Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| interaction of vestibular, echolocation, and visual modalities guiding flight by the big brown bat, eptesicus fuscus. | the big brown bat (eptesicus fuscus) is an aerial-feeding insectivorous species that relies on echolocation to avoid obstacles and to detect flying insects. spatial perception in the dark using echolocation challenges the vestibular system to function without substantial visual input for orientation. ir thermal video recordings show the complexity of bat flights in the field and suggest a highly dynamic role for the vestibular system in orientation and flight control. to examine this role, we ca ... | 2004 | 15156093 |
| characterization of an ecori family of satellite dna from two species of the genus eptesicus (vespertilionidae; chiroptera). | we have cloned and sequenced a 321 bp band of repetitive dna from eptesicus fuscus and e. serotinus observed after gel electrophoresis of ecori digested genomic dna in both species. southern blot analysis of genomic dna (from both species) digested with the same enzyme showed the existence of a ladder pattern indicating that the repetitive dna is arrayed in tandem. the repetitive sequences have a monomer unit of 321 bp which is composed of two subunits of 160 bp, suggested by the existence of a ... | 2004 | 15609553 |
| azimuth-dependent recovery cycle affects directional selectivity of bat inferior collicular neurons determined with sound pulses within a pulse train. | in our previous study, we have shown that the recovery cycle of most neurons in the inferior colliculus (ic) of the big brown bat, eptesicus fuscus, is typically longer at ipsilateral azimuth than at contralateral azimuth under free-field stimulation conditions. the present study is to test the hypothesis that this azimuth-dependent recovery cycle may contribute to the variation of directional selectivity of ic neurons with sequential presented sound pulses within a pulse train. a 300-ms pulse t ... | 2004 | 15306265 |
| the bat head-related transfer function reveals binaural cues for sound localization in azimuth and elevation. | directional properties of the sound transformation at the ear of four intact echolocating bats, eptesicus fuscus, were investigated via measurements of the head-related transfer function (hrtf). contributions of external ear structures to directional features of the transfer functions were examined by remeasuring the hrtf in the absence of the pinna and tragus. the investigation mainly focused on the interactions between the spatial and the spectral features in the bat hrtf. the pinna provides g ... | 2004 | 15658710 |
| rabies in a captive colony of big brown bats (eptesicus fuscus). | our research has focused on the ecology of commensal populations of big brown bats (eptesicus fuscus) in fort collins, colorado (usa), in relation to rabies virus (rv) transmission. we captured 35 big brown bats (eptesicus fuscus) in late summer 2001 and held them captive for 4.8 mo. the bats were initially placed in an indoor cage for 1 mo then segregated into groups of two to six per cage. two of the bats succumbed to rabies virus (rv) within the first month of capture. despite group housing, ... | 2004 | 15465706 |
| west nile virus antibodies in bats from new jersey and new york. | eighty-three serum samples were obtained from big brown (eptesicus fuscus), little brown (myotis lucifugus), and northern long-eared (myotis septentriotalis) bats (chiroptera: vespertilionidae), from new jersey and new york (usa) between july and october 2002. samples were analyzed for neutralizing antibodies to west nile virus (wnv) and st. louis encephalitis (sle) virus. one little brown bat and one northern long-eared bat tested positive for wnv neutralizing antibodies. no bats had antibodies ... | 2004 | 15362837 |
| experimental feeding of dde and pcb to female big brown bats (eptesicus fuscus). | twenty-two female big brown bats (eptesicus fuscus) were collected in a house attic in montgomery county, maryland. seventeen were fed mealworms (tenebrio molitor larvae) that contained 166 ppm dde; the other five were fed uncontaminated mealworms. after 54 days of feeding, six dosed bats were frozen and the remaining 16 were starved to death. in a second experiment, 21 female big brown bats were collected in a house attic in prince georges county, maryland. sixteen were fed mealworms that conta ... | 2004 | 404435 |
| ectoparasite associations of bats from central pennsylvania. | between april and october 1997, 689 bats representing seven species were captured at pennsylvania's canoe creek state park. each bat was sampled for ectoparasitic arthropods, and four species were collected from 13.2% of the host individuals. ectoparasites include the bat flea myodopsylla insignis (rothschild), the wing mite spinturnix americanus (banks), the bed bug cimex adjunctus barber, and the soft tick ornithodoros kelleyi cooley & kohls. prevalence, relative density, and mean intensity we ... | 2003 | 14765658 |
| comparative analysis of expression and secretion of placental leptin in mammals. | increased plasma level of leptin appears to be a ubiquitous feature of pregnant mammals. the mechanisms by which leptin levels are increased may be species specific, however, with some species upregulating adipose leptin production and others expressing leptin in the placenta. placental leptin expression was examined in representative species of the two most abundant mammalian orders, rodentia and chiroptera, and in cultured human choriocarcinoma (bewo) cells. leptin mrna was expressed in bewo c ... | 2003 | 12702488 |
| corticofugal modulation of amplitude domain processing in the midbrain of the big brown bat, eptesicus fuscus. | recent studies have shown that the corticofugal system systematically modulates and improves subcortical signal processing in the frequency, time and spatial domains. the present study examined corticofugal modulation of amplitude sensitivity of 113 corticofugally inhibited neurons in the central nucleus of the inferior colliculus (ic) of the big brown bat, eptesicus fuscus. cortical electrical stimulation decreased the number of impulses and increased the response latency of these neurons. they ... | 2003 | 14553907 |
| defining torpor in free-ranging bats: experimental evaluation of external temperature-sensitive radiotransmitters and the concept of active temperature. | a variety of definitions involving body temperature (tb), metabolic rate and behavior have been used to define torpor in mammals and birds. this problem is confounded in some studies of free-ranging animals that employ only skin temperature (tsk), a measure that approximates but may not precisely reflect tb. we assess the accuracy of tsk in the context of a recent definition for torpor called active temperature. we compared the active temperatures of individual big brown bats (eptesicus fuscus), ... | 2003 | 12764630 |
| expression of the kv1.1 ion channel subunit in the auditory brainstem of the big brown bat, eptesicus fuscus. | voltage-gated potassium channels play an important role in shaping membrane properties that underlie neurons' discharge patterns and the ways in which they transform their input. in the auditory system, low threshold potassium currents such as those created by kv1.1 subunits contribute to precise phaselocking and to transient onset responses that provide time markers for temporal features of sounds. the purpose of the present study was to compare information about the distribution of neurons exp ... | 2003 | 12761827 |
