The evolution of the electroencephalographic response evoked by transformational apparent motion with age

Abstract

The aim of this study was to determine how the visual evoked responses associated to Transformational apparent motion (TAM) develop in a normal population. Fifty human observers, ranging from 3 to 27 years of age, passively viewed a high contrast sinusoidal concentric grating (spatial frequency: 0.8 c/deg; size: 10 deg2), followed by the same grating, radially modulated in amplitude so as to produce a star looking stimulus. The successive presentations of these two stimuli resulted in a TAM (Tse, Cavanagh & Nakayama, 1998). This TAM was presented 50 to 150 times during which the EEG was recorded. The results show a P100-N170-P230 complex at various occipito-temporal electrodes. The topography of this visual evoked potential complex changes considerably with age. In particular, the latencies between the peaks of the components correlate negatively with age, reaching a ceiling at around 14 years of age. As a whole, these results indicate that neural processing of TAM varies from birth to adulthood and that the perceptual maturation of the motion visual system is not complete before adolescence. We offer an explanation in terms of the stabilisation of synaptic density in the various visual areas (Zemon et al., 1997).

Footnotes

 This research was supported by grants from the Canadian Institutes of Health Research (CIHR).