Neural mechanisms to exploit positional geometry for collision avoidance

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Mealybug avoidance responses to ladybird semiochemicals

The predatory ladybird Cryptolaemus montrouzieri Mulsant is a very effective natural enemy of the citrus mealybug, Planococcus citri (Risso), and has a worldwide distribution. This study investigated how the citrus mealybug responded to semiochemicals from the ladybird. In laboratory experiments, mealybug response to semiochemicals left by ladybirds on leaf surfaces was measured. The results indicated that the presence of ladybirds can change the settling behaviour of P. citri. The exposure of plant material to C. montrouzieri had a significant influence on the settling of mealybugs added to the same plant. The distribution of citrus mealybugs in the Petri dishes was significantly affected by the previous presence of ladybirds. The avoidance response may aid in the biological control of mealybugs by coccinellids released onto crops infested with mealybugs.     

Laboratory observations on locust responses to wind-borne grass odour

Starved desert locust hoppers respond to wind-borne grass odour by turning and moving upwind toward the odour source. The conclusion from previous work, that this orientation reaction depends on unequal olfactory stimulation of the two antennae (osmotropotaxis), has been re-examined in further experiments. Agitating hoppers, by handling them singly or by tumbling a crowd of them together just before releasing them in a wind tunnel, induced rapid upwind movement by both starved and fed hoppers even in the absence of grass odour. Repeated agitation led to increasing locomotor excitability accompanied by increasing upwind bias. Bilateral antennectomy depressed activity, but agitated antennaless hoppers also moved upwind with an without grass odour, provided they were very starved. Vaselining or amputating one antenna, or fixing the two antennae in a crossed-over position, impaired but did not prevent upwind-orientated movement in response to grass odour. It is concluded that the normal upwind movement in response to grass odour is not osmotropotaxis but anemotaxis: the grass odour activates the insects and at the same time switches on their positive orientation reaction to the wind itself. A repellent odour also activates the insects and induces anemotaxis, which is now negative. Thus a variety of stimuli which excite locomotor activity simultaneously switch on anemotaxis, either positive or negative.

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Résumé A jeun les larves du criquet pélerin réagissent à l'odeur d'herbe apportée par le vent en se tournant et en se déplaçant face au vent vers le lieu d'où vient l'odeur. Cette orientation avait été attributée, à la suite de travaux antérieurs, à la stimulation olfactive inégale des deux antennes (osmotropotaxie). Ce phénomène a été réexaminé.L'agitation des larves, soit par maniement individuel, soit par secouage en masse, juste avant de les lâcher dans un tunnel aerodynamique, a eu pour effet sur les larves, qu'elles fussent à jeun ou rassasiées, de les faire se diriger face au vent même en l'absence d'odeur d'herbe. La répétition de ce traitement a accru l'excitabilité locomotrice et également la tendance à aller contre le vent. L'antennectomie bilatérale a réduit l'activité locomotrice mais ces larves sans antennes, préalablement agitées, se sont aussi dirigées contre le vent avec ou sans odeur d'herbe, à condition qu'elles aient été longtemps à jeun.En vaselinant une antenne, ou en faisant l'ablation unilatérale, ou encore en entrecroisant les deux antennes, on a atténué mais non pas supprimé le processus d'orientation face au vent en présence de l'odeur d'herbe.Il en a été conclu que le déplacement normal contre le vent en présence de l'odeur d'herbe n'est pas une osmotropotaxie mais une anémotaxie positive; en faite, l'odeur active bien les criquets et en même temps déclenche une réaction d'orientation au vent. Une odeur repoussante active aussi les criquets et déclenche l'anémotaxie, cette fois négative. Donc differents stimuli qui excitent l'activité locomotrice déclenchent en même temps une anémo taxie positive ou négative.

