scholarly journals Visual ecology and potassium conductances of insect photoreceptors

2016 ◽  
Vol 115 (4) ◽  
pp. 2147-2157 ◽  
Author(s):  
Roman Frolov ◽  
Esa-Ville Immonen ◽  
Matti Weckström
Keyword(s):  
Membrane Conductance ◽  
Visual Ecology ◽  
Calliphora Vicina ◽  
Visually Guided ◽  
Negative Effects ◽  
Voltage Range ◽  
Kv Channels ◽  
Flying Insects ◽  
Potassium Conductances ◽  
And Behavior

Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies, it was suggested that diurnal, rapidly flying insects predominantly express sustained K+ conductances, whereas crepuscular and nocturnally active animals exhibit strongly inactivating Kv conductances. The latter was suggested to function for minimizing cellular energy consumption. In this study we further explore the evolutionary adaptations of the photoreceptor channelome to visual ecology and behavior by comparing K+ conductances in 15 phylogenetically diverse insects, using patch-clamp recordings from dissociated ommatidia. We show that rapid diurnal flyers such as the blowfly ( Calliphora vicina) and the honeybee ( Apis mellifera) express relatively large noninactivating Kv conductances, conforming to the earlier hypothesis in Diptera. Nocturnal and/or slow-moving species do not in general exhibit stronger Kv conductance inactivation in the physiological membrane voltage range, but the photoreceptors in species that are known to rely more on vision behaviorally had higher densities of sustained Kv conductances than photoreceptors of less visually guided species. No statistically significant trends related to visual performance could be identified for the rapidly inactivating Kv conductances. Counterintuitively, strong negative correlations were observed between photoreceptor capacitance and specific membrane conductance for both sustained and inactivating fractions of Kv conductance, suggesting insignificant evolutionary pressure to offset negative effects of high capacitance on membrane filtering with increased conductance.

If I Had Something to Add, I Would

2020 ◽  
Vol 19 (2) ◽  
pp. 86-96
Author(s):  
Isaac A. Lindquist ◽  
Emily E. Adams ◽  
Joseph A. Allen
Keyword(s):  
Job Attitudes ◽  
Negative Effects ◽  
Meeting Effectiveness ◽  
And Behavior ◽  
Attitudes And Behavior

Abstract. Most employees participate in workplace meetings, and their experiences in meetings can vary greatly, which can lead to positive or negative effects on both job attitudes and behavior. In this study, we examined the effect that a meeting attendee’s competence in the meeting topic had on their participation in the meeting and their perception of meeting effectiveness. Results indicated those with higher levels of competence in the meeting topic were more likely to participate and through participation found their meeting more effective; this relationship was stronger when employee dissent in the meetings was high. Leaders should ensure that those who are present in a meeting are competent in the topic of the meeting and encourage them to participate.

The influence of media on upbringing and behavior of children

GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 656-666
Author(s):  
Dr. Entisar Al-Obaidi
Keyword(s):  
New Technologies ◽  
The Internet ◽  
Negative Effects ◽  
Online Newspapers ◽  
Media Messages ◽  
Other Information ◽  
Family Home ◽  
Effects Of Media ◽  
And Behavior ◽  
Harmful Effects

Media refers to the channels of communication through which we distribute news, education, movies, music, advertising messages and other information. It includes physical and online newspapers and magazines, television, radio, telephone, the Internet, fax and billboards, are a dominant force in lives of children. Although television is remaining the predominant medium for children and adolescents, the new technologies are become more popular. We have to concern about the potential harmful effects of media "messages and images"; however, the positive and negative effects of media should be recognized. Parents have to establish the plan for all media in family home. Media that are influences on children should be recognized by "schools, policymakers, product advertisers, and entertainment producers".

