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R R Capranica

Publications and source records attributed to R R Capranica.

At least 19 recordsLinked to original sources
PubMed1992

Hormone-induced vocal behavior and midbrain auditory sensitivity in the green treefrog, Hyla cinerea.

Twenty four castrated male, 6 intact male, and 11 intact female Hyla cinerea were injected subcutaneously with 25 micrograms arginine-vasotocin (AVT) and induced to call 1 h later in response to the playback of a conspecific mating call. Eighteen castrated males and 8 intact females were implanted 5 mg androgen pellets for 3 weeks prior to the neuropeptide injection. Among castrated males, 6/9 testosterone (T) implanted, 4/9 dihydrotestosterone (DHT) implanted and 2/6 non implanted individuals produced calls after being administered AVT. 5/6 intact non implanted males and 6/8 T intact implanted females also called, and 3 intact non implanted females remained silent after the injection. Evoked calls had a mid-frequency spectral peak at about 1900 Hz which is absent in field-recorded mating calls of this species. Calls of implanted females and castrated non implanted males were shorter than those of castrated implanted and intact non implanted males. Audiograms measured before hormone implants showed dips of enhanced sensitivity at about 0.5, 0.9 and 3.0 kHz in males and females. After AVT injection, thresholds at frequencies within the 0.7-1.5 kHz range were increased in castrated males. Such reduction in sensitivity points to an inhibition of the auditory system during hormone induced vocal activation.

Acoustic Stimulation↗
PubMed1992

A comparison of anesthetic agents and their effects on the response properties of the peripheral auditory system.

Anesthetic agents were compared in order to identify the most appropriate agent for use during surgery and electrophysiological recordings in the auditory system of the tokay gecko (Gekko gecko). Each agent was first screened for anesthetic and analgesic properties and, if found satisfactory, it was subsequently tested in electrophysiological recordings in the auditory nerve. The following anesthetic agents fulfilled our criteria and were selected for further screening: sodium pentobarbital (60 mg/kg); sodium pentobarbital (30 mg/kg) and oxymorphone (1 mg/kg); 3.2% isoflurane; ketamine (440 mg/kg) and oxymorphone (1 mg/kg). These agents were subsequently compared on the basis of their effect on standard response properties of auditory nerve fibers. Our results verified that different anesthetic agents can have significant effects on most of the parameters commonly used in describing the basic response properties of the auditory system in vertebrates. We therefore conclude from this study that the selection of an appropriate experimental protocol is critical and must take into consideration the effects of anesthesia on auditory responsiveness. In the tokay gecko, we recommend 3.2% isoflurane for general surgical procedures; and for electrophysiological recordings in the eighth nerve we recommend barbiturate anesthesia of appropriate dosage in combination if possible with an opioid agent to provide additional analgesic action.

Acoustic Stimulation↗
PubMed1987

Correlation between auditory thalamic area evoked responses and species-specific call characteristics. II. H. Hyla cinerea (Anura: Hylidae).

Evoked potentials were recorded from the posterior dorsal thalamus of green treefrogs (Hyla cinerea) in response to single tones and combinations of two and three tones. 1. The responses to two tones were largest when one of the component tones was 500 Hz and when the second component was between 2000 and 4000 Hz (Fig.3). 2. The response to 500 + 3000 Hz showed nonlinear facilitation; i.e., the amplitude of the response was greater than the sum of the responses to the component tones alone (Figs. 4, 5). This result provides evidence that cells functioning as 'AND' gates will be found in this center. 3. When a third tone around 1200 Hz was added to a stimulus of 500 + 3000 Hz a 65% decrease in the evoked response amplitude occurred (Fig. 6). 4. The largest evoked response amplitude to a two-tone stimulus (500 + 3000 Hz) occurred when the rise-time was less than 50 ms (Fig. 7). 5. The two-tone tuning was found to be temperature dependent. The optimal lower frequency tone shifted downward with decreasing temperatures (Fig. 8). 6. When the temperatures of the neurophysiological and the behavioral experiments are matched, the optimal stimuli for evoking a large response are closely correlated to the parameters of the acoustic stimuli preferred by gravid H. cinerea females in discrimination tests. This center therefore appears to be very important for the processing of complex species-specific sounds.

Acoustic Stimulation↗
PubMed1987

Tympanic and extratympanic sound transmission in the leopard frog.

