Behavioral Studies of Auditory Information Processing

Moss, Cynthia F.; Schnitzler, Hans‐Ulrich

doi:10.1007/978-1-4612-2556-0_3

Cited by 118 publications

(104 citation statements)

References 102 publications

(192 reference statements)

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“…The bat guides its flight and forages in darkness by emitting ultrasonic vocal signals and listening to the echoes returning to its ears from objects in space (Griffin, 1958;Moss and Schnitzler, 1995). Binaural differences in arrival time, intensity, and spectrum of echoes encode the location of an object in azimuth and elevation (Lawrence and Simmons, 1982;Simmons et al, 1983;Pollak, 1988).…”

Section: Abstract: Superior Colliculus; Echolocation; Bats; Acousticmentioning

confidence: 99%

“…In individual species, the organization of the SC reflects the importance of a particular sensory modality to an animal's goal-directed behavioral responses. By analogy with the role of the SC in the saccadic eye-movement system of primates (Sparks, 1986), in gaze-control orientation behavior in cat and barn owl (Knudsen, 1982;Middlebrooks and Knudsen, 1984;Du Lac and Knudsen, 1990;Munoz et al, 1991), and in prey-catching behavior in pit viper and frog (Hartline et al, 1978;Grobstein, 1988), the SC of the echolocating bat may play a role in integrating sensory and motor signals that drive this animal's acoustic orientation by sonar.The bat guides its flight and forages in darkness by emitting ultrasonic vocal signals and listening to the echoes returning to its ears from objects in space (Griffin, 1958;Moss and Schnitzler, 1995). Binaural differences in arrival time, intensity, and spectrum of echoes encode the location of an object in azimuth and elevation (Lawrence and Simmons, 1982;Simmons et al, 1983;Pollak, 1988).…”

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Spatially Selective Auditory Responses in the Superior Colliculus of the Echolocating Bat

Valentine

Moss

1997

J. Neurosci.

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When a bat approaches a target, it continuously modifies its echolocation sounds and relies on incoming echo information to shape the characteristics of its subsequent sonar cries. In addition, acoustic information about the azimuth and elevation of a sonar target elicits orienting movements of the head and pinnae toward the sound source. This requires a common sensorimotor interface, where echo information is used to guide motor behaviors.Using single-unit neurophysiological methods and free-field auditory stimulation, we present data on biologically relevant specializations in the superior colliculus (SC) of the bat for orientation by sonar. In the bat's SC, two classes of spatially tuned neurons are distinguished by their sensitivity to echoes. One population shows facilitated, delay-tuned responses to pairs of sounds, simulating sonar emissions and echoes. Delay tuning, related to encoding target range, may play a role in guiding motor responses in echolocation, because the bat adjusts its emissions with changes in target distance. The delay-facilitated response depends on the direction of stimulation and on the temporal relationship between the simulated emission and echo in the sound pair, suggesting that this class of neurons represents the location of a target in three dimensions. A second population encodes the target in two dimensions, azimuth and elevation, and does not show a facilitated response to echoes delivered from any locus. Encoding of azimuth and elevation may be important for directing head aim, and this class may function in transforming auditory spatial information into signals used to guide acoustic orientation. Key words: superior colliculus; echolocation; bats; acoustic orientation; spatial perception; sensorimotor integrationThe midbrain superior colliculus (SC; optic tectum) of vertebrates is thought to play a role in spatial perception and in the translation of multisensory signals into commands for the control of quick (saccadic) orienting responses. In individual species, the organization of the SC reflects the importance of a particular sensory modality to an animal's goal-directed behavioral responses. By analogy with the role of the SC in the saccadic eye-movement system of primates (Sparks, 1986), in gaze-control orientation behavior in cat and barn owl (Knudsen, 1982;Middlebrooks and Knudsen, 1984;Du Lac and Knudsen, 1990;Munoz et al., 1991), and in prey-catching behavior in pit viper and frog (Hartline et al., 1978;Grobstein, 1988), the SC of the echolocating bat may play a role in integrating sensory and motor signals that drive this animal's acoustic orientation by sonar.The bat guides its flight and forages in darkness by emitting ultrasonic vocal signals and listening to the echoes returning to its ears from objects in space (Griffin, 1958;Moss and Schnitzler, 1995). Binaural differences in arrival time, intensity, and spectrum of echoes encode the location of an object in azimuth and elevation (Lawrence and Simmons, 1982;Simmons et al., 1983;Pollak, 1988). The third dim...

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Section: Abstract: Superior Colliculus; Echolocation; Bats; Acousticmentioning

confidence: 99%

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confidence: 99%

Spatially Selective Auditory Responses in the Superior Colliculus of the Echolocating Bat

Valentine

Moss

1997

J. Neurosci.

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“…Each pulse forms a beam of sound that echoes off objects in its path. Bats compute the direction and distance to obstacles and prey from a spectrotemporal analysis of the returning echoes (for review, see Moss and Schnitzler, 1995). In contrast to vision, the information from echolocation arrives intermittently in time, yielding snapshots of information.…”

Section: Introductionmentioning

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.

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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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“…Each sonar broadcast impinges on objects at different distances to form a stream of echoes returning at different delays. Bats determine the distance to objects from the delay of echoes that arrive during the interval that follows each broadcast (8,9), and they can judge the depth of the target "scene" (10) from the echo-stream duration (ESD). The bat's auditory system registers echo delays out to 30 ms or more, equivalent to distances of at least 5 m (11).…”

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FM echolocating bats shift frequencies to avoid broadcast–echo ambiguity in clutter

Hiryu

Bates²,

Simmons

et al. 2010

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

100

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Sonar broadcasts are followed by echoes at different delays from objects at different distances. When broadcasts are emitted rapidly in cluttered surroundings, echo streams from successive broadcasts overlap and cause ambiguity in matching echoes to corresponding broadcasts. To identify reactions to ambiguity in clutter, echolocating bats that emit multiple-harmonic FM sounds were trained to fly into a dense, extended array of obstacles (multiple rows of vertically hanging chains) while the sonar sounds the bat emitted were recorded with a miniature radio microphone carried by the bat. Flight paths were reconstructed from thermal-infrared video recordings. Successive rows of chains extended more than 6 m in depth, so each broadcast was followed by a series of echoes from multiple rows of chains that lasted up to 40 ms. Bats emitted sounds in pairs ("strobe groups") at short (20-40 ms) interpulse intervals (IPIs) alternating with longer IPIs (>50 ms). For many short IPIs, the stream of echoes from the first broadcast was still arriving when the second broadcast was emitted. This overlap caused ambiguity about matching echoes with broadcasts. Bats shifted frequencies of the first sound in each strobe group upward and the second sound downward by 3-6 kHz. When overlap and ambiguity ceased, frequency shifts ceased also. Frequency differences were small compared with the total broadcast band, which was 75-80 kHz wide, but the harmonic structure of echoes enhances the differences in spectrograms. Bats could use time-frequency comparisons of echoes with broadcasts to assign echoes to the corresponding broadcasts and thus avoid ambiguity.bat sonar | clutter interference | echo delay | FM sounds

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Behavioral Studies of Auditory Information Processing

Cited by 118 publications

References 102 publications

Spatially Selective Auditory Responses in the Superior Colliculus of the Echolocating Bat

Spatially Selective Auditory Responses in the Superior Colliculus of the Echolocating Bat

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

FM echolocating bats shift frequencies to avoid broadcast–echo ambiguity in clutter

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