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M F Suesserman

Publications and source records attributed to M F Suesserman.

4 recordsLinked to original sources
PubMed1993

Lumped-parameter model for in vivo cochlear stimulation.

This paper presents a lumped-parameter model that stimulates the in vivo electrical properties of a guinea pig cochlea implanted with a multielectrode stimulating array. A basic model of the low-frequency electroanatomy in a normally functioning guinea pig cochlea is developed by adding critical membrane capacitances to Strelioff's resistive network model [1]. The basic model of normal cochlear tissues is modified to account for anatomical and physiological differences between a normal and implanted cochlea, which results in an impedance model of an implanted cochlea. Simulating the results of in vivo cochlear stimulation verifies the accuracy with which the modified cochlear model represents electrical properties within an electrically stimulated cochlea. Generalized simulations using this model suggest a straightforward phasing scheme capable of achieving sharply focused, channel-independent multielectrode cochlear stimulation.

Animals↗
PubMed1993

Quantitative in vivo measurements of inner ear tissue resistivities: I. In vitro characterization.

An in vivo resistivity measurement system, based on the four-electrode reflection-coefficient technique that nondestructively measures the complex resistivity of cochlear tissues, is described. Details of the theory and instrumentation used for noninvasive measurement of resistivity are presented. In vitro experiments both characterize the accuracy of the proposed resistivity measurement system and establish general criteria for ensuring that a particular theoretical model accurately represents the experimentally measured geometry. Two idealized geometries (two-layer planar and two-layer spherical) are measured experimentally; error analyses using experimental results describe the maximum error with which the experimental system noninvasively estimates resistivity from experimental reflection coefficient measurements. The precise accuracy of a noninvasive resistivity estimate depends on both the variability for experimentally measuring the reflection coefficient of a particular geometry and the average value of the measured reflection coefficient. For example, two-point measurements of an in vitro two-layer planar interface allow noninvasive estimation of complex resistivity with total errors of less than 1%. In addition to characterizing accuracy of resistivity estimates for different in vitro geometries, two general criteria were established: 1) any inhomogeneity within 13.3 times the average interelectrode separation (i.e., within 1662.5 microns for an interelectrode separation of 125 microns) from the microelectrode array must be included in the geometry of the theoretical model and 2) all inhomogeneous boundaries with a radius of curvature greater than 100 times the average interelectrode separation (i.e., greater than 12.5 mm for an average electrode separation of 125 microns) are accurately represented by a planar geometric model.(ABSTRACT TRUNCATED AT 250 WORDS)

Cochlea↗
PubMed1991

In vitro measurement and characterization of current density profiles produced by non-recessed, simple recessed, and radially varying recessed stimulating electrodes.

Potential fields induced by nonrecessed, simple recessed, and radially varying recessed electrode designs were measured in vitro. Comparison of experimental results with theoretical analyses substantiated the experimental measurement technique and emphasized the importance of considering both nonuniform charge injection and surface electrochemistry when designing implantable stimulating electrodes. Radially varying recesses produced uniform charge injection at the electrode surface and at the aperture-tissue interface. In general, the radially varying recessed electrodes provided a combination of uniform charge injection and flexibility in design and fabrication that warrants their incorporation into all appropriate planar stimulating electrode designs.

Electric Conductivity↗