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R J Dooling

Publications and source records attributed to R J Dooling.

At least 37 records · Page 2Linked to original sources
PubMed1996

Testosterone induction of male-like vocalizations in female budgerigars (Melopsittacus undulatus).

Budgerigars possess a complex learned vocal repertoire that includes a long rambling song called warble. While both males and females can warble, there are marked sex differences in the amount of song produced. Males generally warble daily at a high rate, while females rarely sing. Both the quantity and the quality of male warble are influenced by circulating levels of testosterone. Males have higher circulating levels of testosterone than females. In this study we asked whether administering testosterone to adult female budgerigars would activate male-like vocal behavior. Four females were implanted with 8-mm Silastic implants filled with testosterone and recorded before and after implantation. Within 10-14 days, all four birds showed: (1) changes in there color to the male-like condition (blue), (2) male-typical patterns of precopulatory behavior, and (3) an increase in their rate of warbling to male-like levels. Sound analysis revealed that the acoustic structure of the testosterone-induced female warble is similar to the male warble. These data indicate that sex differences in budgerigar vocal behavior are not based on early organizational effects of steroid hormones, but rather are probably the result of adult sex differences in circulating testosterone levels.

Animals↗
PubMed1996

[Continuous proliferation of supporting cells and indications for hair cell differentiation in the inner ear of adult song birds with genetic cochlear hearing loss].

Our previous investigations demonstrated that the Belgian Waterslagers (BWS) canary (Serinus canarius) was affected by an inherited sensorineural hearing loss. Compared to normal canaries of others strains, hair cell numbers in these birds were reduced on average by 30%. Since other birds are able to replace similar hair cell numbers after cochlear trauma, we investigated if BWS have the potential for supporting cell proliferation with subsequent hair cell differentiation or if they lack the repair mechanisms known to operate in other birds. In the present study the S-phase marker bromodeoxyuridine (BrdU) was used to demonstrate DNA synthesis and thus cell proliferation. We found on average six labelled nuclei per basilar papilla in BWS. This number of proliferating cells was in accordance with previous estimates of newly generated hair cells as based on the frequency of immature-appearing hair cells observed by scanning electron microscopy. We conclude that the division of supporting cells in BWS precedes the differentiation of hair cells. In contrast to BWS we found on average only one supporting cell division per day in normal canaries of other strains. However, this supporting cell proliferation in normal birds is probably not related to a loss of hair cells and does not lead to the differentiation of new hair cells. Our data indicate that differentiation of hair cells after supporting cell division occurs only if the rate of supporting cell proliferation is increased above the normal low level (probably by the loss of hair cells). Since BWS do not repair their basilar papilla despite a 30% hair cell loss (as compared to normal canaries) although they continuously produce new hair cells, we suggest that the regulation of the regeneration process is abnormal.

Animals↗
PubMed1995

Peripheral basis for the auditory deficit in Belgian Waterslager canaries (Serinus canarius).

Recently, behavioural thresholds obtained in canaries of the Belgian Waterslager strain showed that these birds have an inherited auditory deficit. Canaries of this strain have absolute auditory thresholds at frequencies above 2.0 kHz that are as much as 40 dB above the threshold of canaries of other strains. We obtained audiograms from cochlear microphonics and from compound action potentials from the 8th nerve of Waterslager and non-Waterslager canaries and compare these results to previous behavioural data on hearing in this species. We also examined the growth of evoked potential amplitude-intensity functions in Waterslager and non-Waterslager canaries. Together with reflectance measurements of middle-ear function from both Waterslager and non-Waterslager canaries, we conclude that the origin of auditory deficit in Waterslager canaries lies in the cochlea.

Acoustic Stimulation↗
PubMed1995

Critical bands and critical-ratio bandwidth in the European starling.

