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1.
R. Rübsamen G. Neuweiler G. Marimuthu 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,165(6):755-769
Summary The postnatal development of midbrain tonotopy was investigated in the inferior colliculus (IC) of the south Indian CF-FM batHipposideros speoris. The developmental progress of the three-dimensional frequency representation was determined by systematic stereotaxic recordings of multiunit clusters from the 1st up to the 7th postnatal week. Additional developmental measures included the tuning characteristics of single units (Figs. 3f; 4f; 5f), the analysis of the vocalised pulse repertoire (Figs. 3e, 4e, 5e), and morphometric reconstructions of the brains of all experimental animals (Fig. 1).The maturation of auditory processing could be divided into two distinct, possibly overlapping developmental periods: First, up to the 5th week, the orderly tonotopy in the IC developed, beginning with the low frequency representation and progressively adding the high frequency representation. With regard to the topology of isofrequency sheets within the IC, maturation progresses from dorsolateral to ventromedial (Figs. 3c, 4c). At the end of this phase the entire IC becomes specialised for narrowly tuned and sensitive frequency processing. This includes the establishment of the auditory fovea, i.e. the extensive spatial representation of a narrow band of behaviorally relevant frequencies in the ventromedial part of the IC. In the 5th postnatal week the auditory fovea is concerned with frequencies from 100–118 kHz (Fig. 4c, d). During subsequent development, the frequency tuning of the auditory fovea increases by 20–25 kHz and finally attains the adult range of ca. 125–140 kHz. During this process, neither the bandwidth of the auditory fovea (15–20 kHz) nor the absolute sensitivity of its units (ca. 50 dB SPL) were changed. Further maturation occurred at the single unit level : the sharpness of frequency tuning increased from the 5th to the 7th postnatal weeks (Q-10-dB-values up to 30–60), and upper thresholds emerged (Figs. 4f, 5f).Although in the adult the frequency of the auditory fovea matches that of the vocalised pulses, none of the juvenile bats tested from the 5th to the 7th weeks showed such a frequency match between vocalisation and audition (Figs. 4e, 5e).The results show that postnatal maturation of audition in hipposiderid bats cannot be described by a model based on a single developmental parameter.Abbreviations
BF
best frequency
-
CF
constant frequency
-
Cer
cerebellum
-
CN
cochlear nucleus
-
CO
auditory cortex
-
CUF
cuneiform nucleus
-
DAB
days after birth
-
FAL
forearm length
-
FM
frequency modulation
-
IC
inferior colliculus
-
NLL
nucleus of the lateral lemniscus
-
PAG
periaqueductal gray
-
SC
superior colliculus 相似文献
2.
Summary Injection of tritiated leucine and proline into the nucleus ovoidalis of the Guinea Fowl (Numida meleagris) produces terminal labeling in the palaeostriatum and in three adjacent zones (field L1–L3) of the auditory neostriatum (AN). L2, situated between L1 and L3, receives the main input and corresponds to the former field L of Rose. These neuroanatomically defined zones of the auditory neostriatum are also characterized by differing properties of their neurons. Injection of radioactive material into the auditory neostriatum produces labeling of (i) a palaeostriatal, (ii) a ventral hyperstriatal, and (iii) an additional neostriatal area (Nd). Injection into the hyperstriatum ventrale reveals connections (i) to field L2, (ii) to the palaeostriatum, (iii) to Nd, and (iv) to the archistriatum. After injection into the palaeostriatum, labeling can be observed (i) in the neostriatum dorsale, (ii) in the hyperstriatum ventrale, (iii) in the archistriatum, (iv) in the diencephalic nuclei, nucleus ansae lenticularis and nucleus spiriformis lateralis, and (v) in the mesencephalic nuclei, nucleus tegmenti pedunculo-pontinus and nucleus intercollicularis. These results show that a widespread connectivity exists among primary and presumably higher order auditory areas in the forebrain of birds. Connections also exist between these auditory areas and presumed vocal-motor areas (neostriatum dorsale, archistriatum, nucleus intercollicularis).Abbreviations A
Archistriatum
- AL
Ansa lenticularis
- AN
Auditory neostriatum
- Bas
Nucleus basalis
- CA
Commissura anterior
- Cb
Cerebellum
