Predicting distributed retinal source activity from ERG data. II. Multiple stimulus approach

For pt.I see ibid., vol.35, no.11, p.941-7 (1988). The objective of this research is the noninvasive prediction of retinal cell activity; more specifically, the goal is to assess the healthiness of discrete regions of the retina. The authors describe a multiple-stimulus approach which involves a single-potential measurement of the cornea as is commonly done clinically at present, but which multiple-flash stimuli. The technique is ultimately dependent on the patient's ability to focus on the external flash stimulus pattern. The individual components of the ERG (electroretinogram), which are directly associated with specific parts of the stimulus pattern (and thus, localized regions on the retina), are stripped off of the composite ERG using signal-correlation techniques. At the heart of this approach is the requirement that the isolated stimuli are each individually uncorrelated to one another, i.e., they are random in time. An analytical ERG is constructed to test the efficacy of the use of single- and double-kernel correlations for predicting retinal impulse responses.<>     

Microcomputer analyses of clinical ERG, EOG, and other tests of retinal function

The electroretinogram (ERG) and electro-oculogram (EOG) are two of the most frequently used visual electrodiagnostic tests of retinal function. The ERG and EOG are easily measured, but there are many engineering difficulties in processing their signal data because the response amplitudes are relatively small, and the relevant signals are buried in electromagnetic and biologic noise. These tests tend to be time consuming, so they lend themselves to automatic control. This article describes the engineering designs relative to a microprocessor-based electrophysiologic laboratory at Emory University Clinic to perform ERG, EOG, and other clinical tests of retinal function. A comparable system that offered both the ability to accept data from a variety of transducers and the flexibility to permit all of the planned testing protocols was not available from any commercial source.     

Real-Time Computer for First-and Second-Order Wiener Kernels

This correspondence describes the design and application of an instrument which computes real-time estimates of first- and second-order Wiener kernels. The instrument performs the appropriate correlations between the measured response and a ternary conversion of the white-noise stimulus. An example application is described for a study of the human electroretinogram.     

Wiener Kernels and Frequency Response Functions for the Human Retina

The human electroretinogram (ERG) was analyzed for white noise and sinusoidal stimuli. The frequency response function calculated for white noise stimuli matched the Bode plot obtained using sinusoidal stimuli. Similaly, the second-order kernel accurately predicted the second harmonic of the measured sine wave responses.