scholarly journals Non-visual crypsis: a review of the empirical evidence for camouflage to senses other than vision

2008 ◽  
Vol 364 (1516) ◽  
pp. 549-557 ◽  
Author(s):  
Graeme D Ruxton
Keyword(s):  
Predation Risk ◽  
Empirical Evidence ◽  
Sensory System ◽  
Sensory Perception ◽  
Sensory Systems ◽  
Conclusive Evidence ◽  
Chemical Camouflage ◽  
Background Matching

I review the evidence that organisms have adaptations that confer difficulty of detection by predators and parasites that seek their targets primarily using sensory systems other than vision. In other words, I will answer the question of whether crypsis is a concept that can usefully be applied to non-visual sensory perception. Probably because vision is such an important sensory system in humans, research in this field is sparse. Thus, at present we have very few examples of chemical camouflage, and even these contain some ambiguity in deciding whether they are best seen as examples of background matching or mimicry. There are many examples of organisms that are adaptively silent at times or in locations when or where predation risk is higher or in response to detection of a predator. By contrast, evidence that the form (rather than use) of vocalizations and other sound-based signals has been influenced by issues of reducing detectability to unintended receivers is suggestive rather than conclusive. There is again suggestive but not completely conclusive evidence for crypsis against electro-sensing predators. Lastly, mechanoreception is highly understudied in this regard, but there are scattered reports that strongly suggest that some species can be thought of as being adapted to be cryptic in this modality. Hence, I conclude that crypsis is a concept that can usefully be applied to senses other than vision, and that this is a field very much worthy of more investigation.

scholarly journals Neurophysiology goes wild: from exploring sensory coding in sound proof rooms to natural environments

2021 ◽  
Vol 207 (3) ◽  
pp. 303-319
Author(s):  
Heiner Römer
Keyword(s):  
Sensory System ◽  
Sensory Systems ◽  
Natural Environments ◽  
Sensory Coding ◽  
Noise Levels ◽  
Sensory Physiology ◽  
Sound Localisation ◽  
Physical Environments ◽  
History Of ◽  
Adaptive Behaviours

AbstractTo perform adaptive behaviours, animals have to establish a representation of the physical “outside” world. How these representations are created by sensory systems is a central issue in sensory physiology. This review addresses the history of experimental approaches toward ideas about sensory coding, using the relatively simple auditory system of acoustic insects. I will discuss the empirical evidence in support of Barlow’s “efficient coding hypothesis”, which argues that the coding properties of neurons undergo specific adaptations that allow insects to detect biologically important acoustic stimuli. This hypothesis opposes the view that the sensory systems of receivers are biased as a result of their phylogeny, which finally determine whether a sound stimulus elicits a behavioural response. Acoustic signals are often transmitted over considerable distances in complex physical environments with high noise levels, resulting in degradation of the temporal pattern of stimuli, unpredictable attenuation, reduced signal-to-noise levels, and degradation of cues used for sound localisation. Thus, a more naturalistic view of sensory coding must be taken, since the signals as broadcast by signallers are rarely equivalent to the effective stimuli encoded by the sensory system of receivers. The consequences of the environmental conditions for sensory coding are discussed.

ENTROPY MINIMIZATION: A DESIGN PRINCIPLE FOR SENSORY PERCEPTION?

1992 ◽  
Vol 03 (supp01) ◽  
pp. 81-90 ◽  
Author(s):  
Joseph J. Atick
Keyword(s):  
Information Theory ◽  
Knowledge Acquisition ◽  
Data Reduction ◽  
Design Principle ◽  
Variational Principles ◽  
Sensory Perception ◽  
Sensory Systems ◽  
Sensory Pathways ◽  
Reduction Problem ◽  
Predictive Design

We speculate on how computational strategies suggested by Information theory could be useful for knowledge acquisition in sensory systems. The focus of our exploration is the idea that perception is a data reduction problem and as such sensory transformations should be predictable from the data reduction problem and as such sensory transformations should be predictable terms of variational principles involving the minimization of two types of entropy. The analysis suggests a scheme in which the two can be combined to produce a predictive design principle for sensory pathways.