Critical bands (CB) and critical-ratio (CR) bandwidth were determined in five European starlings (Sturnus vulgaris) using a GO/NOGO procedure and the method of constant stimuli. Test-tone frequencies were 1, 2, 4, and 6.3 kHz. Critical ratios were independent of the level of the white noise masker. The lowest CR of 21.8 dB was found at 1 kHz, and the CR monotonically increased on average by 2.3 dB per octave. CR-bandwidths at a masker spectrum level of 41 dB were 151, 191, 437, and 501 Hz at 1, 2, 4, and 6.3 kHz, respectively. With the exception of the test-tone frequency of 6.3 kHz, the size of the critical bands measured with a band-narrowing procedure was similar to that of the CR-bandwidth. CBs were 135, 233, 345, and 1156 Hz at 1, 2, 4, and 6.3 kHz, respectively. A repeat measurement at 6.3 kHz with another speaker position yielded a CB of 860 Hz. The results of this psychoacoustic study in the starling are discussed with respect to comparative data from other vertebrates and to neurophysiological bandwidth measurements of tuning curves of auditory-nerve fibres.

Acoustic Stimulation↗
PubMed1995

Discrimination of synthetic full-formant and sinewave/ra-la/continua by budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia guttata).

Discrimination of three synthetic versions of a/ra-la/ speech continuum was studied in two species of birds. The stimuli used in these experiments were identical to those used in a previous study of speech perception by humans [Best et al., Percept. Psychophys. 45, 237-250 (1989)]. Budgerigars and zebra finches were trained using operant conditioning and tested on three different series of acoustic stimuli: three-formant synthetic speech, sinewave versions of those tokens, and isolated F3 tones from the sinewave speech. Both species showed enhanced discrimination performance near the /l/-/r/ boundary in the full-formant speech continuum, whereas for the F3 continuum, neither species showed a peak near this boundary. These results are similar to human discrimination of the same continua. Budgerigars also showed a peak in discrimination of the sinewave analog continuum paralleling that for full-formant syllables, similar to humans who are induced to perceive sinewave speech as speech. Zebra finches, by contrast, showed a relatively flat function mirroring their performance for F3 sinewaves, similar to humans who are induced to perceive sinewave speech as nonspeech. These data provide new evidence of species similarities and differences in the discrimination of speech and speechlike sounds. These data also strengthen and refine previous findings on the sensitivities of the vertebrate auditory system to the acoustic distinctions between speech sound categories.

Animals↗
PubMed1995

[Indications of continuous hair cell regeneration in a song bird with genetically-induced cochlear hearing loss].

In recent years evidence has accumulated that birds in contrast to mammals have a great capacity to replace lost hair cells after cochlear trauma. Despite this capacity for cochlear repair, a hereditary hearing deficit for frequencies above 2 kHz has been described in a peculiar strain of canaries (Belgian Water-slagers). Because previous thresholds were determined by psychophysical methods, the origin of the hearing loss could not be identified. In order to determine if this loss originated in the cochlea and if these birds lack the potential for hair cell regeneration, we carried out physiological and morphological analyses of the hearing organ. Our results showed that most of the hair cells displayed severe pathologies. Also, found were small, microvilli-covered cells that resembled forms described during normal hair cell development. Small microvilli-covered cells with small sterovillar bundles have been described as regenerating hair cells in other birds after severe cochlear insults. These observations indicate that adult Belgian Waterslager canaries continuously produce new cochlear hair cells. They do not, however, succeed in reforming a normal basilar papilla. We believe that these birds are a promising model for future studies of cochlear hair cell repair mechanisms.

Animals↗
PubMed1994

Inner-ear abnormalities and their functional consequences in Belgian Waterslager canaries (Serinus canarius).

Recent reports of elevated auditory thresholds in canaries of the Belgian Waterslager strain have shown that this strain has an inherited auditory deficit in which absolute auditory thresholds at high frequencies (i.e. above 2.0 kHz) are as much as 40 dB less sensitive than the thresholds of mixed-breed canaries and those of other strains. The measurement of CAP audiograms showed that the hearing deficit is already present at the level of the auditory nerve (Gleich and Dooling, 1992). Here we show gross abnormalities in the anatomy of the basilar papilla of Belgian Waterslager canaries at the level of the hair cell. The extent of these abnormalities was correlated with the amount of hearing deficit as measured behaviorally.

Acoustic Stimulation↗
PubMed1994

Vocal plasticity in budgerigars (Melopsittacus undulatus): evidence for social factors in the learning of contact calls.

