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Brown AD, Hayward T, Portfors CV, Coffin AB. On the value of diverse organisms in auditory research: From fish to flies to humans. Hear Res 2023; 432:108754. [PMID: 37054531 PMCID: PMC10424633 DOI: 10.1016/j.heares.2023.108754] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/28/2023] [Accepted: 03/27/2023] [Indexed: 03/31/2023]
Abstract
Historically, diverse organisms have contributed to our understanding of auditory function. In recent years, the laboratory mouse has become the prevailing non-human model in auditory research, particularly for biomedical studies. There are many questions in auditory research for which the mouse is the most appropriate (or the only) model system available. But mice cannot provide answers for all auditory problems of basic and applied importance, nor can any single model system provide a synthetic understanding of the diverse solutions that have evolved to facilitate effective detection and use of acoustic information. In this review, spurred by trends in funding and publishing and inspired by parallel observations in other domains of neuroscience, we highlight a few examples of the profound impact and lasting benefits of comparative and basic organismal research in the auditory system. We begin with the serendipitous discovery of hair cell regeneration in non-mammalian vertebrates, a finding that has fueled an ongoing search for pathways to hearing restoration in humans. We then turn to the problem of sound source localization - a fundamental task that most auditory systems have been compelled to solve despite large variation in the magnitudes and kinds of spatial acoustic cues available, begetting varied direction-detecting mechanisms. Finally, we consider the power of work in highly specialized organisms to reveal exceptional solutions to sensory problems - and the diverse returns of deep neuroethological inquiry - via the example of echolocating bats. Throughout, we consider how discoveries made possible by comparative and curiosity-driven organismal research have driven fundamental scientific, biomedical, and technological advances in the auditory field.
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Affiliation(s)
- Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St, Seattle, WA, 98105 USA; Virginia-Merrill Bloedel Hearing Research Center, University of Washington, 1701 NE Columbia Rd, Seattle, WA, 98195 USA.
| | - Tamasen Hayward
- College of Arts and Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA
| | - Christine V Portfors
- School of Biological Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA
| | - Allison B Coffin
- College of Arts and Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA; School of Biological Sciences, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA; Department of Integrative Physiology and Neuroscience, Washington State University, 14204 NE Salmon Creek Ave, Vancouver, WA 98686 USA.
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2
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Oscillatory discharges in the auditory midbrain of the big brown bat contribute to coding of echo delay. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:173-187. [PMID: 36383255 DOI: 10.1007/s00359-022-01590-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 10/17/2022] [Accepted: 10/20/2022] [Indexed: 11/17/2022]
Abstract
Subsequent to his breakthrough discovery of delay-tuned neurons in the bat's auditory midbrain and cortex, Albert Feng proposed that neural computations for echo delay involve intrinsic oscillatory discharges generated in the inferior colliculus (IC). To explore further the presence of these neural oscillations, we recorded multiple unit activity with a novel annular low impedance electrode from the IC of anesthetized big brown bats and Seba's short-tailed fruit bats. In both species, responses to tones, noise bursts, and FM sweeps contain long latency components, extending up to 60 ms post-stimulus onset, organized in periodic, oscillatory-like patterns at frequencies of 360-740 Hz. Latencies of this oscillatory activity resemble the wide distributions of single neuron response latencies in the IC. In big brown bats, oscillations lasting up to 30 ms after pulse onset emerge in response to single FM pulse-echo pairs, at particular pulse-echo delays. Oscillatory responses to pulses and evoked responses to echoes overlap extensively at short echo delays (5-7 ms), creating interference-like patterns. At longer echo delays, responses are separately evident to both pulses and echoes, with less overlap. These results extend Feng's reports of IC oscillations, and point to different processing mechanisms underlying perception of short vs long echo delays.
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3
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Beetz MJ, Hechavarría JC. Neural Processing of Naturalistic Echolocation Signals in Bats. Front Neural Circuits 2022; 16:899370. [PMID: 35664459 PMCID: PMC9157489 DOI: 10.3389/fncir.2022.899370] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/21/2022] [Indexed: 11/18/2022] Open
Abstract
Echolocation behavior, a navigation strategy based on acoustic signals, allows scientists to explore neural processing of behaviorally relevant stimuli. For the purpose of orientation, bats broadcast echolocation calls and extract spatial information from the echoes. Because bats control call emission and thus the availability of spatial information, the behavioral relevance of these signals is undiscussable. While most neurophysiological studies, conducted in the past, used synthesized acoustic stimuli that mimic portions of the echolocation signals, recent progress has been made to understand how naturalistic echolocation signals are encoded in the bat brain. Here, we review how does stimulus history affect neural processing, how spatial information from multiple objects and how echolocation signals embedded in a naturalistic, noisy environment are processed in the bat brain. We end our review by discussing the huge potential that state-of-the-art recording techniques provide to gain a more complete picture on the neuroethology of echolocation behavior.