- CP
Commissura posterior
- DLP
Nucleus dorsolateralis posterior thalami
- DTh
Dorsal thalamus
- E
Ectostriatum
- EM
Nucleus ectomamillaris
- FA
Tractus fronto-archistriatalis
- FPL
Fasciculus prosencephali lateralis
- GLv
Nucleus geniculatus lateralis, pars ventralis
- HA
Hyperstriatum accessorium
- HD
Hyperstriatum dorsale
- HIS
Hyperstriatum intercalatum superius
- HV
Hyperstriatum ventrale
- HVc
Hyperstriatum ventrale, pars caudale
- I
Injection site
- ICo
Nucleus intercollicularis
- ICT
Nucleus intercalatus thalami
- Imc
Nucleus isthmi, pars magnocellularis
- Ipc
Nucleus isthmi, pars parvocellularis
- l1, L2, L3
Auditory neostriatum: zones L1, L2, L3
- LAD
Lamina archistriatalis dorsalis
- LH
Lamina hyperstriatica
- LMD
Lamina medullaris dorsalis
- LPO
Lobus parolfactorius
- M
Mesencephalon
- MLd
Nucleus mesencephalicus lateralis, pars dorsalis
- N
Neostriatum
- nAL
Nucleus ansae lenticularis
- Nc
Neostriatum caudale
- Nd
Neostriatum dorsale
- OM
Tractus occipito-mesencephalicus
- OMv
Nucleus nervi oculomotorii, pars ventralis
- Ov
Nucleus ovoidalis
- PA
Palaeostriatum augmentatum
- PP
Palaeostriatum primitivum
- PT
Nucleus praetectalis
- PVM
Nucleus periventricularis magno-cellularis
- RSd
Nucleus reticularis superior, pars dorsalis
- RSv
Nucleus reticularis superior, pars ventralis
- Rt
Nucleus rotundus
- SMe
Stria medullaris
- SpL
Nucleus spiriformis lateralis
- SpM
Nucleus spiriformis medialis
- SRt
Nucleus subrotundus
- TeO
Tectum opticum
- TOv
Tractus ovoidalis
- TPc
Nucleus tegmenti pedunculo-pontinus
- TrO
Tractus opticus
- TSM
Tractus septo-mesencephalicus
- Ve
Ventricle
The authors are indebted to Mrs. I. Röder and Mrs. M. Hansel for their aid in the preparation of the histological material and the illustrationsThis work was supported by the Deutsche Forschungsgemeinschaft, Sche 132/4 相似文献
3.
M. Vater A. S. Feng M. Betz 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1985,157(5):671-686
Summary The frequency-place map of the horseshoe bat cochlea was studied with the horseradish peroxidase (HRP) technique involving focal injections into various, physiologically defined regions of cochlear nucleus (CN). The locations of labeled spiral ganglion cells and their termination sites on inner hair cells of the organ of Corti from injections into CN-regions responsive to different frequencies were analyzed in three dimensional reconstructions of the cochlea. Horseshoe bats from different geographical populations were investigated. They emit orientation calls with constant frequency (CF) components around 77 kHz (Rhinolophus rouxi from Ceylon) and 84 kHz (Rhinolophus rouxi from India) and their auditory systems are sharply tuned to the respective CF-components.The HRP-map shows that in both populations: (i) the frequency range around the CF-component of the echolocation signal is processed in the second half-turn of the cochlea, where basilar membrane (BM) is not thickened, secondary spiral lamina (LSS) is still present and innervation density is maximal; (ii) frequencies more than 5 kHz above the CF-component are processed in the first halfturn, where the thickened BM is accompanied by LSS and innervation density is low; (iii) frequencies below the spectral content of the orientation call are represented in apical turns showing no morphological specializations. The data demonstrate that the cochlea of horseshoe bats is normalized to the frequency of the individual specific CF-component of the echolocation call.The HRP-map can account for the overrepresentation of neurons sharply tuned to the CF-signal found in the central auditory system. A comparison of the HRP-map with a map derived with the swollen nuclei technique following loud sound exposure (Bruns 1976b) reveals that the latter is shifted towards cochlear base by about 4 mm. This discrepancy warrants a new interpretation of the functional role of specialized morphological structures of the cochlea within the mechanisms giving rise to the exceptionally high frequency selectivity of the auditory system.Abbreviations
AVCN
anteroventral CN
-
BF
best frequency
-
BM
basilar membrane
-
CF
constant frequency
-
CN
cochlear nucleus
-
DCN
dorsal CN
-
FM
frequency modulated
-
HRP
horseradish peroxidase
-
IHC
inner hair cell
-
LSS
secondary spiral lamina
-
OHC
outer hair cell
-
PVCN
posteroventral CN
-
RF
resting frequency
-
RRc
Rhinolophus rouxi from Ceylon
-
RRi
Rhinolophus rouxi from India 相似文献
4.
