1
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Zhang L, Du Q. Parameter estimation of the hyperbolic frequency-modulated bat calls using hyperbolic scale transform. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 156:16-28. [PMID: 38949290 DOI: 10.1121/10.0026454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 06/02/2024] [Indexed: 07/02/2024]
Abstract
Echolocating bats are known to vary their waveforms at the phases of searching, approaching, and capturing the prey. It is meaningful to estimate the parameters of the calls for bat species identification and the technological improvements of the synthetic systems, such as radar and sonar. The type of bat calls is species-related, and many calls can be modeled as hyperbolic frequency- modulated (HFM) signals. To obtain the parameters of the HFM-modeled bat calls, a reversible integral transform, i.e., hyperbolic scale transform (HST), is proposed to transform a call into two-dimensional peaks in the "delay-scale" domain, based on which harmonic separation and parameter estimation are realized. Compared with the methods based on time-frequency analysis, the HST-based method does not need to extract the instantaneous frequency of the bat calls, only searching for peaks. The verification results show that the HST is suitable for analyzing the HFM-modeled bat calls containing multiple harmonics with a large energy difference, and the estimated parameters imply that the use of the waveforms from the searching phase to the capturing phase is beneficial to reduce the ranging bias, and the trends in parameters may be useful for bat species identification.
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Affiliation(s)
- Liang Zhang
- Department of Early Warning Technology, Air Force Early Warning Academy, Wuhan, 430019, China
| | - Qinglei Du
- Department of Early Warning Technology, Air Force Early Warning Academy, Wuhan, 430019, China
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2
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Moss CF, Ortiz ST, Wahlberg M. Adaptive echolocation behavior of bats and toothed whales in dynamic soundscapes. J Exp Biol 2023; 226:jeb245450. [PMID: 37161774 PMCID: PMC10184770 DOI: 10.1242/jeb.245450] [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] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Journal of Experimental Biology has a long history of reporting research discoveries on animal echolocation, the subject of this Centenary Review. Echolocating animals emit intense sound pulses and process echoes to localize objects in dynamic soundscapes. More than 1100 species of bats and 70 species of toothed whales rely on echolocation to operate in aerial and aquatic environments, respectively. The need to mitigate acoustic clutter and ambient noise is common to both aerial and aquatic echolocating animals, resulting in convergence of many echolocation features, such as directional sound emission and hearing, and decreased pulse intervals and sound intensity during target approach. The physics of sound transmission in air and underwater constrains the production, detection and localization of sonar signals, resulting in differences in response times to initiate prey interception by aerial and aquatic echolocating animals. Anti-predator behavioral responses of prey pursued by echolocating animals affect behavioral foraging strategies in air and underwater. For example, many insect prey can detect and react to bat echolocation sounds, whereas most fish and squid are unresponsive to toothed whale signals, but can instead sense water movements generated by an approaching predator. These differences have implications for how bats and toothed whales hunt using echolocation. Here, we consider the behaviors used by echolocating mammals to (1) track and intercept moving prey equipped with predator detectors, (2) interrogate dynamic sonar scenes and (3) exploit visual and passive acoustic stimuli. Similarities and differences in animal sonar behaviors underwater and in air point to open research questions that are ripe for exploration.
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Affiliation(s)
- Cynthia F. Moss
- Johns Hopkins University, Departments of Psychological and Brain Sciences, Neuroscience and Mechanical Engineering, 3400 N. Charles St., Baltimore, MD 21218, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sara Torres Ortiz
- Marine Biological Research Center, University of Southern Denmark, Hindsholmvej 11, 5300 Kerteminde, Denmark
| | - Magnus Wahlberg
- Marine Biological Research Center, University of Southern Denmark, Hindsholmvej 11, 5300 Kerteminde, Denmark
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3
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Wohlgemuth M, Salles A, Moss C. Spatial attention in natural tasks [version 1; peer review: 2 approved with reservations]. MOLECULAR PSYCHOLOGY 2022; 1:4. [PMID: 37325441 PMCID: PMC10269881 DOI: 10.12688/molpsychol.17488.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Little is known about fine scale neural dynamics that accompany rapid shifts in spatial attention in freely behaving animals, primarily because reliable indicators of attention are lacking in standard model organisms engaged in natural tasks. The echolocating bat can serve to bridge this gap, as it exhibits robust dynamic behavioral indicators of overt spatial attention as it explores its environment. In particular, the bat actively shifts the aim of its sonar beam to inspect objects in different directions, akin to eye movements and foveation in humans and other visually dominant animals. Further, the bat adjusts the temporal features of sonar calls to attend to objects at different distances, yielding a metric of acoustic gaze along the range axis. Thus, an echolocating bat's call features not only convey the information it uses to probe its surroundings, but also provide fine scale metrics of auditory spatial attention in 3D natural tasks. These explicit metrics of overt spatial attention can be leveraged to uncover general principles of neural coding in the mammalian brain.
