Publications

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response properties and location of neurons selective for sinusoidal frequency modulations in the inferior colliculus of the big brown bat.most animal vocalizations, including echolocation signals used by bats, contain frequency-modulated (fm) components. previous studies have described a class of neurons in the inferior colliculus (ic) of the big brown bat that respond exclusively to sinusoidally frequency modulated (sfm) signals and fail to respond to pure tones, noise, amplitude-modulated tones, or single fm sweeps. the aims of this study were to further characterize these neurons' response properties and to determine whether th ...200717634338
acoustic mimicry in a predator-prey interaction.mimicry of visual warning signals is one of the keystone concepts in evolutionary biology and has received substantial research attention. by comparison, acoustic mimicry has never been rigorously tested. visualizing bat-moth interactions with high-speed, infrared videography, we provide empirical evidence for acoustic mimicry in the ultrasonic warning sounds that tiger moths produce in response to echolocating bats. two species of sound-producing tiger moths were offered successively to naïve, ...200717517637
tone-specific and nonspecific plasticity of the auditory cortex elicited by pseudoconditioning: role of acetylcholine receptors and the somatosensory cortex.experience-dependent plastic changes in the central sensory systems are due to activation of both the sensory and neuromodulatory systems. nonspecific changes of cortical auditory neurons elicited by pseudoconditioning are quite different from tone-specific changes of the neurons elicited by auditory fear conditioning. therefore the neural circuit evoking the nonspecific changes must also be different from that evoking the tone-specific changes. we first examined changes in the response properti ...200818596186
corticofugal modulation of the paradoxical latency shifts of inferior collicular neurons.the central auditory system creates various types of neurons tuned to different acoustic parameters other than a specific frequency. the response latency of auditory neurons typically shortens with an increase in stimulus intensity. however, approximately 10% of collicular neurons of the little brown bat show a "paradoxical latency-shift (pls)": long latencies to intense sounds but short latencies to weak sounds. these neurons presumably are involved in the processing of target distance informat ...200818596179
postnatal bone elongation of the manus versus pes: analysis of the chondrocytic differentiation cascade in mus musculus and eptesicus fuscus.bones elongate postnatally by endochondral ossification as cells of the cartilaginous growth plate undergo a differentiation cascade of proliferation, cellular hypertrophy and matrix synthesis. interspecific comparisons of homologous bones elongating at different rates has been a useful approach for studying the dynamics of this process. the purpose of this study was to measure quantitative stereological parameters of growth plates of the third digit of the manus and pes of the laboratory mouse, ...200818160802
neuronal connexin expression in the cochlear nucleus of big brown bats.we present immunohistochemical data describing the presence and distribution of connexins, structural component of gap junctions, in the cochlear nuclei of adult big brown bats (eptesicus fuscus). echolocating big brown bats show microsecond scale echo-delay sensitivity that requires accurate synchronization of neuronal responses to the timing of echoes. midbrain and auditory cortical neuronal response timing is similar to that observed in other non-echolocating mammals, suggesting that lower au ...200818241843
an analysis of correspondence between unique rabies virus variants and divergent big brown bat (eptesicus fuscus) mitochondrial dna lineages.the literature supports that unique rabies virus (rabv) variants are often compartmentalized in different species of bats. in colorado, two divergent mtdna lineages of big brown bats (eptesicus fuscus) co-occur. rabv associated with this species also segregates into two clades. we hypothesized that unique rabv variants might be associated with mtdna lineages of colorado big brown bats. dna was extracted from brain tissue of rabid big brown bats, the nd2 gene was amplified to determine mtdna line ...200818398562
susceptibility of north american big brown bats (eptesicus fuscus) to infection with european bat lyssavirus type 1.the aim of this study was to determine the susceptibility of insectivorous bats (using the big brown bat as a model) to infection with european bat lyssavirus type 1a (eblv-1a), to assess the dynamics of host immune responses and to evaluate the opportunity for horizontal viral transmission within colonies. two isolates of eblv-1a, originating from slovakia (eblv-1ask) and germany (eblv-1age), were tested. four different routes of inoculation were used with isolate eblv-1ask [10(4.8) mouse intra ...200818632972
experimental infection of big brown bats (eptesicus fuscus) with west caucasian bat virus (wcbv).big brown bats (eptesicus fuscus), either recently captured individuals or survivors from previous experimental infection with irkut virus (irkv), were inoculated with west caucasian bat virus (wcbv), intramuscularly into the masseter (n=7) or neck (n=8) muscles, or orally (n=6). three bats inoculated into the neck muscles developed rabies and died between days 10 and 18. viral rna was detected in a number of tissues but isolation was successful only from the brain. an oral swab of one of these ...200818634495
experimental rabies virus infection of big brown bats (eptesicus fuscus).a captive colony of adult big brown bats (eptesicus fuscus) was experimentally infected with a rabies virus (rabv) variant isolated from the salivary glands of a naturally infected big brown bat and passaged once through murine neuroblastoma cell culture. bats were divided into 11 groups, which were composed of one to three noninfected and one to three infected individuals each. twenty of 38 animals were infected intramuscularly into both left and right masseter muscles; they received a total of ...200818689646
echo frequency selectivity of duration-tuned inferior collicular neurons of the big brown bat, eptesicus fuscus, determined with pulse-echo pairs.during hunting, insectivorous bats such as eptesicus fuscus progressively vary the repetition rate, duration, frequency and amplitude of emitted pulses such that analysis of an echo parameter by bats would be inevitably affected by other co-varying echo parameters. the present study is to determine the variation of echo frequency selectivity of duration-tuned inferior collicular neurons during different phases of hunting using pulse-echo (p-e) pairs as stimuli. all collicular neurons discharge m ...200818804149
flying in silence: echolocating bats cease vocalizing to avoid sonar jamming.although it has been recognized that echolocating bats may experience jamming from the signals of conspecifics, research on this problem has focused exclusively on time-frequency adjustments in the emitted signals to minimize interference. here, we report a surprising new strategy used by bats to avoid interference, namely silence. in a quantitative study of flight and vocal behavior of the big brown bat (eptesicus fuscus), we discovered that the bat spends considerable time in silence when flyi ...200818725624
