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Dive into the research topics where Erich E. Sutter is active.

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Featured researches published by Erich E. Sutter.


Vision Research | 1992

The field topography of ERG components in man—I. The photopic luminance response

Erich E. Sutter; Duong Tran

A technique of multi-input systems analysis is used to explore the field topography of ERG responses to local luminance modulation. Variations in amplitude and wave form are studied within the central 23 degrees. Outside the fovea, the amplitude appears to follow a simple power law rx as a function of eccentricity r where x is approximately -2/3. The largest inter-subject variability is found in the fovea. Some nasal-temporal asymmetry is observed in all subjects with higher response densities in the temporal field outside the blind spot. The topography of the luminance response shares all these properties with the density of retinal cones.


Journal of Microcomputer Applications | 1992

The brain response interface: communication through visually-induced electrical brain responses

Erich E. Sutter

Abstract This paper discusses an experimental communication system for severely disabled persons that utilizes electrical responses from the brain. Scientific background and methodology as well as the results of a preliminary evaluation are presented.


SIAM Journal on Computing | 1991

The fast m-transform: a fast computation of cross-correlations with binary m-sequences

Erich E. Sutter

An algorithm is presented for the fast computation of the m-transform, a Hadamard transform intimately related to cross-correlation of analog signals with binary m-sequences. It is shown that m-transforms are in the same Hadamard equivalence class as Walsh–Hadamard transforms and can, thus, becomputed by means of the Fast Walsh Transform (FWT) algorithm, preceded and followed by a permutation. The FWT is performed in place in the original data array, while the permutations are executed during loading and reading of this array. Real-time generation of the array addresses for loading and reading adds little to execution time of the FWT. The implementation described here lends itself particularly well to applications in linear and nonlinear systems analysis.


Journal of The Optical Society of America A-optics Image Science and Vision | 1996

Imaging localized retinal dysfunction with the multifocal electroretinogram.

Marcus A. Bearse; Erich E. Sutter

Conventional electroretinographic techniques do not permit efficient mapping of retinal responsiveness for the detection of small dysfunctional areas. This study explores the application of a new technique that makes such mapping possible. It utilizes a multifocal electroretinogram technique based on binary m sequences that simultaneously tests a large number of small retinal areas by multiplexing their responses onto a single signal derived from the human cornea. The focal responses are subsequently extracted for the derivation of high-resolution maps that characterize retinal responsiveness. The required recording times are short enough to make such testing feasible in the clinic. In this study we demonstrate the high sensitivity of the technique by mapping a small area that has been partially bleached by a strobe flash in a normal retina and by mapping dysfunctional areas in three patients with different, well-documented retinal pathologies. The results suggest that the multifocal electroretinogram has the potential to become a valuable clinical tool.


Vision Research | 1999

The optic nerve head component of the human ERG

Erich E. Sutter; Marcus A. Bearse

The local responses of the multifocal ERG reveal continuous changes in the second order waveforms from the nasal to the temporal retina. Scrutiny of these changes suggests the presence of an additive component whose latency increases with the distance of the stimulus from the optic nerve head. This observation led to the hypothesis of a contributing source in the vicinity of the optic nerve head whose signal is delayed in proportion to the fiber length from the stimulated retinal patch to the nerve head. The hypothesis was tested with two independent methods. In Method 1, a set of different local response waveforms was approximated by two fixed components whose relative latency was allowed to vary and the fit of this two component model was evaluated. In Method 2, two signals were derived simultaneously using different placements for the reference electrode. The placements were selected to produce a different ratio of the signal contributions from the retina and the nerve head in the two recording channels. The signals were then combined at a ratio that canceled the retinal component. Method 1 yielded an excellent fit of the two component model. Waveforms and latencies of the hypothetical optic nerve head component derived from the two methods agree well with each other. The local latencies also agree with the propagation delays measured in the nerve fiber layer of the monkey retina. In combination, these findings provide strong evidence for a signal source near the optic nerve head.


Vision Research | 1997

M and P components of the VEP and their visual field distribution.

Heidi A. Baseler; Erich E. Sutter

To study components related to parallel processing of information across the visual field, multi-focal pattern reversal visual evoked potentials (VEPs) were recorded using binary m-sequences. Contrast, chromatic, spatial and temporal characteristics of the stimuli were varied in order to favor contributions from either M or P pathways. Responses were decomposed into two additive components whose behavior was consistent with that of M and P mechanisms. The results suggest that contributions to the VEP from the M pathway precede those from the P pathway, and that the ratio of P/M contributions decreases with eccentricity.