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Affiliation(s)
| | - Angeles Salles
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Cynthia Moss
- Department of Psychological & Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Neuroscience, Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
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4
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Håkansson J, Mikkelsen C, Jakobsen L, Elemans CPH. Bats expand their vocal range by recruiting different laryngeal structures for echolocation and social communication. PLoS Biol 2022; 20:e3001881. [PMID: 36445872 PMCID: PMC9707786 DOI: 10.1371/journal.pbio.3001881] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 10/19/2022] [Indexed: 12/03/2022] Open
Abstract
Echolocating bats produce very diverse vocal signals for echolocation and social communication that span an impressive frequency range of 1 to 120 kHz or 7 octaves. This tremendous vocal range is unparalleled in mammalian sound production and thought to be produced by specialized laryngeal vocal membranes on top of vocal folds. However, their function in vocal production remains untested. By filming vocal membranes in excised bat larynges (Myotis daubentonii) in vitro with ultra-high-speed video (up to 250,000 fps) and using deep learning networks to extract their motion, we provide the first direct observations that vocal membranes exhibit flow-induced self-sustained vibrations to produce 10 to 95 kHz echolocation and social communication calls in bats. The vocal membranes achieve the highest fundamental frequencies (fo's) of any mammal, but their vocal range is with 3 to 4 octaves comparable to most mammals. We evaluate the currently outstanding hypotheses for vocal membrane function and propose that most laryngeal adaptations in echolocating bats result from selection for producing high-frequency, rapid echolocation calls to catch fast-moving prey. Furthermore, we show that bats extend their lower vocal range by recruiting their ventricular folds-as in death metal growls-that vibrate at distinctly lower frequencies of 1 to 5 kHz for producing agonistic social calls. The different selection pressures for echolocation and social communication facilitated the evolution of separate laryngeal structures that together vastly expanded the vocal range in bats.
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Affiliation(s)
- Jonas Håkansson
- Sound Communication and Behavior Group, Department of Biology, University of Southern Denmark, Odense M, Denmark,* E-mail: (JH); (CPHE)
| | - Cathrine Mikkelsen
- Sound Communication and Behavior Group, Department of Biology, University of Southern Denmark, Odense M, Denmark
| | - Lasse Jakobsen
- Sound Communication and Behavior Group, Department of Biology, University of Southern Denmark, Odense M, Denmark
| | - Coen P. H. Elemans
- Sound Communication and Behavior Group, Department of Biology, University of Southern Denmark, Odense M, Denmark,* E-mail: (JH); (CPHE)
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5
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Sarel A, Palgi S, Blum D, Aljadeff J, Las L, Ulanovsky N. Natural switches in behaviour rapidly modulate hippocampal coding. Nature 2022; 609:119-127. [PMID: 36002570 PMCID: PMC9433324 DOI: 10.1038/s41586-022-05112-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 07/14/2022] [Indexed: 11/30/2022]
Abstract
Throughout their daily lives, animals and humans often switch between different behaviours. However, neuroscience research typically studies the brain while the animal is performing one behavioural task at a time, and little is known about how brain circuits represent switches between different behaviours. Here we tested this question using an ethological setting: two bats flew together in a long 135 m tunnel, and switched between navigation when flying alone (solo) and collision avoidance as they flew past each other (cross-over). Bats increased their echolocation click rate before each cross-over, indicating attention to the other bat1–9. Hippocampal CA1 neurons represented the bat’s own position when flying alone (place coding10–14). Notably, during cross-overs, neurons switched rapidly to jointly represent the interbat distance by self-position. This neuronal switch was very fast—as fast as 100 ms—which could be revealed owing to the very rapid natural behavioural switch. The neuronal switch correlated with the attention signal, as indexed by echolocation. Interestingly, the different place fields of the same neuron often exhibited very different tuning to interbat distance, creating a complex non-separable coding of position by distance. Theoretical analysis showed that this complex representation yields more efficient coding. Overall, our results suggest that during dynamic natural behaviour, hippocampal neurons can rapidly switch their core computation to represent the relevant behavioural variables, supporting behavioural flexibility. During rapid behavioural switches in flying bats, hippocampal neurons can rapidly switch their core computation to represent the relevant behavioural variables, supporting behavioural flexibility.
