Sensory acquisition in active sensing systems

Nelson, Mark; MacIver, Malcolm A.

doi:10.1007/s00359-006-0099-4

Cited by 208 publications

(192 citation statements)

References 95 publications

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“…We estimated the visual sensory volume (18,29,82) for this object by a spherical sector of specified radius (from visual range calculations), azimuth, and elevation. (85), providing a conservative estimate of aerial volume.…”

Section: Methodsmentioning

confidence: 99%

Massive increase in visual range preceded the origin of terrestrial vertebrates

MacIver

Schmitz

Mugan

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The evolution of terrestrial vertebrates, starting around 385 million years ago, is an iconic moment in evolution that brings to mind images of fish transforming into four-legged animals. Here, we show that this radical change in body shape was preceded by an equally dramatic change in sensory abilities akin to transitioning from seeing over short distances in a dense fog to seeing over long distances on a clear day. Measurements of eye sockets and simulations of their evolution show that eyes nearly tripled in size just before vertebrates began living on land. Computational simulations of these animal's visual ecology show that for viewing objects through water, the increase in eye size provided a negligible increase in performance. However, when viewing objects through air, the increase in eye size provided a large increase in performance. The jump in eye size was, therefore, unlikely to have arisen for seeing through water and instead points to an unexpected hybrid of seeing through air while still primarily inhabiting water. Our results and several anatomical innovations arising at the same time suggest lifestyle similarity to crocodiles. The consequent combination of the increase in eye size and vision through air would have conferred a 1 million-fold increase in the amount of space within which objects could be seen. The "buena vista" hypothesis that our data suggest is that seeing opportunities from afar played a role in the subsequent evolution of fully terrestrial limbs as well as the emergence of elaborated action sequences through planning circuits in the nervous system. fish-tetrapod transition | vision | visual ecology | terrestriality | prospective cognition B efore terrestrial vertebrates arose, their ancestors inhabited underwater environments, where vision is highly compromised compared with vision above water. The visual difference between life in water and life above it is comparable with driving fast on a foggy road, where our responses must be rapid and simple, vs. driving in clear daylight conditions, where deliberation over more complex choices is enabled by the vast increase in sensory range. Nonetheless, although an immense quantity of work has been done on the emergence of limbs during the evolution of land vertebrates, how visual capability changed during the transition from water to land has not been explored. In part, this lack of exploration is because computational visual ecology-necessary to interpret the fossil data-has not been combined with early tetrapod paleontology. Through combining these disciplines, here we probe the evolutionary history of the switch in our visual sensory ecology from water to air. Surprisingly, our results show that eyes tripled in size just before full-time life on land evolved. Convergent lines of evidence, including our own, strongly support the hypothesis that a crocodilian ecotype-using the greatly enhanced visual capabilities conferred by vision through air to prey on the bounty of unexploited invertebrates that long preceded the vertebrates onto ...

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Section: Methodsmentioning

confidence: 99%

Massive increase in visual range preceded the origin of terrestrial vertebrates

MacIver

Schmitz

Mugan

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…However, two specific groups of freshwater fish are capable of 'active electrolocation' as they both emit and sense an electric field, similar to active sensing systems such as radar and sonar (Nelson & MacIver 2006). Those active electrolocators can move around and hunt in total darkness just like BCF.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic object recognition using pressure sensing

2010

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Hydrodynamic sensing is instrumental to fish and some amphibians. It also represents, for underwater vehicles, an alternative way of sensing the fluid environment when visual and acoustic sensing are limited. To assess the effectiveness of hydrodynamic sensing and gain insight into its capabilities and limitations, we investigated the forward and inverse problem of detection and identification, using the hydrodynamic pressure in the neighbourhood, of a stationary obstacle described using a general shape representation. Based on conformal mapping and a general normalization procedure, our obstacle representation accounts for all specific features of progressive perceptual hydrodynamic imaging reported experimentally. Size, location and shape are encoded separately. The shape representation rests upon an asymptotic series which embodies the progressive character of hydrodynamic imaging through pressure sensing. A dynamic filtering method is used to invert noisy nonlinear pressure signals for the shape parameters. The results highlight the dependence of the sensitivity of hydrodynamic sensing not only on the relative distance to the disturbance but also its bearing.

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“…echolocation ͉ jamming avoidance ͉ passive listening ͉ spatial hearing A ctive sensing enables a wide range of animal species to orient and forage under conditions where light levels are low or absent (1). Self-produced acoustic or electric signals give rise to information about the environment that is used to guide a variety of behaviors.…”

mentioning

confidence: 99%

Flying in silence: Echolocating bats cease vocalizing to avoid sonar jamming

Chiu

Xian

Moss

2008

Proc. Natl. Acad. Sci. U.S.A.

113

105

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Although it has been recognized that echolocating bats may experience jamming from the signals of conspecifics, research on this problem has focused exclusively on time-frequency adjustments in the emitted signals to minimize interference. Here, we report a surprising new strategy used by bats to avoid interference, namely silence. In a quantitative study of flight and vocal behavior of the big brown bat (Eptesicus fuscus), we discovered that the bat spends considerable time in silence when flying with conspecifics. Silent behavior, defined here as at least one bat in a pair ceasing vocalization for more than 0.2 s (200 ms), occurred as much as 76% of the time (mean of 40% across 7 pairs) when their separation was shorter than 1 m, but only 0.08% when a single bat flew alone. Spatial separation, heading direction, and similarity in call design of paired bats were related to the prevalence of this silent behavior. Our data suggest that the bat uses silence as a strategy to avoid interference from sonar vocalizations of its neighbor, while listening to conspecific-generated acoustic signals to guide orientation. Based on previous neurophysiological studies of the bat's auditory midbrain, we hypothesize that environmental sounds (including vocalizations produced by other bats) and active echolocation evoke neural activity in different populations of neurons. Our findings offer compelling evidence that the echolocating bat switches between active and passive sensing to cope with a complex acoustic environment, and these results hold broad implications for research on navigation and communication throughout the animal kingdom.echolocation ͉ jamming avoidance ͉ passive listening ͉ spatial hearing A ctive sensing enables a wide range of animal species to orient and forage under conditions where light levels are low or absent (1). Self-produced acoustic or electric signals give rise to information about the environment that is used to guide a variety of behaviors. Echolocating animals produce ultrasonic signals and determine the direction, distance, and features of objects in the environment from the arrival time, amplitude, and spectrum of sonar reflections (2). Electric fish generate discharges from an electric organ in the tail, and sense the location and features of nearby objects from amplitude and phase changes in the electric field (3).With the benefits of active sensing also come challenges, namely the potential for interference from signals produced by neighboring conspecifics. Past research has uncovered strategies by which echolocating bats and electric fish avoid jamming through active adjustments in the signals they produce to probe the environment. Wave-type weakly electric fish modify the electric organ discharge frequency, and pulse-type weakly electric fish change the timing of electric organ discharge to avoid interference from the signals of neighbors (3). In echolocating bats, spectral and/or temporal adjustments in the characteristics of sonar vocalizations, which yield acoustic separation between s...

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Sensory acquisition in active sensing systems

Cited by 208 publications

References 95 publications

Massive increase in visual range preceded the origin of terrestrial vertebrates

Massive increase in visual range preceded the origin of terrestrial vertebrates

Hydrodynamic object recognition using pressure sensing

Flying in silence: Echolocating bats cease vocalizing to avoid sonar jamming

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