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Affiliation(s)
- M. Jerome Beetz
- Zoology II, Biocenter, University of Würzburg, Würzburg, Germany
| | - Julio C. Hechavarría
- Institute of Cell Biology and Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
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4
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Enhanced representation of natural sound sequences in the ventral auditory midbrain. Brain Struct Funct 2020; 226:207-223. [PMID: 33315120 PMCID: PMC7817570 DOI: 10.1007/s00429-020-02188-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 11/24/2020] [Indexed: 11/30/2022]
Abstract
The auditory midbrain (inferior colliculus, IC) plays an important role in sound processing, acting as hub for acoustic information extraction and for the implementation of fast audio-motor behaviors. IC neurons are topographically organized according to their sound frequency preference: dorsal IC regions encode low frequencies while ventral areas respond best to high frequencies, a type of sensory map defined as tonotopy. Tonotopic maps have been studied extensively using artificial stimuli (pure tones) but our knowledge of how these maps represent information about sequences of natural, spectro-temporally rich sounds is sparse. We studied this question by conducting simultaneous extracellular recordings across IC depths in awake bats (Carollia perspicillata) that listened to sequences of natural communication and echolocation sounds. The hypothesis was that information about these two types of sound streams is represented at different IC depths since they exhibit large differences in spectral composition, i.e., echolocation covers the high-frequency portion of the bat soundscape (> 45 kHz), while communication sounds are broadband and carry most power at low frequencies (20–25 kHz). Our results showed that mutual information between neuronal responses and acoustic stimuli, as well as response redundancy in pairs of neurons recorded simultaneously, increase exponentially with IC depth. The latter occurs regardless of the sound type presented to the bats (echolocation or communication). Taken together, our results indicate the existence of mutual information and redundancy maps at the midbrain level whose response cannot be predicted based on the frequency composition of natural sounds and classic neuronal tuning curves.
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Hechavarría JC, Jerome Beetz M, García-Rosales F, Kössl M. Bats distress vocalizations carry fast amplitude modulations that could represent an acoustic correlate of roughness. Sci Rep 2020; 10:7332. [PMID: 32355293 PMCID: PMC7192923 DOI: 10.1038/s41598-020-64323-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 03/04/2020] [Indexed: 02/07/2023] Open
Abstract
Communication sounds are ubiquitous in the animal kingdom, where they play a role in advertising physiological states and/or socio-contextual scenarios. Human screams, for example, are typically uttered in fearful contexts and they have a distinctive feature termed as "roughness", which depicts amplitude fluctuations at rates from 30-150 Hz. In this article, we report that the occurrence of fast acoustic periodicities in harsh sounding vocalizations is not unique to humans. A roughness-like structure is also present in vocalizations emitted by bats (species Carollia perspicillata) in distressful contexts. We report that 47.7% of distress calls produced by bats carry amplitude fluctuations at rates ~1.7 kHz (>10 times faster than temporal modulations found in human screams). In bats, rough-like vocalizations entrain brain potentials and are more effective in accelerating the bats' heart rate than slow amplitude modulated sounds. Our results are consistent with a putative role of fast amplitude modulations (roughness in humans) for grabbing the listeners attention in situations in which the emitter is in distressful, potentially dangerous, contexts.
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Affiliation(s)
- Julio C Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany.
| | - M Jerome Beetz
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany
- Zoology II Emmy-Noether Animal Navigation Group, Biocenter, University of Würzburg, Würzburg, Germany
| | | | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany
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6
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Macias S, Bakshi K, Smotherman M. Functional organization of the primary auditory cortex of the free-tailed bat Tadarida brasiliensis. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2020; 206:429-440. [PMID: 32036404 DOI: 10.1007/s00359-020-01406-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/20/2020] [Accepted: 01/22/2020] [Indexed: 12/19/2022]
Abstract
The Mexican free-tailed bat, Tadarida brasiliensis, is a fast-flying bat that hunts by biosonar at high altitudes in open space. The auditory periphery and ascending auditory pathways have been described in great detail for this species, but nothing is yet known about its auditory cortex. Here we describe the topographical organization of response properties in the primary auditory cortex (AC) of the Mexican free-tailed bat with emphasis on the sensitivity for FM sweeps and echo-delay tuning. Responses of 716 units to pure tones and of 373 units to FM sweeps and FM-FM pairs were recorded extracellularly using multielectrode arrays in anesthetized bats. A general tonotopy was confirmed with low frequencies represented caudally and high frequencies represented rostrally. Characteristic frequencies (CF) ranged from 15 to 70 kHz, and fifty percent of CFs fell between 20 and 30 kHz, reflecting a hyper-representation of a bandwidth corresponding to search-phase echolocation pulses. Most units showed a stronger response to downward rather than upward FM sweeps and forty percent of the neurons interspersed throughout AC (150/371) showed echo-delay sensitivity to FM-FM pairs. Overall, the results illustrate that the free-tailed bat auditory cortex is organized similarly to that of other FM-type insectivorous bats.
