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the echolocation calls of the spotted bat euderma maculatum are relatively inaudible to mothsprevious 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 ...19979317482
organization of forelimb motoneuron pools in two bat species (eptesicus fuscus and myotis lucifugus).the present investigation provides further evidence of the conservation of motor nuclei in amniotes. the position of six forelimb and shoulder motor pools were mapped in two species of bat, eptesicus fuscus and myotis lucifugus. the intraspinal locations of motor pools were revealed by labeling with the retrograde neuronal tracer wga-hrp injected into the bellies of six muscles: m. pectoralis, m. spinodeltoideus, mm. triceps brachii (long and lateral heads), m. infraspinatus, m. supraspinatus, a ...19979311421
responses of bat inferior collicular neurons to recorded echolocation pulse trains.under free field stimulation conditions, we studied the responses of inferior collicular neurons of the big brown bat, eptesicus fuscus, to echolocation pulse trains which were recorded during the entire process of hunting. the entire series of recorded echolocation pulse trains was edited in different sequences according to echolocation pulses of different hunting phases. when stimulated with all edited sequences of echolocation pulse trains, the temporal characteristics and the relative positi ...19979170550
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, ...19979309868
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 ...19979449819
temporal integration in the echolocating bat, megaderma lyra.temporal integration is a crucial feature of auditory temporal processing. we measured the psychophysical temporal integration of acoustic intensity in the echolocating bat megaderma lyra using a two-alternative forced-choice procedure. a measuring paradigm was chosen in which the absolute threshold for pairs of short tone pips was determined as a function of the temporal separation between the pips. the time constants determined with this paradigm are a crucial characteristic of the sonar syste ...19968951448
the degradation of distance discrimination in big brown bats (eptesicus fuscus) caused by different interference signals.the ability of two big brown bats (eptesicus fuscus) to discriminate the distance to an electronically synthesized "phantom" target by echolocation was tested in the presence of interfering signals presented slightly before the target echo. interfering signals were chosen to have differing degrees of similarity to the typical echolocation emission used by the bat in this task (which was the signal used to create the phantom target), and we predicted that the degree of disruption of ranging would ...19968888581
temporally patterned pulse trains affect directional sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus.the directional sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus, was studied under free field stimulation conditions with 3 temporally patterned trains of sound pulses which differed in pulse repetition rate and duration. the directional sensitivity curves of 92 neurons studied can be described as hemifield, directionally-selective, or non-directional according to the variation in the number of impulses with pulse train direction. when these neurons were stimula ...19968785008
representation of perceptual dimensions of insect prey during terminal pursuit by echolocating bats.the echolocating big brown bat, eptesicus fuscus, broadcasts brief frequency-modulated (fm) ultrasonic sounds and perceives objects from echoes of these sounds returning to its ears. eptesicus is an insectivorous species that uses sonar to locate and track flying prey. although the bat normally hunts in open areas, it nevertheless is capable of chasing insects into cluttered environments such as vegetation, where it completes interceptions in much the same manner as in the open except that it ha ...19968776847
corticofugal control of central auditory sensitivity in the big brown bat, eptesicus fuscus.using bats as a model auditory system, we studied corticofugal control of auditory sensitivity of neurons in the inferior colliculus. we demonstrate for the first time that the corticocollicular pathway continuously regulates acoustic signal processing in the inferior colliculus by increasing the threshold, reducing the auditory spatial response area, and sharpening the frequency tuning curve of recorded inferior collicular neurons. regulation of auditory sensitivity of recorded inferior collicu ...19968832656
effects of gonadal sex steroids on sexual behavior in the big brown bat, eptesicus fuscus, upon arousal from hibernation.vespertilionid bats are thought to have a dissociated pattern of reproduction; mating occurs in autumn as well as during periodic arousals from hibernation when testes are regressed and ovaries are "in stasis." sex steroid levels in both sexes are basal at this time. this pattern would indicate that sex steroids per se may not be activating sexual behavior. gonadectomy of male and female big brown bats, eptesicus fuscus, months before the mating season, did not significantly affect the probabili ...19968797024
distribution of gabaa, gabab, and glycine receptors in the central auditory system of the big brown bat, eptesicus fuscus.quantitative autoradiographic techniques were used to compare the distribution of gabaa, gabab, and glycine receptors in the subcortical auditory pathway of the big brown bat, eptesicus fuscus. for gabaa receptors, the ligand used was 35s-t-butylbicyclophosphorothionate (tbps) for gabab receptors, 3h-gaba was used as a ligand in the presence of isoguvacine to block binding to gabaa sites; for glycine, the ligand used was 3h-strychnine. in the subcortical auditory nuclei there appears to be at le ...19968723704
whole-cell patch-clamp recording reveals subthreshold sound-evoked postsynaptic currents in the inferior colliculus of awake bats.the inferior colliculus receives excitatory and inhibitory input from parallel auditory pathways that differ in discharge patterns, latencies, and binaural properties. processing in the inferior colliculus may depend on the temporal sequence in which excitatory and inhibitory synaptic inputs are activated and on the resulting balance between excitation and inhibition. to explore this issue at the cellular level, we used the novel approach of whole-cell patch-clamp recording in the midbrain of aw ...19968622130
integration time for short broad band clicks in echolocating fm-bats (eptesicus fuscus).vespertilionid fm-bats (four eptesicus fuscus and one vespertilio murinus) were trained in an electronic phantom target simulator to detect synthetic echoes consisting of either one or two clicks. the threshold sound pressure for single clicks was around 47 db pespl for all five bats corresponding to a threshold energy of -95 db re 1 pa2*s. by varying the interclick interval, delta t, for double clicks it was shown that the threshold intensity was around -3 db relative to the threshold for singl ...19968592305
spatial tuning of neurons in the inferior colliculus of the big brown bat: effects of sound level, stimulus type and multiple sound sources.we examined factors that affect spatial receptive fields of single units in the central nucleus of the inferior colliculus of eptesicus fuscus. pure tones, frequency- or amplitude-modulated sounds, or noise bursts were presented in the free-field, and responses were recorded extracellularly. for 58 neurons that were tested over a 30 db range of sound levels, 7 (12%) exhibited a change of less than 10 degrees in the center point and medical border of their receptive field. for 28 neurons that wer ...19968965261