     

Saccadic flight strategy facilitates collision avoidance: closed-loop performance of a cyberfly

Behavioural and electrophysiological experiments suggest that blowflies employ an active saccadic strategy of flight and gaze control to separate the rotational from the translational optic flow components. As a consequence, this allows motion sensitive neurons to encode during translatory intersaccadic phases of locomotion information about the spatial layout of the environment. So far, it has not been clear whether and how a motor controller could decode the responses of these neurons to prevent a blowfly from colliding with obstacles. Here we propose a simple model of the blowfly visual course control system, named cyberfly, and investigate its performance and limitations. The sensory input module of the cyberfly emulates a pair of output neurons subserving the two eyes of the blowfly visual motion pathway. We analyse two sensory–motor interfaces (SMI). An SMI coupling the differential signal of the sensory neurons proportionally to the yaw rotation fails to avoid obstacles. A more plausible SMI is based on a saccadic controller. Even with sideward drift after saccades as is characteristic of real blowflies, the cyberfly is able to successfully avoid collisions with obstacles. The relative distance information contained in the optic flow during translatory movements between saccades is provided to the SMI by the responses of the visual output neurons. An obvious limitation of this simple mechanism is its strong dependence on the textural properties of the environment.     

Full-state tracking control of a mobile robot using neural networks

In this paper a nonholonomic mobile robot with completely unknown dynamics is discussed. A mathematical model has been considered and an efficient neural network is developed, which ensures guaranteed tracking performance leading to stability of the system. The neural network assumes a single layer structure, by taking advantage of the robot regressor dynamics that expresses the highly nonlinear robot dynamics in a linear form in terms of the known and unknown robot dynamic parameters. No assumptions relating to the boundedness is placed on the unmodeled disturbances. It is capable of generating real-time smooth and continuous velocity control signals that drive the mobile robot to follow the desired trajectories. The proposed approach resolves speed jump problem existing in some previous tracking controllers. Further, this neural network does not require offline training procedures. Lyapunov theory has been used to prove system stability. The practicality and effectiveness of the proposed tracking controller are demonstrated by simulation and comparison results.     

Somatosensory cortical unit responses during avoidance conditioning to sound

Unit responses of the primary somatosensory cortical-projection area were recorded in cats with established conditioned avoidance to sound during the conditioned response. Five types of changes in unit activity were distinguished during the conditioned reflex. The responses were 400–1000 msec in duration; their time of onset coincided with that of the expected reinforcing stimulus. As a rule the change in unit activity was preceded by changes in the electromyogram of the corresponding limb muscles. Among neurons responding to the conditioning stimulus, the proportion with a short latent period of response to electrical stimulation of the skin was less than during investigation of ordinary unit responses to the same stimulus.     

Isometric force generated by locust skeletal muscle: responses to single stimuli

A mathematical model of the locust hind leg extensor muscle is described. The model accounts for the force response of the muscle to well-separated input stimuli under isometric conditions. Experimental data was collected by stimulating the extensor muscle and measuring the force generated at the tibia. In developing a model it was assumed that the response to a single isolated stimulus was linear. A linear model was found to fit well to the response to an isolated stimulus. No assumptions were made about the model order and models of various order were fitted to data in the frequency domain, using a least squares fit. The stimulus can be approximated as an impulse, with the response to each stimulus well described by a linear second-order system. Using a third-order model provided a better fit to data, but the improvement in fit was marginal and the model uses one extra parameter. A fourth-order model, which is often used to describe the behaviour of isometric muscle was found to overfit the data. Using a second-order model provides a simpler way of describing the behaviour of an isometric twitch.     

Using mobile phone technology to treat alcohol use disorder: study protocol for a randomized controlled trial

Background

A primary concern within the healthcare system is to make treatment more accessible as well as attractive for the great majority of alcohol-dependent people who feel reluctant to participate in the treatment programs available. This paper presents the protocol for a randomized controlled trial (RCT) to test the efficacy of two different technical devices (mobile phone application and breathalyzer) on alcohol consumption.

Methods

The study is a three-armed RCT with follow-ups 3 and 6 months after randomization. In total, 375 adults (age 18+ years) diagnosed with alcohol use disorder (AUD) will be invited to participate in a 3-month intervention. The primary outcome is the number of days with heavy drinking, defined as four or more standard drinks (12 g alcohol/drink) and measured by the timeline follow back (TLFB) and Alcohol Use Disorder Identification Test (AUDIT) instruments at 3-month and 6-month follow-up. Secondary outcome measures include weekly alcohol consumption, measured by the TLFB, AUDIT, and phosphatidylethanol in blood values at 3-month and 6-month follow-up (number of days with blood alcohol concentration levels exceeding 60 mg/100 ml).