| the effect of bicuculline application on azimuth-dependent recovery cycle of inferior collicular neurons of the big brown bat, eptesicus fuscus. | the recovery cycle of auditory neurons is an important neuronal property, which determines a neuron's ability to respond to pairs of sounds presented at short inter-sound intervals. this property is particularly important for bats, which rely upon analysis of returning echoes to extract the information about targets after emission of intense orientation sounds. because target direction often changes throughout the course of hunting, the changing echo direction may affect the recovery cycle and t ... | 2003 | 12729962 |
| time-frequency model for echo-delay resolution in wideband biosonar. | a time/frequency model of the bat's auditory system was developed to examine the basis for the fine (approximately 2 micros) echo-delay resolution of big brown bats (eptesicus fuscus), and its performance at resolving closely spaced fm sonar echoes in the bat's 20-100-khz band at different signal-to-noise ratios was computed. the model uses parallel bandpass filters spaced over this band to generate envelopes that individually can have much lower bandwidth than the bat's ultrasonic sonar sounds ... | 2003 | 12703724 |
| temporal masking reveals properties of sound-evoked inhibition in duration-tuned neurons of the inferior colliculus. | the inferior colliculus (ic) is the first place in the central auditory pathway where duration-selective neurons are found. previous neuropharmacological and electrophysiological studies have shown that they are created there and have led to a conceptual model in which excitatory and inhibitory inputs are offset in time so that the cell fires only when sound duration is such that onset- and offset-evoked excitation coincide; the response is suppressed by inhibition at other durations. we tested ... | 2003 | 12684492 |
| binaural interaction in the inferior colliculus of the big brown bat, eptesicus fuscus. | binaural interaction plays an important role in shaping response properties of central auditory neurons. using single unit recording and iontophoresis, we examined frequency tuning curves (ftcs), interaural intensity difference (iid) curves, and rate-intensity functions of inferior collicular (ic) neurons of the big brown bat, eptesicus fuscus, under closed system or free field stimulation conditions. we isolated 46 ei (excitation-inhibition), 24 eo (monaural excitation) and 6 ee (excitation-exc ... | 2003 | 12618322 |
| augmentation of plasticity of the central auditory system by the basal forebrain and/or somatosensory cortex. | auditory conditioning (associative learning) or focal electric stimulation of the primary auditory cortex (ac) evokes reorganization (plasticity) of the cochleotopic (frequency) map of the inferior colliculus (ic) as well as that of the ac. the reorganization results from shifts in the best frequencies (bfs) and frequency-tuning curves of single neurons. since the importance of the cholinergic basal forebrain for cortical plasticity and the importance of the somatosensory cortex and the corticof ... | 2003 | 12522162 |
| auditory encoding during the last moment of a moth's life. | the simple auditory system of noctuoid moths has long been a model for anti-predator studies in neuroethology, although these ears have rarely been experimentally stimulated by the sounds they would encounter from naturally attacking bats. we exposed the ears of five noctuoid moth species to the pre-recorded echolocation calls of an attacking bat (eptesicus fuscus) to observe the acoustic encoding of the receptors at this critical time in their defensive behaviour. the b cell is a non-tympanal r ... | 2003 | 12477898 |
| gabaergic inhibition and the effect of sound direction on rate-intensity functions of inferior collicular neurons of the big brown bat, eptesicus fuscus. | gabaergic inhibition shapes many auditory response properties of neurons in the inferior colliculus of the big brown bat, eptesicus fuscus. this study examined the role of gabaergic inhibition on direction-dependent rate-intensity functions of bat inferior collicular neurons. when plotted at three sound directions (60 degrees contralateral, 0 degrees and 60 degrees ipsilateral relative to recording site), most collicular neurons had nonmonotonic and saturated rate-intensity functions at 60 degre ... | 2003 | 12974299 |
| the sonar beam pattern of a flying bat as it tracks tethered insects. | this paper describes measurements of the sonar beam pattern of flying echolocating bats, eptesicus fuscus, performing various insect capture tasks in a large laboratory flight room. the beam pattern is deduced using the signal intensity across a linear array of microphones. the positions of the bat and insect prey are obtained by stereoscopic reconstruction from two camera views. results are reported in the form of beam-pattern plots and estimated direction of the beam axis. the bat centers its ... | 2003 | 12942989 |
| echo delay versus spectral cues for temporal hyperacuity in the big brown bat, eptesicus fuscus. | big brown bats can discriminate between echoes that alternate in delay (jitter) by as little as 10-15 ns and echoes that are stationary in delay. this delay hyperacuity seems so extreme that it has been rejected in favor of an explanation in terms of artifacts in echoes, most likely spectral in nature, that presumably are correlated with delay. using different combinations of digital, analog, and cable delays, we dissociated the overall delay of jittering echoes from the size of the analog compo ... | 2003 | 12879356 |
| evaluation of an auditory model for echo delay accuracy in wideband biosonar. | in a psychophysical task with echoes that jitter in delay, big brown bats can detect changes as small as 10-20 ns at an echo signal-to-noise ratio of approximately 49 db and 40 ns at approximately 36 db. this performance is possible to achieve with ideal coherent processing of the wideband echoes, but it is widely assumed that the bat's peripheral auditory system is incapable of encoding signal waveforms to represent delay with the requisite precision or phase at ultrasonic frequencies. this ass ... | 2003 | 14514218 |
| development of reorganization of the auditory cortex caused by fear conditioning: effect of atropine. | reorganization of the frequency map in the central auditory system is based on shifts in the best frequencies (bfs; hereafter, bf shifts), together with the frequency-response curves, of auditory neurons. in the big brown bat, conditioning with acoustic stimulation followed by electric leg-stimulation causes bf shifts of collicular and cortical neurons. the collicular bf shift develops quickly and is short term, whereas the cortical bf shift develops slowly and is long term. the acetycholine lev ... | 2003 | 12966181 |
| the effect of sound duration on rate-amplitude functions of inferior collicular neurons in the big brown bat, eptesicus fuscus. | during echolocation, the amplitude and duration of echo pulses of the big brown bat, eptesicus fuscus, covary throughout the entire course of hunting. the purpose of this study was to examine if variation in sound duration might affect the amplitude selectivity of inferior collicular (ic) neurons of this bat species under free-field stimulation conditions. a family of rate-amplitude functions of each ic neuron was obtained with different sound durations. the effect of sound duration on the neuro ... | 2002 | 12062764 |
| selectivity for echo spectral interference and delay in the auditory cortex of the big brown bat eptesicus fuscus. | the acoustic environment for an echolocating bat can contain multiple objects that reflect echoes so closely separated in time that they are almost completely overlapping. this results in a single echo with a spectrum characterized by deep notches due to interference. the object of this study was to document the possible selectivity, or lack thereof, of auditory neurons to the temporal separation of biosonar signals on a coarse (ms) and fine (micros) temporal scale. we recorded single-unit activ ... | 2002 | 12037185 |
