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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 662 (1992), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 157 (1985), S. 749-761 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Vocalizations of South African clawed frogs are produced by contractions of laryngeal muscles innervated by motor neurons of the caudal medulla (within cranial nerve nucleus IX–X). We have traced afferents to laryngeal motor neurons in male and female frogs using retrograde axonal transport of horseradish peroxidase conjugated to wheat germ agglutinin (HRP-WGA). 2. After iontophoretic injection of HRP-WGA into n. IX–X, retrogradely labelled neurons were seen in the contralateral n. IX–X, in rhombencephalic reticular nuclei, and in the pre-trigeminal nucleus of the dorsal tegmental area (DTAM) of both males and females. 3. Injection of HRP-WGA into DTAM resulted in labelled cells in the striatum, preoptic area and thalamus. Posterior to DTAM, labelled cells were found in the rhombencephalic reticular nuclei as well as n. IX–X of males. Results in females were similar with the exception that n. IX–X labelled cells were only seen after very large injections of unconjugated HRP into DTAM and surrounding tegmentum. Thus, the projection of n. IX–X neurons to DTAM is not as robust in females as males. 4. These anatomical studies revealed candidate brain nuclei contributing to the generation of vocal behaviors and confirmed some features of a model for anuran vocal behavior proposed by Schmidt (1976). 5. Comparison of calling candidate brain nuclei to the location of steroid accumulating neurons (Kelley 1981) reveals that most calling nuclei contain hormone concentrating cells. Androgens may act to promote calling by influencing neural activity at multiple sites within the vocalization pathway.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 158 (1986), S. 517-527 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We examined effects of exogenous androgen (testosterone and dihydrotestosterone) on vocalizations of ovariectomized, adult female South African clawed frogs,Xenopus laevis. When paired with sexually active males, all ovariectomized females exhibited ticking, the unreceptive or ‘release’ call. Ticking consists of low amplitude, regularly spaced clicks with a mean interclick interval of 154 ms. When androgen-treated and paired with sexually active males, these ovariectomized females also exhibited an aberrant call (atypical ticking) in which click multiples replaced the single clicks of ticking. Mean ICI's for atypical ticking were 37 ms for click doublets and 22 ms for click quadruplets. Androgen treatment decreased the total time spent vocalizing (typical and atypical ticking) by ovariectomized females. All androgen-treated females were then tested repeatedly with sexually receptive females in an attempt to elicit the male-typical vocalization, mate calling. Six of 17 females did not vocalize at all, even when gonadotropin injected. Eight females gave rapid (mean ICI, 36 ms) trains of clicks in an irregular temporal pattern (tick-like calls). Three females gave brief trills with alternating fast and slow components. Comparison of mate calllike vocalizations of androgen-treated females to mate calling of males reveals that calls in females are considerably shorter in duration (female: 0.32 min versus male: 45 min) and slower in tempo (ICI's; fast trill, female: 21 ms, male: 14 ms; slow trill, female: 36 ms, male: 28 ms). Incomplete masculinization of the vocal pattern of females by androgen treatment in adulthood may be due to developmental constraints on the modifiability of the neurons and muscles responsible for calling.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 154 (1984), S. 617-624 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Brains of intactRana pipiens frogs exposed to a visual stimulus adequate to release behavior that resembled components of preycatching showed heavy bilateral accumulation of14C-2-deoxyglucose (2DG) in the optic nerve and optic tract and in all known primary visual projection areas of the diencephalon and mesencephalon (Fig. 2). 2. Removal of visual input by optic nerve section caused a marked reduction in 2DG accumulation in all areas of the visual pathway. However, no effect on the deep cellular layers of the optic tectum was apparent until the VIII nerve was also bilaterally sectioned (Fig. 3). This result suggested a significant acoustic or vestibular effect on metabolic activity in these deep tectal layers. 3. Autoradiograms produced by14C-2DG had sufficient resolution to allow quantitative analysis of label in specific laminae of the optic tectum. Such analysis (Fig. 4 and Table 1) supported qualitative observations and showed that, while sensory input to the superficial neuropil and cell layer 6 is primarily visual, the activity of the deeper cell layers (layers 4 and 2) is also significantly influenced by acoustic or vestibular input. 