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Affiliation(s)
- Silvio Macias
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
| | - Kushal Bakshi
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Michael Smotherman
- Department of Biology, Texas A&M University, College Station, TX, 77843, USA
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7
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Butman JA, Suga N. Inhibitory mechanisms shaping delay-tuned combination-sensitivity in the auditory cortex and thalamus of the mustached bat. Hear Res 2019; 373:71-84. [PMID: 30612026 DOI: 10.1016/j.heares.2018.12.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/11/2018] [Accepted: 12/21/2018] [Indexed: 10/27/2022]
Abstract
Delay-tuned auditory neurons of the mustached bat show facilitative responses to a combination of signal elements of a biosonar pulse-echo pair with a specific echo delay. The subcollicular nuclei produce latency-constant phasic on-responding neurons, and the inferior colliculus produces delay-tuned combination-sensitive neurons, designated "FM-FM" neurons. The combination-sensitivity is a facilitated response to the coincidence of the excitatory rebound following glycinergic inhibition to the pulse (1st harmonic) and the short-latency response to the echo (2nd-4th harmonics). The facilitative response of thalamic FM-FM neurons is mediated by glutamate receptors (NMDA and non-NMDA receptors). Different from collicular FM-FM neurons, thalamic ones respond more selectively to pulse-echo pairs than individual signal elements. A number of differences in response properties between collicular and thalamic or cortical FM-FM neurons have been reported. However, differences between thalamic and cortical FM-FM neurons have remained to be studied. Here, we report that GABAergic inhibition controls the duration of burst of spikes of facilitative responses of thalamic FM-FM neurons and sharpens the delay tuning of cortical ones. That is, intra-cortical inhibition sharpens the delay tuning of cortical FM-FM neurons that is potentially broad because of divergent/convergent thalamo-cortical projections. Compared with thalamic neurons, cortical ones tend to show sharper delay tuning, longer response duration, and larger facilitation index. However, those differences are statistically insignificant.
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Affiliation(s)
- John A Butman
- Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA.
| | - Nobuo Suga
- Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA.
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8
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Macías S, Luo J, Moss CF. Natural echolocation sequences evoke echo-delay selectivity in the auditory midbrain of the FM bat, Eptesicus fuscus. J Neurophysiol 2018; 120:1323-1339. [PMID: 29924708 DOI: 10.1152/jn.00160.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Echolocating bats must process temporal streams of sonar sounds to represent objects along the range axis. Neuronal echo-delay tuning, the putative mechanism of sonar ranging, has been characterized in the inferior colliculus (IC) of the mustached bat, an insectivorous species that produces echolocation calls consisting of constant frequency and frequency modulated (FM) components, but not in species that use FM signals alone. This raises questions about the mechanisms that give rise to echo-delay tuning in insectivorous bats that use different signal designs. To investigate whether stimulus context may account for species differences in echo-delay selectivity, we characterized single-unit responses in the IC of awake passively listening FM bats, Eptesicus fuscus, to broadcasts of natural sonar call-echo sequences, which contained dynamic changes in signal duration, interval, spectrotemporal structure, and echo-delay. In E. fuscus, neural selectivity to call-echo delay emerges in a population of IC neurons when stimulated with call-echo pairs presented at intervals mimicking those in a natural sonar sequence. To determine whether echo-delay selectivity also depends on the spectrotemporal features of individual sounds within natural sonar sequences, we studied responses to computer-generated echolocation signals that controlled for call interval, duration, bandwidth, sweep rate, and echo-delay. A subpopulation of IC neurons responded selectively to the combination of the spectrotemporal structure of natural call-echo pairs and their temporal patterning within a dynamic sonar sequence. These new findings suggest that the FM bat's fine control over biosonar signal parameters may modulate IC neuronal selectivity to the dimension of echo-delay. NEW & NOTEWORTHY Echolocating bats perform precise auditory temporal computations to estimate their distance to objects. Here, we report that response selectivity of neurons in the inferior colliculus of a frequency modulated bat to call-echo delay, or target range tuning, depends on the temporal patterning and spectrotemporal features of sound elements in a natural echolocation sequence. We suggest that echo responses to objects at different distances are gated by the bat's active control over the spectrotemporal patterning of its sonar emissions.
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Affiliation(s)
- Silvio Macías
- Department of Psychological and Brain Sciences, Johns Hopkins University , Baltimore, Maryland
| | - Jinhong Luo
- Department of Psychological and Brain Sciences, Johns Hopkins University , Baltimore, Maryland
| | - Cynthia F Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University , Baltimore, Maryland
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Martin LM, García-Rosales F, Beetz MJ, Hechavarría JC. Processing of temporally patterned sounds in the auditory cortex of Seba's short-tailed bat,Carollia perspicillata. Eur J Neurosci 2018; 46:2365-2379. [PMID: 28921742 DOI: 10.1111/ejn.13702] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 11/29/2022]
Abstract
This article presents a characterization of cortical responses to artificial and natural temporally patterned sounds in the bat species Carollia perspicillata, a species that produces vocalizations at rates above 50 Hz. Multi-unit activity was recorded in three different experiments. In the first experiment, amplitude-modulated (AM) pure tones were used as stimuli to drive auditory cortex (AC) units. AC units of both ketamine-anesthetized and awake bats could lock their spikes to every cycle of the stimulus modulation envelope, but only if the modulation frequency was below 22 Hz. In the second experiment, two identical communication syllables were presented at variable intervals. Suppressed responses to the lagging syllable were observed, unless the second syllable followed the first one with a delay of at least 80 ms (i.e., 12.5 Hz repetition rate). In the third experiment, natural distress vocalization sequences were used as stimuli to drive AC units. Distress sequences produced by C. perspicillata contain bouts of syllables repeated at intervals of ~60 ms (16 Hz). Within each bout, syllables are repeated at intervals as short as 14 ms (~71 Hz). Cortical units could follow the slow temporal modulation flow produced by the occurrence of multisyllabic bouts, but not the fast acoustic flow created by rapid syllable repetition within the bouts. Taken together, our results indicate that even in fast vocalizing animals, such as bats, cortical neurons can only track the temporal structure of acoustic streams modulated at frequencies lower than 22 Hz.