The inner ear of the leopard frog, Rana pipiens, receives sound via two separate pathways: the tympanic-columellar pathway and an extra-tympanic route. The relative efficiency of the two pathways was investigated. Laser interferometry measurements of tympanic vibration induced by free-field acoustic stimulation reveal a broadly tuned response with maximal vibration at 800 and 1500 Hz. Vibrational amplitude falls off rapidly above and below these frequencies so that above 2 kHz and below 300 Hz tympanic vibration is severely reduced. Electrophysiological measurements of the thresholds of single eighth cranial nerve fibers from both the amphibian and basilar papillae in response to pure tones were made in such a way that the relative efficiency of tympanic and extratympanic transmission could be assessed for each fiber. Thresholds for the two routes are very similar up to 1.0 kHz, above which tympanic transmission eventually becomes more efficient by 15-20 dB. By varying the relative phase of the two modes of stimulation, a reduction of the eighth nerve response can be achieved. When considered together, the measurements of tympanic vibration and the measurements of tympanic and extratympanic transmission thresholds suggest that under normal conditions in this species (1) below 300 Hz extratympanic sound transmission is the main source of inner ear stimulation; (2) for most of the basilar papilla frequency range (i.e., above 1.2 kHz) tympanic transmission is more important; and (3) both routes contribute to the stimulation of amphibian papilla fibers tuned between those points. Thus acoustic excitation of the an uran's inner ear depends on a complex interaction between tympanic and extratympanic sound transmission.

Animals↗
PubMed1987

Correlation between auditory evoked responses in the thalamus and species-specific call characteristics. I. Rana catesbeiana (Anura: Ranidae).

This evoked potential study of the bullfrog's auditory thalamic area (an auditory responsive region in the posterior dorsal thalamus) shows that complex processing, distinct from that reported in lower auditory regions, occurs in this center. An acoustic stimulus consisting of two tones, one which stimulates either the low-frequency or the mid-frequency sensitive population of auditory nerve fibers from the amphibian papilla and the other the high-frequency sensitive population of fibers from the basilar papilla, evoked a maximal response. The amplitude of the response to the simultaneous stimulation of the two auditory organs was, in some locations, much larger than the linear sum of the responses to the individual tones presented separately. Bimodal spectral stimuli that had relatively long rise-times (greater than or equal to 100 ms) evoked much larger responses than similar sounds with short rise-times. The optimal rise-times were close to those occurring in the bullfrog's mating call. The response was dependent on the waveform periodicity and harmonic content, with a fundamental frequency of 200 Hz producing a larger response than those with fundamentals of 50, 100 or 300 Hz. Six of the natural calls in the bullfrog's vocal repertoire were tested and the mating call and warning call were found to evoke the best responses. Each of these calls stimulate the two auditory organs simultaneously. The evoked response had a long refractory period which could not be altered by lesioning the efferent telencephalic pathways. The type of spectral and temporal information extracted by the auditory thalamic area suggests that this center is involved in processing complex sounds and likely plays an important role in the bullfrog's detection of some of its vocal signals.

Acoustic Stimulation↗
PubMed1986

Bilateral syringeal interaction in vocal production of an oscine bird sound.

The vocal organ, or syrinx, of oscine birds has two parts, each of which has generally been presumed to operate independently of the other. A significant counter-example is now demonstrated in the production of a common vocalization by the black-capped chickadee (Parus atricapillus), in which the two acoustic sources interact in a nonlinear fashion. This bird produces a sound with multiple frequency components that are heterodyne products resulting from cross-modulation between two signals, thus providing evidence that avian phonation can involve cooperative coupling between the two syringeal sources.

Animals↗
PubMed1986

Bilateral syringeal coupling during phonation of a songbird.

The syrinx of oscine birds ("true songbirds") is a double vocal organ, and each side has generally been presumed to function independently under separate neural control during phonation. A significant counterexample is demonstrated here in the production of a common vocalization by the black-capped chickadee (Parus atricapillus), in which the 2 acoustic sources of the syrinx interact in a nonlinear fashion. The chickadee produces a sound with multiple frequency components that superficially resemble harmonics. An analysis of vocal production after unilateral and bilateral syringeal denervation shows instead that these frequency components are sum and difference frequencies, or heterodyne frequencies, resulting from cross-modulation between the 2 syringeal sides. A limited form of this bilateral coupling may be achieved after unilateral denervation of either syringeal side but not after bilateral denervation. Unilaterally denervated birds are capable of significant improvement in coupling after 10 d, too short a period for neural regrowth. These results suggest that coupling arises from a passive physical interaction between the 2 syringeal sources which is activated or regulated in some fashion by neural control from either side.