N. G. Bibikov 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,173(1):123-131
Statistical properties of spontaneous firing were studied in 79 single auditory units located in the dorsal medullar (cochlear) nucleus of unanaesthetized curarized marsh frogs (Rana ridibunda). The great majority of these units showed irregular spontaneous activity with mean rates in the range 1–30 spikes · s–1. In 53% of the cells the auto-renewal functions of the spontaneous activity monotonically rose to an asymptotic value, but 41% of the cells produced auto-renewal functions which showed a pronounced peak after a dead-time period. Five low-frequency auditory neurons revealed periodic firing in the absence of controlled stimuli. The preferred period did not correspond to the unit's best frequency but demonstrated a modest correlation with the best modulation frequency of the unit's response to amplitude-modulated tones and with the duration of the after-onset dip in peri-stimulus time histograms.Abbreviations AM
amplitude modulation
- ARF
auto-renewal function
- DMN
dorsal medullar nucleus
- PST
peristimulus time
- SA
spontaneous activity
- TID
time interval distribution
- RMG
response modulation gain 相似文献
5.
An auditory fovea in the barn owl cochlea 总被引:1,自引:0,他引:1
Christine Köppl Otto Gleich Geoffrey A. Manley 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,171(6):695-704
The distribution of frequencies along the basilar papilla of the barn owl (Tyto alba) was studied by labelling small groups of primary auditory neurones of defined frequency response and tracing them to their peripheral innervation sites. The exact location of marked neurones was determined in cochlear wholemounts with the aid of a special surface preparation technique. The average basilar papilla length (in fixed, embedded specimens) was 10.74 mm.The resulting frequency map shows the basic vertebrate pattern with the lowest frequencies represented apically and increasingly higher frequencies mapped at progressively more basal locations. However, the length of basilar papilla devoted to different frequency ranges, i.e. the space per octave, varies dramatically in the barn owl. The lower frequencies (up to 2 kHz) show values between about 0.35 and 1 mm/octave, which are roughly equivalent to values reported for other birds. Above that, the space increases enormously, the highest octave (5–10 kHz) covering about 6 mm, or more than half of the length of the basilar papilla.Such an overrepresentation of a narrow, behaviourally very important frequency band is also seen in some bats, where it has been termed an acoustic or auditory fovea.Abbreviations CF
characteristic frequency
- HRP
horseradish peroxidase
- NA
Nucleus angularis
- NM
Nucleus magnocellularis 相似文献
6.
Marcus Müller Bodo Laube Hynek Burda Volkmar Bruns 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,171(4):469-476
Summary The cochlea of the mole rat Cryptomys hottentotus was investigated with physiological and anatomical methods. In order to reveal the place-frequency map of the cochlea, iontophoretic HRP-applications were made in the cochlear nucleus at physiologically characterized locations. Subsequent HRP-transport in auditory nerve fibres and labeling patterns of spiral ganglion cells within the cochlea were evaluated.A cochlear place-frequency map was constructed from 17 HRP-applications in the cochlear nucleus at positions where neurons had characteristic frequencies between 0.1 and 12.6 kHz. As in other mammals, high frequencies were found to be represented at the cochlear base, low frequencies at the cochlear apex. The placefrequency map had three distinct parts which were characterized by their different slopes. A clear overrepresentation of the frequencies between 0.6 and 1 kHz was revealed, in this frequency range the slope of the place-frequency map amounted to 5.3 mm/octave. As calculated from the regression analysis, below 0.6 kHz the slope of the cochlear place-frequency map amounted to 0.24 mm/octave, above 1 kHz to 0.9 mm/octave.As in other mammals width of the basilar membrane (BM) increased from the cochlear base towards the cochlear apex. Also in concordance with the findings in other mammals, BM-thickness decreased from the cochlear base to the apex. However, it was remarkable to find that there was no or little change in BM-width and thickness between 40 and 85% BM-length. It was also revealed that scala tympani was only 1/10th the size found in the rat or other mammals of similar body size.On the basis of the cochlear place-frequency map and the morphological findings we speculate that in Cryptomys hottentotus an acoustic fovea is present in the frequency range between 0.6 and 1 kHz. In analogy to echolocating bats, about half of the cochlea is devoted to the analysis of a narrow frequency band within the hearing range.Abbreviations
BM
basilar membrane
-
CF
characteristic frequency
-
CN
cochlear nucleus 相似文献
7.