gaba-mediated modulation of the discharge pattern and rate-level function of two simultaneously recorded neurons in the inferior colliculus of the big brown bat, eptesicus fuscus.neurons in the central nucleus of the inferior colliculus (ic) receive excitatory and inhibitory inputs from both lower and higher auditory nuclei. interaction of these two opposing inputs shapes response properties of ic neurons. in this study, we examine the interaction of excitation and inhibition on the responses of two simultaneously recorded ic neurons using a probe and a masker under forward masking paradigm. we specifically study whether a sound that serves as a probe to elicit responses ...200818551991
evidence for spatial representation of object shape by echolocating bats (eptesicus fuscus).big brown bats were trained in a two-choice task to locate a two-cylinder dipole object with a constant 5 cm spacing in the presence of either a one-cylinder monopole or another two-cylinder dipole with a shorter spacing. for the dipole versus monopole task, the objects were either stationary or in motion during each trial. the dipole and monopole objects varied from trial to trial in the left-right position while also roving in range (10-40 cm), cross range separation (15-40 cm), and dipole asp ...200818537406
bats use magnetite to detect the earth's magnetic field.while the role of magnetic cues for compass orientation has been confirmed in numerous animals, the mechanism of detection is still debated. two hypotheses have been proposed, one based on a light dependent mechanism, apparently used by birds and another based on a "compass organelle" containing the iron oxide particles magnetite (fe(3)o(4)). bats have recently been shown to use magnetic cues for compass orientation but the method by which they detect the earth's magnetic field remains unknown. ...200818301753
when echolocating bats do not echolocate.echolocating bats are known to continuously generate high frequency sonar pulses and listen to the reflecting echoes to localize objects and orient in the environment. however, silent behavior has been reported in a recent paper, which demonstrated that the big brown bat (eptesicus fuscus) can fly a relative long distant (0.6 to 8 m) without echolocating when flying with another conspecific in a large flight room.1 methodology and conclusion developed in this study have the potential for further ...200819704880
detection of targets colocalized in clutter by big brown bats (eptesicus fuscus).echolocating big brown bats (eptesicus fuscus) frequently catch insects during aerial pursuits in open spaces, but they also capture prey swarming on vegetation, and from substrates. to evaluate perception of targets on cluttered surfaces, big brown bats were trained in a two-alternative forced-choice task to locate a target, varying in height, that was embedded partway in holes (clutter) cut in a foam surface. the holes were colocalized with the possible positions of the target at distances ran ...200818647008
a genetic analysis of group movement in an isolated population of tree-roosting bats.group fission is an important dispersal mechanism for philopatric adults. in cypress hills interprovincial park, saskatchewan, tree-roosting big brown bats (eptesicus fuscus) exhibit fission-fusion roosting behaviour. during 2004-2007, the majority of females previously resident to roosting area 1 (ra1) moved to a new roosting area (ra4). we examined how genetic relationships, inferred from data for microsatellite loci and mitochondrial dna, influenced new roost area (ra) selection during 2006 w ...200818559322
jamming avoidance response of big brown bats in target detection.when searching for prey, big brown bats (eptesicus fuscus) enhance the range of their sonar by concentrating more energy in the nearly constant-frequency (cf) tail portion of their frequency-modulated (fm) sweeps. we hypothesize that this portion of their signals may be vulnerable to interference from conspecifics using the same frequencies in their own emissions. to determine how bats modify their signals when confronted with an interfering stimulus, we compared the echolocation calls of bats w ...200818083738
bat inferior collicular neurons have the greatest frequency selectivity when determined with best-duration pulses.during hunting, insectivorous bats such as eptesicus fuscus progressively increase the pulse repetition rate, shorten the pulse duration, and lower the frequency and amplitude of emitted pulses as they search, approach and finally intercept insects or negotiate obstacles. as such, analysis of an echo parameter by the bat is inevitably affected by other co-varying echo parameters. the present study examined the effect of pulse duration on frequency selectivity of neurons in the central nucleus of ...200818485591
echo duration selectivity of the bat varies with pulse-echo amplitude difference.during hunting, insectivorous bats progressively decrease the pulse duration, pulse amplitude and pulse-echo gap as they search, approach and finally intercept the prey. our earlier study shows that echo duration selectivity of most neurons in the central nucleus of the inferior colliculus of eptesicus fuscus improves with decreasing pulse duration and pulse-echo gap. in this study, we show that most collicular neurons discharged maximally to a best echo duration using three biologically relevan ...200818303584
free-flight encounters between praying mantids (parasphendale agrionina) and bats (eptesicus fuscus).through staged free-flight encounters between echolocating bats and praying mantids, we examined the effectiveness of two potential predator-evasion behaviors mediated by different sensory modalities: (1) power dive responses triggered by bat echolocation detected by the mantis ultrasound-sensitive auditory system, and (2) ;last-ditch' maneuvers triggered by bat-generated wind detected by the mantis cercal system. hearing mantids escaped more often than deafened mantids (76% vs 34%, respectively ...200818245632
forelimb versus hindlimb skeletal development in the big brown bat, eptesicus fuscus: functional divergence is reflected in chondrocytic performance in autopodial growth plates.the morphology of the chiropteran forelimb demonstrates musculoskeletal specializations for powered flight essentially unique among mammals, including extreme elongation of the distal skeletal elements. recent studies have focused primarily on the relative timing and levels of gene expression during early stages of endochondral ossification in the chiropteran embryo for clues to the molecular basis of the evolutionary origins of flight in these species. the goal of the current study was to exami ...200818160801
purkinje cell compartmentation of the cerebellum of microchiropteran bats.transverse boundaries divide the mammalian cerebellar cortex into transverse zones, and within each zone the cortex is further subdivided into a symmetrical array of parasagittal stripes. this topography is highly conserved across the mammalia. bats have a remarkable cerebellum with presumed adaptations to flight and to echolocation, but nothing is known of its compartmentation. we have therefore used two purkinje cell compartmentation antigens, zebrin ii/aldolase c and phospholipase cbeta4, to ...200919731335