| the role of gabaergic inhibition in shaping directional selectivity of bat inferior collicular neurons determined with temporally patterned pulse trains. | this study examined the role of gabaergic inhibition in shaping directional selectivity of neurons in the inferior colliculus of the big brown bat, eptesicus fuscus. when determined with temporally patterned pulse trains at different pulse repetition rates, 93 inferior colliculus neurons displayed three types of directional selectivity curves. a directionally selective curve always showed a maximum to a certain azimuthal angle (the best angle). a hemifield curve showed a maximum to a range of co ... | 2002 | 12466957 |
| interaction between excitation and inhibition affects frequency tuning curve, response size and latency of neurons in the auditory cortex of the big brown bat, eptesicus fuscus. | neurons in the auditory cortex (ac) receive convergent excitatory and inhibitory inputs from the lower auditory nuclei. interaction between these two opposing inputs shapes different response properties of ac neurons. in this study, we examined how this interaction might affect the frequency tuning curves (ftcs), number of impulses and latency of ac neurons in the big brown bat, eptesicus fuscus, using a probe (excitatory tone) and a masker (inhibitory tone) under different stimulation condition ... | 2002 | 12433418 |
| gabaergic inhibition contributes to pulse repetition rate-dependent frequency selectivity in the inferior colliculus of the big brown bat, eptesicus fuscus. | this study examined the effect of bicuculline application on sharpness of frequency tuning curves (ftcs) of bat inferior collicular neurons plotted under three different pulse repetition rates (prrs) of 10, 30 and 90 pulses per second. the sharpness of ftcs of collicular neurons, which was expressed in q(n) (q(10), q(20), q(30)) and bandwidths (90, 75 and 50% of the maximal response at the best frequency), improved with increasing prr. however, this prr-dependent frequency selectivity of collicu ... | 2002 | 12383969 |
| interaction of excitation and inhibition in inferior collicular neurons of the big brown bat, eptesicus fuscus. | neurons in the inferior colliculus (ic) of the midbrain receive convergent excitatory and inhibitory inputs from both lower and higher auditory nuclei. interaction of these two opposing inputs shapes different response properties of ic neurons. in this study, we examined this interaction of excitation and inhibition in ic neurons using a probe (excitatory pulse) and a masker (inhibitory pulse) under different stimulation conditions. inhibition of probe-elicited responses by a masker, i.e. maskin ... | 2002 | 12121747 |
| the effect of two-tone stimulation on responses of two simultaneously recorded neurons in the inferior colliculus of the big brown bat, eptesicus fuscus. | this study examined auditory responses of two simultaneously recorded neurons in the central nucleus of bat inferior colliculus (ic) under two-tone stimulation conditions. we specifically examined how a sound within the excitatory frequency tuning curve (ftc) of one ic neuron might affect responses of the other ic neuron in amplitude and frequency domains. under this specific two-tone stimulation condition, responses of 82% neurons were suppressed and their excitatory ftcs sharpened. responses o ... | 2002 | 12117516 |
| transformation of external-ear spectral cues into perceived delays by the big brown bat, eptesicus fuscus. | the external-ear transfer function for big brown bats (eptesicus fuscus) contains two prominent notches that vary from 30 to 55 khz and from 70 to 100 khz, respectively, as sound-source elevation moves from -40 to +10 degrees. these notches resemble a higher-frequency version of external-ear cues for vertical localization in humans and other mammals. however, they also resemble interference notches created in echoes when reflected sounds overlap at short time separations of 30-50 micros. psychop ... | 2002 | 12083212 |
| potential use of chemical cues for colony-mate recognition in the big brown bat, eptesicus fuscus. | bats should benefit from recognition of their roost-mates when colonies form stable social units that persist over time. we used y-maze experiments and gas chromatography-olfactometry (gc-o) to evaluate whether female big brown bats eptesicus fuscus (chiroptera: vespertilionidae) use chemical cues to distinguish among conspecifics. in dual-choice y-maze experiments, females chose the scent of another female from their own roost over a conspecific female from a different roost in a majority of tr ... | 2002 | 12035929 |
| orienting responses and vocalizations produced by microstimulation in the superior colliculus of the echolocating bat, eptesicus fuscus. | an echolocating bat actively controls the spatial acoustic information that drives its behavior by directing its head and ears and by modulating the spectro-temporal structure of its outgoing sonar emissions. the superior colliculus may function in the coordination of these orienting components of the bat's echolocation system. to test this hypothesis, chemical and electrical microstimulation experiments were carried out in the superior colliculus of the echolocating bat, eptesicus fuscus, a spe ... | 2002 | 11919691 |
| temporally patterned sound pulse trains affect intensity and frequency sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus. | this study examined the effect of temporally patterned pulse trains on intensity and frequency sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus. intensity sensitivity of inferior collicular neurons was expressed by the dynamic range and slope of rate-intensity functions. inferior collicular neurons with non-monotonic rate-intensity functions have smaller dynamic ranges and larger slopes than neurons with monotonic or saturated rate-intensity functions. intensity ... | 2001 | 11763959 |
| gabaergic and glycinergic neural inhibition in excitatory frequency tuning of bat inferior collicular neurons. | this study examined the effect of gabaergic and glycinergic inhibition on excitatory frequency tuning curves (ftcs) of inferior collicular (ic) neurons of the big brown bat, eptesicus fuscus. the excitatory ftcs of 70 ic neurons were either v-shaped (57, 81%), closed (11, 16%), or double-peaked (2, 3%). by means of a two-tone stimulation paradigm, inhibitory ftcs were obtained at one frequency flank only (low-frequency flank: 11, 16%; high-frequency flank: 7, 10%), at both frequency flanks (36, ... | 2001 | 11715077 |
| a computational sensorimotor model of bat echolocation. | a computational sensorimotor model of target capture behavior by the echolocating bat, eptesicus fuscus, was developed to understand the detection, localization, tracking, and interception of insect prey in a biological sonar system. this model incorporated acoustics, target localization processes, flight aerodynamics, and target capture planning to produce model trajectories replicating those observed in behavioral insect capture trials. estimates of target range were based on echo delay, azimu ... | 2001 | 11519584 |
| medial superior olive of the big brown bat: neuronal responses to pure tones, amplitude modulations, and pulse trains. | the structure and function of the medial superior olive (mso) is highly variable among mammals. in species with large heads and low-frequency hearing, mso is adapted for processing interaural time differences. in some species with small heads and high-frequency hearing, the mso is greatly reduced in size; in others, including those echolocating bats that have been examined, the mso is large. moreover, the mso of bats appears to have undergone different functional specializations depending on the ... | 2001 | 11698513 |