E F Evans 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》1992,336(1278):295-306
The past 30 years has seen a remarkable development in our understanding of how the auditory system--particularly the peripheral system--processes complex sounds. Perhaps the most significant has been our understanding of the mechanisms underlying auditory frequency selectivity and their importance for normal and impaired auditory processing. Physiologically vulnerable cochlear filtering can account for many aspects of our normal and impaired psychophysical frequency selectivity with important consequences for the perception of complex sounds. For normal hearing, remarkable mechanisms in the organ of Corti, involving enhancement of mechanical tuning (in mammals probably by feedback of electro-mechanically generated energy from the hair cells), produce exquisite tuning, reflected in the tuning properties of cochlear nerve fibres. Recent comparisons of physiological (cochlear nerve) and psychophysical frequency selectivity in the same species indicate that the ear's overall frequency selectivity can be accounted for by this cochlear filtering, at least in bandwidth terms. Because this cochlear filtering is physiologically vulnerable, it deteriorates in deleterious conditions of the cochlea--hypoxia, disease, drugs, noise overexposure, mechanical disturbance--and is reflected in impaired psychophysical frequency selectivity. This is a fundamental feature of sensorineural hearing loss of cochlear origin, and is of diagnostic value. This cochlear filtering, particularly as reflected in the temporal patterns of cochlear fibres to complex sounds, is remarkably robust over a wide range of stimulus levels. Furthermore, cochlear filtering properties are a prime determinant of the 'place' and 'time' coding of frequency at the cochlear nerve level, both of which appear to be involved in pitch perception. The problem of how the place and time coding of complex sounds is effected over the ear's remarkably wide dynamic range is briefly addressed. In the auditory brainstem, particularly the dorsal cochlear nucleus, are inhibitory mechanisms responsible for enhancing the spectral and temporal contrasts in complex sounds. These mechanisms are now being dissected neuropharmacologically. At the cortical level, mechanisms are evident that are capable of abstracting biologically relevant features of complex sounds. Fundamental studies of how the auditory system encodes and processes complex sounds are vital to promising recent applications in the diagnosis and rehabilitation of the hearing impaired. 相似文献
8.
Elena Rosengauer Heiner Hartwich Anna Maria Hartmann Anya Rudnicki Somisetty Venkata Satheesh Karen B. Avraham Hans Gerd Nothwang 《PloS one》2012,7(11)
Histogenesis of the auditory system requires extensive molecular orchestration. Recently, Dicer1, an essential gene for generation of microRNAs, and miR-96 were shown to be important for development of the peripheral auditory system. Here, we investigated their role for the formation of the auditory brainstem. Egr2::Cre-mediated early embryonic ablation of Dicer1 caused severe disruption of auditory brainstem structures. In adult animals, the volume of the cochlear nucleus complex (CNC) was reduced by 73.5%. This decrease is in part attributed to the lack of the microneuronal shell. In contrast, fusiform cells, which similar to the granular cells of the microneural shell are derived from Egr2 positive cells, were still present. The volume reduction of the CNC was already present at birth (67.2% decrease). The superior olivary complex was also drastically affected in these mice. Nissl staining as well as Vglut1 and Calbindin 1 immunolabeling revealed that principal SOC nuclei such as the medial nucleus of the trapezoid body and the lateral superior olive were absent. Only choline acetyltransferase positive neurons of the olivocochlear bundle were observed as a densely packed cell group in the ventrolateral area of the SOC. Mid-embryonic ablation of Dicer1 in the ventral cochlear nucleus by Atoh7::Cre-mediated recombination resulted in normal formation of the cochlear nucleus complex, indicating an early embryonic requirement of Dicer1. Quantitative RT-PCR analysis of miR-96 demonstrated low expression in the embryonic brainstem and up-regulation thereafter, suggesting that other microRNAs are required for proper histogenesis of the auditory brainstem. Together our data identify a critical role of Dicer activity during embryonic development of the auditory brainstem. 相似文献
9.