Membrane Properties Related to the Firing Behavior of Zebrafish Motoneurons

2003 ◽  
Vol 89 (2) ◽  
pp. 657-664 ◽  
Author(s):  
Robert R. Buss ◽  
Charles W. Bourque ◽  
Pierre Drapeau
Keyword(s):  
Action Potential ◽  
Action Potentials ◽  
Membrane Conductance ◽  
Membrane Properties ◽  
High Threshold ◽  
Calcium Dependent ◽  
Larval Zebrafish ◽  
Plateau Potential ◽  
Potassium Conductances ◽  
Action Potential Burst

The physiological and pharmacological properties of the motoneuron membrane and action potential were investigated in larval zebrafish using whole cell patch current-clamp recording techniques. Action potentials were eliminated in tetrodotoxin, repolarized by tetraethylammonium (TEA) and 3,4-diaminopyridine (3,4-AP)-sensitive potassium conductances, and had a cobalt-sensitive, high-threshold calcium component. Depolarizing current injection evoked a brief (approximately 10–30 ms) burst of action potentials that was terminated by strong, outwardly rectifying voltage-activated potassium and calcium-dependent conductances. In the presence of intracellular cesium ions, a prolonged plateau potential often followed brief depolarizations. During larval development (hatching to free-swimming), the resting membrane conductance increased in a population of motoneurons, which tended to reduce the apparent outward rectification of the membrane. The conductances contributing to action potential burst termination are hypothesized to play a role in patterning the synaptically driven motoneuron output in these rapidly swimming fish.

Membrane currents, contractions, and aftercontractions in cardiac Purkinje fibers

1982 ◽  
Vol 243 (1) ◽  
pp. H77-H86 ◽  
Author(s):  
S. L. Lipsius ◽  
W. R. Gibbons
Keyword(s):  
Outward Current ◽  
Membrane Conductance ◽  
Isometric Tension ◽  
Membrane Current ◽  
Membrane Currents ◽  
Purkinje Fibers ◽  
Cardiac Purkinje Fibers ◽  
And Behavior ◽  
Normal Calcium ◽  
Current Behavior

We examined relationships between isometric tension and membrane currents in sheep Purkinje fibers voltage clamped by the two-microelectrode method. Oscillatory restitution of contractility was accompanied by a small oscillation in membrane current and by an aftercontraction. The membrane current oscillation resembled the transient inward current (TI) others have reported in the presence of strophanthidin. Twitches produced by voltage clamp depolarizations did not correlate with net outward current in normal solution, but when the early outward current was blocked by 0.5 mM 4-aminopyridine, the residual outward current did correlate with twitches elicited by strong depolarizing clamps, particularly in solutions containing higher than normal calcium concentrations. The results illustrate important similarities and differences between membrane current behavior in sheep Purkinje fibers and behavior others have reported in calf fibers. Correlations between restitution, aftercontractions, and TI's, and between twitch tension and a component of outward current, may arise because of calcium regulation of membrane conductance, electrogenic Na-Ca exchange, or a combination of these and other mechanisms.

scholarly journals Acute social isolation alters neurogenomic state in songbird forebrain

2019 ◽  
Vol 117 (38) ◽  
pp. 23311-23316 ◽  
Author(s):  
Julia M. George ◽  
Zachary W. Bell ◽  
Daniel Condliffe ◽  
Kirstin Dohrer ◽  
Teresa Abaurrea ◽  
...  
Keyword(s):  
Gene Expression ◽  
Social Isolation ◽  
Axonal Guidance ◽  
Sequencing Analysis ◽  
Negative Effects ◽  
Auditory Forebrain ◽  
Gene Sets ◽  
Brain And Behavior ◽  
And Behavior ◽  
The Brain

Prolonged social isolation has negative effects on brain and behavior in humans and other social organisms, but neural mechanisms leading to these effects are not understood. Here we tested the hypothesis that even brief periods of social isolation can alter gene expression and DNA methylation in higher cognitive centers of the brain, focusing on the auditory/associative forebrain of the highly social zebra finch. Using RNA sequencing, we first identified genes that individually increase or decrease expression after isolation and observed general repression of gene sets annotated for neurotrophin pathways and axonal guidance functions. We then pursued 4 genes of large effect size: EGR1 and BDNF (decreased by isolation) and FKBP5 and UTS2B (increased). By in situ hybridization, each gene responded in different cell subsets, arguing against a single cellular mechanism. To test whether effects were specific to the social component of the isolation experience, we compared gene expression in birds isolated either alone or with a single familiar partner. Partner inclusion ameliorated the effect of solo isolation on EGR1 and BDNF, but not on FKBP5 and UTS2B nor on circulating corticosterone. By bisulfite sequencing analysis of auditory forebrain DNA, isolation caused changes in methylation of a subset of differentially expressed genes, including BDNF. Thus, social isolation has rapid consequences on gene activity in a higher integrative center of the brain, triggering epigenetic mechanisms that may influence processing of ongoing experience.

