Abstract
Distinct neural areas are involved in the global processing of form and motion cues. These two types of visual processing also develop at different rates, and may be differentially vulnerable to early brain injury or atypical neurodevelopment (Braddick et al., 2003, 2007). Children born extremely prematurely show elevated global motion coherence thresholds relative to full-term peers (Downie et al., 2003; Jakobson et al., 2006), and those with white matter pathology do not show normal sensitivity to biological motion (Pavolva et al., 2003, 2004). Here, we measured sensitivity to global form, global motion, and biological motion in a sample of 23 5- to 9-year-old children born at 4.1, ps [[lt]]0.05), with performance being correlated with birthweight and gestational age for global form sensitivity only. For each premature child, we calculated a deficit score for each task (ratio of threshold for premature child vs mean threshold for 3 age-matched controls). A deficit score of 1 indicates performance comparable to controls', while a score greater than 1 indicates some level of impairment. A series of one-sample t-tests revealed that mean deficit scores were significantly greater than 1 for biological motion and global motion (ps [[lt]].03). In contrast, the mean deficit score for global form was not significantly different from 1. Rates of clinically significant impairment (deficit score ≥ 2) were 4 times more common for global motion than for global form (p [[lt]].04). Our findings of greater deficits in biological motion and global motion than in global form in preterm children compliment previous studies demonstrating dorsal stream vulnerability (e.g., Braddick et al., 2003, 2007).
Grant to LSJ from the Natural Sciences and Engineering Research Council (Canada).