responses of bat inferior collicular and auditory cortical neurons to pulsatile amplitude modulated sound pulses.under free field stimulation conditions, this study examined the responses of inferior collicular and cortical neurons of the big brown bat, eptesicus fuscus, to pulsatile amplitude modulated sound pulses by means of temporally patterned pulse trains. when the pulse trains were delivered at different pulse repetition rates between 1 and 100 pps, inferior collicular neurons can follow pulse repetition at a higher rate than can auditory cortical neurons. 85% of 40 inferior collicular neurons studi ...19968955563
sound source elevation and external ear cues influence the discrimination of spectral notches by the big brown bat, eptesicus fuscus.measurements of external ear transfer functions in the echolocating bat eptesicus fuscus have revealed a prominent spectral notch that decreases in center frequency (50 to 30-35 khz) as elevation decreases [wotton et al., j. acoust. soc. am. 98, 1423-1445 (1995)]. to examine the influence of this notch, four eptesicus were trained to discriminate between two sets of electronically generated artificial echoes. the negative (unrewarded) stimulus contained a test spectral notch at a specific freque ...19968817902
origin of ascending projections to the nuclei of the lateral lemniscus in the big brown bat, eptesicus fuscus.the nuclei of the lateral lemniscus in the echolocating bat, eptesicus fuscus, are large and highly differentiated. in each nucleus, different characteristic response properties predominate. to determine whether the dissimilar response properties are due in part to differential ascending input, we examined the retrograde transport from small deposits of horseradish peroxidase (hrp) or hrp conjugated with wheat germ agglutinin (wga-hrp) in the nuclei of the lateral lemniscus. the intermediate nuc ...19957545702
spatially dependent acoustic cues generated by the external ear of the big brown bat, eptesicus fuscus.to measure the directionality of the external ear of the echolocating bat, eptesicus fuscus, the left or right eardrum of a dead bat was replaced by a microphone which recorded signals received from a sound source that was moved around the stationary head. the test signal was a 0.5-ms fm sweep from 100 khz to 10 khz (covering all frequencies in the bat's biosonar sounds). notches and peaks in transfer functions for 7 tested ears varied systematically with changes in elevation. for the most promi ...19957560511
responses of pontine neurons of the big brown bat, eptesicus fuscus, to temporally patterned sound pulses.under free field stimulation conditions, this study examined the responses of pontine neurons of eptesicus fucus to temporally patterned sound pulses by means of repetitive single pulses and pulse trains. among 93 pontine neurons isolated, 90 always discharged less than 5 impulses to sound pulses presented during this study and 3 discharged impulses throughout the whole duration of each presented pulse. responses to sound pulses at different repetition rates were examined in 65 neurons. the numb ...19957559171
steering by echolocation: a paradigm of ecological acoustics.1. flights of three big brown bats (eptesicus fuscus) landing on a hand and catching a suspended mealworm were video analysed. 2. results were consistent with the bats using the same basic control procedure in the quite different approach tasks--namely keeping tau (r) = kr and tau (a)/tau (r) = k alpha r. here r is the current distance to the destination; alpha is the angle between the current direction of the destination and the goal direction of final approach (beta min); tau (r) = r/r, tau (a ...19957707270
the haemoproteid parasite, bioccala deanei, from a colombian bat, eptesicus fuscus (vespertilionidae). 19957741601
delay-tuned neurons in the midbrain of the big brown bat.1. the auditory midbrain in eptesicus contains delay-tuned neurons that encode target range. most delay-tuned neurons respond poorly to tones or individual frequency-modulated (fm) sweeps and require combinations of fm sweeps. they are combination sensitive and delay tuned. the index of facilitation (if), a coefficient measuring combination sensitivity for individual delay-tuned neurons, ranged from 0.14 to 1.0, with an average of 0.64 +/- 0.24 (mean +/- sd). of the 33 facilitated responses from ...19957608757
fos-like immunoreactivity elicited by sound stimulation in the auditory neurons of the big brown bat eptesicus fuscus.c-fos immunocytochemistry was used as a rapid and sensitive technique for identification of sound activated neurons in the cerebral cortex, the cerebellum and subcortical nuclei of the big brown bat, eptesicus fuscus. when bats were stimulated with sounds under the both-ears opened conditions, fos-like immunoreactive neurons were bilaterally and symmetrically distributed in all subcortical auditory nuclei, the auditory cortex, the superior colliculus, the pontine nuclei and the cerebellar deep n ...19947895036
echo spl influences the ranging performance of the big brown bat, eptesicus fuscus.four bats of the species eptesicus fuscus were trained in a two-alternative forced-choice procedure to discriminate between two phantom targets that differed in range. the rewarded stimulus was located at a distance of 52.7 cm, while the other unrewarded stimulus was further away. only one target was presented at a time. in the first experiment we measured the range discrimination performance at an echo spl of -28 db relative to the bat's sonar transmission. a 75% correct performance level was a ...19947965921
observations on the pineal gland of the big brown bat, eptesicus fucus: possible correlation of melanin intensification with constant darkness.our initial observation of the macroscopically pigmented pineal gland of the big brown bat, eptesicus fuscus, led to this study. information has been lacking on pigmentation in the pineal and its significance in mammals in general and bats in particular. this report begins to address this situation.19947825733
sensorimotor model of bat echolocation and prey capture.a model of the bat sensorimotor system is developed using acoustics, signal processing, and control theory to illustrate the fundamental issues in accomplishing prey capture with echolocation. this model indicates that successful nonpredictive tracking of an ideal prey can be accomplished with a very simple system. circular apertures approximate the mouth and ears for deriving acoustic beam patterns, using the big brown bat eptesicus fuscus as a model. fundamental and overtone frequency componen ...19947963018
jamming bat echolocation: the dogbane tiger moth cycnia tenera times its clicks to the terminal attack calls of the big brown bat eptesicus fuscus.certain tiger moths emit high-frequency clicks to an attacking bat, causing it to break off its pursuit. the sounds may either orient the bat by providing it with information that it uses to make an attack decision (aposematism) or they may disorient the bat by interrupting the normal flow of echo information required to complete a successful capture (startle, jamming). at what point during a bat's attack does an arctiid emit its clicks? if the sounds are aposematic, the moth should emit them ea ...19947964403
