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At least 1,117 records · Page 62Linked to original sources
PubMed1981

Mapping of the auditory area in the cerebellar vermis and hemispheres of the little brown bats, Myotis lucifugus.

Mapping of auditory area in the cerebellar vermis and hemispheres of little brown bats, Myotis lucifugus, shows that a large area of the bat's cerebellum contains units responding to acoustic stimuli. These units had latencies between 4 and 34 msec and best frequencies between 33.0 and 92.5 kHZ. The Q10-dB values of their tuning curves ranged from 2.0 to 19.7. Most of the units studied fired only a few impulses during a stimulus with minimum thresholds between 22 and 90 dB SPL. Units in the cerebellar vermis tend to have higher best frequencies and shorter latencies than those in the cerebellar hemispheres. However, there is no evidence of clear tonotopic organization therein.

Animals↗
PubMed1981

Are CNS neurons polyploid? A critical analysis based upon cytophotometric study of the DNA content of cerebellar and olfactory bulbar neurons of the bat.

A cytophotometric study of the nuclear DNA content of bat cerebellar and olfactory bulbar neurons was performed with particular attention to corrections for distributional error and non-specific light loss and to selection of appropriate control nuclei for the establishment of reliable haploid and diploid DNA values. Feulgen stained sections were measured with an integrating, scanning microdensitometer for correction of distributional error. The values thus obtained were further corrected in 3 different ways to subtract the contribution of background absorbance at 546 nm. Bat haploid (1c) DNA values were derived from spermatozoa, and diploid (2c) values from pancreatic acinar cells, hepatocytes and non-hepatocyte liver cells. Microglia of olfactory bulb also had 2c values. After correction, all neurons measured, except Purkinje cells, had DNA values more closely approximating the tetraploid (4c) than the diploid (2c) level. Purkinje neurons had mean DNA values closer to 2c than to 4c, but inherent technical difficulties in measuring these very large, light staining nuclei has created less confidence in the values obtained than for those of the other neurons. This uncertainty, plus the apparent existence of two populations of Purkinje neurons, one 2c and the other hyperdiploid, suggested by the DNA distribution curves, make it difficult to eliminate the possibility of polyploidization of Purkinje neurons. A critical analysis of various cytophotometric, radioautographic and biochemical approaches to the problem of CNS neuron polyploidization has revealed potentially serious flaws in many of them, rendering virtually impossible interpretation of the numerous contradictory results in the literature. Standardization of the cytophotometric technique and improvement of the radioautographic approach seem to be prerequisite to the resolution of the existing dilemma.

Animals↗
PubMed1984

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 response center of a neuron changes with different pinna orientations (Figs. 2 and 3) providing a bat with versatility in maximizing the sensitivity of its echolocation system.

Acoustic Stimulation↗
PubMed1989

Electrical stimulation of bat superior colliculus influences responses of inferior collicular neurons to acoustic stimuli.

The influence of electrical stimulation of the superior colliculus (SC) on acoustically evoked responses of inferior collicular (IC) neurons was examined in 24 barbiturate-anesthetized Rufous horseshoe bats, Rhinolophus rouxi. Acoustic stimuli (50 ms, 0.5 ms rise-decay times) were delivered from a loudspeaker placed 68 cm in front of each bat and a total of 354 IC neurons were isolated. The response latencies of these neurons were mainly between 7.5 and 17.5 ms. When the ipsilateral SC was electrically stimulated, responses of 227 (64%) neurons were not affected, but responses of the remaining (127 neurons, 36%) were either inhibited (102 neurons, 29%) or facilitated (25 neurons, 7%). The degree of inhibition and the response latency of the inhibited neurons increased with the amplitude of electrical stimulation. Inhibition of a neuron's activity was also dependent upon the time interval between acoustic and electrical stimuli. The best inhibitory latency measured at maximal inhibition was between 12 and 20 ms. Conversely, facilitation shortened the response latency of IC neurons and the degree of facilitation increased with the amplitude of the acoustic stimulus. Since the SC plays an essential role in orienting an animal's responses toward sensory stimuli, our findings suggest that the SC may affect the processing of acoustic signals in the auditory system during acoustically guided orientation.

Acoustic Stimulation↗
PubMed1992

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. Then the basic response properties of the neuron to a sound delivered from the response center were studied. As in inferior collicular and auditory cortical neurons, pontine neurons can be characterized as phasic responders, phasic bursters and tonic responders. They have both monotonic and non-monotonic intensity-rate functions. However, most of them are broadly tuned as are cerebellar neurons. Auditory spatial sensitivity was studied for 144 pontine neurons. In 9 neurons, variation of MT with a BF sound delivered from several azimuthal and elevational angles along the horizontal and vertical planes crossing the neuron's response center was measured. In addition, variation in the number of impulses with several stimulus intensities at 10 dB increments above a neuron's MT delivered from each angle was also studied. The auditory spatial sensitivity of other pontine neurons was studied by measuring the response area of each neuron with stimulus intensities at 3, 5, 10, 15 or 40 dB above its lowest MT. The response areas of pontine neurons expanded asymmetrically with stimulus intensity, but the size of the response area was not correlated with either MT or BF. In half of the pontine neurons studied, the response area expanded greatly and eventually covered almost the entire frontal auditory space. The response areas of the other half of the pontine neurons only expanded to a restricted area of frontal auditory space. Two possible neural mechanisms underlying these two types of response areas are hypothesized. The response centers of all 144 neurons were located within a small area of the frontal auditory space. The locations of response centers of these neurons are not correlated with their BFs. The distribution pattern of these response centers is comparable to that of superior collicular and cerebellar neurons but is different from that of inferior collicular and auditory cortical neurons. The results of our study suggest that auditory information is integrated in the pontine nuclei before being further sent into the cerebellum.