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Affiliation(s)
- Lisa M Martin
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Max-von-Laue-Straße 13, 60438, Frankfurt/Main, Germany
| | - Francisco García-Rosales
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Max-von-Laue-Straße 13, 60438, Frankfurt/Main, Germany
| | - M Jerome Beetz
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Max-von-Laue-Straße 13, 60438, Frankfurt/Main, Germany
| | - Julio C Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Max-von-Laue-Straße 13, 60438, Frankfurt/Main, Germany
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Beetz MJ, Kordes S, García-Rosales F, Kössl M, Hechavarría JC. Processing of Natural Echolocation Sequences in the Inferior Colliculus of Seba's Fruit Eating Bat, Carollia perspicillata. eNeuro 2017; 4:ENEURO.0314-17.2017. [PMID: 29242823 PMCID: PMC5729038 DOI: 10.1523/eneuro.0314-17.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/17/2017] [Accepted: 11/25/2017] [Indexed: 11/21/2022] Open
Abstract
For the purpose of orientation, echolocating bats emit highly repetitive and spatially directed sonar calls. Echoes arising from call reflections are used to create an acoustic image of the environment. The inferior colliculus (IC) represents an important auditory stage for initial processing of echolocation signals. The present study addresses the following questions: (1) how does the temporal context of an echolocation sequence mimicking an approach flight of an animal affect neuronal processing of distance information to echo delays? (2) how does the IC process complex echolocation sequences containing echo information from multiple objects (multiobject sequence)? Here, we conducted neurophysiological recordings from the IC of ketamine-anaesthetized bats of the species Carollia perspicillata and compared the results from the IC with the ones from the auditory cortex (AC). Neuronal responses to an echolocation sequence was suppressed when compared to the responses to temporally isolated and randomized segments of the sequence. The neuronal suppression was weaker in the IC than in the AC. In contrast to the cortex, the time course of the acoustic events is reflected by IC activity. In the IC, suppression sharpens the neuronal tuning to specific call-echo elements and increases the signal-to-noise ratio in the units' responses. When presenting multiple-object sequences, despite collicular suppression, the neurons responded to each object-specific echo. The latter allows parallel processing of multiple echolocation streams at the IC level. Altogether, our data suggests that temporally-precise neuronal responses in the IC could allow fast and parallel processing of multiple acoustic streams.
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Affiliation(s)
- M. Jerome Beetz
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt am Main 60438, Germany
- Department of Behavioral Physiology and Sociobiology, Biozentrum, University of Würzburg, Am Hubland, Würzburg 97074, Germany
| | - Sebastian Kordes
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt am Main 60438, Germany
| | - Francisco García-Rosales
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt am Main 60438, Germany
| | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt am Main 60438, Germany
| | - Julio C. Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt am Main 60438, Germany
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11
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Suzuki M, Suga N. Acuity in ranging based on delay-tuned combination-sensitive neurons in the auditory cortex of mustached bats. Hear Res 2017; 350:189-204. [PMID: 28505528 DOI: 10.1016/j.heares.2017.04.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 04/07/2017] [Accepted: 04/28/2017] [Indexed: 11/29/2022]
Abstract
A 1.0-ms echo delay from an emitted bio-sonar pulse at 25 °C corresponds to a 17.3-cm target distance. In the auditory cortex of the mustached bat, Pteronotus parnellii, neurons tuned to a specific delay (best delay) of an echo from an emitted pulse are clustered in the FF, dorsal fringe and ventral fringe areas. ("FF" stands for the frequency-modulated components of a pulse and its echo.) Those delay-tuned neurons are systematically arranged in the FF area according to their best delays and form a 18-ms-long delay axis. Using the neurophysiological data, the theoretical acuity at a 75% correct level was computed as just-noticeable changes in (a) the location of maximally responding delay-tuned neurons, (b) the location of the center of all responses in the FF area, and (c) the weighted sum of responses of all delay-tuned neurons. The acuity is range-dependent: the shorter the target range, the higher the acuity is. The just-noticeable changes in target range are 7.57-46.2, 0.50-2.32 and 0.22-2.53 mm at the target ranges of up to 140 cm for (a), (b) and (c), respectively. When the dorsal and ventral fringe areas are included in the computation, the just-noticeable changes become smaller than those in the FF area alone. Those acuities computed are comparable to certain behavioral acuities.
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Affiliation(s)
- Masakiyo Suzuki
- Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA.
| | - Nobuo Suga
- Department of Biology, Washington University, One Brookings Drive, St. Louis, MO 63130, USA.
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12
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Beetz MJ, Hechavarría JC, Kössl M. Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams. Sci Rep 2016; 6:35991. [PMID: 27786252 PMCID: PMC5081524 DOI: 10.1038/srep35991] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 10/10/2016] [Indexed: 11/09/2022] Open
Abstract
Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical "default mode" that allows selectively focusing on close obstacle even without active attention from the animals.