scholarly journals Event-related functional MRI of awake behaving pigeons at 7T

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mehdi Behroozi ◽  
Xavier Helluy ◽  
Felix Ströckens ◽  
Meng Gao ◽  
Roland Pusch ◽  
...  
Keyword(s):  
Functional Mri ◽  
Color Discrimination ◽  
Motion Artifacts ◽  
Stress Conditions ◽  
Neural Mechanisms ◽  
Single Shot ◽  
Visually Guided ◽  
Hemodynamic Response Function ◽  
Species Specific ◽  
And Behavior

Abstract Animal-fMRI is a powerful method to understand neural mechanisms of cognition, but it remains a major challenge to scan actively participating small animals under low-stress conditions. Here, we present an event-related functional MRI platform in awake pigeons using single-shot RARE fMRI to investigate the neural fundaments for visually-guided decision making. We established a head-fixated Go/NoGo paradigm, which the animals quickly learned under low-stress conditions. The animals were motivated by water reward and behavior was assessed by logging mandibulations during the fMRI experiment with close to zero motion artifacts over hundreds of repeats. To achieve optimal results, we characterized the species-specific hemodynamic response function. As a proof-of-principle, we run a color discrimination task and discovered differential neural networks for Go-, NoGo-, and response execution-phases. Our findings open the door to visualize the neural fundaments of perceptual and cognitive functions in birds—a vertebrate class of which some clades are cognitively on par with primates.

Helping That Hurts Intended Beneficiaries: A New Perspective on the Dark Side of Helping Organizational Citizenship Behavior

2017 ◽  
Author(s):  
Anna Lennard ◽  
Linn Van Dyne
Keyword(s):  
Organizational Citizenship ◽  
Organizational Citizenship Behavior ◽  
Performance Outcomes ◽  
Dark Side ◽  
Citizenship Behavior ◽  
Affective States ◽  
Negative Consequences ◽  
Negative Effects ◽  
New Perspective ◽  
And Behavior

Organizational citizenship behavior (OCB) is essential for organizations to gain and maintain competitive advantage in environments with constantly evolving demands. Although most of the literature implicitly assumes that OCB predicts positive work attitudes, affective states, cognitions, and behavior for employees and organizations, some work raises the question of when OCB fails to produce positive consequences, and scholars have called for a more balanced perspective that acknowledges possible negative consequences of OCB. In this chapter, we focus on the unintended negative outcomes of helping OCB to recipients. More specifically, we consider factors that paradoxically cause positively intended helping to backfire and have negative effects on recipients. To date, most research on outcomes of OCB has focused on performance outcomes. In contrast, we focus on nonperformance outcomes for recipients of helping because nonperformance outcomes are more proximal and can shed light on processes that influence more distal outcomes, such as performance.

From motor to visually guided bimanual affordance learning

2019 ◽  
Vol 28 (2) ◽  
pp. 63-78 ◽  
Author(s):  
Martí Sánchez-Fibla ◽  
Sébastien Forestier ◽  
Clément Moulin-Frier ◽  
Jordi-Ysard Puigbò ◽  
Paul FMJ Verschure
Keyword(s):  
Visual Servoing ◽  
Learning Approaches ◽  
Visually Guided ◽  
Perceptual Cues ◽  
Motor Equivalence ◽  
Field Gradients ◽  
Bimanual Interaction ◽  
Event Based ◽  
And Behavior ◽  
The Brain

The mechanisms of how the brain orchestrates multi-limb joint action have yet to be elucidated and few computational sensorimotor (SM) learning approaches have dealt with the problem of acquiring bimanual affordances. We propose a series of bidirectional (forward/inverse) SM maps and its associated learning processes that generalize from uni- to bimanual interaction (and affordances) naturally, reinforcing the motor equivalence property. The SM maps range from a SM nature to a solely sensory one: full body control, delta SM control (through small action changes), delta sensory co-variation (how body-related perceptual cues covariate with object-related ones). We make several contributions on how these SM maps are learned: (1) Context and Behavior-Based Babbling: generalizing goal babbling to the interleaving of absolute and local goals including guidance of reflexive behaviors; (2) Event-Based Learning: learning steps are driven by visual, haptic events; and (3) Affordance Gradients: the vectorial field gradients in which an object can be manipulated. Our modeling of bimanual affordances is in line with current robotic research in forward visuomotor mappings and visual servoing, enforces the motor equivalence property, and is also consistent with neurophysiological findings like the multiplicative encoding scheme.

