Abstract
Visual and visuocognitive measures potentially provide sensitive early indicators of brain development in children at risk from perinatal brain injury (PBI). Here we report findings from the 'Dolphin' trial of preterm and term-born infants with PBI graded on MRI as 1 (normal/mild), 2 (moderate), or 3 (severe). Infants were tested 3-4 times between 0-24 months, using two VERP latency measures, fixation shifts (FS) to detect early attention deficits, and the ABCDEFV functional vision battery (Atkinson et al, 2002). VERPs were recorded in 57 PBI infants for a contrast reversing grating (2-8 reversals/sec). Latency measures from (a) the transient P1 peak at 2 r/sec; (b) the gradient of steady-state phase against frequency ('calculated'), were compared with typically developing infants (Lee et al ,2012). Transient latencies in most PBI and all typically developing infants reached adult levels around 100 ms by age 4-5 months. In contrast, calculated latency, which in typical development asymptotes to adult levels before age 1 year, averaged over 200 ms for PBI infants. The calculated measure, reflecting the time course of cortical processing beyond initial activation of V1, is thus more sensitive to cerebral impairment. On FS, 33 PBI infants, tested between 4-8 months post-term age, made significantly more errors and longer latencies to shift attention, with performance worsening across PBI severity, compared to typically developing infants (Atkinson & Braddick, 2012). These attention deficits in PBI infants , which reflect poor cortical control, were more marked when the initially centrally fixated target remained visible when the second peripheral target appeared ('competition'). On the ABCDEFV many PBI infants showed deficits particularly on visuo-motor, visual field and spatial tasks related to dorsal stream function. We will discuss the relation of VERP latencies, attentional performance, and functional vision tasks to developing brain mechanisms and their remediation in PBI.
Meeting abstract presented at VSS 2014