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Affiliation(s)
- Ayelet Sarel
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shaked Palgi
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Dan Blum
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Johnatan Aljadeff
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.,Department of Neurobiology, University of California, San Diego, CA, USA
| | - Liora Las
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Nachum Ulanovsky
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel.
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6
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Halley AC, Baldwin MKL, Cooke DF, Englund M, Pineda CR, Schmid T, Yartsev MM, Krubitzer L. Coevolution of motor cortex and behavioral specializations associated with flight and echolocation in bats. Curr Biol 2022; 32:2935-2941.e3. [PMID: 35617952 DOI: 10.1016/j.cub.2022.04.094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/01/2022] [Accepted: 04/27/2022] [Indexed: 11/26/2022]
Abstract
Bats have evolved behavioral specializations that are unique among mammals, including self-propelled flight and echolocation. However, areas of motor cortex that are critical in the generation and fine control of these unique behaviors have never been fully characterized in any bat species, despite the fact that bats compose ∼25% of extant mammalian species. Using intracortical microstimulation, we examined the organization of motor cortex in Egyptian fruit bats (Rousettus aegyptiacus), a species that has evolved a novel form of tongue-based echolocation.1,2 We found that movement representations include an enlarged tongue region containing discrete subregions devoted to generating distinct tongue movement types, consistent with their behavioral specialization generating active sonar using tongue clicks. This magnification of the tongue in motor cortex is comparable to the enlargement of somatosensory representations in species with sensory specializations.3-5 We also found a novel degree of coactivation between the forelimbs and hindlimbs, both of which are involved in altering the shape and tension of wing membranes during flight. Together, these findings suggest that the organization of motor cortex has coevolved with peripheral morphology in bats to support the unique motor demands of flight and echolocation.
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Affiliation(s)
- Andrew C Halley
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Mary K L Baldwin
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA
| | - Dylan F Cooke
- Biomedical Physiology and Kinesiology, Simon Fraser University, 8888 University Drive E K9625, Burnaby, BC V5A 1S6, Canada
| | - Mackenzie Englund
- Department of Psychology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 USA
| | - Carlos R Pineda
- Department of Psychology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 USA
| | - Tobias Schmid
- Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, MC#3370, Berkeley, CA 94720, USA
| | - Michael M Yartsev
- Helen Wills Neuroscience Institute, University of California, Berkeley, 175 Li Ka Shing Center, MC#3370, Berkeley, CA 94720, USA; Department of Bioengineering, University of California, Berkeley, 306 Stanley Hall, Berkeley, CA 94720, USA
| | - Leah Krubitzer
- Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, USA; Department of Psychology, University of California, Davis, 1 Shields Avenue, Davis, CA 95616 USA.
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7
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Liberti WA, Schmid TA, Forli A, Snyder M, Yartsev MM. A stable hippocampal code in freely flying bats. Nature 2022; 604:98-103. [PMID: 35355012 PMCID: PMC10212506 DOI: 10.1038/s41586-022-04560-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 02/17/2022] [Indexed: 12/31/2022]
Abstract
Neural activity in the hippocampus is known to reflect how animals move through an environment1,2. Although navigational behaviour may show considerable stability3-6, the tuning stability of individual hippocampal neurons remains unclear7-12. Here we used wireless calcium imaging to longitudinally monitor the activity of dorsal CA1 hippocampal neurons in freely flying bats performing highly reproducible flights in a familiar environment. We find that both the participation and the spatial selectivity of most neurons remain stable over days and weeks. We also find that apparent changes in tuning can be largely attributed to variations in the flight behaviour of the bats. Finally, we show that bats navigating in the same environment under different room lighting conditions (lights on versus lights off) exhibit substantial changes in flight behaviour that can give the illusion of neuronal instability. However, when similar flight paths are compared across conditions, the stability of the hippocampal code persists. Taken together, we show that the underlying hippocampal code is highly stable over days and across contexts if behaviour is taken into account.
