Executive functions in individuals with Williams syndrome.

BACKGROUND: The present study was aimed at investigating working memory (WM) and executive functions capacities in individuals with Williams syndrome (WS) as compared with mental-age matched typically developing (TD) children. METHOD: In order to serve the study goal, a sizeable battery of tasks tapping WM as well as attention, memory, planning, categorisation, shifting and inhibition abilities was administered to 15 individuals with WS (mean chronological age of 19.11 and mean mental age of 6.10), and to a group of 15 TD children (mean chronological age of 7.6 and mean mental age of 6.9). RESULTS: Participants with WS showed deficits in both verbal and visual-spatial modalities for selective and sustained attention, short-term memory and WM, planning and inhibition. However, considering categorisation and shifting abilities, relatively unimpaired performance emerged on those tasks relying on verbal materials. CONCLUSIONS: These findings are both relevant to improve our knowledge about certain qualitative aspects of the anomalous cognitive development in WS as well as for its eventual clinical implications.

Children' s radial arm maze performance as a function of age and sex.

The present study analyzes the development of the spatial abilities in children aged 36-95 months and the sex-related differences by means of the free-choice and forced-choice paradigms of the eight-arm radial maze task. Clear age-related improvements were evidenced. However, a temporal window with an abrupt acceleration of specific spatial competencies acquisition was detected. The females aged 51-58 months started the task performing about 2.5 errors and ended it performing no more than 0.5 errors. The same pattern of performance was exhibited by the males aged 59-66 months. Also in the final span the 4.5-year-old females behave as the 6-year-old males. The significant correlations between 45 degrees angles and span values in the free-choice paradigm indicated that all children tended to solve the task by employing low working memory load and by using mainly efficient procedural strategies. Furthermore, children's ability to retain earlier information was influenced by both age and sex factors as indicated by the forced-choice paradigm findings. The present findings demonstrating the earlier acquisition of spatial competencies of the females in comparison to males, could reflect differences in foraging strategies between sexes, and/or differences in the anatomo-physiological development of specific brain structures, and/or different modulating effects of sexual hormones.

Spatial competences in Williams syndrome: a radial arm maze study.

This study was aimed at evaluating spatial function in subjects with Williams syndrome by using the radial arm maze task and comparing their spatial abilities with those of mental age-matched control subjects. Two different paradigms were administered: the free-choice version for analyzing the aspects linked mainly to procedural and mnesic components, the forced-choice version for disentangling components linked to spatial working memory from the procedural ones. The findings evidenced a deficit in the acquisition of procedural competences as well as in the spatial memory processes in Williams subjects. In the free-choice paradigm, they performed worse than control subjects on all parameters analyzed. Namely, they needed more time to complete the task, did not collect all rewards, exhibited low values of the spatial span as well as low percentages of correct visits, and displayed a reduced use of the most efficient exploration strategies. Even in the forced-choice paradigm, Williams subjects made a number of errors significantly higher than control subjects. The marked impairment in spatial information processing is discussed on the light of neuro-anatomical alterations reported in Williams subjects.