functional role of gabaergic and glycinergic inhibition in the intermediate nucleus of the lateral lemniscus of the big brown bat.the intermediate nucleus of the lateral lemniscus (inll) is a major input to the inferior colliculus (ic), the auditory midbrain center where multiple pathways converge to create neurons selective for specific temporal features of sound. however, little is known about how inll processes auditory information or how it contributes to integrative processes at the ic. inll receives excitatory projections from the cochlear nucleus and inhibitory projections from the medial nucleus of the trapezoid bo ...200919369365
interpulse interval modulation by echolocating big brown bats (eptesicus fuscus) in different densities of obstacle clutter.big brown bats (eptesicus fuscus) use biosonar to find insect prey in open areas, but they also find prey near vegetation and even fly through vegetation when in transit from roosts to feeding sites. to evaluate their reactions to dense, distributed clutter, bats were tested in an obstacle array consisting of rows of vertically hanging chains. chains were removed from the array to create a curved corridor of three clutter densities (high, medium, low). bats flew along this path to receive a food ...200919322570
behavioral responses of big brown bats to dives by praying mantises.insectivorous echolocating bats face a formidable array of defenses employed by their airborne prey. one such insect defense is the ultrasound-triggered dive, which is a sudden, rapid drop in altitude, sometimes all the way to the ground. although many previous studies have investigated the dynamics of such dives and their effect on insect survival rate, there has been little work on how bats may adapt to such an insect defense employed in the middle of pursuit. in this study we investigated how ...200919218521
role of broadcast harmonics in echo delay perception by big brown bats.big brown bats (eptesicus fuscus) emit frequency-modulated (fm) echolocation sounds containing two principal down-sweeping harmonics (fm(1) approximately 55-25 khz, fm(2) approximately 105-50 khz). to determine whether each harmonic contributes to perception of echo delay, bats were trained to discriminate between "split-harmonic" echoes that differed in delay. the bat's broadcasts were picked up with microphones, and fm(1) and fm(2) were separated with highpass and lowpass filters at about 55 k ...200918989677
tiger moth jams bat sonar.in response to sonar-guided attacking bats, some tiger moths make ultrasonic clicks of their own. the lepidopteran sounds have previously been shown to alert bats to some moths' toxic chemistry and also to startle bats unaccustomed to sonic prey. the moth sounds could also interfere with, or "jam," bat sonar, but evidence for such jamming has been inconclusive. using ultrasonic recording and high-speed infrared videography of bat-moth interactions, we show that the palatable tiger moth bertholdi ...200919608920
naïve bats discriminate arctiid moth warning sounds but generalize their aposematic meaning.naïve red (lasiurus borealis müller) and big brown (eptesicus fuscus beauvois) bats quickly learn to avoid noxious sound-producing tiger moths. after this experience with a model tiger moth, bats generalize the meaning of these prey-generated sounds to a second tiger moth species producing a different call. here we describe the three-dimensional kinematic and bioacoustic details of this behaviour, first, as naïve bats learn to deal with an unpalatable model tiger moth and subsequently, as they a ...200919561203
adaptive echolocation behavior in bats for the analysis of auditory scenes.echolocating bats emit sonar pulses and listen to returning echoes to probe their surroundings. bats adapt their echolocation call design to cope with dynamic changes in the acoustic environment, including habitat change or the presence of nearby conspecifics/heterospecifics. seven pairs of big brown bats, eptesicus fuscus, were tested in this study to examine how they adjusted their echolocation calls when flying and competing with a conspecific for food. results showed that differences in five ...200919376960
acoustic scanning of natural scenes by echolocation in the big brown bat, eptesicus fuscus.echolocation allows bats to orient and localize prey in complete darkness. the sonar beam of the big brown bat, eptesicus fuscus, is directional but broad enough to provide audible echo information from within a 60-90 deg. cone. this suggests that the big brown bat could interrogate a natural scene without fixating each important object separately. we tested this idea by measuring the directional aim and duration of the bat's sonar beam as it performed in a dual task, obstacle avoidance and inse ...200919282498
spatial unmasking in the echolocating big brown bat, eptesicus fuscus.masking affects the ability of echolocating bats to detect a target in the presence of clutter targets. it can be reduced by spatially separating the targets. spatial unmasking was measured in a two-alternative-forced-choice detection experiment with four big brown bats detecting a wire at 1 m distance. depth dependent spatial unmasking was investigated by the bats detecting a wire with a diameter of 1.2 mm in front of a masker with a threshold distance of 11 cm behind the wire. for angle depend ...200919263055
involvement of gaba-mediated inhibition in shaping the frequency selectivity of neurons in the inferior colliculus of the big brown bat, eptesicus fuscus.in central auditory signal processing, neural inhibition plays an important role in sharpening the selectivity of auditory neurons. the present study examines the involvement of gaba-mediated inhibition in shaping the frequency selectivity of neurons in the bat inferior colliculus (ic) using forward masking paradigm and bicuculline application. at each study session, we recorded two ic neurons with a pair of electrodes and reciprocally studied whether a sound that served as a probe to elicit res ...200919764352
detection of high levels of european bat lyssavirus type-1 viral rna in the thyroid gland of experimentally-infected eptesicus fuscus bats.two common bat lyssavirus species have been identified in many european countries: european bat lyssavirus type-1 and -2 (eblv-1 and eblv-2). only limited knowledge on the susceptibility of the natural eblv-hosts, insectivorous bats, to lyssavirus infection is available. our study was undertaken to evaluate the susceptibility and pathology associated with an eblv-1 infection in eptesicus fuscus following different routes of virus inoculation including intracranial (n = 6), intramuscular (n = 14) ...200919497087
detection of polyoma and corona viruses in bats of canada.several instances of emerging diseases in humans appear to be caused by the spillover of viruses endemic to bats, either directly or through other animal intermediaries. the objective of this study was to detect, identify and characterize viruses in bats in the province of manitoba and other regions of canada. bats were sampled from three sources: live-trapped myotis lucifugus from manitoba, rabies-negative eptesicus fuscus, m. lucifugus, m. yumanensis, m. septentrionalis, m. californicus, m. ev ...200919357225
examining the mechanisms responsible for lower ros release rates in liver mitochondria from the long-lived house sparrow (passer domesticus) and big brown bat (eptesicus fuscus) compared to the short-lived mouse (mus musculus).lower ros release rate in long-lived species is likely caused by decreased reduction of electron transport chain (etc) complexes, but how this is achieved remains largely unknown. we compared liver mitochondrial h(2)o(2) release rates among endotherms of comparable size and metabolic rate: house sparrow and big brown bat (both long-lived) and house mouse (short-lived). we hypothesized that low ros release rates in long-lived species result from (i) lower mitochondrial respiration rate, (ii) incr ...200919464314
