Visual and visuocognitive development in children born very prematurely
In: Progress in Brain Research; From Action to Cognition, S. 123-149
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In: Progress in Brain Research; From Action to Cognition, S. 123-149
In: Progress in Brain Research; From Action to Cognition, S. 151-168
In: Developmental science, Band 15, Heft 1, S. 74-86
ISSN: 1467-7687
AbstractIndividuals with Williams syndrome (WS) have impairments in visuospatial tasks and in manual visuomotor control, consistent with parietal and cerebellar abnormalities. Here we examined whether individuals with WS also have difficulties in visually controlling whole‐body movements. We investigated visual control of stepping down at a change of level in children with WS (5–16‐year‐olds), who descended a single step while their movement was kinematically recorded. On each trial step height was set unpredictably, so that visual information was necessary to perceive the step depth and position the legs appropriately before landing. Kinematic measures established that children with WS did not use visual information to slow the leg at an appropriate point during the step. This pattern contrasts with that observed in typically developing 3‐ and 4‐year‐old children, implying severe impairment in whole‐body visuomotor control in WS. For children with WS, performance was not significantly predicted by low‐level visual or balance problems, but improved significantly with verbal age. The results suggest some plasticity and development in WS whole‐body control. These data clearly show that visuospatial and visuomotor deficits in WS extend to the locomotor domain. Taken together with evidence for parietal and cerebellar abnormalities in WS, these results also provide new evidence for the role of these circuits in the visual control of whole‐body movement.
In: Developmental science, Band 11, Heft 4, S. 583-595
ISSN: 1467-7687
Abstract Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body‐, environment‐, and object‐based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body‐ and environment‐based frames of reference. Crucially, object‐based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark‐based representations supplement those based on the body and on self‐motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.
In: Developmental science, Band 12, Heft 6, S. 946-955
ISSN: 1467-7687
AbstractWe report asymmetrical cortical responses (steady‐state visual evoked potentials) to radial expansion and contraction in human infants and adults. Forty‐four infants (22 3‐month‐olds and 22 4‐month‐olds) and nine adults viewed dynamic dot patterns which cyclically (2.1 Hz) alternate between radial expansion (or contraction) and random directional motion. The first harmonic (F1) response in the steady‐state VEP response must arise from mechanisms sensitive to the global radial motion structure. We compared F1 amplitudes between expansion‐random and contraction‐random motion alternations. F1 amplitudes for contraction were significantly larger than those for expansion for the older infants and adults but not for the younger infants. These results suggest that the human cortical motion mechanisms have asymmetrical sensitivity for radial expansion vs. contraction, which develops at around 4 months of age. The relation between development of sensitivity to radial motion and cortical motion mechanisms is discussed.