Relevant ◽  
Dynamic Temperature ◽  
Dna Crystals ◽  
Helical Geometry ◽  
Work Knowledge

Solution and crystal data are reported for DNA 18-mers with sequences related to those of bacterial noncoding single-stranded DNA segments called repetitive extragenic palindromes (REPs). Solution CD and melting data showed that the CG-rich, near-palindromic REPs from various bacterial species exhibit dynamic temperature-dependent and concentration-dependent equilibria, including architectures compatible with not only hairpins, which are expected to be biologically relevant, but also antiparallel duplexes and bimolecular tetraplexes. Three 18-mer oligonucleotides named Hpar-18 (PDB entry 6rou), Chom-18 (PDB entry 6ros) and its brominated variant Chom-18Br (PDB entry 6ror) crystallized as isomorphic right-handed A-like duplexes. The low-resolution crystal structures were solved with the help of experimental phases for Chom-18Br. The center of the duplexes is formed by two successive T–T noncanonical base pairs (mismatches). They do not deform the double-helical geometry. The presence of T–T mismatches prompted an analysis of the geometries of these and other noncanonical pairs in other DNA crystals in terms of their fit to the experimental electron densities (RSCC) and their geometric fit to the NtC (dinucleotide conformational) classes (https://dnatco.datmos.org/). Throughout this work, knowledge of the NtC classes was used to refine and validate the crystal structures, and to analyze the mismatches.

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