scholarly journals Estimating the effect of tracking tag weight on insect movement using video analysis: A case study with a flightless orthopteran

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0255117
Author(s):  
Oto Kaláb ◽  
David Musiolek ◽  
Pavel Rusnok ◽  
Petr Hurtik ◽  
Martin Tomis ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Temperatures ◽  
Video Analysis ◽  
Movement Speed ◽  
Negative Effects ◽  
Insect Movement ◽  
The Mean ◽  
And Behavior ◽  
Light Medium

In this study, we describe an inexpensive and rapid method of using video analysis and identity tracking to measure the effects of tag weight on insect movement. In a laboratory experiment, we assessed the tag weight and associated context-dependent effects on movement, choosing temperature as a factor known to affect insect movement and behavior. We recorded the movements of groups of flightless adult crickets Gryllus locorojo (Orthoptera:Gryllidae) as affected by no tag (control); by light, medium, or heavy tags (198.7, 549.2, and 758.6 mg, respectively); and by low, intermediate, or high temperatures (19.5, 24.0, and 28.3°C, respectively). Each individual in each group was weighed before recording and was recorded for 3 consecutive days. The mean (± SD) tag mass expressed as a percentage of body mass before the first recording was 26.8 ± 3.7% with light tags, 72 ± 11.2% with medium tags, and 101.9 ± 13.5% with heavy tags. We found that the influence of tag weight strongly depended on temperature, and that the negative effects on movement generally increased with tag weight. At the low temperature, nearly all movement properties were negatively influenced. At the intermediate and high temperatures, the light and medium tags did not affect any of the movement properties. The continuous 3-day tag load reduced the average movement speed only for crickets with heavy tags. Based on our results, we recommend that researchers consider or investigate the possible effects of tags before conducting any experiment with tags in order to avoid obtaining biased results.

scholarly journals Influence of Ambiguity on Success of Public Infrastructural Megaprojects in Kenya

2018 ◽  
Vol 6 (03) ◽  
Author(s):  
Austin Baraza Omonyo ◽  
Prof. Roselyn Gakure ◽  
Prof. Romanus Odhiambo
Keyword(s):  
Negative Influence ◽  
Best Interest ◽  
Negative Effects ◽  
Cross Sectional ◽  
Order And Disorder ◽  
Multiple Method ◽  
The Face ◽  
Schedule Risk ◽  
New Perspective ◽  
And Behavior

The objective of this study was to investigate the influence of ambiguity on success of public infrastructural megaprojects in Kenya. The need for this study arose from the thesis that ambiguity is a key cause of complexity that results in infrastructural megaprojects being delivered over budget, behind schedule, with benefit shortfalls, over and over again. The study was designed as multiple-method research based on virtual constructionist ontology recognizing that complexity is the mid-point between order and disorder. A cross-sectional census survey of completed public infrastructural megaprojects was conducted using two interlinked questionnaires. Quantitative data was analyzed using descriptive and inferential statistics while qualitative data was analyzed using expert judgment, scenario mapping and retrospective sense-making. The projects surveyed majorly utilized fixed price contracts with the outcome of increased delivery within budget than within schedule. The results showed that ambiguity had significant negative influence on process and overall success of public infrastructural megaprojects but had no significant relationship with product and organizational success. Projects in which the client assumed responsibility for cost and schedule risk had higher chances of meeting both cost and schedule objectives. In order to manage the negative effects of ambiguity, we recommend a new perspective to contract design of public infrastructural megaprojects based on complexity science, blending both outcome and behavior-based contracts. Such contracts should ensure that, in the face of ambiguity, the contractors are able to act in the best interest of their clients and that the clients have access to quality Project Management Information Systems.

Sign in / Sign up

Export Citation Format

Share Document