| hyperleptinemia in pregnant bats is characterized by increased placental leptin secretion in vitro. | hyperleptinemia is a common feature of pregnancy in mammals. the source of increased plasma leptin is uncertain. we examined leptin secretory rates in vitro to test the hypothesis that leptin secretion is upregulated during pregnancy. two species of insectivorous bats were examined, myotis lucifugus and eptesicus fuscus, because of their unique reproductive cycle. body mass and plasma leptin significantly increased with gestation and decreased during lactation. adiposity increased in midgestatio ... | 2001 | 11394641 |
| an electrophysiological study of neural pathways for corticofugally inhibited neurons in the central nucleus of the inferior colliculus of the big brown bat, eptesicus fuscus. | this electrophysiological study tests the hypothesis that one possible neural pathway for corticofugally inhibited neurons in the central nucleus of the inferior colliculus (icc) of the big brown bat, eptesicus fuscus, is mediated through excitatory projections from the auditory cortex (ac) to the external nucleus of the ic (icx), which then sends inhibitory inputs to the icc. this study shows that all neurons in the icx are broadly tuned to stimulus frequency. electrical stimulation in the ac t ... | 2001 | 11355376 |
| the effect of sound intensity on duration-tuning characteristics of bat inferior collicular neurons. | previous studies have shown that inferior collicular neurons of the big brown bat, eptesicus fuscus, serve as short-, band-, long- and all-pass filters for sound durations. neurons with band-, short- and long-pass filtering characteristics discharged maximally to a specific sound duration or a range of sound durations. in contrast, neurons with all-pass filtering characteristics do not have duration selectivity. to determine if duration-tuning characteristics of collicular neurons were tolerant ... | 2001 | 11318379 |
| plasticity of bat's central auditory system evoked by focal electric stimulation of auditory and/or somatosensory cortices. | recent findings indicate that the corticofugal system would play an important role in cortical plasticity as well as collicular plasticity. to understand the role of the corticofugal system in plasticity, therefore, we studied the amount and the time course of plasticity in the inferior colliculus (ic) and auditory cortex (ac) evoked by focal electrical stimulation of the ac and also the effect of electrical stimulation of the somatosensory cortex on the plasticity evoked by the stimulation of t ... | 2001 | 11247978 |
| frequency discrimination threshold at search call frequencies in the echolocating bat, eptesicus fuscus. | while searching for prey in open spaces, epteisicus fuscus emits long-duration, downward frequency-modulated calls which cover a frequency band of about 28-22 khz. in the ascending auditory pathways of e. fuscus, neurons tuned to these search call frequencies are characterised by a remarkably high frequency selectivity and very sensitive absolute thresholds. we investigated whether this narrow tuning is reflected in an exceptional psychoacoustic frequency discrimination ability. the average freq ... | 2001 | 11467501 |
| effects of acetylcholine and atropine on plasticity of central auditory neurons caused by conditioning in bats. | in the big brown bat (eptesicus fuscus), conditioning with acoustic stimuli followed by electric leg-stimulation causes shifts in frequency-tuning curves and best frequencies (hereafter bf shifts) of collicular and cortical neurons, i.e., reorganization of the cochleotopic (frequency) maps in the inferior colliculus (ic) and auditory cortex (ac). the collicular bf shift recovers 180 min after the conditioning, but the cortical bf shift lasts longer than 26 h. the collicular bf shift is not cause ... | 2001 | 11431503 |
| type i external skeletal fixation of radial fractures in microchiropterans. | an adult male big brown bat (eptesicus fuscus) and an adult female hoary bat (lasiurus cinereus) were presented with open transverse middiaphyseal left radial fractures. initial repair was attempted by intramedullary pinning. when the fractures did not heal, intramedullary pins were removed and type i external skeletal fixators were placed. the fractures healed, and the big brown bat regained normal flight but the hoary bat did not. | 2001 | 12785704 |
| cyclodiene insecticide, dde, ddt, arsenic, and mercury contamination of big brown bats (eptesicus fuscus) foraging at a colorado superfund site. | rocky mountain arsenal (rma) national wildlife area, near denver, colorado, is a superfund site contaminated by past military and industrial uses, including pesticide manufacturing. from an ecosystem standpoint, the most critical contaminants at rma are certain cyclodiene insecticides and metabolites, p,p'-dde, p,p'-ddt, arsenic, and mercury. bats are important ecosystem components that can be impacted by persistent contaminants because of their position in the food chain and their potential lon ... | 2001 | 11116346 |
| food chain aspects of chlordane poisoning in birds and bats. | we have observed recurring chlordane poisonings of large numbers of common grackles (quiscalus quiscula), european starlings (sturnus vulgaris), and american robins (turdus migratorius) at suburban roosts in new jersey during the month of july. this paper describes aspects of the food chain uptake of chlordane that account for the periodicity of these poisonings. chlordane concentrations ranged from < 0.02 to 20.3 microg/g wet weight in 11 soil samples collected from residential lawns and a golf ... | 2001 | 11243332 |
| antigenic and genetic divergence of rabies viruses from bat species indigenous to canada. | antigenic characterisation of over 350 chiropteran rabies viruses of the americas, especially from species reported rabid in canada, distinguished 13 viral types. in close accord with this classification, nucleotide sequencing of representative isolates, at both the n and g loci, identified four principal phylogenetic groups (i-iv), sub-groups of which circulated in particular bat species. amongst the north american bat viruses, there was a notable division between group i specimens associated w ... | 2001 | 11226582 |
| exposure of hooded capuchin monkeys (cebus apella cay) to a rabid bat at a zoological park. | on 27 may 1999, a big brown bat (eptesicus fuscus) was discovered on an island exhibit at the denver zoo that contained a troop of 15 hooded capuchin monkeys (cebus apella cay). the monkeys were attacking the bat when it was discovered. the bat was collected and humanely euthanatized without direct handling and submitted to the colorado department of public health and environment virology laboratory for rabies evaluation. the monkeys had not been vaccinated against rabies virus. the next day, th ... | 2001 | 12790408 |
| bat ectoparasites from the trans-pecos region of texas, including notes from big bend national park. | ectoparasites of 13 species of molossid, mormoopid, and vespertilionid bats from the trans-pecos region of texas were studied, as follows: antrozous pallidus (leconte), corynorhinus townsendii (cooper), eptesicus fuscus (palisot de beauvois), lasiurus cinereus (palisot de beauvois), mormoops megalophylla (peters), myotis thysanodes g. s. miller, myotis velifer (j. a. allen), myotis volans (h. allen), myotis yumanensis (h. allen), nyctinomops femorosaccus (merriam), nyctinomops macrotis (gray), p ... | 2001 | 11372965 |
