The course and morphology of efferent nerve fibres in the papilla basilaris of the pigeon (Columba livia)

Keppler, Christiane; Schermuly, Lothar; Klinke, Rainer

doi:10.1016/0378-5955(94)90194-5

Cited by 19 publications

(14 citation statements)

References 16 publications

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“…Several investigators have seen efferent axons of two different sizes innervating the avian basilar papilla. These thicker and thinner axons tend to form calyx‐like terminals on short hair cells (and continue to the hyaline cell area) and bouton terminals on tall hair cells, respectively (Whitehead & Morest, 1981; Keppler et al ., 1994). However, there may not be a sharp distinction between the two types, but rather a continuum, at least for the terminals, which correlates with the gradual transition between the hair‐cell types (Firbas & Müller, 1983; Fischer, 1992, 1994b; Fischer et al ., 1992; Keppler et al ., 1994).…”

Section: Discussionsupporting

confidence: 91%

“…This is most strikingly evident in their different innervation, with the tall hair cells receiving all of the afferent connections (reviews in Fischer, 1994a; Gleich & Manley, 2000). Both tall and short hair cells are efferently innervated, however, different populations of efferent neurons may be the respective sources (Takasaka & Smith, 1971; Whitehead & Morest, 1981; Firbas & Müller, 1983; Keppler et al ., 1994; Zidanic & Fuchs, 1996; Carr & Code, 2000). Some efferent fibres that target the short hair cells also contact the hyaline cells, a specialized nonsensory cell type of unknown function, adjacent to the outer (or abneural) border of the hair‐cell epithelium (Takasaka & Smith, 1971; Keppler et al ., 1994; Zidanic & Fuchs, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Efferent axons in the avian auditory nerve

Köppl

2001

Eur J of Neuroscience

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The sensory hair cells of the inner ear receive both afferent and efferent innervation. The efferent supply to the auditory organ has evolved in birds and mammals into a separate complex system, with several types of neurons of largely unknown function. In this study, the efferent axons in four different species of birds (chicken, starling, barn owl and emu) were examined anatomically. Total numbers of efferents supplying the cochlear duct (auditory basilar papilla and the vestibular lagenar macula) were determined; separate estimates of the efferents to the lagenar macula only were also derived and subtracted. The numbers for auditory efferents thus varied between 120 (chicken) and 1068 (barn owl). Considering the much larger numbers of hair cells in the basilar papilla, each efferent is predicted to branch extensively. However, pronounced species-specific differences as well as regional differences along the tonotopic gradient of the basilar papilla were documented. Myelinated and unmyelinated axons were found, with mean diameters of about 1 microm and about 0.5 microm, respectively. This suggests two basic populations of efferents, however, they did not appear to be distinguished sharply. Evidence is presented that some efferents lose their myelination at the transition from central oligodendrocyte to peripheral Schwann cell myelin. Finally, a comparison of the four bird species evaluated suggests that the efferent population with smaller, unmyelinated axons is the phylogenetically more primitive one. A new population probably arose in parallel with the evolution and differentiation of the specialized hair-cell type it innervates, the short hair cell.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Efferent axons in the avian auditory nerve

Köppl

2001

Eur J of Neuroscience

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“…Although few investigations have attempted to characterize the precise roles of these two categories of hair cells in auditory processing, it is known that avian THC are involved in the mechanoelectrical transduction of sound signals whereas SHC are responsible for the sensitivity of the ear, modulating and regulating its responsiveness (Chiappe, Kozlov & Hudspeth, 2007). Besides the sensory hair cells, nonsensory hyaline cells located abneurally on the crocodilian and avian basilar papilla receive efferent innervation and may act in the regulation of the mechanical properties of the basilar papilla (Keppler, Schermuly & Klinke, 1994; Ofsie & Cotanche, 1996). In birds as well as in the spectacled caiman, the basilar papilla is topographically organized: the base, which has more SHC, is more sensitive to high frequencies than the apex with its more numerous THC (Fig.…”