Distance or contact calls of 6 unrelated adult male budgerigars (Melopsittacus undulatus) were recorded before and during 8 weeks of social contact. The 6 birds were housed in 2 separate groups of 3 each in adjoining cages. Birds in each cage could hear but not see the birds in the neighboring cage. At the beginning of the study, none of the birds shared any contact call types. The first appearance of 1 bird's imitation of a cagemate's contact call type occurred after 1 week. Call type repertoires continued to change; some call types dropped out of the repertoires, and others were modified over time. Birds in the same cage shared the same dominant call type 8 weeks later, and the dominant call types differed between the 2 cages. Thus, budgerigars can learn calls as adults, and call type convergence is achieved through mutual vocal imitation of social companions. In the absence of social but not aural contact, vocal imitation was greatly reduced.

Animal Communication↗
PubMed1993

Perception of conspecific faces by budgerigars (Melopsittacus undulatus): II. Synthetic models.

Perception of faces by budgerigars (Melopsittacus undulatus) was studied with computerized images modeled after natural faces. Individual facial characteristics were varied with all others held constant; then relative importance among several features was determined by varying each within a single experiment. Characteristics with the potential to signal important biological information (e.g., age or sex) were perceptually salient, whereas characteristics that vary among faces but have limited potential to signal important information were not. Model faces were also presented in a normal or an altered configuration. Birds discriminated among faces in a normal configuration more easily than among models with an altered configuration even when the facial features on which the discrimination was based differed in the same way; this suggests that configurational cues play an important role in face perception by budgerigars.

Animals↗
PubMed1992

Auditory perception of conspecific and heterospecific vocalizations in birds: evidence for special processes.

Budgerigars (Melopsittacus undulatus), canaries (Serinus canaria), and zebra finches (Poephila guttata castanotis) were tested for their ability to discriminate among distance calls of each species. For comparison, starlings (Sturnus vulgaris) were tested on the same sounds. Response latencies to detect a change in a repeating background of sound were taken as a measure of the perceptual similarity among calls. All 4 species showed clear evidence of 3 perceptual categories corresponding to the calls of the 3 species. Also, budgerigars, canaries, and zebra finches showed an enhanced ability to discriminate among calls of their own species over the calls of the others. Starlings discriminated more efficiently among canary calls than among budgerigar or zebra finch calls. The results show species differences in discrimination of species-specific acoustic communication signals and provide insight into the nature of specialized perceptual processes.

Animal Communication↗
PubMed1992

Perception of conspecific faces by budgerigars (Melopsittacus undulatus): I. Natural faces.

Perception of faces by 4 budgerigars (Melopsittacus undulatus), a species of small parrot, was studied with a same-different discrimination task. Reaction times were taken as a measure of the similarity between pairs of faces and analyzed with multidimensional scaling to reveal patterns of similarity among the faces. The perception of natural faces was tested to determine which characteristics were perceptually salient. Color, patterns of markings, darkness of the iris, and size of the pupil corresponded to the observed patterns of similarity among the faces. Differences among budgerigar faces were more salient than differences among zebra finch faces, and budgerigar faces were perceptually distinct from the faces of other avian species. The results from these experiments provide a basis for understanding the ways in which these signals function in the coordination of social behaviors.

Animals↗
PubMed1991

Perception of distance calls by budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata): assessing species-specific advantages.

Budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata) share a common functional class of vocalizations called distance calls. The perception of species-specific distance calls by both species was measured with a habituation-dishabituation operant paradigm. Changes in discrimination performance were noted as listening conditions were modified or stimulus properties were altered. Both species showed better performance for calls of their own species. For zebra finches this tendency increased slightly when a background noise was added to the testing environment. Shifting the frequency region of the calls affected the discrimination performance of male budgerigars but not females or zebra finches. Reversing the temporal order of the calls affected the perceptual advantage for conspecific vocalizations in zebra finches but not in budgerigars. These results highlight species differences in perceiving acoustic communication signals.

Animals↗
PubMed1991

Sound localization in small birds: absolute localization in azimuth.