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Affiliation(s)
- M. Jerome Beetz
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany
| | - Julio C. Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany
| | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, Frankfurt/M., Germany
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13
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Macías S, Hechavarría JC. Short delays and low pulse amplitudes produce widespread activation in the target-distance processing area of auditory cortex of the mustached bat. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2016; 140:917. [PMID: 27586724 DOI: 10.1121/1.4960547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
While approaching an object, echolocating bats decrease the amplitude of their vocalizations. This behavior is known as "echo-level compensation." Here, the activation pattern of the cortical FM-FM (frequency modulated) area of the mustached bat is assessed by using acoustic stimuli that correspond to sonar signals and their echoes emitted during echo-level compensation behavior. Activation maps were calculated from the delay response areas of 86 cortical neurons, and these maps were used to explore the topography of cortical activation during echolocation and its relation to the bats' cortical "chronotopy." Chronotopy predicts short echo-delays to be represented by rostral auditory cortex neurons while caudal neurons represent long echo-delays. The results show that a chronotopic activation of the cortex is evident only at loud pulse amplitudes [80-90 dB sound pressure level (SPL)]. In response to fainter pulse levels (60-70 dB SPL), as those produced as the animals zoom-in on targets, chronotopic activation of the cortex becomes less clear because units throughout the FM-FM area start firing, especially in response to short echo-delays. The fact that cortical activity is more widespread in response to combinations of short echo-delays and faint pulse amplitudes could represent an adaptation that enhances cortical activity in the late stages of echo-level compensation.
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Affiliation(s)
- Silvio Macías
- Institut für Zellbiologie und Neurowissenschaft, J. W. Goethe Universität Frankfurt, Max-von-Laue-Strausse 13, 60439 Frankfurt am Main, Germany
| | - Julio C Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, J. W. Goethe Universität Frankfurt, Max-von-Laue-Strausse 13, 60439 Frankfurt am Main, Germany
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14
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Beetz MJ, Hechavarría JC, Kössl M. Temporal tuning in the bat auditory cortex is sharper when studied with natural echolocation sequences. Sci Rep 2016; 6:29102. [PMID: 27357230 PMCID: PMC4928181 DOI: 10.1038/srep29102] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/15/2016] [Indexed: 11/09/2022] Open
Abstract
Precise temporal coding is necessary for proper acoustic analysis. However, at cortical level, forward suppression appears to limit the ability of neurons to extract temporal information from natural sound sequences. Here we studied how temporal processing can be maintained in the bats' cortex in the presence of suppression evoked by natural echolocation streams that are relevant to the bats' behavior. We show that cortical neurons tuned to target-distance actually profit from forward suppression induced by natural echolocation sequences. These neurons can more precisely extract target distance information when they are stimulated with natural echolocation sequences than during stimulation with isolated call-echo pairs. We conclude that forward suppression does for time domain tuning what lateral inhibition does for selectivity forms such as auditory frequency tuning and visual orientation tuning. When talking about cortical processing, suppression should be seen as a mechanistic tool rather than a limiting element.
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Affiliation(s)
- M Jerome Beetz
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, 60438, Frankfurt/M., Germany
| | - Julio C Hechavarría
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, 60438, Frankfurt/M., Germany
| | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft, Goethe-Universität, 60438, Frankfurt/M., Germany
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15
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Macías S, Mora EC, Hechavarría JC, Kössl M. Echo-level compensation and delay tuning in the auditory cortex of the mustached bat. Eur J Neurosci 2016; 43:1647-60. [DOI: 10.1111/ejn.13244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Silvio Macías
- Institut für Zellbiologie und Neurowissenschaft; J.W. Goethe Universität Frankfurt; Max-von-Laue-Str. 13 60439 Frankfurt am Main Germany
| | - Emanuel C. Mora
- Instituto de Ciencias Biomédicas; Universidad Autónoma de Chile; El Llano Subercaseaux 2801; San Miguel Santiago, Chile
| | - Julio C. Hechavarría
- Institut für Zellbiologie und Neurowissenschaft; J.W. Goethe Universität Frankfurt; Max-von-Laue-Str. 13 60439 Frankfurt am Main Germany
| | - Manfred Kössl
- Institut für Zellbiologie und Neurowissenschaft; J.W. Goethe Universität Frankfurt; Max-von-Laue-Str. 13 60439 Frankfurt am Main Germany
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16
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Macías S, Hechavarría JC, Kössl M. Temporal encoding precision of bat auditory neurons tuned to target distance deteriorates on the way to the cortex. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2016; 202:195-202. [DOI: 10.1007/s00359-016-1067-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 01/04/2016] [Accepted: 01/06/2016] [Indexed: 12/01/2022]
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17
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Synaptic mechanisms shaping delay-tuned combination-sensitivity in the auditory thalamus of mustached bats. Hear Res 2016; 331:69-82. [DOI: 10.1016/j.heares.2015.10.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/24/2015] [Accepted: 10/20/2015] [Indexed: 11/21/2022]
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18
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Kössl M, Hechavarria J, Voss C, Schaefer M, Vater M. Bat auditory cortex – model for general mammalian auditory computation or special design solution for active time perception? Eur J Neurosci 2015; 41:518-32. [PMID: 25728173 DOI: 10.1111/ejn.12801] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 11/03/2014] [Accepted: 11/06/2014] [Indexed: 01/28/2023]
Abstract
Audition in bats serves passive orientation, alerting functions and communication as it does in other vertebrates. In addition, bats have evolved echolocation for orientation and prey detection and capture. This put a selective pressure on the auditory system in regard to echolocation-relevant temporal computation and frequency analysis. The present review attempts to evaluate in which respect the processing modules of bat auditory cortex (AC) are a model for typical mammalian AC function or are designed for echolocation-unique purposes. We conclude that, while cortical area arrangement and cortical frequency processing does not deviate greatly from that of other mammals, the echo delay time-sensitive dorsal cortex regions contain special designs for very powerful time perception. Different bat species have either a unique chronotopic cortex topography or a distributed salt-and-pepper representation of echo delay. The two designs seem to enable similar behavioural performance.