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Affiliation(s)
| | - Tobias A Schmid
- Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA, USA
| | - Angelo Forli
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA
| | | | - Michael M Yartsev
- Department of Bioengineering, UC Berkeley, Berkeley, CA, USA.
- Helen Wills Neuroscience Institute, UC Berkeley, Berkeley, CA, USA.
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8
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Rossborough J, Salles A, Stidsholt L, Madsen PT, Moss CF, Hoffman LF. Inflight head stabilization associated with wingbeat cycle and sonar emissions in the lingual echolocating Egyptian fruit bat, Rousettus aegyptiacus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 207:757-772. [PMID: 34716764 DOI: 10.1007/s00359-021-01518-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/12/2021] [Accepted: 10/14/2021] [Indexed: 11/29/2022]
Abstract
Sensory processing of environmental stimuli is challenged by head movements that perturb sensorimotor coordinate frames directing behaviors. In the case of visually guided behaviors, visual gaze stabilization results from the integrated activity of the vestibuloocular reflex and motor efference copy originating within circuits driving locomotor behavior. In the present investigation, it was hypothesized that head stabilization is broadly implemented in echolocating bats during sustained flight, and is temporally associated with emitted sonar signals which would optimize acoustic gaze. Predictions from these hypotheses were evaluated by measuring head and body kinematics with motion sensors attached to the head and body of free-flying Egyptian fruit bats. These devices were integrated with ultrasonic microphones to record sonar emissions and elucidate the temporal association with periods of head stabilization. Head accelerations in the Earth-vertical axis were asymmetric with respect to wing downstroke and upstroke relative to body accelerations. This indicated that inflight head and body accelerations were uncoupled, outcomes consistent with the mechanisms that limit vertical head acceleration during wing downstroke. Furthermore, sonar emissions during stable flight occurred most often during wing downstroke and head stabilization, supporting the conclusion that head stabilization behavior optimized sonar gaze and environmental interrogation via echolocation.
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Affiliation(s)
- Jackson Rossborough
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Box 951624, Los Angeles, CA, 90095-1624, USA
| | - Angeles Salles
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
| | | | - Peter T Madsen
- Department of Biology, Aarhus University, Aarhus, Denmark
| | - Cynthia F Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Larry F Hoffman
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Box 951624, Los Angeles, CA, 90095-1624, USA.
- Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA.
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9
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Smarsh GC, Tarnovsky Y, Yovel Y. Hearing, echolocation, and beam steering from day 0 in tongue-clicking bats. Proc Biol Sci 2021; 288:20211714. [PMID: 34702074 PMCID: PMC8548796 DOI: 10.1098/rspb.2021.1714] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/06/2021] [Indexed: 11/12/2022] Open
Abstract
Little is known about the ontogeny of lingual echolocation. We examined the echolocation development of Rousettus aegyptiacus, the Egyptian fruit bat, which uses rapid tongue movements to produce hyper-short clicks and steer the beam's direction. We recorded from day 0 to day 35 postbirth and assessed hearing and beam-steering abilities. On day 0, R. aegyptiacus pups emit isolation calls and hyper-short clicks in response to acoustic stimuli, demonstrating hearing. Auditory brainstem response recordings show that pups are sensitive to pure tones of the main hearing range of adult Rousettus and to brief clicks. Newborn pups produced clicks in the adult paired pattern and were able to use their tongues to steer the sonar beam. As they aged, pups produced click pairs faster, converging with adult intervals by age of first flights (7-8 weeks). In contrast with laryngeal bats, Rousettus echolocation frequency and duration are stable through to day 35, but shift by the time pups begin to fly, possibly owing to tongue-diet maturation effects. Furthermore, frequency and duration shift in the opposite direction of mammalian laryngeal vocalizations. Rousettus lingual echolocation thus appears to be a highly functional sensory system from birth and follows a different ontogeny from that of laryngeal bats.
