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Biomedical subjects

R P Michelson

Publications and source records attributed to R P Michelson.

8 recordsLinked to original sources
PubMed1991

Magnetic field changes associated with caloric stimulation of the human vestibular organ.

Caloric stimulation of the ear produces a shift of the vestibular resting potential. The current produced by the change in this potential produces a corresponding change in the associated magnetic field. A sensitive magnetic detector (second-derivative gradiometer) was used to detect a large shift in the magnetic field close to the ears of two normal subjects who underwent cold thermic ear stimulation. The shift in the magnetic field tracked the reflex responses in both individuals. This technique could offer a noninvasive direct measure of end-organ function.

Caloric Tests↗
PubMed1979

Protocol for determining the auditory percepts of electrical stimulation of the cochlea.

The percepts of electrical stimulation of the auditory nerve can best be determined in man. An eight channel bipolar electrode array has been developed which allows discreet stimulation of segments of auditory nerve via the scala tympani. In addition, a programmable stimulator has been developed which allows the delivery of different waveforms and stimulus patterns. Hopefully this will begin to allow the generation of the elements of speech.

Animals↗
PubMed1976

Cochlear implants.

All presently devised single channel devices generate a primitive sensation of hearing by the mechanism of 'periodicity pitch'. No 'place pitch' encoding is possible. Although some enhancement of communicative skills with lip reading results, unaided speech discrimination is not possible. Definite psychological advantages for the totally deaf have been observed with these simple devices. Multiple segments of auditory nerve must be stimulated in a manner which will simulate the complex patterns of neural activity necessary for speech discrimination. Electrode optimization and the pathophysiological consequences of electrical stimulation of the auditory nerve can best be determined in animals. The perceptual consequences of electrical stimulation of the auditory nerve, however, can best be determined in man. How much we will have to innovate the methods of aural rehabilitation will depend upon how well we can generate perceptual speech patterns by electrical excitation of the auditory nerve.

Acoustic Stimulation↗
PubMed1975

Auditory evoked frequency following responses in man.

A sound-evoked sinusoidal response was recorded from the temporal scalp area in six humans. This evoked signal is similar in its characteristics to (and may correspond with) the "frequency-following response" of Worden and Marsh recorded on the scalp in man by Moushegian and colleagues. The site of origin of the response recorded in these subjects is not known, but it is of interest that the aspect of the scalp, and that the influence of arousal state on response amplitude paralleled the described effects of changes in arousal state on the primary auditory cortical evoked response. This technique may allow for the direct measurement of auditory thresholds across the frequency domain. This is possible because measured responses can be obtained at sound levels of the order of 15 to 20 dB across the frequency range from 300 to 2,500 Hz.

Acoustic Stimulation↗
PubMedDate not supplied

Present status and future development of the cochlear prosthesis.

Presently devised single channel devices generate relatively primitive sensation of hearing. They provide some enhancement of communication skills for the totally deaf. Definite psychological advantages for the totally deaf have been observed. Pitch discrimination is by the mechanism of "periodicity pitch." No "place" pitch encoding is possible. The recognition of complex sounds is not possible. Multiple segments of auditory nerve must be stimulated in a manner which will stimulate the complex patterns of neural activity necessary for speech discrimination. Electrodes can be optimized and the pathophysiological consequences of electrical stimulation can be determined in experimental animals. The perceptual consequences of electrical stimulation, however, can best be determined in man himself. How much we will have to rely on known and future methods of aural rehabilitation will depend upon how well perceptual speech patterns can be generated by electrical stimulation of the auditory nerve.

Animals↗