responses of inferior collicular neurons of the fm bat, eptesicus fuscus, to pulse trains with varied pulse amplitudes.under free field stimulation conditions, we studied the responses of inferior collicular neurons of the fm bat, eptesicus fuscus, to pulse trains with varied pulse amplitudes. each pulse train consisted of 7 pulses of 4 ms delivered at 24 ms interpulse-intervals (i.e. 42 pulses/s). for a control pulse train, all pulse amplitudes were equal to a neuron's best amplitude which, when delivered in single pulses, elicited maximal number of impulses from the neuron. the amplitudes of individual pulses ...19947806473
pulse repetition rate increases the minimum threshold and latency of auditory neurons.the effect of pulse repetition rate on auditory sensitivity of the big brown bat, eptesicus fuscus, was studied by determining the minimum threshold, response latency and recovery cycle of inferior collicular neurons at different repetition rates under free field stimulation conditions. in general, collicular neurons shortened the response latency and increased the number of impulses monotonically or non-monotonically with stimulus intensity. they recovered at least 50% when the interpulse inter ...19947982089
the brain-stem auditory-evoked response in the big brown bat (eptesicus fuscus) to clicks and frequency-modulated sweeps.three experiments were performed to evaluate the effects of stimulus level on the brain-stem auditory-evoked response (baer) in the big brown bat (eptesicus fuscus), a species that uses frequency-modulated (fm) sonar sounds for echolocation. in experiment 1, the effects of click level on the baer were investigated. clicks were presented at levels of 30 to 90 db pspl in 10-db steps. each animal responded reliably to clicks at levels of 50 db pspl and above, showing a baer containing four peaks in ...19947930082
synonymy of longibucca eptesica with longibucca lasiura (nematoda: rhabditoidea) and new host and geographic records.the genus longibucca chitwood, 1933 (nematoda: rhabditoidea) is reviewed based on examination of museum and adult specimens collected from 4 species of bats (myotis lucifugus, myotis ciliolabrum, eptesicus fuscus, and lasionycteris noctivagans) in alberta, canada. two species are considered valid, namely longibucca vivipara chitwood, 1933, and longibucca lasiura mcintosh and chitwood, 1934. longibucca eptesica elsea, 1953 is considered a synonym of l. lasiura. new hosts of longibucca lasiura inc ...19948195954
frequency tuning and response latencies at three levels in the brainstem of the echolocating bat, eptesicus fuscus.to determine the level at which certain response characteristics originate, we compared monaural auditory responses of neurons in ventral cochlear nucleus, nuclei of lateral lemniscus and inferior colliculus. characteristics examined were sharpness of frequency tuning, latency variability for individual neurons and range of latencies across neurons. exceptionally broad tuning curves were found in the nuclei of the lateral lemniscus, while exceptionally narrow tuning curves were found in the infe ...19948014918
neural tuning for sound duration: role of inhibitory mechanisms in the inferior colliculus.duration is a biologically important feature of sound. some neurons in the inferior colliculus of the big brown bat, eptesicus fuscus, are tuned to sound duration, but it is unclear at what level the tuning originates or what neural mechanisms are responsible for it. the application of antagonists of the inhibitory neurotransmitters gamma-aminobutyric acid or glycine to neurons in the inferior colliculus eliminated duration tuning. whole-cell patch-clamp recordings of synaptic currents suggested ...19948171341
complex sound analysis in the fm bat eptesicus fuscus, correlated with structural parameters of frequency modulated signals.big brown bats, eptesicus fuscus, were presented with artificial frequency modulated (fm) echoes that simulated an object becoming progressively closer to the bat. a stereotyped approach phase behavioral response of the bat to the virtual approaching target was used to determine the ability of the bat to analyze fm signals for target distance information. the degree to which the bats responded with approach phase behavior to a virtual approaching target was similar when they were presented with ...19948006857
the epidemiology of bat rabies in new york state, 1988-92.in 1993 new york and texas each reported a human rabies case traced to a rare variant of rabies virus found in an uncommon species of bat. this study examined the epidemiology of bat rabies in new york state. demographic, species, and animal-contact information for bats submitted for rabies testing from 1988-92 was analysed. the prevalence of rabies in 6810 bats was 4.6%. nearly 90% of the 308 rabid bats identified to species were the common big brown bat (eptesicus fuscus), which comprised 62% ...19947995360
capillary-fiber geometry in pectoralis muscles of one of the smallest bats.we previously reported striking similarities in the structural capacity for o2 flux in the highly aerobic flight muscles of a hummingbird and bat despite their significant differences in capillary-fiber geometry and number, and fiber size. however, the bats of that study (eptesicus fuscus, bw 15-16 g) were about 5 times larger than the hummingbirds (selasphorus rufus; bw 3-4 g). in this study, we examined the flight muscle in a bat of approximately the same size as the hummingbird to determine w ...19948191038
tonotopic and functional organization in the auditory cortex of the big brown bat, eptesicus fuscus.1. in eptesicus the auditory cortex, as defined by electrical activity recorded from microelectrodes in response to tone bursts, fm sweeps, and combinations of fm sweeps, encompasses an average cortical surface area of 5.7 mm2. this area is large with respect to the total cortical surface area and reflects the importance of auditory processing to this species of bat. 2. the predominant pattern of organization in response to tone bursts observed in each cortex is tonotopic, with three discernible ...19938294966
calcium-binding protein-containing neuronal populations in mammalian visual cortex: a comparative study in whales, insectivores, bats, rodents, and primates.this study is focused on comparative analysis of gamma-aminobutyric acid-positive (gabaergic) neuronal populations in primary visual cortex of totally aquatic toothed whales and select terrestrial mammals with different evolutionary histories and various ecological adaptations. the distribution of neuronal populations containing the calcium-binding proteins calbindin and parvalbumin, which are recognized markers for the gabaergic neurons in cerebral cortex, is compared in five species of toothed ...19938324371
a computational model of echo processing and acoustic imaging in frequency-modulated echolocating bats: the spectrogram correlation and transformation receiver.the spectrogram correlation and transformation (scat) model of the sonar receiver in the big brown bat (eptesicus fuscus) consists of a cochlear component for encoding the bat's frequency modulated (fm) sonar transmissions and multiple fm echoes in a spectrogram format, followed by two parallel pathways for processing temporal and spectral information in sonar echoes to reconstruct the absolute range and fine range structure of multiple targets from echo spectrograms. the outputs of computations ...19938270744