Discussion

Improving ways of collecting data on alcohol consumption, as well as the treatment system with regards to AUD, is of vital importance. Mobile phone technology, with associated applications, is widely recognized as a potentially powerful tool in the prevention and management of disease. This study will provide unique knowledge regarding the use of new technology as instruments for measuring alcohol consumption and, also, as a possible way to decrease it.

Trial registration

ISRCTN, ISRCTN14515753. Registered on 31 May 2018.

     

Using lobster noses to inspire robot sensor design

Robots are needed to locate the sources of toxic chemical plumes. Lobsters, which track odor plumes for many ecologically crucial activities, can provide inspiration for robot designers. Before accurate search strategies for robots can be developed, how odor molecules are captured by the lobster's chemosensors must be understood. A recent study by Koehl et al. shows how lobster olfactory antennules alter the patterns of concentration in turbulent odor plumes during odor sampling.     

Influence of a mobile robot on the spatial behaviour of quail chicks

Quail chicks encountered an autonomous mobile robot during their early development. The robot incorporated a heat source that stimulated following of chicks. The spatial behaviour of grown-up chicks was tested in an exploration test and a detour test. Chicks that grew with the mobile robot exhibited better spatial abilities than chicks grown with a static heat source. We discuss these results in the perspective of animal-robot interaction and of the role of early spatial experience on the behavioural development.     

Physiological regulation and functional significance of shade avoidance responses to neighbors

Plants growing in dense vegetations compete with their neighbors for resources such as water, nutrients and light. The competition for light has been particularly well studied, both for its fitness consequences as well as the adaptive behaviors that plants display to win the battle for light interception. Aboveground, plants detect their competitors through photosensory cues, notably the red:far-red light ratio (R:FR). The R:FR is a very reliable indicator of future competition as it decreases in a plant-specific manner through red light absorption for photosynthesis and is sensed with the phytochrome photoreceptors. In addition, also blue light depletion is perceived for neighbor detection. As a response to these light signals plants display a suite of phenotypic traits defined as the shade avoidance syndrome (SAS). The SAS helps to position the photosynthesizing leaves in the higher zones of a canopy where light conditions are more favorable. In this review we will discuss the physiological control mechanisms through which the photosensory signals are transduced into the adaptive phenotypic responses that make up the SAS. Using this mechanistic knowledge as a starting point, we will discuss how the SAS functions in the context of the complex multi-facetted environments, which plants usually grow in.Key words: competition, shade avoidance, hormones, cell wall, adaptive plasticity, photoreceptor, light     

Fly-like visuomotor responses of a robot using aVLSI motion-sensitive chips

 We explore the use of continuous-time analog very-large-scale-integrated (aVLSI) neuromorphic visual preprocessors together with a robotic platform in generating bio-inspired behaviors. Both the aVLSI motion sensors and the robot behaviors described in this work are inspired by the motion computation in the fly visual system and two different fly behaviors. In most robotic systems, the visual information comes from serially scanned imagers. This restricts the form of computation of the visual image and slows down the input rate to the controller system of the robot, hence increasing the reaction time of the robot. These aVLSI neuromorphic sensors reduce the computational load and power consumption of the robot, thus making it possible to explore continuous-time visuomotor control systems that react in real-time to the environment. The motion sensor provides two outputs: one for the preferred direction and the other for the null direction. These motion outputs are created from the aggregation of six elementary motion detectors that implement a variant of Reichardt's correlation algorithm. The four analog continuous-time outputs from the motion chips go to the control system on the robot which generates a mixture of two behaviors – course stabilization and fixation – from the outputs of these sensors. Since there are only four outputs, the amount of information transmitted to the controller is reduced (as compared to using a CCD sensor), and the reaction time of the robot is greatly decreased. In this work, the robot samples the motion sensors every 3.3 ms during the behavioral experiments. Received: 4 October 1999 / Accepted in revised form: 26 April 2001     