S. S. Boatright-Horowitz A. Megela Simmons 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1995,177(5):577-590
During metamorphosis, the lateral line system of ranid frogs (Rana catesbeiana) degenerates and an auditory system sensitive to airborne sounds develops. We examined the onset of function and developmental changes in the central auditory system by recording multi-unit activity from the principal nucleus of the torus semicircularis (TSp) of bullfrogs at different postmetamorphic stages in response to tympanically-presented auditory stimuli. No responses were recorded to stimuli of up to 95 dB SPL from latemetamorphic tadpoles, but auditory responses were recorded within 24 hours of completion of metamorphosis. Audiograms from froglets (SVL < 5.5 cm) were relatively flat in shape with high thresholds, and showed a decrease in most sensitive frequency (MSF) from about 2500 Hz to about 1500 Hz throughout the first 7–10 days after completion of metamorphosis. Audiograms from frogs larger than 5.5 cm showed continuous downward shifts in MSF and thresholds, and increases in sharpness around MSF until reaching adult-like values. Spontaneous activity in the TSp increased throughout postmetamorphic development. The torus increased in volume by approximately 50% throughout development and displayed changes in cell density and nuclear organization. These observations suggest that the onset of sensitivity to tympanically presented airborne sounds is limited by peripheral, rather than central, auditory maturation.Abbreviations
CF
characteristic frequency
-
MSF
most sensitive frequency
-
PB
phasic burst
-
PL
primary like
-
S
sustained
-
SVL
snout-vent length
-
TS
torus semicircularis
-
TSl
laminar nucleus of TS
-
TSm
magnocellular nucleus of TS
-
TSp
principal nucleus of TS
-
TW
tympanic width 相似文献
10.
Michael B. Calford 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1988,162(4):491-502
Summary Extracellular recordings were made from the midbrain auditory area to determine the limits of auditory frequency sensitivity in a variety of birds. The audiograms of some species show a consistent missing frequency range of 1/3 to 1/2 an octave, to which no neurons are tuned. All species, except owls, have a low upper frequency limit in comparison with mammals of similar headwidth. A consideration of both the upper frequency limits and the missing frequency ranges led to the conclusion that frequencies which do not generate localization cues are not represented in the midbrain. The upper frequency limit appears to match the upper limit of generation of significant interaural and monaural intensity cues to localization. The variation of these cues with frequency was examined through a simple model of the birds' sound receiving system which incorporated the interaural canal and considered the tympanic membranes as pressure difference receivers. Apart from coraciiform species, which have low upper frequency limits matching the frequency of the primary missing frequency band of other species, and owls, which have high upper frequency limits, the upper frequency limits of the birds studied are inversely related to head-width.The argument for missing frequency ranges being related to nonlocalizable frequencies is simpler, for it has been found previously, using cochlear microphonic recording, that within a bird's audiogram there are frequency regions with poor directionality cues. These regions appear to correspond to the missing frequency ranges.Abbreviation
nMLD
nucleus mesencephalicus lateralis dorsalis 相似文献
11.
12.
Lubov P. Dmitrieva Gilbert Gottlieb 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1992,171(5):665-671
Summary The development of the brainstem auditory evoked potential (BAEP) was studied in mallard duck (Anas platyrhynchos) embryos and hatchlings from 5–6 days before hatching through two days after hatching in response to tone pips of different frequencies. BAEPs showed a different time of onset and a different rate of development for low, middle, and high frequencies. Although auditory sensitivity in the mid-frequency range (1.0, 1.5, 2.0, and 3.0 kHz) appeared 1–2 days later than in the low-frequency range, development of the BAEPs in the mid-frequency range was almost complete by hatching. In contrast, the development of auditory sensitivity in the low- and high-frequency ranges continued to develop after hatching. Accelerated development of BAEPs to middle frequencies during the embryonic period and to high frequencies after hatching was correlated with the ducklings' exposure to their own mid-frequency and high-frequency vocalizations before and after hatching, respectively.Abbreviations
BAEP
brainstem auditory evoked potential
-
CM
cochlear microphonic
-
CT
contact-contentment call
-
DT
distress call
-
EP
evoked potential 相似文献
13.
Geoffrey A. Manley Otto Gleich Alexander Kaiser Jutta Brix 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,164(3):289-296
Summary Mammals and birds have independently developed different populations of sensory cells grouped across the width of their auditory papillae. Although in mammals there is clear evidence for disparate functions for the two hair-cell populations, the different anatomical pattern in birds has made comparisons difficult. In two species of birds, we have used single-fibre staining techniques to trace physiologically-characterized primary auditory nerve fibres to their peripheral synapses. As in mammals, acoustically-active afferent fibres of these birds innervate exclusively the neurally-lying group of hair cells in a 11 relationship, suggesting important parallels in the functional organization of the auditory papillae in these two vertebrate classes. In addition, we found a strong trend of the threshold to acoustic stimuli at the characteristic frequency across the width of the avian papilla.Abbreviations
IHC
inner hair cell(s)
-
OHC
outer hair cell(s)
-
SHC
short hair cell(s)
-
THC
tall hair cell(s) 相似文献
14.