neurons in the inferior colliculus, auditory cortex and pontine nuclei of the fm bat, eptesicus fucus respond to pulse repetition rate differently.single-neuron responses to pulse repetition rate in the inferior colliculus, auditory cortex and pontine nuclei of the fm bat, eptesicus fuscus were studied under free-field stimulation conditions. the best frequency (bf) and minimum threshold (mt) of each neuron were first determined with a 4 ms pulse broadcast from a specific point (response center) of the bat's frontal auditory space at which the neuron had maximal spatial sensitivity. the neuron's intensity-rate function was then studied wit ...19938348298
evidence for perception of fine echo delay and phase by the fm bat, eptesicus fuscus.the big brown bat, eptesicus fuscus, can perceive small changes in the delay of fm sonar echoes and shifts in echo phase, which interact with delay. using spectral cues caused by interference, eptesicus also can perceive the individual delays of two overlapping fm echoes at small delay separations. these results have been criticized as due to spectral artifacts caused by overlap between stimulus echoes and extraneous sounds (pollak 1993). however, no amplitude or spectral variations larger than ...19938331604
discrimination of two-wavefront echoes by the big brown bat, eptesicus fuscus: behavioral experiments and receiver simulations.1. echolocating bats (eptesicus fuscus) were trained to discriminate between simulated targets consisting of one or two echo-wavefronts with internal time delays of up to 100 microseconds. spectral and temporal properties and total signal energy of the targets were evaluated and predictions for performances of bats derived from receiver models were compared with measured performances. 2. eptesicus fuscus was able to discriminate a one-wavefront target from two-wavefront targets with distinct int ...19938510056
acoustic image representation of a point target in the bat eptesicus fuscus: evidence for sensitivity to echo phase in bat sonar.echolocating bats, eptesicus fuscus, were trained in two distinct behavioral tasks to investigate the images they perceive of a sonar point target. in the first task, bats were trained in a two-alternative forced-choice procedure to detect electronically simulated target echoes at a range of approximately 57 cm. half of the trials in the detection task contained echoes from a stationary target (simulated by a fixed echo delay) and half contained echoes from a jittering target (simulated by an ec ...19938473609
response properties of single units in the dorsal nucleus of the lateral lemniscus and paralemniscal zone of an echolocating bat.1. connectional evidence suggests that the dorsal nucleus of the lateral lemniscus (dnll) and the paralemniscal zone (pl) function as centers for binaural analysis interposed between the superior olivary complex and the midbrain. in addition, the dnll is known to be a major source of inhibitory input to the midbrain. the aim of this study was to characterize the response properties of neurons in dnll and pl of the echolocating bat eptesicus fuscus, a species that utilizes high-frequency hearing ...19938463819
directional sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus, to sounds delivered from selected horizontal and vertical angles.under free field stimulation conditions, directional sensitivity of 336 inferior collicular (ic) neurons of 6 eptesicus fuscus was studied by recording the minimum threshold (mt) and number of impulses of each neuron to a best frequency (bf) sound delivered from selected horizontal and vertical angles. an auditory response center was determined for each neuron by delivering a bf sound from a specific point of the bat's frontal auditory space. at the response center, the neuron had maximal direct ...19938275800
responses of superior collicular neurons of the big brown bat, eptesicus fuscus, to stationary and moving sounds.responses of 59 superior collicular neurons (sc) of the big brown bat, eptesicus fuscus, to stationary and moving sounds were studied under free-field stimulation conditions. neurons responding to sound stimulation were recorded from all three layers of the sc; however, responses of neurons in the superficial and upper intermediate layers generally show poor signal to noise ratio. spatial sensitivity of each sc neuron was studied by determining variation of the number of impulses and minimum thr ...19938020338
a possible neuronal basis for representation of acoustic scenes in auditory cortex of the big brown bat.behavioural studies and field observations demonstrate that echolocating bats simultaneously perceive range, direction and shape of multiple objects in the environment as acoustic images derived from echoes. cortical echo delay-tuned neurons contribute to the perception of object range, because focal inactivation of these neurons disrupts behavioural discrimination of range. we report here that response properties of delay-tuned neurons in the cortical tonotopic area of the bat, eptesicus, trans ...19938350920
auditory response properties and spatial response areas of single neurons in the pontine nuclei of the big brown bat, eptesicus fuscus.using free-field acoustic stimulation conditions, we studied the response properties and spatial sensitivity of 146 pontine neurons of the big brown bat, eptesicus fuscus. the best frequency (bf) and minimum threshold (mt) of a pontine neuron were first determined with a sound broadcast from a loudspeaker placed ahead of the bat. a bf sound was delivered from the loudspeaker as it moved across the frontal auditory space in order to locate the response center at which the neuron had its lowest mt ...19921571779
sonar gain control and echo detection thresholds in the echolocating bat, eptesicus fuscus.the echolocating bat, eptesicus fuscus, detects sonar echoes with a sensitivity that changes according to the time elapsed between broadcasting of each sonar signal and reception of echoes. when tested in an electronic target simulator on a two-choice echo-detection task, the bat's threshold improved by 11.5 db as echo delay changed from 2.3 to 4.6 ms (target ranges of 40 and 80 cm). earlier experiments measured the change in detection threshold for delays from 1 to 6.4 ms (target ranges from ab ...19921556314
stabilization of perceived echo amplitudes in echolocating bats. ii. the acoustic behavior of the big brown bat, eptesicus fuscus, when tracking moving prey.big brown bats, eptesicus fuscus, can be trained to use echolocation to track a small microphone with a food reward attached when it is moved rapidly toward them. this situation mimics prey interception in the wild while allowing very precise recording of the sonar pulses emitted during tracking behavior. the results show that e. fuscus intensity compensates, reducing emitted intensity by 6 db per halving of target range so that the intensity incident upon the target is constant and echo intensi ...19921556313