tone-specific and nonspecific plasticity of inferior colliculus elicited by pseudo-conditioning: role of acetylcholine and auditory and somatosensory cortices.experience-dependent plasticity in the central sensory systems depends on activation of both the sensory and neuromodulatory systems. sensitization or nonspecific augmentation of central auditory neurons elicited by pseudo-conditioning with unpaired conditioning tonal (cs) and unconditioned electric leg (us) stimuli is quite different from tone-specific plasticity, called best frequency (bf) shifts, of the neurons elicited by auditory fear conditioning with paired cs and us. therefore the neural ...200919474174
acid-base state and intermittent breathing in the torpid bat, eptesicus fuscus.the effects of intermittent breathing on acid-base state and blood gases were characterized in the torpid bat, eptesicus fuscus, during steady-state torpor between body temperatures (tb) of 5 and 37 degrees c. arterial blood samples were taken from indwelling catheters without disturbing the torpid state. arterial ph (pha) of samples taken without knowledge of ventilatory state rose by 0.15 units from 37 to 5 degrees c with a delta pha/delta tb slope over this range of -0.0055 u/degrees c. howev ...20091626139
spatial and temporal dynamics of rabies virus variants in big brown bat populations across canada: footprints of an emerging zoonosis.phylogenetic analysis of a collection of rabies viruses that currently circulate in canadian big brown bats (eptesicus fuscus) identified five distinct lineages which have emerged from a common ancestor that existed over 400 years ago. four of these lineages are regionally restricted in their range while the fifth lineage, comprising two-thirds of all specimens, has emerged in recent times and exhibits a recent demographic expansion with rapid spread across the canadian range of its host. four o ...201020406385
host immunity to repeated rabies virus infection in big brown bats.bats are natural reservoirs for the majority of lyssaviruses globally, and are unique among mammals in having exceptional sociality and longevity. given these facets, and the recognized status of bats as reservoirs for rabies viruses (rabvs) in the americas, individual bats may experience repeated exposure to rabv during their lifetime. nevertheless, little information exists with regard to within-host infection dynamics and the role of immunological memory that may result from abortive rabv inf ...201020519458
renal infection by a new coccidian genus in big brown bats (eptesicus fuscus).a novel coccidian parasite from the kidney of big brown bats (eptesicus fuscus) is described. this coccidian (nephroisospora eptesici nov. gen., n. sp.) was associated with a generally mild, focal or multifocal, well-demarcated cortical renal lesion less than 1 mm in diameter. the lesion represented cystic, dilated tubules with hypertrophied tubular epithelial cells and was present in the kidneys of 29 of 590 bats. numerous coccidian parasites in various stages of development were present within ...201019863159
organization of the primary somatosensory cortex and wing representation in the big brown bat, eptesicus fuscus.bats are the only mammals capable of true powered flight. the bat wing exhibits specializations, allowing these animals to perform complicated flight maneuvers like landing upside-down, and hovering. the wing membrane contains various tactile receptors, including hair-associated merkel receptors that might be involved in stabilizing bat flight. here, we studied the neuronal representation of the wing membrane in the primary somatosensory cortex (s1) of the anesthetized big brown bat, eptesicus f ...201020878405
metagenomic analysis of the viromes of three north american bat species: viral diversity among different bat species that share a common habitat.effective prediction of future viral zoonoses requires an in-depth understanding of the heterologous viral population in key animal species that will likely serve as reservoir hosts or intermediates during the next viral epidemic. the importance of bats as natural hosts for several important viral zoonoses, including ebola, marburg, nipah, hendra, and rabies viruses and severe acute respiratory syndrome-coronavirus (sars-cov), has been established; however, the large viral population diversity ( ...201020926577
effects of filtering of harmonics from biosonar echoes on delay acuity by big brown bats (eptesicus fuscus).big brown bats emit fm biosonar sounds containing two principal harmonics (fm1 approximately 55-22 khz;fm2 approximately 105-45 khz). to examine the role of harmonics, they were selectively filtered from stimuli in electronic-echo delay discrimination experiments. positive stimuli were delayed by 3.16 ms (55 cm simulated target range); negative stimuli were by delayed by 3.96 ms (68 cm). this large 800-micros delay difference (nearly 14 cm) was easily discriminated for echoes containing equal-st ...201020707464
tissue mercury concentrations and adrenocortical responses of female big brown bats (eptesicus fuscus) near a contaminated river.much of the research on mercury (hg) in wild vertebrates has focused on piscivores and other animals at high trophic levels. however, recent studies indicated that insectivorous terrestrial vertebrates may also be at risk. in the present study, we examined blood and fur hg concentrations as well as the adrenocortical responses of insectivorous big brown bats (eptesicus fuscus) near the hg-contaminated south river, va and a nearby reference area. baseline glucocorticoids and adrenocortical respon ...201020596767
spatial perception and adaptive sonar behavior.bat echolocation is a dynamic behavior that allows for real-time adaptations in the timing and spectro-temporal design of sonar signals in response to a particular task and environment. to enable detailed, quantitative analyses of adaptive sonar behavior, echolocation call design was investigated in big brown bats, trained to rest on a stationary platform and track a tethered mealworm that approached from a starting distance of about 170 cm in the presence of a stationary sonar distracter. the d ...201021218910
effects of competitive prey capture on flight behavior and sonar beam pattern in paired big brown bats, eptesicus fuscus.foraging and flight behavior of echolocating bats were quantitatively analyzed in this study. paired big brown bats, eptesicus fuscus, competed for a single food item in a large laboratory flight room. their sonar beam patterns and flight paths were recorded by a microphone array and two high-speed cameras, respectively. bats often remained in nearly classical pursuit (cp) states when one bat is following another bat. a follower can detect and anticipate the movement of the leader, while the lea ...201020833928
source levels of echolocation signals vary in correlation with wingbeat cycle in landing big brown bats (eptesicus fuscus).recordings of the echolocation signals of landing big brown bats with a two-dimensional 16-microphone array revealed that the source level reduction of 7 db per halving of distance is superimposed by a variation of up to 12 db within single call groups emitted during the approach. this variation correlates with the wingbeat cycle. the timing of call emission correlates with call group size. first pulses of groups containing many calls are emitted earlier than first calls in groups with fewer cal ...201020833918
