Fourier-analysed steady-state VEPs in pre-school children with and without normal binocularity.
Pre-school children aged 4-5 were examined with steady-state VEP in response to a sinusoidal grating pattern with a spatial frequency of 4 c/deg, reversing at rates 5, 10, and 15 Hz. Normal children (n = 10) were compared with subjects lacking stereo perception (n = 6) and with subjects showing significant unilateral amblyopia with visual acuity in the worse eye <0.5 (n = 7). Fast Fourier Transform was used for analysis of the crude steady-state VEP responses. Compared to normals, the subjects lacking stereo perception showed a significantly lower power of the second harmonic in the response evoked by binocular stimulation with gratings reversed at 15 Hz. The amblyopic group showed a significant difference between the dominant and the non-dominant eye regarding the first harmonic power in the responses evoked by gratings reversed at 5 and 10 Hz. These findings are discussed in relation to the magnocellular and parvocellular visual pathways and suggested models for linear and non-linear processing of visual signals.
Johansson
Björn
B
Department of Ophthalmology, Faculty of Health Sciences, University Hospital, SE-581 85, Linköping, Sweden. bjorn.johansson@lio.se
Jakobsson
Peter
P
D000550:Amblyopia / Q000503:physiopathology*; D002675:Child, Preschool; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005583:Fourier Analysis; D006801:Humans; D015357:Vision Disparity / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*