Acoustic Stimulation↗
PubMed1993

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 with a 4 ms BF pulse delivered at 10 dB increments above its MT in order to determine the best intensity to which the neuron discharged maximally. The neuron's discharge pattern and number of impulses to 32 trials of 300 ms train stimuli, which consisted of different number of 4 ms BF and best intensity pulses (1, 2, 3, 8, 12, 19, 24, 29 pulses/train) and delivered at an interpulse interval of 1000, 250, 170, 100, 40, 25, 15, 12 and 10 ms (i.e. at a pulse repetition rate of 1, 4, 6, 10, 25, 40, 67, 83, 100 pulses/s), were sequentially recorded. All neurons recorded from the inferior colliculus, auditory cortex and pontine nuclei discharged phasically (1-3 impulses) but they responded to the pulse repetition rate in different manners. More than 63% of 38 inferior collicular and 65 pontine neurons studied discharged impulses to each pulse within a train stimulus when the pulse repetition rate was up to 40 pulses/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1987

Pressure regulation in muscle of unanesthetized bats.

In unanesthetized bats direct microvascular pressure measurements were made in the tensor plagiopatagii muscle without surgical intervention. Pressure recordings showed great variability due to vasomotion and other physiological stimuli, but were in the same order of magnitude as described in muscle of other species in the anesthetized state. A substantial part of the pressure gradient is dissipated at the level of the small arterioles. Arterial pressure was changed by depressurizing a box containing the body of the bat, while the muscle was under atmospheric condition. In all larger arterioles and in 12 of 19 smaller arterioles a linear relation existed between microvascular pressure and box pressure. Of 19 small arterioles, 7 exhibited a clear biphasic regulatory response to a decrease in arterial pressure. The data are discussed in relation to different models of regulation.

Anesthesia↗
PubMed1986

Circannual cycles of body mass food intake and reproductive condition in male pallid bats.

Gonadectomy did not eliminate circannual cycles of body mass and food intake in male pallid bats maintained for up to 30 months in short or long photoperiods at a constant temperature of 23 +/- 2 degrees C. Generation and expression of circannual rhythms is independent of the annual testicular cycle. Initial peak body and testicular masses were recorded within one month of each other but the peak in food intake occurred approximately eight months after animals attained peaks in body mass. Increased metabolic efficiency appears to act independently of changes in food intake to effect seasonal increases in body mass of pallid bats.

Animals↗
PubMed1982

A morphometric analysis of the lung of a species of bat.

The lungs of five adult Epauleted Fruit-bats (Epomophorus wahlbergi) of mean body weight 96 g were analysed morphometrically. The lung volume per unit body weight was 0.043 cm3/g, the surface area of the tissue barrier (i.e., the effective alveolar surface area) component of the blood-gas pathway per unit body weight was 138 cm2/g, and the surface density of the tissue barrier (surface area of the tissue barrier per unit volume of parenchyma) was 121 mm2/mm3. The harmonic mean thickness of the tissue barrier was between 0.267 and 0.349 micron. The morphometric pulmonary diffusing capacity per unit body weight (DLO2/W) was 0.02 ml O2 per min per mm Hg per g. These values are compared with those of shrews and birds. It is suggested that in bats enlargement of the lungs, small subdivisions of the air spaces, and a thin blood-gas barrier, could be linked with previously reported circulatory adaptations to account for the high oxygen consumption during flight.

Animals↗
PubMed1991

Arrhythmic breathing in torpid pipistrelle bats, Pipistrellus pipistrellus.

The arrhythmic breathing pattern of torpid female pipistrelle bats (Pipistrellus pipistrellus) was monitored using Doppler radar. A total of 98 h of radar measurements were made on 11 individuals over 17 experiments, during which time 974 apneic intervals were monitored, over ambient temperatures (Ta, degrees C) ranging from -1 to 14 degrees C, and body masses ranging from 4.6 to 7.4 g. As Ta declined, a greater proportion of all breaths occurred in discrete breathing bouts. Apneic intervals lengthened at lower Ta, but were not related to body mass. Mean apneic length, averaged over 1 degree C intervals, was best described by the least squares fit regression equation: ln (apneic length in s) = 7.07-0.811 ln (Ta + 1), (r2 = 0.96, P less than 0.01). Ventilation frequency (breaths.min-1), averaged over a breathing bout and the subsequent apnea, increased as Ta increased, and was not related to body mass. Mean ventilation frequency (f), averaged over 1 degree C intervals, was best described by the least squares fit regression equation: f = 0.812 + 0.499 Ta (r2 = 0.92, P less than 0.01). Using previously published values for O2 consumption (VO2) in torpid pipistrelles, and tidal volume and O2 extraction efficiency at 4 degrees C in torpid bats of the same mean size (6.2 g), we calculated that at 4 degrees C ventilation would, on average, supply only 14.2-21.3% of VO2. This suggests that in torpid pipistrelles the glottis may remain open during apnea, allowing a significant diffusive influx of O2 into the lungs.

