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N Y Kiang

Publications and source records attributed to N Y Kiang.

10 recordsLinked to original sources
PubMed1991

Unmyelinated axons of the auditory nerve in cats.

This paper describes some central terminations of type II spiral ganglion neurons as labeled by extracellular injections of horseradish peroxidase (HRP) into the auditory nerve of cats. After histological processing with diaminobenzidine, both thick (2-4 microns) and thin (0.5 microns) fibers of the auditory nerve were stained. Whenever traced, thick fibers always originated from type I spiral ganglion neurons and thin fibers always from type II ganglion neurons. Because the labeling of type II axons faded as fibers projected into the cochlear nucleus, this report is limited to regions of the ventral cochlear nucleus near the auditory nerve root. The central axons of type II neurons are unmyelinated, have simple yet variable branching patterns in the cochlear nucleus, and form both en passant and terminal swellings. Under the light microscope, most swellings are located in the neuropil but they are also found in the vicinity of cell bodies, nodes of Ranvier of type I axons, and blood vessels. Eighteen en passant swellings in the neuropil were located by light microscopy and resectioned for electron microscopy; two of these swellings exhibited ultrastructural features characteristic of chemical synapses. The data indicate that inputs from outer hair cells might be able to influence auditory processing in the cochlear nucleus through type II primary neurons.

Animals↗
PubMed1976

Analysis of discharges recorded simultaneously from pairs of auditory nerve fibers.

Spike trains were recorded simultaneously from pairs of auditory nerve fibres in anesthetized cats. Tests for correlation between spike trains were developed for spontaneous activity and for discharge patterns resulting from single-tone stimuli. The application of these tests to the recordings indicates that the responses of auditory nerve fibers to a tone and to silence can be described as statistically independent point processes. This result implies that the initiation of spikes in these fibers is governed by localized processes specific for each fiber.

Acoustic Stimulation↗
PubMed1975

A block model of the cat cochlear nucleus.

A three-dimensional block model of the cochlear nucleus of the cat was constructed from histologic sections. Boundaries of various subdivisions, based on cytoarchitectonic criteria, were included in the model. Usage of the block model in correlating physiological and anatomical data is illustrated by localizing characteristic waveforms of gross evoked responses and characteristic frequencies of single units.

Animals↗
PubMed1975

Single unit activity in the posteroventral cochlear nucleus of the cat.

Single unit activity in the posteroventral cochlear nucleus (PVCN) was recorded for a variety of stimulus conditions. The units were classified according to their response characteristics. The locations of units were plotted onto a three-dimensional block model of the cochlear nucleus. Certain types of units that responded best to the onsets of stimuli were located predominantly in the octopus cell region of the PVCN. The remainder of the PVCN, which contains a rather heterogeneous collection of small and multipolar cells, was found to contain several types of units with the dominant type being "chopper" units.

Acoustic Stimulation↗
PubMed1975

Single unit activity in the dorsal cochlear nucleus of the cat.

Single unit activity was examined in three component layers of the dorsal cochlear nucleus (DCN): the molecular layer, the fusiform cell layer, and the polymorphic layer (deep DCN). Electrophysiological units were classified into types on the basis of their activity under a variety of stimulus conditions. In the molecular layer spike activity was small and difficult to isolate. Almost all units in the fusiform cell layer could be classified as either "pauser" or "buildup" units. Classification of units in the deep DCN was sometimes difficult, but "pauser," "chopper," and some "on" units were found. The "on" types of units tended to be located in the more superficial part of the deep DCN. Unit locations were referred to a three-dimensional block model of the cochlear nucleus.

Acoustic Stimulation↗
PubMedDate not supplied

Recording auditory-nerve potentials as an office procedure.

Recording auditory-nerve potentials from human subjects is already a routine procedure in the laboratory. In order to bring such recording capabilities into the office of practicing otologists, a number of difficulties had to be overcome. First, a small signal averager was built and incorporated into a stimulus generating and response recording system. The entire system was made portable and self-sufficient. The effects of electrical interference and background acoustic noise were shown to be tolerable. After studies of how responses vary with electrode location, electrodes were designed to be placed on the ear canal so that no invasive procedures were necessary. Methods were found to simplify the procedure so that recordings can be made in a matter of minutes by one person working alone.

Acoustic Stimulation↗
PubMedDate not supplied

Auditory-nerve activity in cats exposed to ototoxic drugs and high-intensity sounds.

The response characteristics of auditory-nerve fibers in normal cats are compared with those in cats exposed to kanamycin and high-intensity sounds. The pathophysiology is characterized by an elevation of the tuning-curve "tips," which is sometimes associated with hypersensitivity of the "tails". Plots of unit thresholds are correlated with patterns of sensory-cell losses in the cochlea. There can be significant shifts in unit threshold without significant loss of hair cells; however, significant hair cell loss is always accompanied by highly abnormal unit thresholds. The presence of inner hair cells seems to be essential for the long-term survival of spiral ganglion cells. An incidental observation is that in the "normal" animal there is almost always a prominent "notch" at 3-4 kHz in the plots of threshold at characteristic frequency, which may have been produced by environmental noise.

Animals↗
PubMedDate not supplied

Fundamental considerations in designing auditory implants.

The usual premise underlying developmental work on cochlear prostheses as prospective cures for profound deafness is that the auditory nerve can be electrically stimulated in such a manner that communicative skills can be developed or maintained. Physiologic recordings from single fibers in the cat's auditory nerve and attempts to model these responses have generated a description of how the auditory nerve codes complex sounds such as speech. This work suggests that certain minimal cues might have to be present at the level of the auditory nerve in order that adequate discrimination of specific speech signals can take place. The prospects for achieving a useful prosthesis in the near future will be evaluated in terms of what can be expected from current attempts to code the artificial stimulation properly.

Acoustic Stimulation↗