| molecular evolution of leptin. | leptin, a hormone produced mainly by adipocytes, is involved in the regulation of food intake, metabolism, and reproduction. the objective of this study was to determine the evolutionary relationships of leptin genes. partial nucleotide sequences of leptin were cloned and sequenced from six mammalian species: large hairy armadillo (chaetophractus villosus), rabbit (oryctolagus cuniculus), big brown bat (eptesicus fuscus) [corrected], striped skunk (mephitis mephitis), raccoon (procyon lotor), an ... | 2001 | 11703084 |
| uptake of dietary pcb by pregnant big brown bats (eptesicus fuscus) and their fetuses. | 2001 | 98190 | |
| sound localization in a new-world frugivorous bat, artibeus jamaicensis: acuity, use of binaural cues, and relationship to vision. | passive sound-localization acuity and its relationship to vision were determined for the echolocating jamaican fruit bat (artibeus jamaicensis). a conditioned avoidance procedure was used in which the animals drank fruit juice from a spout in the presence of sounds from their right, but suppressed their behavior, breaking contact with the spout, whenever a sound came from their left, thereby avoiding a mild shock. the mean minimum audible angle for three bats for a 100-ms noise burst was 10 degr ... | 2001 | 11206172 |
| auditory scene analysis by echolocation in bats. | echolocating bats transmit ultrasonic vocalizations and use information contained in the reflected sounds to analyze the auditory scene. auditory scene analysis, a phenomenon that applies broadly to all hearing vertebrates, involves the grouping and segregation of sounds to perceptually organize information about auditory objects. the perceptual organization of sound is influenced by the spectral and temporal characteristics of acoustic signals. in the case of the echolocating bat, its active co ... | 2001 | 11681397 |
| tick (acari) infestations of bats in new mexico. | a total of 278 bats belonging to 16 species was examined for ticks from various sites in new mexico from 1994 to 1998. seven species of bats were parasitized by ticks: larvae of ornithodoros kelleyi cooley & kohls, ornithodoros rossi kohls, sonenshine & clifford (argasidae), or both. both species of ticks are reported from new mexico for the first time. infestation prevalences for parasitized bats ranged from 2 to 25% on different host species for o. kelleyi and from 7 to 25% for o. rossi. the p ... | 2001 | 11476346 |
| brief and short-term corticofugal modulation of subcortical auditory responses in the big brown bat, eptesicus fuscus. | recent studies show that the auditory corticofugal system modulates and improves ongoing signal processing and reorganizes frequency map according to auditory experience in the central nucleus of bat inferior colliculus. however, whether all corticofugally affected collicular neurons are involved in both types of modulation has not been determined. in this study, we demonstrate that one group (51%) of collicular neurons participates only in corticofugal modulation of ongoing signal processing, w ... | 2000 | 11110836 |
| direction-dependent corticofugal modulation of frequency-tuning curves of inferior collicular neurons in the big brown bat, eptesicus fuscus. | this study examined if corticofugal modulation of subcortical frequency-tuning curves varied with sound direction. both excitatory and inhibitory frequency tuning curves of inferior collicular neurons of the big brown bat, eptesicus fuscus were plotted before and during electrical stimulation in the auditory cortex at two sound directions (contra-40 degrees and ipsi-40 degrees). most collicular neurons had broader excitatory frequency-tuning curves at contra-40 degrees but had broader inhibitory ... | 2000 | 11138792 |
| echolocation behavior of big brown bats, eptesicus fuscus, in the field and the laboratory. | echolocation signals were recorded from big brown bats, eptesicus fuscus, flying in the field and the laboratory. in open field areas the interpulse intervals (ipi) of search signals were either around 134 ms or twice that value, 270 ms. at long ipi's the signals were of long duration (14 to 18-20 ms), narrow bandwidth, and low frequency, sweeping down to a minimum frequency (fmin) of 22-25 khz. at short ipi's the signals were shorter (6-13 ms), of higher frequency, and broader bandwidth. in woo ... | 2000 | 11108382 |
| bicuculline application affects discharge patterns, rate-intensity functions, and frequency tuning characteristics of bat auditory cortical neurons. | this study examined the effect of bicuculline application on the auditory response properties in the auditory cortex of the big brown bat, eptesicus fuscus. all auditory cortical neurons studied discharged either 1-2 or 3-7 impulses to 4 ms sound stimuli. cortical neurons with high best frequencies tended to have high minimum thresholds. bicuculline application increased the number of impulses and shortened the response latencies of all cortical neurons as well as changing the discharge patterns ... | 2000 | 11077201 |
| corticofugal inhibition compresses all types of rate-intensity functions of inferior collicular neurons in the big brown bat. | recent studies have shown that the auditory corticofugal system modulates and improves signal processing in the frequency, time and spatial domains. in this study, we examine corticofugal modulation of rate-intensity functions of inferior collicular (ic) neurons of the big brown bat, eptesicus fuscus, by electrical stimulation in the primary auditory cortex (ac). cortical electrical stimulation compressed all types of rate-intensity functions so as to increase the slope but decrease the dynamic ... | 2000 | 11033094 |
| experience-dependent plasticity in the auditory cortex and the inferior colliculus of bats: role of the corticofugal system. | in the big brown bat, eptesicus fuscus, the response properties of neurons and the cochleotopic (frequency) maps in the auditory cortex (ac) and inferior colliculus can be changed by auditory conditioning, weak focal electric stimulation of the ac, or repetitive delivery of weak, short tone bursts. the corticofugal system plays an important role in information processing and plasticity in the auditory system. our present findings are as follows. in the ac, best frequency (bf) shifts, i.e., reorg ... | 2000 | 10884432 |
| neural inhibition sharpens auditory spatial selectivity of bat inferior collicular neurons. | this study examines the role of neural inhibition in auditory spatial selectivity of inferior collicular neurons of the big brown bat, eptesicus fuscus, using a two-tone inhibition paradigm. two-tone inhibition decreases auditory spatial response areas but increases the slopes of directional sensitivity curves of inferior collicular neurons. inferior collicular neurons have either directionally-selective or hemifield directional sensitivity curves. a directionally-selective curve always has a pe ... | 2000 | 10798726 |
| vocal control of acoustic information for sonar discriminations by the echolocating bat, eptesicus fuscus. | this study aimed to determine whether bats using frequency modulated (fm) echolocation signals adapt the features of their vocalizations to the perceptual demands of a particular sonar task. quantitative measures were obtained from the vocal signals produced by echolocating bats (eptesicus fuscus) that were trained to perform in two distinct perceptual tasks, echo delay and doppler-shift discriminations. in both perceptual tasks, the bats learned to discriminate electronically manipulated playba ... | 2000 | 10790052 |