Animals↗
PubMed1984

Antibody-mediated immune response in the bat, Pteropus giganteus.

Among mammals, the Chiroptera (Bats) have been perhaps the least studied with respect to systematic accounts of immune responses. To resolve this omission in comparative immunology, we have begun to analyze aspects of immunity of the large frugivorous bat, Pteropus giganteus with respect to antibody secreting plaque forming cells and serum antibodies as measured by haemagglutination titres. Homologous complement was more effective than guinea pig or rabbit complement in lysing SRBC for developing plaques. Kinetic of antibody response to three different doses of SRBC has been studied. We observed a peak primary response and its decay after a single antigenic challenge which were notably delayed, and a same dose of antigen could produce 2-Mercaptoethanol resistant PFC and HA-tires.

Animals↗
PubMed1989

Developmental aspects of the neocortex of the bat.

Golgi studies on the cerebral cortex (central region) of newborn and adult bats (Myotis myotis) have shown that (a) extraverted cells in layer II-III are the source of a rich horizontal plexus originating from large numbers of long, proximal axonic collaterals, and (b) significantly greater numbers of basilar and apical dendrites (Student's t-test, P less than 0.001) of extraverted pyramidal cells are found in the newborn than in the adult bat, indicating an overproduction of dendrites during the early stages of development.

Animals↗
PubMed1988

Immunity against the European bat rabies (Duvenhage) virus induced by rabies vaccines: an experimental study in mice.

Protection experiments were performed in mice with different inactivated vaccines prepared with the fixed rabies virus strains: PM (Pitman-Moore), PV4 (Pasteur virus) and LEP (Flury LEP) against an intracerebral challenge with a European bat virus (Duvenhage, strain Hamburg, DUV3). All vaccines protected mice against challenge with CVS (Challenge virus standard). Vaccines prepared with PV4 protected mice against a DUV3 challenge. On the contrary, PM or LEP vaccines did not protect mice against a DUV3 infection. The protection conferred by PV4 vaccines against Duvenhage could be due to the antigenic relationship which seems to exist between PV4 and European bat virus as revealed by serum-virus neutralization, absorption experiments and CTL crossreactivity. The four virus strains PAS, PV4, PM and CVS, originated from the Pasteur virus isolated in 1882 from the brain of a rabid cow, were classified in two groups on the basis of reactivity with neutralizing anti-glycoprotein monoclonal antibodies. One group contained the L. Pasteur (PAS) and the PV4 strains, the second contained PM and CVS strains. The divergence between the two virus groups possibly resulted from distinct passage histories.

Animals↗
PubMed1984

Postnatal changes in hematology of the bat Antrozous pallidus.

Blood oxygen capacity increases with growth as the result of increasing hemoglobin concentration, which is accompanied by increasing red blood cell count and hematocrit. Hematological profile of the postnatal bat approaches that of the adult by 42 days of age when the animal begins to fly. Hematological development in the bat is similar to that in other altricial small mammals.

Aging↗
PubMed1986

Habitat aridity and urine concentrating ability of nearctic, insectivorous bats.

Urine concentrating ability of nearctic, insectivorous bats determined from renal anatomy was significantly correlated to total annual precipitation and potential evapotranspiration to precipitation ratio of the habitat where the animal was collected. Habitat aridity measured by water input accounted for as much variation in urine concentrating ability as habitat aridity measured by both water and energy input. Habitat aridity, regardless of how it was measured, explained only 25% of the among-species variation in urine concentrating ability. Factors other than habitat aridity significantly affect the urine concentrating ability of insectivorous bats.

Animals↗
PubMed1991

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.

Animal Nutritional Physiological Phenomena↗
PubMed1994

Proximate, caloric, nitrogen and mineral composition of bodies of some tropical bats.

Proximate (live mass, water, lipid, ash, non-fat organic), caloric, nitrogen, and mineral (sodium, potassium, calcium, magnesium, and iron) concentrations and total body content of individuals of 24 species of Neotropical and Paleotropical bats were determined. Mass-related, concentration patterns were found for all measured variables, except iron. Concentrations increase with size for nitrogen, calcium, and magnesium but are concave, opening upward, for sodium and potassium. These last two elements reach minimal concentrations in bats weighing about 22 and 28 g dry mass, respectively. Total body content of nitrogen and minerals was compared with amounts in similar-sized birds and tetrapodal mammals.

Adipose Tissue↗