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Affiliation(s)
- Grace C. Smarsh
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, IL 6997801, Israel
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, IL 7610001, Israel
| | - Yifat Tarnovsky
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, IL 6997801, Israel
- School of Neurobiology, Biochemistry, and Biophysics, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, IL 6997801, Israel
| | - Yossi Yovel
- School of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, IL 6997801, Israel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, IL 6997801, Israel
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10
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Rose MC, Styr B, Schmid TA, Elie JE, Yartsev MM. Cortical representation of group social communication in bats. Science 2021; 374:eaba9584. [PMID: 34672724 PMCID: PMC8775406 DOI: 10.1126/science.aba9584] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Social interactions occur in group settings and are mediated by communication signals that are exchanged between individuals, often using vocalizations. The neural representation of group social communication remains largely unexplored. We conducted simultaneous wireless electrophysiological recordings from the frontal cortices of groups of Egyptian fruit bats engaged in both spontaneous and task-induced vocal interactions. We found that the activity of single neurons distinguished between vocalizations produced by self and by others, as well as among specific individuals. Coordinated neural activity among group members exhibited stable bidirectional interbrain correlation patterns specific to spontaneous communicative interactions. Tracking social and spatial arrangements within a group revealed a relationship between social preferences and intra- and interbrain activity patterns. Combined, these findings reveal a dedicated neural repertoire for group social communication within and across the brains of freely communicating groups of bats.
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Affiliation(s)
- Maimon C. Rose
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Boaz Styr
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
| | - Tobias A. Schmid
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
| | - Julie E. Elie
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
| | - Michael M. Yartsev
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA
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11
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Gorman CE, Hulsey CD. Non-trophic Functional Ecology of Vertebrate Teeth: A Review. Integr Comp Biol 2021; 60:665-675. [PMID: 32573716 DOI: 10.1093/icb/icaa086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Teeth are critical to the functional ecology of vertebrate trophic abilities, but are also used for a diversity of other non-trophic tasks. Teeth can play a substantial role in how animals move, manipulate their environment, positively interact with conspecifics, antagonistically interact with other organisms, and sense the environment. We review these non-trophic functions in an attempt to place the utility of human and all other vertebrate dentitions in a more diverse framework that emphasizes an expanded view of the functional importance and ecological diversity of teeth. In light of the extensive understanding of the developmental genetics, trophic functions, and evolutionary history of teeth, comparative studies of vertebrate dentitions will continue to provide unique insights into multi-functionality, many-to-one mapping, and the evolution of novel abilities.
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Affiliation(s)
- Courtney E Gorman
- Department of Biology, University of Konstanz, Konstanz 78457, Germany
| | - C Darrin Hulsey
- Department of Biology, University of Konstanz, Konstanz 78457, Germany
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12
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Arbour JH, Curtis AA, Santana SE. Sensory adaptations reshaped intrinsic factors underlying morphological diversification in bats. BMC Biol 2021; 19:88. [PMID: 33931060 PMCID: PMC8086122 DOI: 10.1186/s12915-021-01022-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 04/01/2021] [Indexed: 11/13/2022] Open
Abstract
Background Morphological evolution may be impacted by both intrinsic (developmental, constructional, physiological) and extrinsic (ecological opportunity and release) factors, but can intrinsic factors be altered by adaptive evolution and, if so, do they constrain or facilitate the subsequent diversification of biological form? Bats underwent deep adaptive divergences in skull shape as they evolved different sensory modes; here we investigate the potential impact of this process on two intrinsic factors that underlie morphological variation across organisms, allometry, and modularity. Results We use comparative phylogenetic and morphometric approaches to examine patterns of evolutionary allometry and modularity across a 3D geometric morphometric dataset spanning all major bat clades. We show that allometric relationships diverge between echolocators and visually oriented non-echolocators and that the evolution of nasal echolocation reshaped the modularity of the bat cranium. Conclusions Shifts in allometry and modularity may have significant consequences on the diversification of anatomical structures, as observed in the bat skull.
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Affiliation(s)
- J H Arbour
- Present Address: Department of Biology, Middle Tennessee State University, Murfreesboro, TN, 37132, USA.,Department of Biology, University of Washington, Seattle, Washington, 98195, USA
| | - A A Curtis
- Department of Biology, University of Washington, Seattle, Washington, 98195, USA
| | - S E Santana
- Department of Biology, University of Washington, Seattle, Washington, 98195, USA. .,Burke Museum of Natural History and Culture, University of Washington, Seattle, Washington, 98195, USA.