Despite the outstanding auditory capabilities of dolphins, there is only limited information available on the cytology of the auditory brain stem nuclei in these animals. Here, we investigated the cochlear nuclei (CN) of five brains of common dolphins (Delphinus delphis) and La Plata dolphins (Pontoporia blainvillei) using cell and fiber stain microslide series representing the three main anatomical planes. In general, the CN in dolphins comprise the same set of subnuclei as in other mammals. However, the volume ratio of the dorsal cochlear nucleus (DCN) in relation to the ventral cochlear nucleus (VCN) of dolphins represents a minimum among the mammals examined so far. Because, for example, in cats the DCN is necessary for reflexive orientation of the head and pinnae towards a sound source, the massive restrictions in head movability in dolphins and the absence of outer ears may be correlated with the reduction of the DCN. Moreover, the same set of main neuron types were found in the dolphin CN as in other mammals, including octopus and multipolar cells. Because the latter two types of neurons are thought to be involved in the recognition of complex sounds, including speech, we suggest that, in dolphins, they may be involved in the processing of their communication signals. Comparison of the toothed whale species studied here revealed that large spherical cells were present in the La Plata dolphin but absent in the common dolphin. These neurons are known to be engaged in the processing of low‐frequency sounds in terrestrial mammals. Accordingly, in the common dolphin, the absence of large spherical cells seems to be correlated with a shift of its auditory spectrum into the high‐frequency range above 20 kHz. The existence of large spherical cells in the VCN of the La Plata dolphin, however, is enigmatic asthis species uses frequencies around 130 kHz. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc. 相似文献
15.
In mammals, auditory hair cells are generated only during embryonic development and loss or damage to hair cells is permanent. However, in non-mammalian vertebrate species, such as birds, neighboring glia-like supporting cells regenerate auditory hair cells by both mitotic and non-mitotic mechanisms. Based on work in intact cochlear tissue, it is thought that Notch signaling might restrict supporting cell plasticity in the mammalian cochlea. However, it is unresolved how Notch signaling functions in the hair cell-damaged cochlea and the molecular and cellular changes induced in supporting cells in response to hair cell trauma are poorly understood. Here we show that gentamicin-induced hair cell loss in early postnatal mouse cochlear tissue induces rapid morphological changes in supporting cells, which facilitate the sealing of gaps left by dying hair cells. Moreover, we provide evidence that Notch signaling is active in the hair cell damaged cochlea and identify Hes1, Hey1, Hey2, HeyL, and Sox2 as targets and potential Notch effectors of this hair cell-independent mechanism of Notch signaling. Using Cre/loxP based labeling system we demonstrate that inhibition of Notch signaling with a γ- secretase inhibitor (GSI) results in the trans-differentiation of supporting cells into hair cell-like cells. Moreover, we show that these hair cell-like cells, generated by supporting cells have molecular, cellular, and basic electrophysiological properties similar to immature hair cells rather than supporting cells. Lastly, we show that the vast majority of these newly generated hair cell-like cells express the outer hair cell specific motor protein prestin. 相似文献
16.
Background
The auditory efferent system has unique neuroanatomical pathways that connect the cerebral cortex with sensory receptor cells. Pyramidal neurons located in layers V and VI of the primary auditory cortex constitute descending projections to the thalamus, inferior colliculus, and even directly to the superior olivary complex and to the cochlear nucleus. Efferent pathways are connected to the cochlear receptor by the olivocochlear system, which innervates outer hair cells and auditory nerve fibers. The functional role of the cortico-olivocochlear efferent system remains debated. We hypothesized that auditory cortex basal activity modulates cochlear and auditory-nerve afferent responses through the efferent system.Methodology/Principal Findings
Cochlear microphonics (CM), auditory-nerve compound action potentials (CAP) and auditory cortex evoked potentials (ACEP) were recorded in twenty anesthetized chinchillas, before, during and after auditory cortex deactivation by two methods: lidocaine microinjections or cortical cooling with cryoloops. Auditory cortex deactivation induced a transient reduction in ACEP amplitudes in fifteen animals (deactivation experiments) and a permanent reduction in five chinchillas (lesion experiments). We found significant changes in the amplitude of CM in both types of experiments, being the most common effect a CM decrease found in fifteen animals. Concomitantly to CM amplitude changes, we found CAP increases in seven chinchillas and CAP reductions in thirteen animals. Although ACEP amplitudes were completely recovered after ninety minutes in deactivation experiments, only partial recovery was observed in the magnitudes of cochlear responses.Conclusions/Significance
These results show that blocking ongoing auditory cortex activity modulates CM and CAP responses, demonstrating that cortico-olivocochlear circuits regulate auditory nerve and cochlear responses through a basal efferent tone. The diversity of the obtained effects suggests that there are at least two functional pathways from the auditory cortex to the cochlea. 相似文献17.