scholarly journals Towards Using the Instrumented Timed Up-and-Go Test for Screening of Sensory System Performance for Balance Control in Older Adults

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 622 ◽  
Author(s):  
Thomas Gerhardy ◽  
Katharina Gordt ◽  
Carl-Philipp Jansen ◽  
Michael Schwenk
Keyword(s):  
Older Adults ◽  
System Performance ◽  
Fall Risk ◽  
Balance Control ◽  
Sensory System ◽  
Sensory Systems ◽  
Community Dwelling ◽  
Functional Mobility ◽  
Timed Up And Go ◽  
Community Dwelling Older Adults

Background: Decreasing performance of the sensory systems’ for balance control, including the visual, somatosensory and vestibular system, is associated with increased fall risk in older adults. A smartphone-based version of the Timed Up-and-Go (mTUG) may allow screening sensory balance impairments through mTUG subphases. The association between mTUG subphases and sensory system performance is examined. Methods: Functional mobility of forty-one community-dwelling older adults (>55 years) was measured using a validated mTUG. Duration of mTUG and its subphases ‘sit-to-walk’, ‘walking’, ‘turning’, ‘turn-to-sit’ and ‘sit-down’ were extracted. Sensory systems’ performance was quantified by validated posturography during standing (30 s) under different conditions. Visual, somatosensory and vestibular control ratios (CR) were calculated from posturography and correlated with mTUG subphases. Results: Vestibular CR correlated with mTUG total time (r = 0.54; p < 0.01), subphases ‘walking’ (r = 0.56; p < 0.01), and ‘turning’ (r = 0.43; p = 0.01). Somatosensory CR correlated with mTUG total time (r = 0.52; p = 0.01), subphases ‘walking’ (r = 0.52; p < 0.01) and ‘turning’ (r = 0.44; p < 0.01). Conclusions: Supporting the proposed approach, results indicate an association between specific mTUG subphases and sensory system performance. mTUG subphases ‘walking’ and ‘turning’ may allow screening for sensory system deterioration. This is a first step towards an objective, detailed and expeditious balance control assessment, however needing validation in a larger study.

General Principles for Sensory Coding

2018 ◽  
Author(s):  
Tatyana O. Sharpee
Keyword(s):  
Sensory System ◽  
Sensory Systems ◽  
Multiple Delays ◽  
Minimal Amount ◽  
Sensory Coding ◽  
Trade Offs ◽  
Almost All ◽  
Comprehensive Framework ◽  
State Of The Environment ◽  
The Impact

Sensory systems exist to provide an organism with information about the state of the environment that can be used to guide future actions and decisions. Remarkably, two conceptually simple yet general theorems from information theory can be used to evaluate the performance of any sensory system. One theorem states that there is a minimal amount of energy that an organism has to spend in order to capture a given amount of information about the environment. The second theorem states that the maximum rate with which the organism can acquire resources from the environment, relative to its competitors, is limited by the information this organism collects about the environment, also relative to its competitors. These two theorems provide a scaffold for formulating and testing general principles of sensory coding but leave unanswered many important practical questions of implementation in neural circuits. These implementation questions have guided thinking in entire subfields of sensory neuroscience, and include: What features in the sensory environment should be measured? Given that we make decisions on a variety of time scales, how should one solve trade-offs between making simpler measurements to guide minimal decisions vs. more elaborate sensory systems that have to overcome multiple delays between sensation and action. Once we agree on the types of features that are important to represent, how should they be represented? How should resources be allocated between different stages of processing, and where is the impact of noise most damaging? Finally, one should consider trade-offs between implementing a fixed strategy vs. an adaptive scheme that readjusts resources based on current needs. Where adaptation is considered, under what conditions does it become optimal to switch strategies? Research over the past 60 years has provided answers to almost all of these questions but primarily in early sensory systems. Joining these answers into a comprehensive framework is a challenge that will help us understand who we are and how we can make better use of limited natural resources.