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Affiliation(s)
- Manfred Kössl
- Institute for Cell Biology and Neuroscience, University of Frankfurt, Max-von-Laue-Str.13, 60438, Frankfurt, Germany
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19
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Schaefer MK, Hechavarría JC, Kössl M. Quantification of mid and late evoked sinks in laminar current source density profiles of columns in the primary auditory cortex. Front Neural Circuits 2015; 9:52. [PMID: 26557058 PMCID: PMC4617414 DOI: 10.3389/fncir.2015.00052] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 09/14/2015] [Indexed: 11/18/2022] Open
Abstract
Current source density (CSD) analysis assesses spatiotemporal synaptic activations at somatic and/or dendritic levels in the form of depolarizing current sinks. Whereas many studies have focused on the short (<50 ms) latency sinks, associated with thalamocortical projections, sinks with longer latencies have received less attention. Here, we analyzed laminar CSD patterns for the first 600 ms after stimulus onset in the primary auditory cortex of Mongolian gerbils. By applying an algorithm for contour calculation, three distinct mid and four late evoked sinks were identified in layers I, III, Va, VIa, and VIb. Our results further showed that the patterns of intracortical information-flow remained qualitatively similar for low and for high sound pressure level stimuli at the characteristic frequency (CF) as well as for stimuli ± 1 octave from CF. There were, however, differences associated with the strength, vertical extent, onset latency, and duration of the sinks for the four stimulation paradigms used. Stimuli one octave above the most sensitive frequency evoked a new, and quite reliable, sink in layer Va whereas low level stimulation led to the disappearance of the layer VIb sink. These data indicate the presence of input sources specifically activated in response to level and/or frequency parameters. Furthermore, spectral integration above vs. below the CF of neurons is asymmetric as illustrated by CSD profiles. These results are important because synaptic feedback associated with mid and late sinks—beginning at 50 ms post stimulus latency—is likely crucial for response modulation resulting from higher order processes like memory, learning or cognitive control.
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Affiliation(s)
- Markus K Schaefer
- Institute for Cell Biology and Neuroscience, AK Neurobiology and Biosensors, Goethe University Frankfurt/Main, Germany
| | - Julio C Hechavarría
- Institute for Cell Biology and Neuroscience, AK Neurobiology and Biosensors, Goethe University Frankfurt/Main, Germany
| | - Manfred Kössl
- Institute for Cell Biology and Neuroscience, AK Neurobiology and Biosensors, Goethe University Frankfurt/Main, Germany
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20
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Suga N. Neural processing of auditory signals in the time domain: Delay-tuned coincidence detectors in the mustached bat. Hear Res 2015; 324:19-36. [DOI: 10.1016/j.heares.2015.02.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 02/15/2015] [Accepted: 02/24/2015] [Indexed: 11/25/2022]
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21
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Level-tolerant duration selectivity in the auditory cortex of the velvety free-tailed bat Molossus molossus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2015; 201:461-70. [DOI: 10.1007/s00359-015-0993-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/20/2015] [Accepted: 02/20/2015] [Indexed: 11/26/2022]
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22
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Genzel D, Hoffmann S, Prosch S, Firzlaff U, Wiegrebe L. Biosonar navigation above water II: exploiting mirror images. J Neurophysiol 2015; 113:1146-55. [DOI: 10.1152/jn.00264.2014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
As in vision, acoustic signals can be reflected by a smooth surface creating an acoustic mirror image. Water bodies represent the only naturally occurring horizontal and acoustically smooth surfaces. Echolocating bats flying over smooth water bodies encounter echo-acoustic mirror images of objects above the surface. Here, we combined an electrophysiological approach with a behavioral experimental paradigm to investigate whether bats can exploit echo-acoustic mirror images for navigation and how these mirrorlike echo-acoustic cues are encoded in their auditory cortex. In an obstacle-avoidance task where the obstacles could only be detected via their echo-acoustic mirror images, most bats spontaneously exploited these cues for navigation. Sonar ensonifications along the bats' flight path revealed conspicuous changes of the reflection patterns with slightly increased target strengths at relatively long echo delays corresponding to the longer acoustic paths from the mirrored obstacles. Recordings of cortical spatiotemporal response maps (STRMs) describe the tuning of a unit across the dimensions of elevation and time. The majority of cortical single and multiunits showed a special spatiotemporal pattern of excitatory areas in their STRM indicating a preference for echoes with (relative to the setup dimensions) long delays and, interestingly, from low elevations. This neural preference could effectively encode a reflection pattern as it would be perceived by an echolocating bat detecting an object mirrored from below. The current study provides both behavioral and neurophysiological evidence that echo-acoustic mirror images can be exploited by bats for obstacle avoidance. This capability effectively supports echo-acoustic navigation in highly cluttered natural habitats.