Vision Research | 2001

Imaging visual function with the multifocal m-sequence technique

Erich E. Sutter

The multifocal m-sequence technique is a versatile set of tools for visual electrophysiology designed to provide access to the complex dynamic interplay of converging signals in the central nervous system. Here, a number of uses for the technique are demonstrated, with examples from human electroretinography. A simple relationship between the binary kernels extracted from a single experiment permits us to distinguish local from lateral interactions in the retina. Transformation of the series of binary kernels into response sequences provides new insight into unexpected fast dynamic properties of retinal responses and facilitates future modeling of the signals as well as identification of the signal sources.


Vision Research | 1998

Assessment of local retinal function in patients with retinitis pigmentosa using the multi-focal ERG technique

Donald C. Hood; Karen Holopigian; Vivienne C. Greenstein; William Seiple; Ju Li; Erich E. Sutter; Ronald E. Carr

To assess local retinal function in patients with retinitis pigmentosa (RP), multi-focal ERGs and local thresholds (static visual fields) were obtained on eight RP patients with visual acuities of 20/25 or better. All eight patients showed multi-focal responses with normal timing within the central 5 deg. However, there were few responses with normal timing in the areas outside the central 7.5 deg, except in the case of the only patient with a 30 Hz full-field response with normal timing. Since full-field ERGs are dominated by responses from the periphery, this finding supplies a foundation for the commonly observed delays in the full-field cone ERGs of patients with RP. With respect to amplitude, only two patients showed multi-focal responses with near normal amplitudes anywhere in the field. The loss of amplitude at any point was not a good predictor of visual sensitivity in the Humphrey visual field. On the other hand, all areas with normal timing had near normal sensitivity. Timing changes appear to be an early indication of local retinal damage to the cone system. Nearly all areas with sensitivity losses greater than 0.5 log unit, and some areas with near normal sensitivity, showed significantly delayed multi-focal ERGs. Finally areas with extreme sensitivity loss show multi-focal responses with a wide range of amplitudes and implicit times across patients, suggesting different mechanisms of disease action in different patients.


Documenta Ophthalmologica | 2000

The interpretation of multifocal binary kernels

Erich E. Sutter

The interpretation of binary kernels derived by means of the mulifocal ERG has frequently been the source of confusion and controversy. The aim of this paper is to provide an intuitive understanding of the concept of kernels and to demonstrate with models and examples, the relationship between the kernels and individual responses. The sample data used to illustrate the various aspects of the technique were derived and analyzed by means of the multifocal VERISTM instrument using bipolar Burian-Allen contact lens electrodes. From the kernel data, response waveforms are synthesized that can be readily compared with those obtained with conventional flash, double flash and multi-flash ERG techniques. From the kernels of a single multifocal record, waveforms are synthesized that describe responses at various times after a preceding focal flash. It is shown that the observed adaptive changes in the waveforms depend not only on the flash interval but also on retinal eccentricity. Features on the response waveform exhibit independent adaptive behavior suggesting that they originate from different retinal sources.On one hand, the examples presented here illustrate the rich information on retinal dynamics contained in the kernels. On the other hand, they demonstrate how the interpretation of multifocal data can be facilitated when the kernel series is transformed into representations with more direct physiological appeal.


Visual Neuroscience | 1995

A topographic study of oscillatory potentials in man

Shuang Wu; Erich E. Sutter

The purpose of this study was to evaluate the use of slow multifocal m-sequence stimulation in analyzing the topographic distribution and underlying mechanisms (including nonlinearities) of the retinal oscillatory potentials (OPs). In giving us access to the response topography and the nonlinear characteristics of the OPs, the m-sequence technique provides us with two important means for the identification and characterization of the signal sources. In this study, we analyzed the OPs into the first- and second-order components and investigated their topographies and luminance dependence. The distribution of both the first- and second-order OP components differed significantly from that of the flicker ERG investigated by Sutter and Tran (1992). At eccentricities and luminance levels favoring activity by both rods and cones, the second-order OPs were particularly prominent, showing the most clear-defined and complex waveform. The topographic distribution of the second-order OPs showed combined features of both rod and cone distributions. On a strong rod-bleaching background, the second-order OPs were eliminated and the first-order OPs showed a reduced amplitude and a shifted latency. These results are consistent with the notion that the second-order component of the OPs is dominated by contributions from rod-cone interactions.

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Marcus A. Bearse

Smith-Kettlewell Institute

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M.K. Menz

Smith-Kettlewell Institute

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John S. Werner

University of California

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M.D. Menz

Smith-Kettlewell Institute

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M Wang

Smith-Kettlewell Institute

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Takuji Kasamatsu

Smith-Kettlewell Institute

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Cm Poloschek

Smith-Kettlewell Institute

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