Neuromuscular responses to impact and collision during elite rugby league match play

The purpose of this study was to investigate the relationship between the prematch and short-term postmatch neuromuscular responses to the intensity, number, and distribution of impacts associated with collisions during elite Rugby League match play. Twenty-two elite male Rugby League players were monitored during 8 regular season competition matches using portable global positioning system (GPS) technology. The intensity, number, and distribution of impact forces experienced by players during match play were recorded using integrated accelerometry. Peak rate of force development (PRFD), peak power (PP), and peak force (PF) were measured during a countermovement jump on a force plate 24 hours prematch, 30 minutes prematch, 30 minutes postmatch and then at 24-hour intervals for a period of 5 days postmatch. The change in the dependent variables at each sample collection time was compared with that at 24 hours prematch and 30-minute prematch measures. There were significant (p < 0.05) decreases in PRFD and PP up to 24 hours postmatch with PF significantly (p < 0.05) being decreased 30 minutes postmatch. Significant (p < 0.05) correlations were found between the total number of impacts and PRFD and PP 30 minutes postmatch. Impact zones 4 (7.1-8.0 G), 5 (>8.1-10.0 G), and 6 (>10.1 G) were significantly (p < 0.05) correlated to PRFD and PP 30 minutes postmatch with the number of zone 5 and 6 impacts significantly (p < 0.05) correlated to PRFD and PP 24 hours postmatch. Elite Rugby League match play resulted in significant neuromuscular fatigue and was highly dependent on the number of heavy collisions >7.1G. Results demonstrate that neuromuscular function is compromised for up to 48 hours postmatch indicating that at least 2 days of modified activity is required to achieve full neuromuscular recovery after elite Rugby League match play. Position-specific demands on energy systems and the influence of repeated blunt force trauma during collisions during elite Rugby League match play should be considered when planning postmatch recovery protocols and training activities to optimize subsequent performance.     

东亚飞蝗不同来源聚集信息素的电生理活性

采用触角电位测定仪器测定不同来源的东亚飞蝗Locustamigratoriamanilensis聚集信息素的生理活性 ,结合行为生物测定的结果分析表明 :来源于粪便中的聚集信息素的活性较高 ,同时 ,使用较高极性溶剂抽提制备蝗蝻粪便中的信息素和采用中极性的溶剂制备成蝗粪便中的聚集信息素 ,其信息素的活性均较高 ;利用低极性溶剂从东亚飞蝗粪便中制备得到的聚集信息素的活性较低 ;采用层析柱吸附浓缩飞蝗粪便中自然挥发出的气味和飞蝗体表的气味并进行生物测定后表明 ,其EAG活性普遍较低 ;因此 ,来自于飞蝗粪便中的且采用合适的溶剂抽提制备的聚集信息素 ,具有较高的生物学活性。     

Adaptation and responses to changes in illumination by second- and third-order neurones of locust ocelli

Intracellular recordings have been made of responses to step, ramp and sinusoidal changes of light by second-order L-neurones and a third-order neurone, DNI, of locust (Locusta migratoria) ocelli.

Self-organization of spiking neural network that generates autonomous behavior in a real mobile robot

In this paper, we propose self-organization algorithm of spiking neural network (SNN) applicable to autonomous robot for generation of adoptive and goal-directed behavior. First, we formulated a SNN model whose inputs and outputs were analog and the hidden unites are interconnected each other. Next, we implemented it into a miniature mobile robot Khepera. In order to see whether or not a solution(s) for the given task(s) exists with the SNN, the robot was evolved with the genetic algorithm in the environment. The robot acquired the obstacle avoidance and navigation task successfully, exhibiting the presence of the solution. After that, a self-organization algorithm based on a use-dependent synaptic potentiation and depotentiation at synapses of input layer to hidden layer and of hidden layer to output layer was formulated and implemented into the robot. In the environment, the robot incrementally organized the network and the given tasks were successfully performed. The time needed to acquire the desired adoptive and goal-directed behavior using the proposed self-organization method was much less than that with the genetic evolution, approximately one fifth.