The accurate perception of sound frequency by vertebrates relies upon the tuning of hair cells, which are arranged along auditory organs according to frequency. This arrangement, which is termed a tonotopic gradient, results from the coordination of many cellular and extracellular features. Seeking the mechanisms that orchestrate those features and govern the tonotopic gradient, we used expression microarrays to identify genes differentially expressed between the high- and low-frequency cochlear regions of the chick (Gallus gallus). Of the three signaling systems that were represented extensively in the results, we focused on the notch pathway and particularly on DNER, a putative notch ligand, and PTPζ, a receptor phosphatase that controls DNER trafficking. Immunohistochemistry confirmed that both proteins are expressed more strongly in hair cells at the cochlear apex than in those at the base. At the apical surface of each hair cell, the proteins display polarized, mutually exclusive localization patterns. Using morpholinos to decrease the expression of DNER or PTPζ as well as a retroviral vector to overexpress DNER, we observed disturbances of hair-bundle morphology and orientation. Our results suggest a role for DNER and PTPζ in hair-cell development and possibly in the specification of tonotopy. 相似文献
18.
Heidi Faber Katharina Braun Werner Zuschratter Henning Scheich 《Cell and tissue research》1989,256(2):247-257
Summary The brain of young domestic chicks was investigated using a Timm sulfide silver method. Serial Vibratome sections were analyzed under the light microscope, and the localization of zinc-positive structures in selected areas was determined at the ultrastructural level. Both strong and differential staining was visible in the avian telencephalon whereas most subtelencephalic structures showed a pale reaction. The highest staining intensity was found in the nonprimary sensory regions of the telencephalon such as the hyperstriatum dorsale, hyperstriatum ventrale, hippocampus, palaeostriatum augmentatum, lobus parolfactorius and caudal parts of neostriatum. There was an overall gradient of staining intensity in neostriatal areas from rostral to caudal with the heaviest zinc deposits in the caudal neostriatum. Primary sensory projection areas, such as the ectostriatum (visual), hyperstriatum intercalatum superius (visual), nucleus basalis (beak representation), the input layer L2 of the auditory field L and the somatosensory area rostral to field L were selectively left unstained. Fiber tracts throughout the brain were free of zinc deposits except for glial cells. In electron micrographs of stained regions, silver grains were localized in some presynaptic boutons of asymmetric synapses (Gray type I), within the cytoplasm of neuronal somata and sporadically in the nucleus. The possible involvement of zinc in synaptic transmission and other processes is discussed.Abbreviations for Anatomical Structures used in the Text and Figures
Ac
Nucleus accumbens
-
Ad
Archistriatum dorsale
-
Ai
Archistriatum intermedium
-
Am
Archistriatum mediale
-
Ap
Archistriatum posterior
-
APH
Area parahippocampalis
-
BAS
Nucleus basalis
-
BO
Bulbus olfactorius
-
Cb
Cerebellum;
-
CbI
Nucleus cerebellaris internus
-
CbM
Nucleus cerebellaris intermedius
-
CDL
Area corticoidea dorsolateralis
-
CPi
Cortex piriformis
-
CT
Commissura tectalis
-
DMP
Nucleus dorsomedialis posterior thalami
-
E
Ectostriatum
-
H
Hyperstriatum
-
HA
Hyperstriatum accessorium
-
HD
Hyperstriatum dorsale
-
HIS
Hyperstriatum intercalatum superius
-
Hp
Hippocampus
-
HV
Hyperstriatum ventrale
-
ICo
Nucleus intercollicularis
-
Ipc
Nucleus isthmi, pars parvocellularis
-
L
Lingula
-
L
1, 2, 3
Field L
-
La
Nucleus laminaris
-
LFM
Lamina frontalis suprema
-
LFS
Lamina frontalis superior
-
LH
Lamina hyperstriatica
-
LMD
Lamina medullaris dorsalis
-
LNH
Rostrolateral neostriatum/Hyperstriatum ventrale
-
LPO
Lobus parolfactorius
-
M
Medulla
-
MLd
Nucleus mesencephalicus lateralis, pars dorsalis
-
MNH
Rostromedial neostriatum/Hyperstriatum ventrale
-
N
Neostriatum
-
NC
Neostriatum caudale
-
NEB
Nucleus of ectostriatal belt
-
NHA
Nucleus of HA
-
PA
Palaeostriatum augmentatum
-
Pap
Nucleus papillioformis
-
PL
Nucleus pontis lateralis
-
PP
Palaeostriatum primitivum
-
RP
Nucleus reticularis pontis caudalis
-
Rt
Nucleus rotundus
-
S
Nucleus septalis
-
SS
Somatosensory area
-
TeO
Tectum opticum
-
Tn
Nucleus taeniae
-
TPO
Area temporoparieto-occipitalis
-
V
Ventricle
-
Va
Vallecula 相似文献
19.