scholarly journals An Artificial Vibrissa-Like Sensor for Detection of Flows

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3892
Author(s):  
Moritz Scharff ◽  
Philipp Schorr ◽  
Tatiana Becker ◽  
Christian Resagk ◽  
Jorge H. Alencastre Miranda ◽  
...  
Keyword(s):  
Compressible Flow ◽  
Surface Texture ◽  
Large Deflection ◽  
Sensory System ◽  
Flow Characteristics ◽  
Elastic Beam ◽  
Sensory Systems ◽  
Tactile Sensors ◽  
Complex Receptor ◽  
Simulation And Experiment

In nature, there are several examples of sophisticated sensory systems to sense flows, e.g., the vibrissae of mammals. Seals can detect the flow of their prey, and rats are able to perceive the flow of surrounding air. The vibrissae are arranged around muzzle of an animal. A vibrissa consists of two major components: a shaft (infector) and a follicle–sinus complex (receptor), whereby the base of the shaft is supported by the follicle-sinus complex. The vibrissa shaft collects and transmits stimuli, e.g., flows, while the follicle-sinus complex transduces them for further processing. Beside detecting flows, the animals can also recognize the size of an object or determine the surface texture. Here, the combination of these functionalities in a single sensory system serves as paragon for artificial tactile sensors. The detection of flows becomes important regarding the measurement of flow characteristics, e.g., velocity, as well as the influence of the sensor during the scanning of objects. These aspects are closely related to each other, but, how can the characteristics of flow be represented by the signals at the base of a vibrissa shaft or by an artificial vibrissa-like sensor respectively? In this work, the structure of a natural vibrissa shaft is simplified to a slender, cylindrical/tapered elastic beam. The model is analyzed in simulation and experiment in order to identify the necessary observables to evaluate flows based on the quasi-static large deflection of the sensor shaft inside a steady, non-uniform, laminar, in-compressible flow.

scholarly journals Neural representation of bat predation risk and evasive flight in moths: a modelling approach

2019 ◽  
Author(s):  
Holger R. Goerlitz ◽  
Hannah M. ter Hofstede ◽  
Marc W. Holderied
Keyword(s):  
Frequency Tuning ◽  
Sensory System ◽  
Safety Margin ◽  
Sensory Systems ◽  
Neural Representation ◽  
Multiple Predators ◽  
Echolocation Calls ◽  
Auditory Receptor ◽  
Multiple Characteristics ◽  
Similar Distance

AbstractMost animals are at risk from multiple predators and can vary anti-predator behaviour based on the level of threat posed by each predator. Animals use sensory systems to detect predator cues, but the relationship between the tuning of sensory systems and the sensory cues related to predator threat are not well-studied at the community level. Noctuid moths have ultrasound-sensitive ears to detect the echolocation calls of predatory bats. Here, combining empirical data and mathematical modelling, we show that moth hearing is adapted to provide information about the threat posed by different sympatric bat species. First, we found that multiple characteristics related to the threat posed by bats to moths correlate with bat echolocation call frequency. Second, the frequency tuning of the most sensitive auditory receptor in noctuid moth ears provides information allowing moths to escape detection by all sympatric bats with similar safety margin distances. Third, the least sensitive auditory receptor usually responds to bat echolocation calls at a similar distance across all moth species for a given bat species. If this neuron triggers last-ditch evasive flight, it suggests that there is an ideal reaction distance for each bat species, regardless of moth size. This study shows that even a very simple sensory system can adapt to deliver information suitable for triggering appropriate defensive reactions to each predator in a multiple predator community.

scholarly journals Organizational sensory systems of Polish enterprises in the context of cooperative relationships

Management ◽  
2019 ◽  
Vol 23 (1) ◽  
pp. 50-60
Author(s):  
Michał Chomicki
Keyword(s):  
Sensory System ◽  
Sensory Systems ◽  
Economic Environment ◽  
Independence Tests ◽  
Cooperative Relationships ◽  
Theoretical Part ◽  
Chi Squared ◽  
The Relationship