stabilization of perceived echo amplitudes in echolocating bats. i. echo detection and automatic gain control in the big brown bat, eptesicus fuscus, and the fishing bat, noctilio leporinus.previous research on echo detection in bats has suggested that the effective threshold is a function of the acoustic clutter in the experimental environment, as might be expected given the low ambient noise levels typical of such psychophysical research. this paper demonstrates that theory of signal detectability (tsd) methodology is applicable to bats and uses it to show that an important element of clutter limiting in eptesicus fuscus and noctilio leporinus is backward masking of phantom targe ...19921313464
pulse repetition rate and duration affect the responses of bat auditory cortical neurons.under free field stimulation conditions, we studied the effect of pulse repetition rate and duration on the responses of auditory cortical neurons of the big brown bat, eptesicus fuscus. the best frequency (bf) and minimum threshold (mt) of each recorded neuron were first determined with a 4 ms pulse delivered from a specific point of the bat's frontal auditory space at which the neuron had maximal spatial sensitivity. then a 4 ms pulse was delivered repetitively at different rates with an inten ...19921308731
apneic oxygen uptake in the torpid bat, eptesicus fuscus.like many mammalian heterotherms, the big brown bat, eptesicus fuscus, breathes intermittently during torpor. by exploiting this bat's preference to roost in crevices, we could separately measure o2 uptake during ventilatory bouts and apneic periods using a flow-through metabolic chamber with a small dead space volume and short time constant. oxygen uptake was measured during apneas ranging from 10 to 150 min duration at body temperatures of 20, 10 and 5 degrees c. the fraction of total o2 uptak ...19921487714
frequency tuning properties of neurons in the inferior colliculus of an fm bat.we examined frequency tuning characteristics of single neurons in the inferior colliculus of the echolocating bat, eptesicus fuscus, in order to determine whether there are different classes of spectral selectivity at this level and to relate frequency tuning properties to the design of the echolocation signal. in unanesthetized but tranquilized animals, we recorded responses from 363 single units to pure tones, frequency-modulated (fm) sweeps, or broad-band noise. most units were selective for ...19921592904
projections to the medial superior olive from the medial and lateral nuclei of the trapezoid body in rodents and bats.in this study we present direct evidence of axonal projections from both the medial and lateral nuclei of the trapezoid body to the medial superior olive. projections were traced by intracellularly labeling cells and axons in a tissue slice preparation of two rodent species, mus musculus and meriones unguiculatus and two bat species, eptesicus fuscus and pteronotus parnellii. the main axon of most principal cells in the medial nucleus of the trapezoid body gives off one or more collateral branch ...19921430335
rabid bat diagnosed in hawaii.since 1966, the hawaii state government has been conducting fluorescent rabies antibody (fra) testing on animal brains as part of a statewide rabies-surveillance program. on april 3, 1991, the department of health (doh) laboratory diagnosed the first case of rabies detected in the state. a large brown bat, eptesicus fuscus fuscus, captured in a transport container that had just been off-loaded from a ship at honolulu harbor, was caught. it's brain was examined and showed typical fluorescent stai ...19921517074
ectoparasitic mites (acari) of sympatric brazilian free-tailed bats and big brown bats in alabama.seven species of mites were recovered from 133 brazilian free-tailed bats, tadarida brasiliensis, and 94 big brown bats, eptesicus fuscus, from february through november 1990 in colonies that shared roosting space in east-central alabama. the macronyssid chiroptonyssus robustipes (ewing) was the most common mite on t. brasiliensis (964 mites, 87% of bats infested) and on e. fuscus (109 mites, 29% of bats infested). however, c. rubustipes normally is a specific parasite of t. brasiliensis. the ma ...19921625301
immunocytochemical localization of luteinizing hormone-releasing hormone (lhrh) in the nervus terminalis and brain of the big brown bat, eptesicus fuscus.little is known about the immunohistochemistry of the nervous system in bats. this is particularly true of the nervus terminalis, which exerts strong influence on the reproductive system during ontogeny and in the adult. luteinizing hormone-releasing hormone (lhrh) was visualized immunocytochemically in the nervus terminalis and brain of juvenile and adult big brown bats (eptesicus fuscus). the peripheral lhrh-immunoreactive (ir) cells and fibers (nervus terminalis) are dispersed along the basal ...19921740548
the monaural nuclei of the lateral lemniscus in an echolocating bat: parallel pathways for analyzing temporal features of sound.in echolocating bats, three cell groups in the lateral lemniscus are conspicuous for their large size and high degree of differentiation. these cell groups are the intermediate nucleus (inll), columnar nucleus (vnllc), and multipolar cell area (vnllm). all receive projections from the contralateral cochlear nucleus. previous anatomical studies suggest the hypothesis that these nuclei are important for analyzing the temporal structure of sound. to investigate this possibility, we recorded respons ...19911941092
encoding repetition rate and duration in the inferior colliculus of the big brown bat, eptesicus fuscus.1. encoding of temporal stimulus parameters by inferior collicular (ic) neurons of eptesicus fuscus was studied by recording their responses to a wide range of repetition rates (rrs) and durations at several stimulus intensities under free field stimulus conditions. 2. the response properties of 424 ic neurons recorded were similar to those reported in previous studies of this species. 3. ic neurons were classified as low-pass, band-pass, and high-pass according to their preference for rrs and/o ...19911941720
arctiid moth clicks can degrade the accuracy of range difference discrimination in echolocating big brown bats, eptesicus fuscus.four big brown bats (eptesicus fuscus) born and raised in captivity were trained using the yes/no psychophysical method to report whether a virtual sonar target was at a standard distance or not. at threshold bats were able to detect a minimum range difference of 6 mm (a delta t of 36 microseconds). following threshold determinations, a click burst 1.8 ms long containing 5 pulses from the ruby tiger moth, phragmatobia fuliginosa (arctiidae), was presented randomly after each phantom echo. the so ...19911920158
discrimination of wingbeat motion by bats, correlated with echolocation sound pattern.bats of the species rhinolophus rouxi, hipposideros lankadiva and eptesicus fuscus were trained to discriminate between two simultaneously presented artificial insect wingbeat targets moving at different wingbeat rates. during the discrimination trials, r. rouxi, h. lankadiva and e. fuscus emitted long-cf/fm, short-cf/fm and fm echolocation sounds respectively. r. rouxi, h. lankadiva and e. fuscus were able to discriminate a difference in wingbeat rate of 2.7 hz, 9.2 hz and 15.8 hz, respectively ...19912046046
encoding of acoustic stimulus intensity by inferior collicular neurons of the big brown bat, eptesicus fuscus.using bats as a model system, we studied the isointensity and isofrequency discharge rate functions of inferior collicular (ic) neurons under free field stimulation conditions in order to understand how the midbrain auditory neurons encode stimulus intensity. for each encountered ic neuron, the best frequency (bf), minimum threshold (mt), tuning curve and intensity rate function for the bf were first determined. then at a fixed stimulus intensity, the number of impulses was measured for several ...19911959436