Russell F. Huffman O. W. Henson Jr. 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1993,171(6):725-734
Summary Acoustic stimuli near 60 kHz elicit pronounced resonance in the cochlea of the mustached bat (Pteronotus parnellii parnellii). The cochlear resonance frequency (CRF) is near the second harmonic, constant frequency (CF2) component of the bat's biosonar signals. Within narrow bands where CF2 and third harmonic (CF3) echoes are maintained, the cochlea has sharp tuning characteristics that are conserved throughout the central auditory system. The purpose of this study was to examine the effects of temperature-related shifts in the CRF on the tuning properties of neurons in the cochlear nucleus and inferior colliculus.Eighty-two single and multi-unit recordings were characterizedin 6 awake bats with chronically implanted cochlear microphonic electrodes. As the CRF changed with body temperature, the tuning curves of neurons sharply tuned to frequencies near the CF2 and CF3 shifted with the CRF in every case, yielding a change in the unit's best frequency. The results show that cochlear tuning is labile in the mustached bat, and that this lability produces tonotopic shifts in the frequency response of central auditory neurons. Furthermore, results provide evidence of shifts in the frequency-to-place code within the sharply tuned CF2 and CF3 regions of the cochlea. In conjunction with the finding that biosonar emission frequency and the CRF shift concomitantly with temperature and flight, it is concluded that the adjustment of biosonar signals accommodates the shifts in cochlear and neural tuning that occur with active echolocation.Abbreviations BF
best frequency
- CF
characteristic frequency
- CF2, CF3
second and third harmonic, constant frequency components of the biosonar signal
- CM
cochlear microphonic
- CN
cochlear nucleus
- CRF
cochlear resonance frequency
- IC
inferior colliculus
- MT
minimum threshold
- OAE
otoacoustic emission
- Q10dB
BF (or CF) divided by the response bandwidth at 10 dB above MT 相似文献
20.
S. D. Schlussman M. A. Kobylack A. A. Dunn-Meynell S. C. Sharma 《Cell and tissue research》1990,262(3):531-541
Summary Horseradish peroxidase was injected unilaterally into the optic tectum of the channel catfish, Ictalurus punctatus. The sources of tectal afferents were thereby revealed by retrogradely labeled neurons in various brain centers. Retrogradely labeled cells were seen in both the ipsilateral and contralateral telencephalon. The superficial pretectal area was labeled on both sides of the brain. Ipsilateral projections were also observed coming from the entopeduncular nucleus. Both the anterior thalamic nucleus and the ventro-medial thalamic nucleus projected to the ipsilateral optic tectum. Cells in the ipsilateral nucleus of the posterior commissure were seen to project to the tectum. Labeled fibers were visualized in the lateral geniculate nucleus ipsilateral to the injected tectum, however, no labeled cell bodies were observed. Therefore, tectal cells project to the lateral geniculate nucleus, but this projection is not reciprocal. No labeled cells were found in the cerebellum. Labeled cells occurred in both the ipsilateral and contralateral medial reticular formation; they were also observed in the ipsilateral nucleus isthmi. A projection was seen coming from the dorsal funicular nucleus. Furthermore, labeled cells were shown in the inferior raphe nucleus.Abbreviations
AP
Area pretectalis
-
C
Cerebellum
-
DPTN
Dorsal posterior tegmental nucleus
-
H
Habenula
-
IRF
Inferior reticular formation
-
LI
Inferior lobe
-
LGN
Lateral geniculate nucleus
-
LR
Lateral recess
-
MB
Mammillary body
-
MRF
Medial reticular formation
-
MZ
Medial zone of the telencephalon
-
NC
Nucleus corticalis
-
NDL-M
Nucleus opticus dorsolateralis/pars medialis
-
NI
Nucleus isthmi
-
NPC
Nucleus of the posterior commissure
-
OPT
Optic tectum
-
OT
Optic tract
-
PC
Posterior commissure
-
PN
Pineal organ
-
PrOP
Preoptic nucleus
-
PT
Pretectum
-
TBt
Tectobulbar tract
-
TEL
Telencephalon
-
TL
Torus longitudinalis
-
TS
Torus semicircularis
-
VC
Valvula cerebelli
-
VLTN
Ventrolateral thalamic nucleus
-
VMTN
Ventromedial thalamic nucleus 相似文献