| interdependence of spatial and temporal coding in the auditory midbrain. | to date, most physiological studies that investigated binaural auditory processing have addressed the topic rather exclusively in the context of sound localization. however, there is strong psychophysical evidence that binaural processing serves more than only sound localization. this raises the question of how binaural processing of spatial cues interacts with cues important for feature detection. the temporal structure of a sound is one such feature important for sound recognition. as a first ... | 2000 | 10758135 |
| reorganization of the frequency map of the auditory cortex evoked by cortical electrical stimulation in the big brown bat. | in a search phase of echolocation, big brown bats, eptesicus fuscus, emit biosonar pulses at a rate of 10/s and listen to echoes. when a short acoustic stimulus was repetitively delivered at this rate, the reorganization of the frequency map of the primary auditory cortex took place at and around the neurons tuned to the frequency of the acoustic stimulus. such reorganization became larger when the acoustic stimulus was paired with electrical stimulation of the cortical neurons tuned to the freq ... | 2000 | 10758097 |
| neural responses to overlapping fm sounds in the inferior colliculus of echolocating bats. | the big brown bat, eptesicus fuscus, navigates and hunts prey with echolocation, a modality that uses the temporal and spectral differences between vocalizations and echoes from objects to build spatial images. closely spaced surfaces ("glints") return overlapping echoes if two echoes return within the integration time of the cochlea ( approximately 300-400 micros). the overlap results in spectral interference that provides information about target structure or texture. previous studies have sho ... | 2000 | 10758096 |
| spectral cues and perception of the vertical position of targets by the big brown bat, eptesicus fuscus. | big brown bats (eptesicus fuscus) were trained to discriminate between vertical angles subtended by paired beads suspended from fishing line. bats were rewarded for choosing the smaller of the two angles presented. the difference between the angles was changed systematically using a transformed up-down procedure and the bats' ability to detect the difference was measured at different vertical locations. when the beads were centered at +20 degrees (above the horizon), at 0 degree (the horizon), a ... | 2000 | 10687712 |
| range discrimination by big brown bats (eptesicus fuscus) using altered model echoes: implications for signal processing. | the sonar emissions of two big brown bats (eptesicus fuscus) were modeled to create a "normal" echolocation signal for each bat which was then used as an artificial echo to synthesize a phantom target. the bat's task was to indicate which of two phantom targets (presented singly) was the "near" target and which the "far" target. threshold range discrimination at a nominal target distance of 80 cm was about 0.6 cm for both bats. the normal signal was then modified to change the relative energy in ... | 2000 | 10641671 |
| neural measurement of sound duration: control by excitatory-inhibitory interactions in the inferior colliculus. | in the inferior colliculus (ic) of the big brown bat, a subpopulation of cells ( approximately 35%) are tuned to a narrow range of sound durations. band-pass tuning for sound duration has not been seen at lower levels of the auditory pathway. previous work suggests that it arises at the ic through the interaction of sound-evoked, temporally offset, excitatory and inhibitory inputs. to test this hypothesis, we recorded from duration-tuned neurons in the ic and examined duration tuning before and ... | 2000 | 10980020 |
| temporally patterned pulse trains affect duration tuning characteristics of bat inferior collicular neurons. | this study examines the effect of temporally patterned pulse trains on duration tuning characteristics of inferior collicular neurons of the big brown bat. eptesicus fuscus, under free-field stimulation conditions. using a 50% difference between maximal and minimal responses as a criterion, the duration tuning characteristics of inferior collicular neurons determined with pulse trains of different pulse durations are described as band-pass, long-pass, short-pass, and all-pass. each band-pass neu ... | 1999 | 10573869 |
| plasma leptin decreases during lactation in insectivorous bats. | we previously demonstrated high leptin levels during late pregnancy in little brown bats (myotis lucifugus). we now extend these observations to a second species, the big brown bat (eptesicus fuscus), and also report that leptin increases after the first trimester of pregnancy. leptin decreased to baseline 1 week following parturition, with a half-time decay of 2 days. during lactation, leptin was significantly correlated with body mass in e. fuscus, but not in m. lucifugus. no circadian pattern ... | 1999 | 10093906 |
| six new eimeria species from vespertilionid bats of north america. | twenty species of bats (molossidae, vespertilionidae) were collected from california, new mexico, oregon, south carolina, utah, and baja california norte (mexico), and 29 of 404 (7%) animals, including antrozous pallidus, eptesicus fuscus, myotis auriculus, myotis californicus, myotis ciliolabrum, myotis evotis, myotis lucifugus, myotis thysanodes, myotis vivesi, myotis volans, myotis yumanensis, and nycticeius humeralis were infected with eimeria spp., which represent 6 new species. sporulated ... | 1999 | 10386443 |
| apneic oxygen uptake in the torpid pocket mouse perognathus parvus. | the apneas of many torpid mammals can persist longer than estimated o2 stores allow. this suggests that some o2 is acquired during these apneas by either cutaneous uptake or by a nonventilatory flux down an open airway (tracheal flux). previous experiments confirmed apneic o2 uptake in the bat eptesicus fuscus with the conclusion that the uptake most likely occurred by tracheal flux. however, the bat's large cutaneous wing area remained a potential source of cutaneous o2 uptake, leaving uncertai ... | 1998 | 9798250 |
| range resolution and the possible use of spectral information in the echolocating bat, eptesicus fuscus. | individuals of the echolocating bat eptesicus fuscus were trained to discriminate simulated two-wave-front targets with internal time delays of 0 to 100 microns between the wave fronts from a one-wave-front target. the ability of bats to discriminate between such targets can be referred to as range resolution. in eptesicus fuscus, this ability is limited to distinct internal time delays (12, 32-40, and 52-100 microns) between the two wave fronts of a double-wave-front target. analysis of the sim ... | 1998 | 2212300 |
| processing of sinusoidally amplitude modulated signals in the nuclei of the lateral lemniscus of the big brown bat, eptesicus fuscus. | changes in amplitude are a characteristic feature of most natural sounds, including the biosonar signals used by bats for echolocation. previous evidence suggests that the nuclei of the lateral lemniscus play an important role in processing timing information that is essential for target range determination in echolocation. neurons that respond to unmodulated tones with a sustained discharge are found in the dorsal nucleus (dnll), intermediate nucleus (inll) and multipolar cell division of the v ... | 1998 | 9872145 |
| gabaergic and glycinergic inhibition sharpens tuning for frequency modulations in the inferior colliculus of the big brown bat. | discrimination of amplitude and frequency modulated sounds is an important task of auditory processing. experiments have shown that tuning of neurons to sinusoidally frequency- and amplitude-modulated (sfm and sam, respectively) sounds becomes successively narrower going from lower to higher auditory brain stem nuclei. in the inferior colliculus (ic), many neurons are sharply tuned to the modulation frequency of sfm sounds. the purpose of this study was to determine whether gabaergic or glyciner ... | 1998 | 9658029 |