directional sensitivity of bat inferior collicular neurons determined under normal and monaurally plugged ear conditions.in an effort to further understand the combined effect of binaural intensity difference and pinna position on the directional sensitivity of an auditory neuron, we used free field stimulation to study the directional sensitivity of inferior collicular (ic) neurons of the big brown bat, eptesicus fuscus, under the following three ear conditions: normal ears, monaurally plugged ear and monaurally plugged plus pinna bending backward. the best frequency (bf) and minimum threshold (mt) of each neuron ...19911820843
nutritional implications for nitrogen and mineral budgets from analysis of guano of the big brown bat eptesicus fuscus (chiroptera: vespertilionidae).1. analysis of nitrogen, sodium, calcium, magnesium, iron, and potassium levels in big brown bat guano throughout much of the summer roosting period was performed. 2. based on the tenet that low, non-variable levels of an element in feces indicate dietary inadequacy for that element, female big brown bats are routinely and severely stressed for calcium and may become stressed for iron by the end of the summer. similar elemental stresses, although not as severe, exist for males.19911685367
discrimination of jittered sonar echoes by the echolocating bat, eptesicus fuscus: the shape of target images in echolocation.1. behavioral experiments with jittering echoes examined acoustic images of sonar targets in the echolocating bat, eptesicus fuscus, along the echo delay or target range axis. echo phase, amplitude, bandwidth, and signal-to-noise ratio were manipulated to assess the underlying auditory processes for image formation. 2. fine delay acuity is about 10 ns. calibration and control procedures indicate that this represents temporal acuity rather than spectral discrimination. jitter discrimination curve ...19902074548
auditory response properties and directional sensitivity of cerebellar neurons of the echolocating bat, eptesicus fuscus.auditory response properties and directional sensitivity of cerebellar neurons of eptesicus fuscus were studied under free-field stimulation conditions. the best frequency (bf) and minimum threshold (mt) of a recorded neuron were first determined with a sound delivered in front of the bat. discharge pattern and mt were studied with both bf stimuli and one-octave downward and upward sweep fm (frequency-modulated) stimuli. the directional sensitivity of cerebellar neurons was then studied by deter ...19902245329
convergence of temporal and spectral information into acoustic images of complex sonar targets perceived by the echolocating bat, eptesicus fuscus.1. fm echolocating bats (eptesicus fuscus) were trained to discriminate between a two-component complex target and a one-component simple target simulated by electronically-returned echoes in a series of experiments that explore the composition of the image of the two-component target. in experiment i, echoes for each target were presented sequentially, and the bats had to compare a stored image of one target with that of the other. the bats made errors when the range of the simple target corres ...19902332837
frequency and space representation in the inferior colliculus of the fm bat, eptesicus fuscus.the tonotopic organization and spatial sensitivity of 217 inferior collicular (ic) neurons of eptesicus fuscus were studied under free field stimulation conditions. acoustic stimuli were delivered from a loudspeaker placed 21 cm ahead of the bat to determine the best frequency (bf) and minimum threshold (mt) of isolated ic neurons. a bf stimulus was then delivered as the loudspeaker was moved horizontally across the frontal auditory space of the bat to locate the best azimuthal angle (baz) at wh ...19902311706
influence of monaural plugging on postnatal development of auditory spatial sensitivity of inferior collicular neurons of the big brown bat, eptesicus fuscus.postnatal development of auditory sensitivity in the big brown bat, eptesicus fuscus, was studied by determining the auditory spatial sensitivity of inferior collicular (ic) neurons of juvenile bats which were raised under normal (control) or monaurally plugged conditions. the auditory spatial sensitivity of each ic neuron was determined by measuring its variation in number of impulses and minimum threshold to a best frequency sound delivered from different azimuthal angles under free field stim ...19902269023
a view of the world through the bat's ear: the formation of acoustic images in echolocation.echolocating bats perceive objects as acoustic images derived from echoes of the ultrasonic sounds they emit. they can detect, track, identify, and intercept flying insects using sonar. many species, such as the big brown bat, eptesicus fuscus, emit frequency-modulated sonar sounds and perceive the distance to targets, or target range, from the delay of echoes. for eptesicus, a point-target's image has a sharpness along the range axis that is determined by the acuity of echo-delay perception, wh ...19892691182
the acoustic basis for target discrimination by fm echolocating bats.past experiments show that echolocating bats of the species myotis lucifugus and eptesicus fuscus can discriminate among airborne sonar targets presented in the context of pursuit maneuvers for the interception of prey. these bats distinguish between edible mealworms and inedible spheres of various sizes. myotis can distinguish between disks and mealworms similar enough in size that the bat's performance requires the ability to perceive the acoustic equivalent of target shape. previously observe ...19892808908
clutter interference and the integration time of echoes in the echolocating bat, eptesicus fuscus.the ability of the echolocating bat, eptesicus fuscus, to detect a sonar target is affected by the presence of other targets along the same axis at slightly different ranges. if echoes from one target arrive at about the same delay as echoes from another target, clutter interference occurs and one set of echoes masks the other. although the bat's sonar emissions and the echoes themselves are 2 to 5 ms long, echoes (of approximately equal sensation levels--around 15 db sl) only interfere with eac ...19892808907
range estimation by echolocation in the bat eptesicus fuscus: trading of phase versus time cues.bats of the species eptesicus fuscus have been trained to discriminate a stationary simulated target from a target with a virtual distance that jitters from sound to sound. similar to simmons [science 207, 1336-1338 (1979)], a jitter-detection threshold below 1 microsecond was found. however, simmons' decreased performance at a time delay jitter of 30 microseconds could not be replicated, a critical feature used to postulate the idea that bats employ a coherent cross-correlation receiver for ran ...19892745884