thermoregulatory variation among populations of bats along a latitudinal gradient.most studies of hibernation physiology sample individuals from populations within a single geographic area, yet some species have large ranges meaning populations likely experience area-specific levels of energetic challenges. as well, few studies have assessed within-season variation. since physiological adjustments often are influenced by environmental factors, and the types of environments vary with geography, we expected variance in hibernation patterns among geographically separated populat ...201020213177
on population encoding and decoding of auditory information for bat echolocation.in this article, we study the neural encoding of acoustic information for fm-bats (such as eptesicus fuscus) in simulation. in echolocation research, the frequency-time sound representation as expressed by the spectrogram is often considered as input. the rationale behind this is that a similar representation is present in the cochlea, i.e. the receptor potential of the inner hair cells (ihc) along the length of the cochlea, and hence similar acoustic information is relayed to the brain. in this ...201020204397
comparison of auditory responses in the medial geniculate and pontine gray of the big brown bat, eptesicus fuscus.the inferior colliculus has been well studied for its role of transmitting information from the brainstem to the thalamocortical system. however, it is also the source of a major pathway to the cerebellum, via the pontine gray (pg). we compared auditory responses from single neurons in the medial geniculate body (mgb) and pg of the awake big brown bat. mgb neurons were selective for a variety of stimulus types whereas pg neurons only responded to pure tones or simple fm sweeps. best frequencies ...201121145384
a tale of two genomes: contrasting patterns of phylogeographic structure in a widely distributed bat.one of the most widely distributed bats in the new world, the big brown bat (eptesicus fuscus) exhibits well-documented geographic variation in morphology and life history traits, suggesting the potential for significant phylogeographic structure as well as adaptive differentiation among populations. in a pattern broadly consistent with morphologically defined subspecies, we found deeply divergent mitochondrial lineages restricted to different geographic regions. in contrast, sequence data from ...201121143331
is tissue maturation necessary for flight? changes in body composition during postnatal development in the big brown bat.patterns of offspring development reflect the availability of energy and nutrients, limitations on an individual's capacity to use available resources, and tradeoffs between the use of nutrients to support current metabolic demands and tissue growth. to determine if the long period of offspring dependency in bats is associated with the need for an advanced state of tissue maturation prior to flight, we examined body composition during postnatal growth in the big brown bat, eptesicus fuscus. desp ...201121046406
social learning of a novel foraging task by big brown bats (eptesicus fuscus).acquiring information via observation of others can be an efficient way to respond to changing situations or learn skills, particularly for inexperienced individuals. many bat species are gregarious, yet few studies have investigated their capacity for learning from conspecifics. we tested whether big brown bats (eptesicus fuscus) can learn a novel foraging task by interacting with knowledgeable conspecifics. in experimental trials 11 naïve bats (7 juveniles, 4 adults) interacted freely with tra ...201122328786
source level reduction and sonar beam aiming in landing big brown bats (eptesicus fuscus).reduction of echolocation call source levels in bats has previously been studied using set-ups with one microphone. by using a 16 microphone array, sound pressure level (spl) variations, possibly caused by the scanning movements of the bat, can be excluded and the sonar beam aiming can be studied. during the last two meters of approach flights to a landing platform in a large flight room, five big brown bats aimed sonar beams at the landing site and reduced the source level on average by 7 db pe ...201122087937
how do tiger moths jam bat sonar?the tiger moth bertholdia trigona is the only animal in nature known to defend itself by jamming the sonar of its predators - bats. in this study we analyzed the three-dimensional flight paths and echolocation behavior of big brown bats (eptesicus fuscus) attacking b. trigona in a flight room over seven consecutive nights to determine the acoustic mechanism of the sonar-jamming defense. three mechanisms have been proposed: (1) the phantom echo hypothesis, which states that bats misinterpret moth ...201121697434
monitoring seasonal bat activity on a coastal barrier island in maryland, usa.research on effects of wind turbines on bats has increased dramatically in recent years because of significant numbers of bats killed by rotating wind turbine blades. whereas most research has focused on the midwest and inland portions of eastern north america, bat activity and migration on the atlantic coast has largely been unexamined. we used three long-term acoustic monitoring stations to determine seasonal bat activity patterns on the assateague island national seashore, a barrier island of ...201120364316
white-nose syndrome and wing damage index scores among summer bats in the northeastern united states.white-nose syndrome (wns) adversely affects millions of bats hibernating in caves of the eastern united states. beginning in 2009, the us fish and wildlife service supported use of a wing damage index (wdi) scoring system (scale of 0 to 3, or no damage to severe) to assess wing damage of bats captured during summer. based on bat captures at 459 mist net sites in pennsylvania, new york, maryland, virginia, and new jersey, usa, we questioned whether wdi scores varied by species group, date, and di ...201121269995
adaptive behavior for texture discrimination by the free-flying big brown bat, eptesicus fuscus.this study examined behavioral strategies for texture discrimination by echolocation in free-flying bats. big brown bats, eptesicus fuscus, were trained to discriminate a smooth 16 mm diameter object (s+) from a size-matched textured object (s-), both of which were tethered in random locations in a flight room. the bat's three-dimensional flight path was reconstructed using stereo images from high-speed video recordings, and the bat's sonar vocalizations were recorded for each trial and analyzed ...201121246202
click-based echolocation in bats: not so primitive after all.echolocating bats of the genus rousettus produce click sonar signals, using their tongue (lingual echolocation). these signals are often considered rudimentary and are believed to enable only crude performance. however, the main argument supporting this belief, namely the click's reported long duration, was recently shown to be an artifact. in fact, the sonar clicks of rousettus bats are extremely short, ~50-100 μs, similar to dolphin vocalizations. here, we present a comparison between the sona ...201121465138