4. The 2DG method allowed assessment of the response of populations of neurons and provided data complimentary to those available from single cell recording studies. Our evidence suggests that tectal cells whose cell bodies are in layers 4 and 2 receive both visual and vestibular inputs, and supports the notion that the deep tectal layers may serve as a multi-modal sensory integration area for orienting towards prey.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 159 (1986), S. 535-544 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mormyrid fish of Africa produce a weak electric pulse called an Electric Organ Discharge (EOD) that functions in electrical guidance and communication. TheEOD waveform describes the appearance of a single pulse which is produced by the electric organ's excitable cells, the electrocytes. For some species, there is a sex difference in the appearance and duration of the EOD waveform, which is under the control of gonadal steroid hormones. We now show, using biochemical techniques, that the steroid-sensitivity of the myogenic electric organ correlates with the presence of comparatively high levels of androgen-binding activity in the cytosol of electrocytes. TheEOD rhythm describes the rate at which the electric organ fires and is under the control of a central electromotor pathway. Sex differences have also been described for the EOD rhythm. Using steroid autoradiographic techniques, we found uptake of tritium-labelled dihydrotestosterone (3H-DHT) by cells within the reticular formation that lie adjacent to the medullary ‘relay nucleus’ which innervates the spinal electromotoneurons that excite the electric organ. However, no DHT-binding was observed in the relay or electromotor nuclei. Steroid-concentrating cells were also found in several other brainstem regions, the hypothalamus, and the thalamus. In particular, a group of DHT-concentrating, motoneuron-like cells were observed in the caudal medulla and were identified as aswimbladder orsonic motor nucleus. The biochemical data suggest that the electric organ has evolved a sensitivity to gonadal steroid hormones that may underlie the development of known sex differences in the EOD waveform. The autoradiographic results suggest that if steroids do affect the development of sex differences in the EOD rhythm, it is at some level removed from known spinal and medullary electromotor nuclei.
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  • 6
    ISSN: 1432-1351
    Keywords: Sexual differentiation ; Song ; Larynx ; Critical period ; Organizational-activational
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In Xenopus laevis, adult males but not females produce courtship songs comprised of rapid trills. Two experiments were conducted to determine whether male-typical singing could be induced in females. At 6 different juvenile stages, male and female frogs were gonadectomized and implanted with testes, grown to sexual maturity, and tested for vocal behavior. All frogs with functional testicular implants sang; females sang as much as males. The frequency spectra of the clicks within trills were fully masculinized in females implanted at PM0, PM1, and PM2. There were deficiencies in song quality in females implanted late in juvenile life. Females receiving testis implants at PM3, PM4, and PM5 did not produce clicks with masculine spectral qualities. In a concurrent experiment, adult males and females were gonadectomized and implanted with testes or silicone tubes containing testosterone proprionate. When tested for vocal behavior 10 to 15 months after implantation, 8/10 androgen-treated males, 3/12 androgen-treated females, 5/5 testes-implanted males, and 2/4 testes-implanted females sang. The females that did sing spent much less time singing than males. The click rates of females were uniformly slower than males and no female produced clicks with a masculine frequency spectrum. Thus, testicular secretions can induce male-typical singing in females until late in juvenile development. However, females exhibit a progressive decline in vocal potential with increasing age, culminating in an almost complete loss of singing ability by adulthood.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1986-01-01
    Print ISSN: 0166-2236
    Electronic ISSN: 1878-108X
    Topics: Biology , Medicine
    Published by Cell Press
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  • 8
    Publication Date: 1986-01-01
    Print ISSN: 0166-2236
    Electronic ISSN: 1878-108X
    Topics: Biology , Medicine
    Published by Cell Press
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  • 9
    Publication Date: 1982-01-01
    Print ISSN: 0166-2236
    Electronic ISSN: 1878-108X
    Topics: Biology , Medicine
    Published by Cell Press
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  • 10
    Publication Date: 2001-08-01
    Print ISSN: 0896-6273
    Electronic ISSN: 1097-4199
    Topics: Biology , Medicine
    Published by Cell Press
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