Search PubMed⌕ Search

Biomedical subjects

A Flock

Publications and source records attributed to A Flock.

At least 109 records · Page 6Linked to original sources
PubMed1970

Receptor potentials from hair cells of the lateral line.

Intracellular recordings from hair cells in the tail lateral line of mudpuppy Necturus maculosus show receptor potentials less than 800 microvolts, peak to peak, from stimuli that are considered large compared to natural stimuli. The hair cells are in neuromasts that are sensitive at the time of recording and are identified by both in vivo and in vitro examination of intracellular staining.

Animals↗
PubMed1966

The ultrastructure of the sensory hairs and associated organelles of the cochlear inner hair cell, with reference to directional sensitivity.

From the apical end of the inner hair cell of the organ of Corti in the guinea pig cochlea protrude four to five rows of stereocilia shaped in a pattern not unlike the wings of a bird. In the area devoid of cuticular substance facing toward the tunnel of Corti lies a consistently present centriole. The ultrastructure of this centriole is similar to that of the basal body of the kinocilium located in the periphery of the sensory hair bundles in the vestibular and lateral line organ sensory cells and to that of the centrioles of other cells. The physiological implications of the anatomical orientation of this centriole are discussed in terms of directional sensitivity.

Animals↗
PubMedDate not supplied

Investigating routes to chaos in the guinea-pig cochlea using the continuous wavelet transform and the short-time Fourier transform.

The continuous wavelet transform (CWT) and the short-time Fourier transform (STFT) were used to analyze the time course of cellular motion in the guinea pig inner ear. The velocity responses of individual outer hair cells and Hensen's cells to amplitude modulated (AM) acoustical signals applied to the ear canal displayed characteristics typical of nonlinear systems, such as the generation of spectral components at harmonics of the carrier frequency. Nonlinear effects were particularly pronounced at the highest stimulus levels, where half-harmonic (and sometimes quarter-harmonic) components were also seen. The generation of these components was consistent with the behavior of a dynamical system entering chaos via a period-doubling route. A negative-stiffness Duffing oscillator model yielded period-doubling behavior similar to that of the experimental data. We compared the effectiveness of the CWT and the STFT for analyzing the responses to AM stimuli. The CWT (calculated using a high-Q Morlet-wavelet basis) and the STFT were both useful for identifying the various spectral components present in the AM velocity response of the cell. The high-Q Morlet wavelet CWT was particularly effective in distinguishing the lowest frequency components present in the response, since its frequency resolution is appreciably better than the STFT at low frequencies. Octave-band-based CWTs (using low-Q Morlet, Meyer, and Daubechies 4-tap wavelets) were largely ineffective in analyzing these signals, inasmuch as the frequency spacing between neighboring spectral components was far less than one octave.

Animals↗
PubMedDate not supplied

Dissociated single cells from the inner ear: strial cells.

Using the enzyme dissociation technique, the authors successfully isolated strial marginal cells and intermediate cells from guinea pig and chinchilla cochleas. Dissociated cells were maintained for in vitro observation under the light microscope for up to 2 hours without gross evidence of cell damage. Such single cells were successfully prepared for scanning or transmission electron microscopic observation, which showed excellent cell shape and preservation of cell organelles. However, there was evidence of increased vesiculation in the dissociated marginal cells, which is interpreted to be evidence of increased pinocytotic activity.

Animals↗
PubMedDate not supplied

Graded and nonlinear mechanical properties of sensory hairs in the mammalian hearing organ.

It is generally agreed that frequency selectivity of the mammalian hearing organ is mainly due to a graded elasticity of the basilar membrane. Recent measurements of basilar membrane motion hair cell receptor potentials and neural tuning curves show that frequency selectivity can be extremely sharp. It has been suggested that in non-mammalian species there are additional tuning mechanisms in the sensory hair cells themselves, either by virtue of their electrical membrane properties or through a gradation in length of their sensory hairs. Indeed, sensory hair mechanical tuning has been demonstrated in the lizard. We have investigated the mechanical properties of sensory hair bundles in the guinea pig organ of Corti, and report here that hair-bundle stiffness increases longitudinally towards the high-frequency end of the cochlea, decreases radially towards the outer rows of cells, and is greater for excitatory than for inhibitory deflection. On the basis of these findings, we suggest that sensory hairs confer frequency-specific, nonlinear mechanical properties on the hearing organ.

Animals↗
PubMedDate not supplied

Studies on the sensory hairs of receptor cells in the inner ear.

The crista ampullaris of the semicircular canal in the frog can be isolated and mounted in a chamber so that the sensory hairs can be observed under high magnification in interference-contrast. The cupula is removed and the sensory hairs can be manipulated and their mechanical properties investigated by a microprobe held in a micromanipulator. The hairs appear quite stiff and pivot around their base. When subjected to force they break as if they are brittle. All the cilia within a bundle move together as if joined to one another. Labelling for electron-microscopy with polycationic ferritin reveals that the membrane surrounding the cilia has a surface coat of negatively charged molecules. When the organ is incubated with polycationic ferritin before fixation the sensory hairs agglutinate. Fusion of the membrane surrounding individual sensory hairs also occurs.

Animals↗
PubMedDate not supplied

Electron probe determination of relative ion distribution in the inner ear.

The relative amounts of potassium and chlorine present in various parts of the inner ear were studied by using an energy dispersive X-ray spectrometer in conjunction with a scanning electron microscope. Whereas the amount of chlorine was high in all compartments investigated, potassium was high in endolymphatic spaces and low in perilymphatic spaces. High contents of potassium and chlorine were also found in the tectorial membrane, in the inner sulcus and in the cupula of the semicircular canal. It is concluded that the tectorial membrane and the cupula do not present a barrier to ions and that therefore the sensory hairs in the inner ear are exposed to the ionic environment provided by the endolymph.

Animals↗