| echo spl, training experience, and experimental procedure influence the ranging performance in the big brown bat, eptesicus fuscus. | four eptesicus fuscus were trained in a range discrimination experiment to choose the closer of two phantom targets. echo attenuation was roving between trials returning echoes ranging from -10 db to -50 db spl (sound pressure level) relative to emission spl. discrimination thresholds were determined. after sufficient training, ranging performance was stable and about the same in the range between -20 db and -50 db with range difference thresholds around 300 microseconds. at -10 db, performance ... | 1998 | 9693992 |
| cryptosporidiosis in a bat (eptesicus fuscus). | cryptosporidial infection was diagnosed histologically in the small intestine of a big brown bat (eptesicus fuscus) from oregon. this is the first report of cryptosporidiosis in a bat. | 1998 | 9645870 |
| passive sound-localization ability of the big brown bat (eptesicus fuscus). | the passive sound-localization ability (i.e. minimum audible angle) of the big brown bat, eptesicus fuscus, was determined using a conditioned avoidance procedure in which the animals were trained to discriminate left sounds from right sounds. the mean threshold of three bats for a 100-ms broadband noise burst was 14 degrees, a value that is about average for mammals. a similar threshold of 15 degrees was obtained for one animal when it was retested with one of its own recorded echolocation call ... | 1998 | 9641317 |
| recovery cycles of neurons in the inferior colliculus, the pontine nuclei and the auditory cortex of the big brown bat, eptesicus fuscus. | this study examines the recovery cycles of neurons in the inferior colliculus (ic), the pontine nuclei (pn) and the auditory cortex (ac) of the big brown bat, eptesicus fuscus, using a pair of identical pulses at different interpulse intervals. although the recovery cycle varies among neurons, on average, ac neurons have the longest recovery cycle and pn neurons have the shortest one. the recovery cycle of ic neurons is slightly longer than pn neurons. neurons tend to have longer recovery cycles ... | 1998 | 9629476 |
| gabaergic disinhibition affects responses of bat inferior collicular neurons to temporally patterned sound pulses. | using the big brown bat, eptesicus fuscus, as a model mammalian auditory system, we studied the effect of gabaergic disinhibition by bicuculline on the responses of inferior collicular (ic) neurons to temporally patterned trains of sound pulses delivered at different pulse repetition rates (prrs) under free-field stimulation conditions. all 66 neurons isolated from eight bats either discharged one to two impulses (phasic on responders, n = 41, 62%), three to eight impulses (phasic bursters, n = ... | 1998 | 9582206 |
| the effect of pulse repetition rate, pulse intensity, and bicuculline on the minimum threshold and latency of bat inferior collicular neurons. | this study examines the effect of pulse repetition rate (prr), pulse intensity, and bicuculline on the minimum threshold (mt) and latency of inferior collicular neurons of the big brown bat, eptesicus fuscus, under free-field stimulation conditions. it tests the hypothesis that changes in mt and latency of collicular neurons are co-dependent on prr. the number of impulses in inferior collicular neurons (n = 245) increased either monotonically (25%) or non-monotonically (75%) with pulse intensity ... | 1998 | 9530836 |
| processing of sinusoidally frequency modulated signals in the nuclei of the lateral lemniscus of the big brown bat, eptesicus fuscus. | neurons in the nuclei of the lateral lemniscus (nll) of the big brown bat, eptesicus fuscus, show several distinctive patterns of response to unmodulated tones. previous work suggests that sustained responders are specialized to transmit information about sound level and duration while onset responders transmit precise timing information. the biosonar signals of e. fuscus consist of multiple, downward frequency modulated sweeps that change in slope and repetition rate as the bat approaches a tar ... | 1998 | 9872144 |
| corticofugal regulation of auditory sensitivity in the bat inferior colliculus. | under free-field stimulation conditions, corticofugal regulation of auditory sensitivity of neurons in the central nucleus of the inferior colliculus of the big brown bat, eptesicus fuscus, was studied by blocking activities of auditory cortical neurons with lidocaine or by electrical stimulation in auditory cortical neuron recording sites. the corticocollicular pathway regulated the number of impulses, the auditory spatial response areas and the frequency-tuning curves of inferior colliculus ne ... | 1998 | 9861704 |
| coexistence of fmrfamide-like and lhrh-like immunoreactivity in the terminal nerve and forebrain of the big brown bat, eptesicus fuscus. | the coexistence of molluscan cardioexcitatory neuropeptide (fmrfamide) and luteinizing hormone-releasing hormone (lhrh) was studied in the nervous system of the big brown bat, eptesicus fuscus, with immunocytochemistry. within mammals, this is the first report of the coexistence of these neuropeptides in the terminal nerve. in juvenile and adult bats, both neuropeptides are distributed identically throughout the terminal nerve (tn), and they coexist in many parts of the prosencephalon from the o ... | 1998 | 9693160 |
| ontogenetic influences on foraging and mass accumulation by big brown bats (eptesicus fuscus). | juvenile flying animals, including bats, often cease increasing, or even decrease in body mass after the onset of flight. the low body mass of juvenile bats may be a result of stresses associated with the initiation of flight, or may be an adaptation to reduce flight costs. to test these hypotheses, the body masses of adults and unknown aged juvenile big brown bats (eptesicus fuscus) were separately compared in august 1990 through to 1995. it was hypothesized that there should be little variatio ... | 1998 | 26412372 |
| experience-dependent corticofugal adjustment of midbrain frequency map in bat auditory system. | recent studies of corticofugal modulation of auditory information processing indicate that cortical neurons mediate both a highly focused positive feedback to subcortical neurons "matched" in tuning to a particular acoustic parameter and a widespread lateral inhibition to "unmatched" subcortical neurons. this cortical function for the adjustment and improvement of subcortical information processing is called egocentric selection. egocentric selection enhances the neural representation of frequen ... | 1998 | 9770543 |
| echo-delay resolution in sonar images of the big brown bat, eptesicus fuscus. | echolocating big brown bats (eptesicus fuscus) broadcast ultrasonic frequency-modulated (fm) biosonar sounds (20-100 khz frequencies; 10-50 microseconds periods) and perceive target range from echo delay. knowing the acuity for delay resolution is essential to understand how bats process echoes because they perceive target shape and texture from the delay separation of multiple reflections. bats can separately perceive the delays of two concurrent electronically generated echoes arriving as litt ... | 1998 | 9770540 |
| a new genus and species of predaceous mite in the parasitic family macronyssidae (acari: mesostigmata). | coprolactistus whitakeri radovsky & krantz, a new genus and species of macronyssidae, is described in all stases. unlike other macronyssids, all of which are vertebrate parasites, c. whitakeri is predaceous, feeding on other mites in bat guano. its morphology confirms the family assignment, and it has the peculiar macronyssid life cycle in which a regressive, nonfeeding deutonymph follows a normal, feeding protonymph. the chelicerae are typically macronyssid despite the predatory diet. available ... | 1998 | 9701940 |