development of echolocation and communication vocalizations in the big brown bat, eptesicus fuscus.big brown bats form large maternity colonies of up to 200 mothers and their pups. if pups are separated from their mothers, they can locate each other using vocalizations. the goal of this study was to systematically characterize the development of echolocation and communication calls from birth through adulthood to determine whether they develop from a common precursor at the same or different rates, or whether both types are present initially. three females and their six pups were isolated fro ...201121327335
alphacoronaviruses in new world bats: prevalence, persistence, phylogeny, and potential for interaction with humans.bats are reservoirs for many different coronaviruses (covs) as well as many other important zoonotic viruses. we sampled feces and/or anal swabs of 1,044 insectivorous bats of 2 families and 17 species from 21 different locations within colorado from 2007 to 2009. we detected alphacoronavirus rna in bats of 4 species: big brown bats (eptesicus fuscus), 10% prevalence; long-legged bats (myotis volans), 8% prevalence; little brown bats (myotis lucifugus), 3% prevalence; and western long-eared bats ...201121589915
Naturally Acquired Rabies Virus Infections in Wild-Caught Bats.Abstract The study of a zoonotic disease requires an understanding of the disease incidence in animal reservoirs. Rabies incidence in bats submitted to diagnostic laboratories does not accurately reflect the true incidence in wild bat populations as a bias exists for testing bats that have been in contact with humans or pets. This article details the rabies incidence in two species of bats collected from natural settings without such bias. In this study, brain smears from 0.6% and 2.5% of wild-c ...201121923271
host and viral ecology determine bat rabies seasonality and maintenance.rabies is an acute viral infection that is typically fatal. most rabies modeling has focused on disease dynamics and control within terrestrial mammals (e.g., raccoons and foxes). as such, rabies in bats has been largely neglected until recently. because bats have been implicated as natural reservoirs for several emerging zoonotic viruses, including sars-like corona viruses, henipaviruses, and lyssaviruses, understanding how pathogens are maintained within a population becomes vital. unfortunate ...201121646516
patterns of tropomyosin and troponin-t isoform expression in jaw-closing muscles of mammals and reptiles that express masticatory myosin.we recently reported that masticatory ('superfast') myosin is expressed in jaw-closing muscles of some rodent species. most mammalian limb muscle fibers express tropomyosin-β (tm-β), along with fast-type or slow-type tropomyosin-β (tm-β), but jaw-closing muscle fibers in members of carnivora express a unique isoform of tm [tm-masticatory (tm-m)] and little or no tm-β. the goal of this study was to determine patterns of tm and troponin-t (tnt) isoform expression in the jaw-closing muscles of rode ...201121389191
perception of echo delay is disrupted by small temporal misalignment of echo harmonics in bat sonar.echolocating big brown bats emit ultrasonic frequency-modulated (fm) biosonar sounds containing two prominent downward-sweeping harmonics (fm1 and fm2) and perceive target distance from echo delay. in naturally occurring echoes, fm1 and fm2 are delayed by the same amount. even though echoes from targets located off-axis or far away are lowpass filtered, which weakens fm2 relative to fm1, their delays remain the same. we show here that misalignment of fm2 with fm1 by only 2.6 μs is sufficient to ...201121228198
dynamics of hippocampal spatial representation in echolocating bats.the "place fields" of hippocampal pyramidal neurons are not static. for example, upon a contextual change in the environment, place fields may "remap" within typical timescales of ~ 1 min. a few studies have shown more rapid dynamics in hippocampal activity, linked to internal processes, such as switches between spatial reference frames or changes within the theta cycle. however, little is known about rapid hippocampal place field dynamics in response to external, sensory stimuli. here, we studi ...201120014379
bats use echo harmonic structure to distinguish their targets from background clutter.when echolocating big brown bats fly in complex surroundings, echoes arriving from irrelevant objects (clutter) located to the sides of their sonar beam can mask perception of relevant objects located to the front (targets), causing "blind spots." because the second harmonic is beamed more weakly to the sides than the first harmonic, these clutter echoes have a weaker second harmonic. in psychophysical experiments, we found that electronically misaligning first and second harmonics in echoes (to ...201121798949
bats use a neuronally implemented computational acoustic model to form sonar images.this paper reexamines neurophysiological results from echolocating big brown bats to propose a new perspective on fm biosonar processing in the auditory system. individual auditory neurons are frequency-tuned and respond to brief, 2-10 ms fm sweeps with an average of one spike per sound to register their tuned frequencies, to detect echo arrival, or to register a local null in the echo spectrum. when initiated by the broadcast, these responses comprise a cascade of single spikes distributed acro ...201222436892
a novel coding mechanism for social vocalizations in the lateral amygdala.the amygdala plays a central role in evaluating the significance of acoustic signals and coordinating the appropriate behavioral responses. to understand how amygdalar responses modulate auditory processing and drive emotional expression, we assessed how neurons respond to and encode information that is carried within complex acoustic stimuli. we characterized responses of single neurons in the lateral nucleus of the amygdala to social vocalizations and synthetic acoustic stimuli in awake big br ...201222090463
is the structure of bat echolocation calls an adaptation to the mammalian hearing system?a common feature of most bat echolocation calls is their hyperbolalike frequency modulation. it is proposed that these calls evolved as an adaptation to the filters in the peripheral hearing system. from an analysis of 420 echolocation sounds of eptesicus fuscus, the bandwidths of filters giving a minimal error of time-delay estimation are predicted; these could be compared to neurophysiological findings.20123411034
auditory spatial sensitivity of inferior collicular neurons of echolocating bats.the sensitivity of 94 inferior collicular (ic) neurons of eptesicus fuscus and myotis lucifugus to spatial location of the acoustic stimulus were studied under free-field stimulus conditions. the best frequency (bf) and minimum threshold (mt) of each neuron were determined with sound delivered in front of the bat. then the variation in discharge rate of the neuron was measured with a bf sound broadcast from a moving loudspeaker at different angular positions along the horizontal, vertical or dia ...20123409031
molecular inferences suggest multiple host shifts of rabies viruses from bats to mesocarnivores in arizona during 2001-2009.in nature, rabies virus (rabv; genus lyssavirus, family rhabdoviridae) represents an assemblage of phylogenetic lineages, associated with specific mammalian host species. although it is generally accepted that rabv evolved originally in bats and further shifted to carnivores, mechanisms of such host shifts are poorly understood, and examples are rarely present in surveillance data. outbreaks in carnivores caused by a rabv variant, associated with big brown bats, occurred repeatedly during 2001-2 ...201222737076