Summary The aim of this paper is to indicate the relationship between the shape of organizational sensory systems of Polish companies and beneficialness of the shape of cooperative relations between these companies with particular kinds of cooperators. The theoretical part of this article was devoted to the identification of the role of cooperative relations in the contemporary economic environment and a brief description of the concept of organizational sensory system, including its influence on cooperation between companies. The survey used the respondents’ indications of frequency of monitoring of elements of organization and its environment and the indication of the beneficialness of the shape of cooperative relationships with suppliers, customers and co-opetitors (in the framework of coopetitive relations). The chi-squared independence tests were used to demonstrate dependencies. In conclusion, it turned out that there are only two statistically significant relations and both of them pertain to relationships with customers.

scholarly journals Complete neuroanatomy and sensor maps of Odonata wings for fly-by-feel flight control

2021 ◽  
Author(s):  
Joseph Fabian ◽  
Igor Siwanowicz ◽  
Myriam Uhrhan ◽  
Masateru Maeda ◽  
Richard Bomphrey ◽  
...  
Keyword(s):  
State Estimation ◽  
Flight Control ◽  
Sensory System ◽  
Distribution Patterns ◽  
Element Model ◽  
Sensory Systems ◽  
The Body ◽  
Dynamic State ◽  
Dynamic Strain ◽  
Wing Model

Fly-by-feel describes how flying animals capture aerodynamic information via their wings' sensory system to implement or enhance flight control. Traditional studies on animal flight emphasized controlling body stability via visual or inertial sensory inputs. In line with this, it has been demonstrated that wing sensory systems can provide inertial state estimation for the body. What about the state estimation of the wings themselves? Little is known about how flying animals utilize their wing sensory systems to monitor the dynamic state of their highly deformable wings. This study is a step toward a comprehensive investigation of how a flying animal senses aerodynamic and aeroelastic features of the wings relevant to flight control. Odonates: dragonflies and damselflies, are a great model for this because they have excellent flight performance and their wing structure has been extensively studied. Here, we developed a strategy to map the entire sensory system of Odonata wings via confocal microscopy. The result is the first complete map of a flying animal's wing sensory system, including both the external sensor morphologies and internal neuroanatomy. This complete search revealed over 750 sensors on each wing for one of the smallest dragonfly species and roughly half for a comparable size damselfly. We found over eight morphological classes of sensors, most of which resembled mechanosensors. Most sensors were innervated by a single neuron with an innervation pattern consistent with minimising wiring length. We further mapped the major veins of 13 Odonate species across 10 families and identified consistent sensor distribution patterns, with sensor count scaling with wing length. To explain the strain sensor density distribution along the major veins, we constructed a high-fidelity finite element model of a dragonfly wing based on micro-CT data. This flapping wing model revealed dynamic strain fields and suggested how increasing sensor count could allow encoding of different wing states. Taken together, the Odonate wing sensory system is well-equipped to implement sophisticated fly-by-feel flight control.

scholarly journals Ethnic favouritism in Kenyan education reconsidered: when a picture is worth more than a thousand regressions

2020 ◽  
Vol 58 (3) ◽  
pp. 425-460
Author(s):  
Rebecca Simson ◽  
Elliott Green
Keyword(s):  
Secondary Education ◽  
Educational Attainment ◽  
Empirical Evidence ◽  
Ethnic Groups ◽  
Regional Distribution ◽  
Conclusive Evidence ◽  
Test Case ◽  
Adequate Account ◽  
Basic Services ◽  
Education In Africa

ABSTRACTDoes a leader's ethnicity affect the regional distribution of basic services such as education in Africa? Several influential studies have argued in the affirmative, by using educational attainment levels to show that children who share the ethnicity of the president during their school-aged years have higher attainment than their peers. In this paper we revisit this empirical evidence and show that it rests on problematic assumptions. Some models commonly used to test for favouritism do not take adequate account of educational convergence and once this is properly accounted for the results are found to be unstable. Using Kenya as a test case, we argue that there is no conclusive evidence of ethnic favouritism in primary or secondary education, but rather a process of educational convergence among the country's larger ethnic groups. This evidence matters, as it shapes how we understand the ethnic calculus of politicians.

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