Nine small birds of 3 species (Melopsittacus undulatus, Serinus canarius, and Poephila guttata) were trained in an operant procedure to fly to sound sources for food reward. The angle between the 2 sound sources was varied on a session-by-session basis, and threshold (i.e., minimum resolvable angle) was taken as the angle that corresponded to a performance level of 75% correct. In all, thresholds were calculated for pure tones of 5 different frequencies, noise bands of 3 different spectral compositions, and species-specific contact or distance calls recorded from each of the 3 species. Thresholds for both simple and complex stimuli were larger than 25 degrees. There were statistically significant species differences for each stimulus set, but these differences were not correlated with species differences in head size. Birds with 1 ear plugged performed as well as binaural birds in this task. Birds deafened in 1 ear, however, performed at chance.

Animals↗
PubMed1990

Hearing and vocalizations in hybrid Waterslager-Roller canaries (Serinus canarius).

A male canary from the Belgian Waterslager strain, which is known for its elevated high-frequency thresholds and a female of German Roller canary with normal high-frequency thresholds were bred. Operant techniques and a psychophysical tracking procedure were used to measure auditory sensitivity of six F1 hybrid canaries from this cross. Three patterns of auditory sensitivity were observed in the six hybrid birds. Four birds showed elevated high-frequency hearing characteristic of the Belgian Waterslager strain; one bird showed normal hearing, and one bird showed an intermediate pattern of auditory sensitivity. A spectral analysis of contact calls recorded from these F1 hybrid canaries showed a spectral distribution of energy which was intermediate between that of Belgian Waterslager strain and the German Roller strain. These results suggest there may be a relation between hearing sensitivity and the spectral distribution of energy in the calls of domestic canaries. Such hybrids may prove useful for examining the genetic basis of more complex behaviors such as vocal learning.

Animals↗
PubMed1990

Detection of auditory sinusoids of fixed and uncertain frequency by budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata).

Three budgerigars and three zebra finches were tested for their ability to detect sinusoidal stimuli in the presence of broadband noise. Masked thresholds for 1, 2, and 4 KHz pure tones were measured with a fixed frequency condition, in which only one test frequency was presented in a session, and with an uncertain frequency condition, in which three signal frequencies were presented in random order in one session. The critical signal/noise ratios obtained in the fixed frequency condition were similar to those reported in a previous study (Okanoya and Dooling, 1987) for both species. When tested in the uncertain frequency condition, critical ratios for zebra finches increased for 1.5 dB at 1 KHz signal but remained unchanged 2 and 4 kHz. The critical ratios for budgerigars showed no difference at any frequency in the uncertain frequency condition. These results suggest that (1) budgerigars and zebra finches are similar in the degree to which attention factors are involved in the detection of signals in noise, and (2) the unusual shape of the budgerigar critical ratio function is not the result of central attentional processes.

Animals↗
PubMed1990

Detection of gaps in noise by budgerigars (Melopsittacus undulatus) and zebra finches (Poephila guttata).

Temporal gap detection thresholds were obtained for two species of birds, budgerigars and zebra finches, which are known to have different auditory filter bandwidths. Both species showed gap detection thresholds of about 2.5 msec for broadband noise stimuli. Comparing octave bands of noise centered at 1, 3, and 5 kHz, zebra finches showed the smallest gap thresholds for the noise band centered at 5 kHz whereas budgerigars showed the smallest gap detection thresholds for the noise band centered at 3 kHz. The results from zebra finches are generally consistent with filter theories of auditory spectro-temporal perception whereas the result from budgerigars are not. In aggregate, these comparative data suggest the relation between spectral and temporal resolving power in these two species may involve different mechanisms.

Animals↗
PubMed1990

Temporal integration in zebra finches (Poephila guttata).

Three zebra finches were trained with operant techniques to respond to pure tones. Absolute thresholds were obtained for nine durations of a 3-kHz tone and five durations of a 1-kHz tone. The temporal integration functions were described using the negative exponential function proposed by Plomp and Bouman [J. Acoust. Soc. Am. 31, 749-758 (1959)]. The time constants obtained for zebra finches are about 250 ms, which are similar to those reported for a number of species, including humans and other bird species.

Animals↗