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Affiliation(s)
- Daria Genzel
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; and
| | - Susanne Hoffmann
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; and
- Chair of Zoology, Technische Universität München, Freising-Weihenstephan, Germany
| | - Selina Prosch
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; and
| | - Uwe Firzlaff
- Chair of Zoology, Technische Universität München, Freising-Weihenstephan, Germany
| | - Lutz Wiegrebe
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany; and
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23
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Blurry topography for precise target-distance computations in the auditory cortex of echolocating bats. Nat Commun 2014; 4:2587. [PMID: 24107903 DOI: 10.1038/ncomms3587] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 09/10/2013] [Indexed: 11/09/2022] Open
Abstract
Echolocating bats use the time from biosonar pulse emission to the arrival of echo (defined as echo delay) to calculate the space depth of targets. In the dorsal auditory cortex of several species, neurons that encode increasing echo delays are organized rostrocaudally in a topographic arrangement defined as chronotopy. Precise chronotopy could be important for precise target-distance computations. Here we show that in the cortex of three echolocating bat species (Pteronotus quadridens, Pteronotus parnellii and Carollia perspicillata), chronotopy is not precise but blurry. In all three species, neurons throughout the chronotopic map are driven by short echo delays that indicate the presence of close targets and the robustness of map organization depends on the parameter of the receptive field used to characterize neuronal tuning. The timing of cortical responses (latency and duration) provides a binding code that could be important for assembling acoustic scenes using echo delay information from objects with different space depths.
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24
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Macías S, Hechavarría JC, Cobo A, Mora EC. Narrow sound pressure level tuning in the auditory cortex of the bats Molossus molossus and Macrotus waterhousii. Hear Res 2014; 309:36-43. [DOI: 10.1016/j.heares.2013.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/09/2013] [Accepted: 11/13/2013] [Indexed: 11/26/2022]
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25
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Kössl M, Hechavarria JC, Voss C, Macias S, Mora EC, Vater M. Neural maps for target range in the auditory cortex of echolocating bats. Curr Opin Neurobiol 2013; 24:68-75. [PMID: 24492081 DOI: 10.1016/j.conb.2013.08.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/16/2013] [Accepted: 08/18/2013] [Indexed: 11/25/2022]
Abstract
Computational brain maps as opposed to maps of receptor surfaces strongly reflect functional neuronal design principles. In echolocating bats, computational maps are established that topographically represent the distance of objects. These target range maps are derived from the temporal delay between emitted call and returning echo and constitute a regular representation of time (chronotopy). Basic features of these maps are innate, and in different bat species the map size and precision varies. An inherent advantage of target range maps is the implementation of mechanisms for lateral inhibition and excitatory feedback. Both can help to focus target ranging depending on the actual echolocation situation. However, these maps are not absolutely necessary for bat echolocation since there are bat species without cortical target-distance maps, which use alternative ensemble computation mechanisms.
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Affiliation(s)
- M Kössl
- Institute for Cell Biology and Neuroscience, Goethe University, Frankfurt, Max-von-Laue-Str. 13, 60439 Frankfurt, Germany.
| | - J C Hechavarria
- Institute for Cell Biology and Neuroscience, Goethe University, Frankfurt, Max-von-Laue-Str. 13, 60439 Frankfurt, Germany
| | - C Voss
- Institute for Cell Biology and Neuroscience, Goethe University, Frankfurt, Max-von-Laue-Str. 13, 60439 Frankfurt, Germany
| | - S Macias
- Department of Animal and Human Biology, Faculty of Biology, Havana University, calle 25 No. 455 entre J e I, Vedado, CP 10400, Ciudad de La Habana, Cuba
| | - E C Mora
- Department of Animal and Human Biology, Faculty of Biology, Havana University, calle 25 No. 455 entre J e I, Vedado, CP 10400, Ciudad de La Habana, Cuba
| | - M Vater
- Institute for Biochemistry and Biology, University of Potsdam, Karl Liebknecht Str. 26, 14476 Golm, Germany
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26
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Heinrich M, Wiegrebe L. Size constancy in bat biosonar? Perceptual interaction of object aperture and distance. PLoS One 2013; 8:e61577. [PMID: 23630598 PMCID: PMC3632596 DOI: 10.1371/journal.pone.0061577] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/11/2013] [Indexed: 11/19/2022] Open
Abstract
Perception and encoding of object size is an important feature of sensory systems. In the visual system object size is encoded by the visual angle (visual aperture) on the retina, but the aperture depends on the distance of the object. As object distance is not unambiguously encoded in the visual system, higher computational mechanisms are needed. This phenomenon is termed "size constancy". It is assumed to reflect an automatic re-scaling of visual aperture with perceived object distance. Recently, it was found that in echolocating bats, the 'sonar aperture', i.e., the range of angles from which sound is reflected from an object back to the bat, is unambiguously perceived and neurally encoded. Moreover, it is well known that object distance is accurately perceived and explicitly encoded in bat sonar. Here, we addressed size constancy in bat biosonar, recruiting virtual-object techniques. Bats of the species Phyllostomus discolor learned to discriminate two simple virtual objects that only differed in sonar aperture. Upon successful discrimination, test trials were randomly interspersed using virtual objects that differed in both aperture and distance. It was tested whether the bats spontaneously assigned absolute width information to these objects by combining distance and aperture. The results showed that while the isolated perceptual cues encoding object width, aperture, and distance were all perceptually well resolved by the bats, the animals did not assign absolute width information to the test objects. This lack of sonar size constancy may result from the bats relying on different modalities to extract size information at different distances. Alternatively, it is conceivable that familiarity with a behaviorally relevant, conspicuous object is required for sonar size constancy, as it has been argued for visual size constancy. Based on the current data, it appears that size constancy is not necessarily an essential feature of sonar perception in bats.