Animals↗
PubMed1985

Neural correlates of temperature coupling in the vocal communication system of the gray treefrog (Hyla versicolor).

The central nervous system of the gray treefrog includes a class of auditory neurons which respond selectively to particular rates of amplitude modulation. When body temperature is increased, the temporal tuning of these neurons shifts to higher rates of modulation. This shift in tuning parallels the temperature-dependent shift in the trill rate in the male's mating call, thus constituting the neural correlate of temperature coupling between the female's behavioral selectivity and the temporal signal characteristics in the male's call.

Animals↗
PubMed1985

Species specificity and temperature dependency of temporal processing by the auditory midbrain of two species of treefrogs.

The mating (advertisement) calls of two sibling species of gray treefrogs, Hyla versicolor and Hyla chrysoscelis, are spectrally identical but differ in trill rate; being higher for H. chrysoscelis. Single-unit recordings were made from the torus semicircularis of both species to investigate the neural mechanisms by which this species-specific temporal feature is analyzed. Using sinusoidally amplitude-modulated (AM) white noise as a stimulus, the temporal selectivity of these midbrain auditory neurons could be described by five response categories: 'AM nonselective' (34%); 'AM high-pass' (7%); 'AM low-pass' (6%); 'AM band-suppression' (12%); 'AM tuned' (40%). The distributions of temporal tuning values (i.e., modulation rate at which each AM-tuned unit responds maximally) are broad; in both species, neurons were found which were tuned to modulation rates greater than those found in their advertisement calls. Nevertheless, the temporal tuning values for H. versicolor (median = 25 Hz) were significantly lower than those for H. chrysoscelis (median = 32.5 Hz). The temporal selectivities of AM band-suppression neurons were found to be temperature dependent. The modulation rate at which a response minimum was observed shifted to higher values as the temperature was elevated. These results extend our earlier findings of temperature-dependent temporal selectivity in the gray treefrog. The selectivity of band-suppression and AM-tuned neurons to various rates of amplitude modulation was largely, but not completely, independent of whether sinusoidal or natural forms of AM were used.

Animals↗
PubMed1985

Sensitivity to amplitude modulated sounds in the anuran auditory nervous system.

Auditory responses were recorded from single units in the eighth nerve and in the midbrain torus semicircularis of the leopard frog (Rana pipiens). Acoustic stimuli included sinusoidally amplitude-modulated (AM) tones and noise, as well as pure tones. Mean spike rates were measured at various rates of AM, and the degree to which a unit's spikes were restricted to a particular phase of the modulation cycle was described by a synchronization coefficient. The firing rate of eighth-nerve fibers was largely independent of the rate of AM over the modulation range 10 to 150 Hz. Further, the general shape of the spike rate vs. AM-rate function was invariant with either depth of modulation or sound-pressure level (SPL). Although virtually all eighth-nerve fibers exhibited significant synchronization to the envelope of AM, the shape of the synchronization function depended on the unit's best-excitatory frequency (BEF). Fibers with highest BEF's, presumed to innervate the basilar papilla, generally showed greater synchronization as the AM rate was increased (up to 100-150 Hz). Fibers tuned to the low-and midfrequency region, which innervate the amphibian papilla, exhibited low-pass synchronization characteristics. As the depth of modulation was reduced, the degree of synchronization of eighth-nerve fibers decreased. For a given depth of modulation an increase in sound level tended to decrease the degree of synchronization, but significant synchronization could still be observed at stimulus intensities at least 65 dB above threshold. On the basis of the spike rate vs. AM-rate functions, the temporal selectivity of single cells in the torus could be characterized by five response types: AM nonselective (spike rate was largely independent of the AM rate); AM high-pass (activity increased as the AM rate was increased); AM low-pass (response was greatest for slow AM rates and decreased at high rates); AM band-suppression (these neurons responded well to low and high AM rates, but responded weakly to intermediate rates); and AM-tuned (spike rate was greatest over a narrow range of modulation rates). In these measurements the depth of modulation was held constant at 100%. The five response categories are not discrete, but rather reflect representative examples along a continuum with regard to temporal selectivity. The temporal selectivity exhibited by toral units in their firing rates was not evident in their AM-synchronization functions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1978

Auditory processing in anurans.