| corticofugal modulation of the midbrain frequency map in the bat auditory system. | the auditory system, like the visual and somatosensory systems, contains topographic maps in its central neural pathways. these maps can be modified by sensory deprivation, injury and experience in both young and adult animals. such plasticity has been explained by changes in the divergent and convergent projections of the ascending sensory system. another possibility, however, is that plasticity may be mediated by descending corticofugal connections. we have investigated the role of descending ... | 1998 | 10195109 |
| arctiid moths and bat echolocation: broad-band clicks interfere with neural responses to auditory stimuli in the nuclei of the lateral lemniscus of the big brown bat. | clicks emitted by arctiid moths interfere with the ranging ability of echolocating bats. to identify possible neural correlates of this interference, we recorded responses of single units in the nuclei of the lateral lemniscus to combinations of a broad-band click and a test signal (pure tones or frequency-modulated sweeps). in 77% of 87 units tested, clicks interfered with neural responses to the test stimuli. the interference fell into two categories: latency ambiguity and suppression. units s ... | 1998 | 9463919 |
| frequency tuning, latencies, and responses to frequency-modulated sweeps in the inferior colliculus of the echolocating bat, eptesicus fuscus. | neurons in the inferior colliculus (ic) of the awake big brown bat, eptesicus fuscus, were examined for joint frequency and latency response properties which could register the timing of the bat's frequency-modulated (fm) biosonar echoes. best frequencies (bfs) range from 10 khz to 100 khz with 50% tuning widths mostly from 1 khz to 8 khz. neurons respond with one discharge per 2-ms tone burst or fm stimulus at a characteristic latency in the range of 3-45 ms, with latency variability (sd) of 50 ... | 1998 | 9447715 |
| detection of jitter in intertarget spacing by the big brown bat eptesicus fuscus. | we trained bats to detect intertarget jitter, i.e., relative motion between two virtual (electronically synthesized) targets. both targets were themselves moving with respect to nearby objects (e.g., the microphone and speaker used to create the virtual targets) so that the only reliable cue available to the bats was variation in intertarget spacing. given a target at 80 cm and another at 95, 110 or 125 cm, the threshold for intertarget jitter (itj) of the two bats tested was < 10 microseconds, ... | 1997 | 9309868 |
| binaural and frequency representation in the primary auditory cortex of the big brown bat, eptesicus fuscus. | this study examines the binaural and frequency representation in the primary auditory cortex (ac) of the big brown bat, eptesicus fuscus, by using an ear-phone stimulation system. all 306 cortical neurons studied were excited by contralateral sound stimulation but they were either excited, inhibited or not affected by ipsilateral sound stimulation. these cortical neurons were columnarly organized according to their binaural and frequency-tuning properties. the excitation-excitation columns which ... | 1997 | 9449819 |
| a backpropagation network model of the monaural localization information available in the bat echolocation system. | the information echolocating bats receive is a combination of the properties of the sound they emit and the sound they receive at the eardrum. convolving the emission and the external ear transfer functions produces the full spectral information contained in the echolocation combination. spatially dependent changes in the magnitude spectra of the emission, external ear transfer functions, and the echolocation combination of eptesicus fuscus could provide localization information to the bat. prin ... | 1997 | 9165742 |
| neural tuning to sound duration in the inferior colliculus of the big brown bat, eptesicus fuscus. | neural tuning to different sound durations may be a useful filter for identification of certain sounds, especially those that are biologically important. the auditory midbrains of mammals and amphibians contain neurons that appear to be tuned to sound duration. in amphibians, neurons are tuned to durations of sound that are biologically important. the purpose of this study was to characterize responses of neurons in the inferior colliculus (ic) of the big brown bat, eptesicus fuscus, to sounds o ... | 1997 | 9163363 |
| neural selectivity and tuning for sinusoidal frequency modulations in the inferior colliculus of the big brown bat, eptesicus fuscus. | most communication sounds and most echolocation sounds, including those used by the big brown bat (eptesicus fuscus), contain frequency-modulated (fm) components, including cyclical fm. because previous studies have shown that some neurons in the inferior colliculus (ic) of this bat respond to linear fm sweeps but not to pure tones or noise, we asked whether these or other neurons are specialized for conveying information about cyclical fm signals. in unanesthetized bats, we tested the response ... | 1997 | 9084622 |
| audiogram of the big brown bat (eptesicus fuscus). | the audiograms of three big brown bats (eptesicus fuscus) were determined using a conditioned avoidance procedure. the average audiogram ranged from 0.850 khz at 106 db to 120 khz at 83 db spl, with a best threshold of 7 db at 20 khz and a distinct decrease in sensitivity at 45 khz. the results confirm those of a previous study by dalland (1965a) that the big brown bat has good high-frequency hearing coupled with poor low-frequency hearing. comparative analysis suggests that the bat's good high- ... | 1997 | 9083817 |
| the combination of echolocation emission and ear reception enhances directional spectral cues of the big brown bat, eptesicus fuscus. | the acoustic information used by bats is produced by a combination of the properties of the sound emission and the reception at the eardrum. the potential localization cues used by bats can only be fully revealed when the magnitude spectra of the emission and the external ear are convolved to produce the echolocation combination magnitude spectra. the spatially dependent changes in the magnitude spectra of the echolocation combination of eptesicus fuscus are described. the emission and external ... | 1997 | 9069638 |
| cytoarchitecture and sound activated responses in the auditory cortex of the big brown bat, eptesicus fuscus. | under free field and closed-system stimulation conditions, we studied the frequency threshold curves, auditory spatial sensitivity and binaurality of neurons in the primary auditory cortex (ac) of the big brown bat, eptesicus fuscus. all 298 recorded ac neurons discharged phasically. they were recorded at depths less than 1,000 microns with response latencies of 7-25 ms, best frequencies (bfs) of 28-97 khz and minimum thresholds (mts) of 8-90 db spl. they received excitatory inputs from the cont ... | 1997 | 9442846 |
| the echolocation calls of the spotted bat euderma maculatum are relatively inaudible to moths | previous studies of the spotted bat euderma maculatum have demonstrated that this bat emits echolocation calls that are lower in frequency, shorter in duration and fainter in intensity compared with those of most other insectivorous bats, acoustic characteristics which should render it less conspicuous to eared moths. we tested this prediction by monitoring electrophysiologically the ears of sympatric noctuoid (noctuid, arctiid and notodontid) moths in a site in western canada. auditory threshol ... | 1997 | 9317482 |