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Affiliation(s)
- Melina Heinrich
- Department Biology II, Ludwig-Maximilians University Munich, Bavaria, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians University Munich, Bavaria, Germany
| | - Lutz Wiegrebe
- Department Biology II, Ludwig-Maximilians University Munich, Bavaria, Germany
- Graduate School of Systemic Neurosciences, Ludwig-Maximilians University Munich, Bavaria, Germany
- Sensory Ecology Group, Max-Planck Institute for Ornithology, Seewiesen, Germany
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27
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Hechavarría JC, Macías S, Vater M, Mora EC, Kössl M. Evolution of neuronal mechanisms for echolocation: specializations for target-range computation in bats of the genus Pteronotus. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2013; 133:570-578. [PMID: 23297928 DOI: 10.1121/1.4768794] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Delay tuning was studied in the auditory cortex of Pteronotus quadridens. All the 136 delay-tuned units that were studied responded strongly to heteroharmonic pulse-echo pairs presented at specific delays. In the heteroharmonic pairs, the first sonar call harmonic marks the timing of pulse emission while one of the higher harmonics (second or third) indicates the timing of the echo. Delay-tuned units are organized chronotopically along a rostrocaudal axis according to their characteristic delay. There is no obvious indication of multiple cortical axes specialized in the processing of different harmonic combinations of pulse and echo. Results of this study serve for a straight comparison of cortical delay-tuning between P. quadridens and the well-studied mustached bat, Pteronotus parnellii. These two species stem from the most recent and most basal nodes in the Pteronotus lineage, respectively. P. quadridens and P. parnellii use comparable heteroharmonic target-range computation strategies even though they do not use biosonar calls of a similar design. P. quadridens uses short constant-frequency (CF)/frequency-modulated (FM) echolocation calls, while P. parnellii uses long CF/FM calls. The ability to perform "heteroharmonic" target-range computations might be an ancestral neuronal specialization of the genus Pteronotus that was subjected to positive Darwinian selection in the evolution.
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Affiliation(s)
- Julio C Hechavarría
- Institute for Cell Biology and Neuroscience, Goethe University, Frankfurt/Main, Germany.
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28
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Auditory cortex of newborn bats is prewired for echolocation. Nat Commun 2012; 3:773. [PMID: 22491321 DOI: 10.1038/ncomms1782] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 03/09/2012] [Indexed: 11/08/2022] Open
Abstract
Neuronal computation of object distance from echo delay is an essential task that echolocating bats must master for spatial orientation and the capture of prey. In the dorsal auditory cortex of bats, neurons specifically respond to combinations of short frequency-modulated components of emitted call and delayed echo. These delay-tuned neurons are thought to serve in target range calculation. It is unknown whether neuronal correlates of active space perception are established by experience-dependent plasticity or by innate mechanisms. Here we demonstrate that in the first postnatal week, before onset of echolocation and flight, dorsal auditory cortex already contains functional circuits that calculate distance from the temporal separation of a simulated pulse and echo. This innate cortical implementation of a purely computational processing mechanism for sonar ranging should enhance survival of juvenile bats when they first engage in active echolocation behaviour and flight.
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29
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Macías S, Mora EC, Hechavarría JC, Kössl M. Properties of echo delay-tuning receptive fields in the inferior colliculus of the mustached bat. Hear Res 2012; 286:1-8. [DOI: 10.1016/j.heares.2012.02.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/23/2012] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
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30
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Hechavarría JC, Cobo AT, Fernández Y, Macías S, Kössl M, Mora EC. Sound-evoked oscillation and paradoxical latency shift in the inferior colliculus neurons of the big fruit-eating bat, Artibeus jamaicensis. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 197:1159-72. [PMID: 21912875 DOI: 10.1007/s00359-011-0678-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 08/23/2011] [Accepted: 08/24/2011] [Indexed: 12/23/2022]
Abstract
Frequency tuning, temporal response pattern and latency properties of inferior colliculus neurons were investigated in the big fruit-eating bat, Artibeus jamaicensis. Neurons having best frequencies between 48-72 kHz and between 24-32 kHz are overrepresented. The inferior colliculus neurons had either phasic (consisting in only one response cycle at all stimulus intensities) or long-lasting oscillatory responses (consisting of multiple response cycles). Seventeen percent of neurons displayed paradoxical latency shift, i.e. their response latency increased with increasing sound level. Three types of paradoxical latency shift were found: (1) stable, that does not depend on sound duration, (2) duration-dependent, that grows with increasing sound duration, and (3) progressive, whose magnitude increases with increasing sound level. The temporal properties of paradoxical latency shift neurons compare well with those of neurons having long-lasting oscillatory responses, i.e. median inter-spike intervals and paradoxical latency shift below 6 ms are overrepresented. In addition, oscillatory and paradoxical latency shift neurons behave similarly when tested with tones of different durations. Temporal properties of oscillation and PLS found in the IC of fruit-eating bats are similar to those found in the IC of insectivorous bats using downward frequency-modulated echolocation calls.
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31
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Ecology and neuroethology of bat echolocation: a tribute to Gerhard Neuweiler. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2011; 197:399-402. [DOI: 10.1007/s00359-011-0633-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 02/10/2011] [Accepted: 02/12/2011] [Indexed: 10/18/2022]
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