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Background: Lead is a pervasive neurotoxicant that has been associated with poorer cognitive, behavioral, and motor outcomes in children. The effects of lead on sensory function have not been well characterized. The aim of this study was to assess the effects of prenatal lead exposure on infant sensory function, as measured by auditory brainstem response (ABR) and grating visual acuity (VA).Methods: Lead was measured in maternal blood in mid- and late-pregnancy (mean gestational age = 15.5 and 39.0 weeks, respectively) and umbilical cord blood in a cohort of full-term infants in rural northeastern China. ABR latencies (peaks I, III, V) were measured in newborns during unsedated sleep (n = 315). The ABR central-to-peripheral (C-P) ratio was calculated as the ratio between the III-V and I-III interpeak intervals. VA was measured in 6-week-olds using Teller Acuity Cards (n = 1019) and assigned as the narrowest grid the infant fixated on. Multivariate linear regression was used to evaluate relationships between tertiles of mid-pregnancy, late-pregnancy, or cord lead and newborn ABR or 6-week VA.Results: Higher late-pregnancy lead levels were associated with higher ABR C-P ratios and lower VA. In covariate-adjusted analyses, mean C-P ratios were 4.6 and 3.2 % higher in infants whose mothers had lead > 3.8 μg/dL and lead = 2-3.8 μg/dL, respectively, than for infants whose mothers had lead < 2 μg/dL (p-trend =0.002). In adjusted analyses for VA, mean scores were 8.5 and 7.2 % lower for maternal lead > 3.8 μg/dL and lead = 2-3.8 μg/dL, respectively, compared to lead < 2 μg/dL (p-trend =0.009).Conclusion: Auditory and visual systems maturation appears delayed in infants with higher prenatal lead exposure during late-pregnancy, even at relatively low levels. Both systems start myelinating in late gestation and mature rapidly in infancy. Higher ABR C-P ratio and lower grating VA scores suggest effects of low-level lead exposure on sensory system myelination. [ABSTRACT FROM AUTHOR]

Infants' understanding of how their actions affect the visibility of hidden objects may be a crucial aspect of the development of search behaviour. To investigate this possibility, 7-month-old infants took part in a two-day training study. At the start of the first session, and at the end of the second, all infants performed a search task with a hiding-well. On both days, infants had an additional training experience. The 'Agency group' learnt to spin a turntable to reveal a hidden toy, whilst the 'Means-End' group learnt the same means-end motor action, but the toy was always visible. The Agency group showed greater improvement on the hiding-well search task following their training experience. We suggest that the Agency group's turntable experience was effective because it provided the experience of bringing objects back into visibility by one's actions. Further, the performance of the Agency group demonstrates generalized transfer of learning across situations with both different motor actions and stimuli in infants as young as 7 months. [ABSTRACT FROM AUTHOR]

Discusses the implantation of intraocular lenses in infancy which resulted to the rapid growth of the eye during the stage and its long-term visual outcomes. Causes and prevalence of cataract among infants; Background on the ocular growth and visual development of babies; Challenges in implanting intraocular lenses.

We monitored changes in looking that emerged when 3- to 6-month-old infants were presented with 48 trials pairing familiar and novel faces. Graphic displays were used to identify changes in looking throughout the task. Many infants exhibited strong side biases produced by infants looking repeatedly in the same direction. Although an overall novelty preference was found for the group, individual infants exhibited brief novelty runs. Few infants began with a familiarity preference. We argue that variable looking patterns emerged during the task from competition between the infants' preference to look to something novel versus their tendency to look back to previous locations. Our data suggest that looking during paired-comparison tasks is a dynamic process dependent on perceptual-motor events happening during the task itself. [ABSTRACT FROM AUTHOR]

Many studies have demonstrated that newborns prefer upright faces over upside-down faces. Based on this evidence, some have suggested that faces represent a special class of stimuli for newborns and there is a qualitative difference between the processes involved in perception of facelike and non-facelike patterns (i.e. structural hypothesis). Others suggest that there is no reason to suppose that faces are different from other patterns, because faces, like any other class of visual stimuli, are subject to filtering by the properties of the visual system (i.e. sensory hypothesis). The core question that will be addressed in the present paper is whether, to manifest itself, face preference requires the unique structure of the face, represented by the relative spatial location of its internal features, or rather some more general properties that other stimuli may also possess. Evidence will be presented supporting the idea that newborns do not respond to facelike stimuli by ‘facedness’ but, rather, by some general structural characteristics that best satisfy the constraints of the immature visual system. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Colour and facial configuration are both very salient aspects of the visual environment for infants, but may both be selectively processed by the right hemisphere (RHS) and under some conditions may compete for RHS resources. The present investigation assessed the relative potency of facial configuration and colour in the two halves of the visual field for 32 infants (with a mean age of 24 weeks). The infants were familiarized to triads of facial figures presented for 250 ms in the left or right visual field. The faces were all different in colour and facial pattern (expression), but one of them (the target) was shown in an upright orientation while the others (distractors) were inverted. The results of paired-comparison recognition tests indicated that the displays had been initially parsed in terms of configurational category (upright faces versus inverted non-faces) in both visual fields, attesting to the primacy of this categorical distinction in both hemispheres. However, the focus for subsequent encoding reflected marked hemispheric discrepancies, with a left visual field (RHS) bias to target colour (comprising the first evidence of this for infants) and a contrary right visual field [left hemisphere (LHS)] advantage for distractor pattern. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]