frequency and space representation in the primary auditory cortex of the frequency modulating bat eptesicus fuscus.1. frequency and space representation in the auditory cortex of the big brown bat, eptesicus fuscus, were studied by recording responses of 223 neurons to acoustic stimuli presented in the bat's frontal auditory space. 2. the majority of the auditory cortical neurons were recorded at a depth of less than 500 microns with a response latency between 8 and 20 ms. they generally discharged phasically and had nonmonotonic intensity-rate functions. the minimum threshold, (mt) of these neurons was betw ...19892585357
nigrotectal projection to the inferior colliculus: horseradish peroxidase transport and tyrosine hydroxylase immunohistochemical studies in rats, cats, and bats.the present study investigated descending projections from the substantia nigra to the auditory tectum. small (0.02-0.05 microliters) injections of a 30-60% aqueous solution of horseradish peroxidase (hrp) were made unilaterally into the inferior colliculus in rats, cats, and bats (eptesicus fuscus). tissue blocks including the substantia nigra, superior colliculus, and inferior colliculus were removed, sectioned, and processed for visualization of hrp. results show that the substantia nigra, pa ...19892565350
bat rabies in illinois: 1965 to 1986.from 1968 to 1986, illinois (usa) citizens and agencies submitted 4,272 bats to the illinois department of public health for rabies testing. of this number, 6% tested positive, a rate comparable to similar studies from other parts of north america. due to sampling biases, the true infection rate among bats in illinois is probably lower than 6%. additional analysis relied on a subsample (n = 2,433) of the specimens collected from 1965 to 1986. prevalences were significantly different among years, ...19892915390
eimeria from bats of the world. ii. a new species in tadarida femorosacca from sonora, mexico.between 1979 and 1980, 104 bats representing 13 species in 4 families were collected in california and new mexico, u.s.a., and baja california and sonora, mexico, and were examined for coccidia; only 3 (3%) had oocysts in their feces. bats examined and their infection rates were: molossidae: 0 of 12 tadarida brasiliensis, 1 of 18 (6%) t. femorosacca; natalidae: 0 of 1 natalus stramineus; phyllostomatidae: 0 of 1 choeronycteris mexicana, 0 of 2 leptonycteris sanborni, 0 of 1 macrotus californicus ...19883357122
pathogenesis of rabies virus from a danish bat (eptesicus serotinus): neuronal changes suggestive of spongiosis.rabies virus strains isolated from a european bat (eptesicus serotinus) in denmark (dbv), a north american big brown bat (eptesicus fuscus) in new york state (ny-bat), and a human in south africa (duvenhage strain (duv-1) were studied by using a panel of monoclonal antibodies and by inoculating mice, cats, and dogs. the ten danish virus isolates from the same bat species reacted identically with a panel of monoclonal antibodies. immunofluorescence, monoclonal antibody, and histopathologic studie ...19883369944
bat rabies in british columbia 1971-1985.rabies virus was demonstrated in 99 of 1154 bats submitted from british columbia between 1971 and 1985. rabies was diagnosed in seven species including big brown bats (eptesicus fuscus), the latter accounting for 51% of all positive cases. colonial species represented 92.9% of all identified bats and 87.7% of all rabid cases. most bats were submitted from the more densely populated areas of the province, and submissions and positive cases both peaked in the month of august. daytime activity and ...198817422945
clutter interference along the target range axis in the echolocating bat, eptesicus fuscus.the sensitivity of the echolocating bat, eptesicus fuscus, for detection of a sonar target is impaired by the presence of additional targets located at similar distances. at a range of 54 cm, sensitivity to one target declines if the range separation to other targets is smaller than 8-9 cm. this loss of sensitivity is an example of clutter interference along the range axis, created by simultaneous masking of one set of echoes by another. echoes that fall within an experimentally defined critical ...19883170946
intracellular labeling of afferents to the lateral superior olive in the bat, eptesicus fuscus.an in vitro tissue slice preparation of the bat brain stem was used to label intracellularly individual axons projecting to the lateral superior olive from two different sources: the medial nucleus of the trapezoid body (mntb) and the anteroventral cochlear nucleus (avcn). the tracing of individually labeled mntb axons into the lateral superior olive reaffirms the long accepted indirect route by which information from the contralateral ear reaches the lateral superior olive. while the mntb appea ...19883170356
auditory space representation in the inferior colliculus of the fm bat, eptesicus fuscus.the auditory spatial response areas of 333 inferior collicular (ic) neurons of eptesicus fuscus were studied under free-field acoustic stimulus conditions. a stimulus was delivered from a loudspeaker placed 14 cm in front of a bat and the best frequency of an encountered neuron was determined. then a best frequency (bf) stimulus was delivered as the loudspeaker was moved across the frontal auditory space to determine the response center of the neuron. at the response center, the neuron had the l ...19873676742
auditory spatial response areas of single neurons and space representation in the cerebellum of echo locating bats.using free-field acoustic stimulation conditions, we studied the auditory spatial response areas of 242 cerebellar neurons of eptesicus fuscus. a best frequency stimulus was delivered from a loudspeaker which was moved across the frontal auditory space in order to determine the response center of each cerebellar neuron. at the response center, the neuron had its lowest minimum threshold. the stimulus was then raised 5-15 db above the lowest minimum threshold of each neuron and the spatial respon ...19873620934
pinna position affects the auditory space representation in the inferior colliculus of the fm bat, eptesicus fuscus.using free-field acoustic stimulus conditions, we studied the auditory space representation in the inferior colliculus (ic) of the big brown bat, eptesicus fuscus, under different pinna positions. stimuli were delivered from a loudspeaker placed 14 cm in front of the bat to determine the best frequency (bf) of an isolated neuron. a bf stimulus was then delivered as the loudspeaker was moved across the frontal auditory space of the bat to locate the response center of the neuron. at the response ...19873610849
anatomical study of neural projections to the superior colliculus of the big brown bat, eptesicus fuscus.auditory inputs to the intermediate and deep layers of the superior colliculus of the bat, eptesicus fuscus, were studied by iontophoretic injection of horseradish peroxidase (hrp) into the superior colliculus. hrp was injected into the recording sites of superior collicular neurons that responded to acoustic stimuli (4 ms duration, 0.5 ms rise-decay times). the results showed that the superior colliculus received its auditory projections mainly from the inferior colliculus bilaterally, but with ...19873620966
experimentally induced rabies in four cats inoculated with a rabies virus isolated from a bat.four cats were inoculated im with rabies virus isolated from the salivary gland of a naturally infected big brown bat (eptesicus fuscus). the 4 cats developed clinical signs of rabies after a median incubation period of 42 days. the median duration of clinical illness was 5 days. results of fluorescent antibody evaluation, mouse inoculation, and tissue culture isolation indicated large differences in virus concentrations in various areas of the cns of individual cats. these differences also were ...19863516030