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13
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Wirthlin M, Chang EF, Knörnschild M, Krubitzer LA, Mello CV, Miller CT, Pfenning AR, Vernes SC, Tchernichovski O, Yartsev MM. A Modular Approach to Vocal Learning: Disentangling the Diversity of a Complex Behavioral Trait. Neuron 2019; 104:87-99. [PMID: 31600518 PMCID: PMC10066796 DOI: 10.1016/j.neuron.2019.09.036] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/18/2019] [Accepted: 09/21/2019] [Indexed: 12/14/2022]
Abstract
Vocal learning is a behavioral trait in which the social and acoustic environment shapes the vocal repertoire of individuals. Over the past century, the study of vocal learning has progressed at the intersection of ecology, physiology, neuroscience, molecular biology, genomics, and evolution. Yet, despite the complexity of this trait, vocal learning is frequently described as a binary trait, with species being classified as either vocal learners or vocal non-learners. As a result, studies have largely focused on a handful of species for which strong evidence for vocal learning exists. Recent studies, however, suggest a continuum in vocal learning capacity across taxa. Here, we further suggest that vocal learning is a multi-component behavioral phenotype comprised of distinct yet interconnected modules. Discretizing the vocal learning phenotype into its constituent modules would facilitate integration of findings across a wider diversity of species, taking advantage of the ways in which each excels in a particular module, or in a specific combination of features. Such comparative studies can improve understanding of the mechanisms and evolutionary origins of vocal learning. We propose an initial set of vocal learning modules supported by behavioral and neurobiological data and highlight the need for diversifying the field in order to disentangle the complexity of the vocal learning phenotype.
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14
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Signatures of echolocation and dietary ecology in the adaptive evolution of skull shape in bats. Nat Commun 2019; 10:2036. [PMID: 31048713 PMCID: PMC6497661 DOI: 10.1038/s41467-019-09951-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 04/10/2019] [Indexed: 11/20/2022] Open
Abstract
Morphological diversity may arise rapidly as a result of adaptation to novel ecological opportunities, but early bursts of trait evolution are rarely observed. Rather, models of discrete shifts between adaptive zones may better explain macroevolutionary dynamics across radiations. To investigate which of these processes underlie exceptional levels of morphological diversity during ecological diversification, we use modern phylogenetic tools and 3D geometric morphometric datasets to examine adaptive zone shifts in bat skull shape. Here we report that, while disparity was established early, bat skull evolution is best described by multiple adaptive zone shifts. Shifts are partially decoupled between the cranium and mandible, with cranial evolution more strongly driven by echolocation than diet. Phyllostomidae, a trophic adaptive radiation, exhibits more adaptive zone shifts than all other families combined. This pattern was potentially driven by ecological opportunity and facilitated by a shift to intermediate cranial shapes compared to oral-emitters and other nasal emitters. What drives changes in morphological diversity? Here, Arbour et al. analyse skull 3D shape evolution across the bat radiation using µCT scan data, finding two phases of skull shape diversification, early adaptive shifts related to echolocation, and more recent shifts related to diet transitions.
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Yu C, Luo J, Wohlgemuth M, Moss CF. Echolocating bats inspect and discriminate landmark features to guide navigation. ACTA ACUST UNITED AC 2019; 222:jeb.191965. [PMID: 30936268 DOI: 10.1242/jeb.191965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 03/26/2019] [Indexed: 11/20/2022]
Abstract
Landmark-guided navigation is a common behavioral strategy for way-finding, yet prior studies have not examined how animals collect sensory information to discriminate landmark features. We investigated this question in animals that rely on active sensing to guide navigation. Four echolocating bats (Eptesicus fuscus) were trained to use an acoustic landmark to find and navigate through a net opening for a food reward. In experimental trials, an object serving as a landmark was placed adjacent to a net opening and an object serving as a distractor was placed next to a barrier (covered opening). The location of the opening, barrier and objects were moved between trials, but the spatial relationships between the landmark and opening, and between the distractor and barrier were maintained. In probe trials, the landmark was placed next to a barrier, while the distractor was placed next to the opening, to test whether the bats relied on the landmark to guide navigation. Vocal and flight behaviors were recorded with an array of ultrasound microphones and high-speed infrared motion-capture cameras. All bats successfully learned to use the landmark to guide navigation through the net opening. Probe trials yielded an increase in both the time to complete the task and the number of net crashes, confirming that the bats relied largely on the landmark to find the net opening. Further, landmark acoustic distinctiveness influenced performance in probe trials and sonar inspection behaviors. Analyses of the animals' vocal behaviors also revealed differences between call features of bats inspecting landmarks compared with distractors, suggesting increased sonar attention to objects used to guide navigation.
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Affiliation(s)
- Chao Yu
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Jinhong Luo
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Melville Wohlgemuth
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
| | - Cynthia F Moss
- Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA
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