Section: Production and Detection Of Acoustic Signalsmentioning

confidence: 99%

Acoustic communication in crocodilians: from behaviour to brain

2009

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Crocodilians and birds are the modern representatives of Phylum Archosauria. Although there have been recent advances in our understanding of the phylogeny and ecology of ancient archosaurs like dinosaurs, it still remains a challenge to obtain reliable information about their behaviour. The comparative study of birds and crocodiles represents one approach to this interesting problem. One of their shared behavioural features is the use of acoustic communication, especially in the context of parental care. Although considerable data are available for birds, information concerning crocodilians is limited. The aim of this review is to summarize current knowledge about acoustic communication in crocodilians, from sound production to hearing processes, and to stimulate research in this field. Juvenile crocodilians utter a variety of communication sounds that can be classified into various functional categories: (1) "hatching calls", solicit the parents at hatching and fine-tune hatching synchrony among siblings; (2) "contact calls", thought to maintain cohesion among juveniles; (3) "distress calls", induce parental protection; and (4) "threat and disturbance calls", which perhaps function in defence. Adult calls can likewise be classified as follows: (1) "bellows", emitted by both sexes and believed to function during courtship and territorial defence; (2) "maternal growls", might maintain cohesion among offspring; and (3) "hisses", may function in defence. However, further experiments are needed to identify the role of each call more accurately as well as systematic studies concerning the acoustic structure of vocalizations. The mechanism of sound production and its control are also poorly understood. No specialized vocal apparatus has been described in detail and the motor neural circuitry remains to be elucidated. The hearing capabilities of crocodilians appear to be adapted to sound detection in both air and water. The ear functional anatomy and the auditory sensitivity of these reptiles are similar in many respects to those of birds. The crocodilian nervous system likewise shares many features with that of birds, especially regarding the neuroanatomy of the auditory pathways. However, the functional anatomy of the telencephalic auditory areas is less well understood in crocodilians compared to birds.

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“…The cochlear efferent system in birds con sists of two populations: (1) thick fibers that contact short and intermediate hair cells over the free basilar membrane and hyaline cells, and (2) thin fibers that contact short or inter mediate hair cells over the free basilar mem brane or tall hair cells over the neural limbus [28,29], Since the hyaline cells contain con tractile proteins, it is conceivable that efferent activation could affect the hyaline cells and alter the tension of the basilar membrane, thereby altering the DPOAE amplitude. We are not aware of any direct evidence to sup port this.…”

Section: Activation O F the Olivocochlear System And Dpoaesmentioning

confidence: 99%

2f<sub>1</sub>-f<sub>2</sub> Distortion Product Otoacoustic Emissions in White Leghorn Chickens (Gallus domesticus):Effects of Frequency Ratio and Relative Level

Burkard

Salvi²,

Chen³

1996

Audiol Neurotol

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The effects of primary tone frequency ratio (f₂/f₁ ratio) and relative level (L₂/L₁) on the amplitude of the cubic difference tone (CDT: 2f₁–f₂) distortion product otoacoustic emissions (DPOAEs) were investigated in adult White Leghorn chickens (Gαllus domesticus). In experiment 1, 9 f₂/f₁ ratios ranging from 1.05 to 1.8 were investigated. Measurements were obtained from both ears of 4 chickens at 7 f₁ frequencies ranging from 0.8 to 4.0 kHz. The primary tones were equal in level, and varied from 20 to 80 dB SPL. The mean CDT amplitude increased with increasing primary tone level once the measurement noise floor was exceeded. The input/ output functions assumed one of two shapes: one in which there was a systematic increase in DPOAE amplitude with increasing primary tone level, and the other in which there was a plateau in the input/output function near 65–70 dB SPL. At the highest primary tone level (80 dB SPL), there was a decrease in the CDT amplitude with increasing f₂/f₁ ratio. At high primary tone levels, the f₂/f₁ ratio which produced the largest CDT was 1.05 or 1.1, while at lower primary tone levels the largest CDT occurred at f₂/f₁ ratios of 1.2–1.3. In experiment 2, L₂ was held constant at 70 dB SPL, and L₁ varied from 50 to 80 dB SPL. For f₁frequencies of 0.8 and 3.2 kHz, there was an increase in the CDT amplitude with increasing L₁, followed by an asymptote at higher levels. In contrast, for 1.6 and 2.0 kHz f₁ frequencies, the amplitude increased, plateaued and then increased again at higher levels. Informal measurements suggest that spontaneous otoacoustic emissions (SOAEs) are rarely seen in chickens. However, a reliable SOAE was observed in 1 chicken, which could be suppressed by external sounds and anoxia.

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The course and morphology of efferent nerve fibres in the papilla basilaris of the pigeon (Columba livia)

Cited by 19 publications

References 16 publications

Efferent axons in the avian auditory nerve

Efferent axons in the avian auditory nerve

Acoustic communication in crocodilians: from behaviour to brain

2f<sub>1</sub>-f<sub>2</sub> Distortion Product Otoacoustic Emissions in White Leghorn Chickens (Gallus domesticus):Effects of Frequency Ratio and Relative Level

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