ECVP 2006 Abstract

Cite as:
Shirai N, Birtles D B, Wattam-Bell J, Yamaguchi M K, Kanazawa S, Atkinson J, Braddick O J, 2006, "Anistropic cortical responses for radial expansion/contraction in infants and adults" Perception 35 ECVP Abstract Supplement

Anistropic cortical responses for radial expansion/contraction in infants and adults

N Shirai, D B Birtles, J Wattam-Bell, M K Yamaguchi, S Kanazawa, J Atkinson, O J Braddick

Radial expansion/contraction can be crucial cues of motion-in-depth perception such as objects approaching/receding or observers' own forward/backward motion. Here we report the anisotropic cortical responses (steady-state VEPs) to radial expansion/contraction in human infants and adults. A total of forty-four infants (twenty-two 3.5 months old and twenty-two 4.5 months old) and nine adults participated in the present study. The participants were exposed to stimuli composed of 2000 moving dots which cyclically alternated their motion directions between radial expansion (or contraction) and random directional motion. The speed of each dot was maintained at 6.8 deg s-1. The pattern alternation occurred every 240 ms. Hence the frequency of pattern alternation in each stimulus was 2.085 Hz. We compared amplitudes of F1 (2.085 Hz) component in steady-state VEPs between expansion - random and contraction - random motion alternations (expansion condition and contraction condition, respectively). We found out that mean F1 amplitudes in the contraction condition were significantly larger than those in the expansion condition for the older infants and adults. These results suggest that the human cortical motion mechanisms have anisotropic sensitivities for radial expansion/contraction and the anisotropy may develop between 3.5 and 4.5 months of age.
[Supported by Medical Research Council (UK) programme grant G7908507 to JA, OJB, JW-B, and grant-in-aid for scientific research from the Japan Society for the Promotion of Science to NS (17-741).]

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