rabies in insectivorous bats of western canada, 1979 to 1983.a total of 1,745, 362, and 536 bats collected in alberta, british columbia, and saskatchewan, respectively, was tested for rabies virus between 1979 and 1983. only one (0.1%) of 769 bats collected at random from buildings was infected with rabies virus in contrast to 95 (5%) of 1,874 symptomatic, rabies-suspect bats submitted for testing. the pattern of infection in the rabies-suspect bats was similar in alberta and saskatchewan, but differed in british columbia. rabies was diagnosed in four spe ...19863735577
major antigenic groups of rabies virus in canada determined by anti-nucleocapsid monoclonal antibodies.a total of 123 rabies virus isolates from various geographical areas in canada were characterized by a panel of 43 anti-nucleocapsid monoclonal antibodies. four major antigenic groups are found in terrestrial mammals: "canadian arctic" from ontario, quebec and the northwest territories; "south-eastern georgian bay" from ontario; "south mid-central skunk" from alberta, saskatchewan and manitoba; and "brook's, alberta skunk" from a restricted area in alberta. bat isolates can be divided into 4 maj ...19863769442
connectional basis for frequency representation in the nuclei of the lateral lemniscus of the bat eptesicus fuscus.to study the role of the lateral lemniscus as a link in the ascending auditory pathway, injections of neuronal tracers were placed in the anteroventral cochlear nucleus (avcn) and in the inferior colliculus of the bat eptesicus fuscus. to correlate the anatomical results with tonotopic organization, the characteristic frequency of cells at each injection site was determined electrophysiologically. pathways from avcn diverge to 3 major targets in the lateral lemniscus, the intermediate nucleus an ...19863020188
accuracy of distance measurement in the bat eptesicus fuscus: theoretical aspects and computer simulations.behavioral experiments of simmons [j. acoust. soc. am. 54, 157-173 (1973) and science 204, 1336-1338 (1979)] on the ranging accuracy in the bat eptesicus fuscus have led to far-reaching postulates on the existence of optimal and phase-conserving processing mechanisms in the bat. in this paper, the results of computer simulations of these experiments are presented. two receiver types are investigated: the fully coherent cross-correlation receiver and the cross-correlation receiver with envelope p ...19863950192
phase evaluation in hypothetical receivers simulating ranging in bats.echo delay discrimination by the bat eptesicus fuscus had been investigated in an experiment with simulated targets jittering in range (simmons 1979). the dip in the resulting psychometric curve was used by simmons to suggest the neuronal implementation of a coherent cross-correlation receiver in the auditory system of bats. by computer simulation it is shown here that the dip may be even more pronounced and less susceptible to noise with alternative receiver configurations which not necessarily ...19863755621
sonar tracking of horizontally moving targets by the big brown bat eptesicus fuscus.when following a moving target, echolocating bats (eptesicus fuscus) keep their heads aimed at the target's position. this tracking behavior seems not to involve predicting the target's trajectory, but is achieved by the bat's pointing its head at the target's last known position. the bat obtains frequent position updates by emitting sonar signals at a high rate. after the lag between head and target positions and the nonunity tracking gain were corrected for, bats' tracking accuracy in the hori ...19854001947
bat rabies in alberta 1979-1982.the infection rate among eight species of bats submitted for rabies diagnosis in alberta during 1979-82 was 4.6%. prevalence of rabies was greatest (24%) for hoary bats lasiurus cinereus, while the big brown bat eptesicus fuscus was the species in which rabies was most commonly diagnosed, and the species submitted most frequently for rabies diagnosis was the little brown bat myotis lucifugus. the rabies infection rate among male hoary bats was significantly greater than in either sex of all othe ...198517422507
retinofugal projections of the big brown bat, eptesicus fuscus and the neotropical fruit bat, artibeus jamaicensis.retinal connections were studied in eptesicus fuscus and artibeus jamaicensis using anterograde axonal degeneration and autoradiographic techniques following unilateral enucleations and uniocular injections of radioactive amino acids. although each retina projected bilaterally to the brainstem, the number of silver grains in the emulsion of autoradiographs indicated that nearly all fibers in the optic nerve entered the contralateral optic tract. ipsilaterally, a major portion of the projection e ...19852983524
automatic gain control in the bat's sonar receiver and the neuroethology of echolocation.the sensitivity of the echolocating bat, eptesicus fuscus, to sonar echoes at different time delays after sonar emissions was measured in a two-choice echo detection experiment. since echo delay is perceptually equivalent to target range, the experiment effectively measured sensitivity to targets at different ranges. the bat's threshold for detecting sonar echoes at a short delay of only 1.0 msec after emissions (corresponding to a range of 17 cm) was 36 db spl (peak to peak), but the threshold ...19846502201
auditory space representation in the superior colliculus of the big brown bat, eptesicus fuscus.the auditory response areas of 123 superior collicular (sc) units of eptesicus fuscus were studied under free-field acoustic stimulus conditions. a stimulus was delivered from a loudspeaker placed 14 cm in front of a bat. the best frequency of a unit was determined by changing the stimulus frequency until the minimum threshold was measured. a best frequency stimulus was then delivered as the loud-speaker was moved across the auditory space to determine the response center of the auditory respons ...19846498487
preference of a revolving target to a stationary one by the big brown bat, eptesicus fuscus.utilizing a three-ramp platform, we studied the detection of a revolving and a stationary target in the presence of background clutter by trained eptesicus fuscus. during the test, the mean amplitude of echo from either target was always larger than that of the background echoes at the bat-to-target distance of 30, 70 and 100 cm. the amplitude of the echo reflected back from a revolving target was modulated between a maximum and a minimum value. an electric motor was used to revolve a target. th ...19846571589
pinna orientation determines the maximal directional sensitivity of bat auditory neurons.the auditory response areas of 192 inferior collicular neurons (ic) of eptesicus fuscus were studied under free field acoustic stimulation. the boundary of the auditory response area of a neuron expands with stimulus intensity (fig. 1). however, there is a response center within each neuron's response area at which the neuron has the maximal sensitivity. all response centers of the 192 neurons are located within a limited space of the bat's contralateral auditory space. the position of the respo ...19846733486
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