Computer analysis of ENG spectral features from patients with congenital nystagmus

Fixed point analysis of nystagmus

“…The difficulty of obtaining reliable estimates of the eigenvalues simply, does not support the use of the fixed point technique as a method for building a quantitative model of a neural system. In the context of nystagmus, the major advantage of the technique is that it enables quantitative descriptions of the effects of experimental manipulations to be obtained despite the variable nature of the waveform (Reccia et al, 1990;Clement et al, 2002;Optican and Miura, 2004). After using the technique to recover examples of the underlying periodic orbits in two cases of nystagmus, we have been able to show that there are significant changes in the peak-to-peak amplitudes of the example cycles with changes in gaze angle.…”

“…It may be idiopathic, associated with a sensory abnormality, or more rarely, a neurological lesion (Harris, 1997). The main difficulty in analysing earlyonset nystagmus waveforms is that they are very variable, so that it has been difficult to obtain consistent results (Reccia et al, 1990;Clement et al, 2002;Optican and Miura, 2004). This is a common problem amongst motor disorders, so that effective techniques for analysing eye movement recordings should have widespread applicability.…”

“…The main peak provides a good measure of the average frequency and amplitude of the early-onset nystagmus waveform. Fourier analysis has revealed that even pure pendular nystagmus, which is often described as sinusoidal, has harmonic components (Reccia et al, 1990;Abadi and Worfolk, 1991).…”

“…The oscillatory movement of early-onset nystagmus can be characterized by the Fourier components of the eye position signal (Dell'Osso et al, 1974;Dickinson and Abadi, 1985;Reccia et al, 1989Reccia et al, , 1990Abadi and Worfolk, 1991;Worfolk and Abadi, 1991;Clement et al, 2002). Typically there is a peak in the power spectrum at the fundamental frequency of the oscillation, together with harmonic components with smaller amplitudes.…”

Can we really walk straight?

“…A n indeterminate form or pattern can be easily quantified using Fourier analysis, which has been used to analyze a variety of biological forms, from crania (Lestrel and Roch, 1986;Lestrel, 1989;Inoue, 1990) and (Halazonetis et al, 1991) to the waveshape of electronystagmograms (Reccia et al, 1990). In this study, taking the step width distance of 64 sequential steps as the axis of the ordinate and step number as the abscissa, Fourier analysis was used to examine patterns of step width change.…”