Electrical response of bat retina to spectral stimulation: comparison of four microchiropteran species

Hope, G. M.; Bhatnagar, Kunwar P.

doi:10.1007/bf01963279

Cited by 53 publications

(45 citation statements)

References 4 publications

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“…It may be possible for a bat to use spatial memory instead of echolocation to avoid fixed obstacles; however, the unpredictable movement of a conspecific eliminated the possibility that the silent bat could rely on spatial memory to avoid in-flight collision. The bat's use of vision was excluded by the low level infrared lighting in the room, which fell outside the spectral sensitivity of the bat's retina (20).…”

Section: Discussionmentioning

confidence: 99%

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

Chiu

Xian

Moss

2008

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

116

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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Section: Discussionmentioning

confidence: 99%

“…We analyzed 30 baseline trials/bat and 20 two-bat trials/pair. Light in the room was long-wavelength filtered (Ͼ650 nm), to prevent the bat from using visual cues for orientation and prey capture (20).…”

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.

116

105

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“…In our study, memory effects were minimized, because the bats were required to fly around and intercept a tethered target placed at random locations and dropped at random times in a large (7.3 ϫ 6.4 ϫ 2.0 m 3 ), empty room. The use of vision in our study was limited by removing light sources visible to the bat (Hope and Bhatnagar, 1979). This paradigm allowed us to test flight guidance by echolocation under different behavioral conditions, which is essential to our conclusions.…”

Section: Discussionmentioning

confidence: 99%

“…The room walls and ceiling were lined with sound absorbent acoustic foam (Sonex One; Acoustical Solutions, Richmond, VA) to reduce reverberations. The room was illuminated by dim, long wavelength light (Ͼ650 nm; light from normal incandescent bulbs passed through a filter plate; Plexiglas G #2711; Atofina Chemicals, Philadelphia, PA) to which the bat is insensitive (Hope and Bhatnagar, 1979). Images from two high-speed video cameras (CCD-based cameras operating at 240 frames per second, synchronized to 1/2 frame accuracy; Kodak MotionCorder; Eastman Kodak, San Diego, CA) were used to reconstruct the three-dimensional flight path of the bat and the trajectory of the prey.…”

Section: Methodsmentioning

confidence: 99%

Steering by Hearing: A Bat’s Acoustic Gaze Is Linked to Its Flight Motor Output by a Delayed, Adaptive Linear Law

Ghose

Moss²

2006

J. Neurosci.

113

108

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Adaptive behaviors require sensorimotor computations that convert information represented initially in sensory coordinates to commands for action in motor coordinates. Fundamental to these computations is the relationship between the region of the environment sensed by the animal (gaze) and the animal's locomotor plan. Studies of visually guided animals have revealed an anticipatory relationship between gaze direction and the locomotor plan during target-directed locomotion. Here, we study an acoustically guided animal, an echolocating bat, and relate acoustic gaze (direction of the sonar beam) to flight planning as the bat searches for and intercepts insect prey. We show differences in the relationship between gaze and locomotion as the bat progresses through different phases of insect pursuit. We define acoustic gaze angle, gaze , to be the angle between the sonar beam axis and the bat's flight path. We show that there is a strong linear linkage between acoustic gaze angle at time t [ gaze (t)] and flight turn rate at time t ϩ into the future [ . flight (t ϩ )], which can be expressed by the formula . flight (t ϩ ) ϭ k gaze (t). The gain, k, of this linkage depends on the bat's behavioral state, which is indexed by its sonar pulse rate. For high pulse rates, associated with insect attacking behavior, k is twice as high compared with low pulse rates, associated with searching behavior. We suggest that this adjustable linkage between acoustic gaze and motor output in a flying echolocating bat simplifies the transformation of auditory information to flight motor commands.

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“…Two high-speed cameras (240framess -1 ; Kodak MotionCorder, San Diego, CA, USA) were placed in adjacent corners of the room to record the positions of bats, the tethered mealworm and the microphones. Only longwavelength lighting (>650nm) was available during data recording to restrict the bat from using visual cues to localize the target and conspecifics (Hope and Bhatnagar, 1979). Video recordings were later used to reconstruct the 3-D flight trajectory of each bat by a custom MATLAB (Mathworks, Natick, MA, USA) program.…”

Section: Experimental Setup and Data Recordingsmentioning

confidence: 99%