extended incubation period of rabies virus in a captive big brown bat (eptesicus fuscus).rabies virus incubation in bats is typically less than 180 days, yet longer incubation periods have been described. we report a 267-day incubation in a big brown bat (eptesicus fuscus) exposed to rabies virus before entering our captive colony.201222493132
stimulus-specific adaptation in specialized neurons in the inferior colliculus of the big brown bat, eptesicus fuscus.the inferior colliculus (ic) of the big brown bat (eptesicus fuscus) contains specialized neurons that respond exclusively to highly specific spectrotemporal patterns such as sinusoidally frequency modulated (sfm) signals or directional frequency modulated sweeps (fm). other specialized cells with i-shaped frequency response areas (fras) are tuned to very narrow frequency bands (1-2 khz) in an amplitude-tolerant manner. in contrast, non-specialized neurons respond to any stimulus with energy in ...201222743044
a deterministic compressive sensing model for bat biosonar.the big brown bat (eptesicus fuscus) uses frequency modulated (fm) echolocation calls to accurately estimate range and resolve closely spaced objects in clutter and noise. they resolve glints spaced down to 2 μs in time delay which surpasses what traditional signal processing techniques can achieve using the same echolocation call. the matched filter (mf) attains 10-12 μs resolution while the inverse filter (if) achieves higher resolution at the cost of significantly degraded detection performan ...201223231133
recovery cycle times of inferior colliculus neurons in the awake bat measured with spike counts and latencies.neural responses in the mammalian auditory midbrain (inferior colliculus; ic) arise from complex interactions of synaptic excitation, inhibition, and intrinsic properties of the cell. temporally selective duration-tuned neurons (dtns) in the ic are hypothesized to arise through the convergence of excitatory and inhibitory synaptic inputs offset in time. synaptic inhibition can be inferred from extracellular recordings by presenting pairs of pulses (paired tone stimulation) and comparing the evok ...201222933992
social vocalizations of big brown bats vary with behavioral context.bats are among the most gregarious and vocal mammals, with some species demonstrating a diverse repertoire of syllables under a variety of behavioral contexts. despite extensive characterization of big brown bat (eptesicus fuscus) biosonar signals, there have been no detailed studies of adult social vocalizations. we recorded and analyzed social vocalizations and associated behaviors of captive big brown bats under four behavioral contexts: low aggression, medium aggression, high aggression, and ...201222970247
echolocation with bat buzz emissions: model and biomimetic sonar for elevation estimation.just prior to capture the buzz ii emissions of some mouth-emitting bats, such as eptesicus fuscus, are observed to exhibit spectra having multiple peaks. this paper proposes an echolocation strategy that uses such spectra with energy concentrated in specific frequency bands for determining target elevation. a biomimetic sonar was implemented to produce a tri-modal spectrum by driving a speaker with a signal rich in harmonics. the emission magnitudes at these harmonic frequencies measured as a fu ...201222280617
variable variation: annual and seasonal changes in offspring sex ratio in a bat.many organisms produce offspring with sex-ratios that deviate from equal numbers of males and females, and numerous adaptive explanations have been proposed. in some species, offspring sex-ratio varies across the reproductive season, again with several explanations as to why this might be adaptive. however, patterns for birds and mammals are inconsistent, and multiple factors are likely involved. long-term studies on a variety of species may help untangle the complexity. i analyzed a long-term d ...201222570704
duration tuning across vertebrates.signal duration is important for identifying sound sources and determining signal meaning. duration-tuned neurons (dtns) respond preferentially to a range of stimulus durations and maximally to a best duration (bd). duration-tuned neurons are found in the auditory midbrain of many vertebrates, although studied most extensively in bats. studies of dtns across vertebrates have identified cells with bds and temporal response bandwidths that mirror the range of species-specific vocalizations. neural ...201222553042
temporal variation in bat wing damage in the absence of white-nose syndrome.white-nose syndrome (wns) is an emerging infectious wildlife disease that has killed more than 5 million bats in the eastern united states since its discovery in winter 2006. the disease is associated with a cold-adapted fungus that infects bats during winter hibernation. wing damage has been documented in bats with wns and could become a useful screening tool for determining whether samples should be submitted for testing. however, because there are no historic records, to our knowledge, of win ...201324502722
spatial memory and stereotypy of flight paths by big brown bats in cluttered surroundings.the big brown bat, eptesicus fuscus, uses echolocation for foraging and orientation. the limited operating range of biosonar implies that bats must rely upon spatial memory in familiar spaces with dimensions larger than a few meters. prior experiments with bats flying in obstacle arrays have revealed differences in flight and acoustic emission patterns depending on the density and spatial extent of the obstacles. using the same method, combined with acoustic microphone array tracking, we flew bi ...201323447667
distinct lineage of vesiculovirus from big brown bats, united states.we identified a novel rhabdovirus, american bat vesiculovirus, from postmortem tissue samples from 120 rabies-negative big brown bats with a history of human contact. five percent of the tested bats were infected with this virus. the extent of zoonotic exposure and possible health effects in humans from this virus are unknown.201324274823
macro- and microgeographic variation in metabolism and hormone correlates in big brown bats (eptesicus fuscus).to better understand intraspecific variation in basal metabolic rate (bmr), we examined environmental, physiological, and/or cellular bases for residual variation in bmr in big brown bats, eptesicus fuscus. we measured bmr and plasma levels of thyroid hormone (t(3)) and leptin in bats captured in maternity colonies in eastern massachusetts (ma; northern population) and in alabama and georgia (alga; southern population) to assess macrogeographic (between- or among-population) and microgeographic ...201319758093
histaminergic modulation of nonspecific plasticity of the auditory system and differential gating.in the auditory system of the big brown bat (eptesicus fuscus), paired conditioned tonal (cs) and unconditioned leg stimuli (us) for auditory fear conditioning elicit tone-specific plasticity represented by best-frequency (bf) shifts that are augmented by acetylcholine, whereas unpaired cs and us for pseudoconditioning elicit a small bf shift and prominent nonspecific plasticity at the same time. the latter represents the nonspecific augmentations of auditory responses accompanied by the broaden ...201323136340
social calls of flying big brown bats (eptesicus fuscus).vocalizations serving a variety of social functions have been reported in many bat species (order chiroptera). while echolocation by big brown bats (eptesicus fuscus) has been the subject of extensive study, calls used by this species for communication have received comparatively little research attention. here, we report on a rich repertoire of vocalizations produced by big brown bats in a large flight room equipped with synchronized high speed stereo video and audio recording equipment. bats w ...201323966949