Anurans (frogs and toads) represent an example of peripheral specialization of the auditory systems. Their inner ear contains two distinct auditory organs: the amphibian papilla and the basilar papilla. Each organ is tuned to different species-specific frequency ranges. Because of this peripheral specialization, anurans offer an excellent opportunity to explore neural decoding of complex sounds in the central auditory system.

Animal Communication↗
PubMed1976

Prenatal experience and avian development: brief auditory stimulation accelerates the hatching of Japanese quail.

A single 2-hour exposure to auditory stimulation at any point during the final 3 days of incubation accelerates the hatching of Japanese quail. The 3-day sensitive period includes both prenatal and perinatal stages of incubation. So far as is known these results provide the first unequivocal evidence that short-term prenatal sensory stimulation can affect the development of an avian embryo.

Acoustic Stimulation↗
PubMed1976

Axonal guidance of developing optic nerves in the frog. I. Anatomy of the projection from transplanted eye primordia.

Right or left eye primordia of Shumway stage 16-18 Rana pipiens embryos were transplanted to the position normally occupied by the ear, where they developed into externally normal eyes. Ganglion cell density in the retina of the transplanted eye was significantly lower than the ganglion cell density in the animal's normal eyes. No significant difference was observed between normal and transplanted inner and outer nuclear layers. In several preparations a large piece of embryonic forebrain was included in the initial eye graft. Optic nerves from the transplanted eyes penetrated this transplanted forebrain and established a dorsocaudal growth trajectory relative to the ectopic tissue's original anterior-posterior and dorsal-ventral axes. After traversing the forebrain, the transplanted optic nerve fibers penetrated the medulla where they invaraibly grew dorsocaudally to take up and maintain a dorsolateral position in the white matter of the spinal cord. The consistent dorsocaudal trajectory established by the translocated optic tract in the ectopic forebrain and in the hindbrain and spinal cord is very similar to the growth trajectory in the normal diencephalon, suggesting that dorsocaudal growth relative to the three major axes of the neural tube is an inherent property of optic nerve fibers. These results also suggest that the polarity cues which guide normal optic tract growth are not unique to the diencephalic regions of the neural tube.

Animals↗
PubMed1976

Axonal guidance of developing optic nerves in the frog. II. electrophysiological studies of the projection from transplanted eye primordia.

When a primordial eye was transplanted to the ear position in Rana pipiens embryos, the optic nerve from the ectopic eye penetrated the medulla and invariably established a tract in the dorsolateral white matter of the ipsilateral spinal cord. In response to visual stimulation of the transplanted eye, extracellular recordings with metal microelectrodes were conducted with the spinal cords of post-metamorphic animals. Visual activity in the spinal cord could only be recorded in those experimental animals in which the transplanted optic nerve succeeded in penetrating the medulla. This activity was frequently encountered in the gray matter of the cord well below the dorsolateral position of the transplanted optic tract. The discharge characteristics and adaptation properties of the visual activity were often similar to that of optic nerve fibers from normal eyes suggesting that axons or their collaterals branch off from the transplanted optic tract and arborize within the spinal cord. However, occassionally stimulation of the transplanted eye evoked activity with adaptation and/or response characteristics unlike that of normal optic nerve fibers. Visual activity in the spincal cords of our experimental animals could be driven by moving small dark objects within circumscribed regions in the visual field of the transplanted eye. However we were unable to find any evidene of a systematic mapping of the transplanted retina within these abnormally penetrated spinal cords.

Adaptation, Physiological↗
PubMed1976

Sexual differences in the auditory system of the tree frog Eleutherodactylus coqui.

Acoustic playback experiments with calling males in their natural habitat and two-choice orientation experiments with females indicate that males and females of the neotropical tree frog Elutherodactylus coqui respond to different notes in the two-note call of the male. This functional dichotomy of the two notes in the male's call reflects a difference in the distribution of the best excitatory frequencies of primary auditory neurons for the males and females. To the best of our knowledge, Eleutherodactylus is the first known example of a vertebrate in which the peripheral auditory sensitivity shows a sexual difference.

Animals↗