Biomedical subjects

R B Patuzzi

Publications and source records attributed to R B Patuzzi.

21 records · Page 2Linked to original sources

PubMed1987

A model of the generation of the cochlear microphonic with nonlinear hair cell transduction and nonlinear basilar membrane mechanics.

A phenomenological model of the generation of the cochlear microphonic of the guinea pig is presented which incorporates sharp tuning and nonlinear growth of the vibration of the cochlear partition, and nonlinear transduction of this response by a single linear array of hair cells (assumed to be the outer hair cells). The contribution to the microphonic potential from each hair cell generator is also assumed to decay exponentially with distance from the hair cell. Using experimentally obtained estimates for the parameters a good agreement between the theoretical microphonic tuning curves and growth functions was obtained without recourse to complex micromechanical motion of the cochlear partition, electrical tuning of the hair cells or a contribution from the inner hair cells of the cochlea.

Acoustic Stimulation↗

PubMed1987

The low-frequency response of inner hair cells in the guinea pig cochlea: implications for fluid coupling and resonance of the stereocilia.

AC receptor potentials within the inner hair cells of the basal turn of the guinea pig cochlea have been recorded for stimuli in the frequency range 20 Hz to 3200 Hz. Comparison of these potentials with potentials recorded in scala media suggests that the stereocilia of many inner hair cells are stimulated by the transverse velocity of the cochlear partition for very low frequency, but above a transition frequency in the range 400 Hz to 1000 Hz they become entrained with partition displacement. It is suggested that such a transition is probably a simple consequence of the fluid coupling that drives these cells, and that mechanical resonance of the free-standing stereocilia of the inner hair cells does not occur in the basal turn of the guinea pig. These results do not, however, preclude the possibility of mechanical resonance involving the stereocilia of the outer hair cells. The results also indicate that the bodies of these cells low-pass filter the intracellular receptor potential, with a cutoff frequency of approximately 1000 Hz.

Acoustic Stimulation↗

PubMedDate not supplied

Auditory evoked response test strategies to reduce cost and increase efficiency: the postauricular muscle response revisited.

We describe a number of techniques in auditory evoked response (AER) testing for hearing loss which should decrease its cost and increase its efficiency, making its use in infant hearing screening more viable. We demonstrate the use of bit-stream averaging of the electrical signals from the head as a cheap alternative to analogue averaging and show that the average waveforms obtained are similar with both techniques. We demonstrate how the postauricular muscle response (PAMR) can be potentiated by lateral rotation of the eyes and argue that uncontrolled eye movements in previous studies have led to an unfounded belief that the PAMR is not stable. When eye rotation is used to potentiate the PAMR, the response becomes very stable and so large in most subjects that it is clearly visible in the raw traces. We also demonstrate that when the PAMR is potentiated by eye rotation, stable PAMR waveforms can be reliably obtained with tone bursts with frequencies up to and above 8 kHz and with sound levels within 30 dB of the subjective detection threshold. As a result the PAMR can be used to rapidly determine an objective audiogram in most subjects within minutes. Finally, we demonstrate a correlation technique for detecting the PAMR without waveform averaging and the need for an expensive computer. We are sure that a combination of these techniques can be used to increase the efficiency of AER screening for infant deafness and lower its cost dramatically.

Audiometry, Pure-Tone↗