echolocation of static and moving objects in two-dimensional space using bat-like frequency-modulation sound.bats use frequency-modulated echolocation to identify and capture moving objects in real three-dimensional space. the big brown bat, eptesicus fuscus, emits linear period modulation sound, and is capable of locating static objects with a range accuracy of less than 1 μs. a previously introduced model can estimate ranges of multiple, static objects using linear frequency modulation (lfm) sound and gaussian chirplets with a carrier frequency compatible with bat emission sweep rates. the delay time ...201323847538
novel poxvirus in big brown bats, northwestern united states.a wildlife hospital and rehabilitation center in northwestern united states received several big brown bats with necrosuppurative osteomyelitis in multiple joints. wing and joint tissues were positive by pcr for poxvirus. thin-section electron microscopy showed poxvirus particles within a-type inclusions. phylogenetic comparison supports establishment of a new genus of poxviridae.201323735421
preputial demodex species in big brown bats (eptesicus fuscus) in eastern tennessee.the presence of preputial demodex species in four captive, wild-caught big brown bats (eptesicus fuscus) in eastern tennessee, usa, examined between 2008 and 2010 is reported. in three of four cases, there was associated folliculitis, dermatitis, or preputial adenitis. there were no clinical signs directly attributable to the mites, although penile prolapse was present in one case. mites were retrieved from preputial skin samples of other archival big brown bats by potassium hydroxide digestion ...201323505712
determining feeding state and rate of mass change in insectivorous bats using plasma metabolite analysis.insectivorous bats regularly experience dramatic and sometimes rapid changes in nutrient stores, yet our ability to study these changes has been limited by available techniques. plasma metabolite analysis has proven effective for studying individual rates of mass change in birds but has not been validated for other taxa. we tested the effectiveness of plasma metabolite analysis by conducting a study with captive big brown bats (eptesicus fuscus) and little brown bats (myotis lucifugus) in the fi ...201319799521
prevalence of neutralizing antibodies to rabies virus in serum of seven species of insectivorous bats from colorado and new mexico, united states.we determined the presence of rabies-virus-neutralizing antibodies (rvna) in serum of 721 insectivorous bats of seven species captured, sampled, and released in colorado and new mexico, united states in 2003-2005. a subsample of 160 bats was tested for rabies-virus rna in saliva. we sampled little brown bats (myotis lucifugus) at two maternity roosts in larimer county, colorado; big brown bats (eptesicus fuscus) at three maternity roosts in morgan county, colorado; and big brown bats at five mat ...201323568912
responses of mice to inoculation with low doses of a bat rabies virus variant.rabies is generally considered a fatal disease, yet neutralizing antibodies to rabies virus (rv) have frequently been found in sera from healthy, insectivorous bats, and mark-recapture studies have demonstrated bats that are still alive years after the first detection of anti-rv antibodies. to explore this phenomenon, we exposed mice to a big brown bat variant of rv, using three routes of inoculation, two doses of virus and two frequencies of exposure. we found the highest rate of seroconversion ...201323381393
unique characteristics of bat rabies viruses in big brown bats (eptesicus fuscus).rabies virus infection has been documented in several north american bat species, including eptesicus fuscus. the virus-host relationship between bats and rabies virus (rv) is not well understood. the incidence of non-lethal rv exposure, based on the presence of viral neutralizing antibodies, demonstrates that exposure to rv does not always lead to clinical infection in bats. it is unknown how the route of exposure, rabies virus variant, or health of the bat affects the outcome following exposur ...201323208279
anthropogenic roost switching and rabies virus dynamics in house-roosting big brown bats.big brown bats (eptesicus fuscus) are the most commonly encountered rabid bat in north america and represent an important source of wildlife rabies epizootics. urban and suburban colonies of e. fuscus are often evicted from their roosts in houses, with poorly understood consequences for bat dispersal, population dynamics, and rabies virus transmission. we combined radiotelemetry and mark-recapture of e. fuscus with enhanced surveillance to understand the frequency of rabies virus exposure in hou ...201323590325
multidisciplinary approach to epizootiology and pathogenesis of bat rabies viruses in the united states.zoonotic disease surveillance is typically initiated after an animal pathogen has caused disease in humans. early detection of potentially high-risk pathogens within animal hosts may facilitate medical interventions to cope with an emerging disease. to effectively spillover to a novel host, a pathogen may undergo genetic changes resulting in varying transmission potential in the new host and potentially to humans. rabies virus (rabv) is one model pathogen to consider for studying the dynamics of ...201323137052
rabies virus infection in eptesicus fuscus bats born in captivity (naïve bats).the study of rabies virus infection in bats can be challenging due to quarantine requirements, husbandry concerns, genetic differences among animals, and lack of medical history. to date, all rabies virus (rabv) studies in bats have been performed in wild caught animals. determining the rabv exposure history of a wild caught bat based on the presence or absence of viral neutralizing antibodies (vna) may be misleading. previous studies have demonstrated that the presence of vna following natural ...201323741396
susceptibility and pathogenesis of little brown bats (myotis lucifugus) to heterologous and homologous rabies viruses.rabies virus (rabv) maintenance in bats is not well understood. big brown bats (eptesicus fuscus), little brown bats (myotis lucifugus), and mexican free-tailed bats (tadarida brasiliensis) are the most common bats species in the united states. these colonial bat species also have the most frequent contact with humans and domestic animals. however, the silver-haired bat (lasionycteris noctivagans) rabv is associated with the majority of human rabies virus infections in the united states and cana ...201323741002
role of the spike glycoprotein of human middle east respiratory syndrome coronavirus (mers-cov) in virus entry and syncytia formation.little is known about the biology of the emerging human group c betacoronavirus, middle east respiratory syndrome coronavirus (mers-cov). because coronavirus spike glycoproteins (s) mediate virus entry, affect viral host range, and elicit neutralizing antibodies, analyzing the functions of mers-cov s protein is a high research priority. mers-cov s on lentivirus pseudovirions mediated entry into a variety of cell types including embryo cells from new world eptesicus fuscus bats. surprisingly, a p ...201324098509
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