Patterns and trajectories in Williams Syndrome: the case of visual orientation discrimination

Re-visiting the 'mysterious myth of attention deficit': A systematic review of the recent evidence

Based on the inclusive and methodologically rigorous framework provided by Ed Zigler's developmental approach, we previously challenged what we called, 'the mysterious myth of attention deficit', the fallacy of attention as a universal deficit among persons with intellectual disability (ID). In this latest update, we conducted a systematic review of studies of essential components of attention among persons with ID published in the interim since the last iteration of the mysterious myth narrative was submitted for publication approximately a decade ago. We searched the databases PubMed and PsycINFO for English-language peer-reviewed studies published from 1 January 2011 through 5 February 2021. In keeping with the developmental approach, the two essential methodological criteria were that the groups of persons with ID were aetiologically homogeneous and that the comparisons with persons with average IQs (or with available norms) were based on an appropriate index of developmental level, or mental age. Stringent use of these criteria for inclusion served to control for bias in article selection. Articles were then categorised based on aetiological group studied and component of visual attention. Based on these criteria, 18 articles were selected for inclusion out of the 2837 that were identified. The included studies involved 547 participants: 201 participants with Down syndrome, 214 participants with Williams syndrome and 132 participants with fragile X syndrome. The findings from these articles call attention to the complexities and nuances in understanding attentional functioning across homogeneous aetiological groups and highlight that functioning must be considered in relation to aetiology; factors associated with the individual, such as developmental level, motivation, styles and biases; and factors associated with both the task, such as context, focus, social and emotional implications, and levels of environmental complexity.

Performance on the Kaufman Brief Intelligence Test-2 by Children With Williams Syndrome

We describe the performance of 292 4- to 17-year-olds with Williams syndrome (WS) on the Kaufman Brief Intelligence Test-2 (KBIT-2; Kaufman & Kaufman, 2004). Mean IQ Composite, Verbal standard score (SS), and Nonverbal SS were in the borderline range relative to the general population, with variability similar to the general population. Correlations between SSs and CA were close to 0, with no significant sex differences. There was a significant effect of maternal education on Verbal SS. The KBIT-2 appropriately captures the full range of performance of 8- to 17-year-olds with WS for the abilities measured and of all but the very lowest-functioning 5- to 7-year-olds. However, the KBIT-2 does not contain easy enough items to adequately assess the abilities of the lowest quartile of 4-year-olds.

Frequency of gamma oscillations in humans is modulated by velocity of visual motion

Gamma oscillations are generated in networks of inhibitory fast-spiking (FS) parvalbumin-positive (PV) interneurons and pyramidal cells. In animals, gamma frequency is modulated by the velocity of visual motion; the effect of velocity has not been evaluated in humans. In this work, we have studied velocity-related modulations of gamma frequency in children using MEG/EEG. We also investigated whether such modulations predict the prominence of the "spatial suppression" effect (Tadin D, Lappin JS, Gilroy LA, Blake R. Nature 424: 312-315, 2003) that is thought to depend on cortical center-surround inhibitory mechanisms. MEG/EEG was recorded in 27 normal boys aged 8-15 yr while they watched high-contrast black-and-white annular gratings drifting with velocities of 1.2, 3.6, and 6.0°/s and performed a simple detection task. The spatial suppression effect was assessed in a separate psychophysical experiment. MEG gamma oscillation frequency increased while power decreased with increasing velocity of visual motion. In EEG, the effects were less reliable. The frequencies of the velocity-specific gamma peaks were 64.9, 74.8, and 87.1 Hz for the slow, medium, and fast motions, respectively. The frequency of the gamma response elicited during slow and medium velocity of visual motion decreased with subject age, whereas the range of gamma frequency modulation by velocity increased with age. The frequency modulation range predicted spatial suppression even after controlling for the effect of age. We suggest that the modulation of the MEG gamma frequency by velocity of visual motion reflects excitability of cortical inhibitory circuits and can be used to investigate their normal and pathological development in the human brain.

Williams syndrome: ophthalmological examination and review of systemic manifestations

PURPOSE

To evaluate the frequency and severity of ophthalmic manifestations and associated diseases, as well as the epidemiological data in patients with Williams syndrome.

METHODS

The authors prospectively studied 30 patients clinically diagnosed as having Williams syndrome as confirmed by the fluorescence in situ hybridization test. Patient history included gender, age, race, education level, previous illnesses, and surgeries. The ophthalmologic examination included best-corrected visual acuity, dynamic and static refraction, extraocular motility test, stereopsis test (Titmus and Lang), and direct and indirect funduscopy.

RESULTS

Thirty patients were included in this study. The mean age was 14.5 ± 1.38 years (range: 7 to 26 years). Fifty percent of the patients were male and 50% were female. Among the children examined, 77% had a refractive error. Hyperopia and astigmatism were noted in 67% and 20% of the patients, respectively, and myopia in 7%. Only one case of amblyopia was noted. On external examination, 23% of children had epicanthus; via biomicroscopy, 3 children with stellate patterns of the irides were observed. Eleven patients (36.6%) had measurable strabismus, 9 (82%) had esotropia, and 2 (18%) had exotropia. Binocular vision was abnormal in 43% of patients. Diffuse arteriovenous tortuosity on funduscopy was observed in 27% of patients.

CONCLUSIONS

Williams syndrome is rare and is associated with multiple phenotypes and diseases that are susceptible to treatment. Multidisciplinary clinical management is critical and, in some cases, surgical intervention is required.

Global dot integration in typically developing children and in Williams syndrome

Williams Syndrome (WS) is a neurodevelopmental disorder that results in deficits in visuospatial perception and cognition. The dorsal stream vulnerability hypothesis in WS predicts that visual motion processes are more susceptible to damage than visual form processes. We asked WS participants and typically developing children to detect the global structure Glass patterns, under "static" and "dynamic" conditions in order to evaluate this hypothesis. Sequentially presented Glass patterns are coined as dynamic because they induce illusory motion, which is modeled after the interaction between orientation (form) and direction (motion) mechanisms. If the dorsal stream vulnerability holds in WS participants, then they should process real and illusory motion atypically. However, results are consistent with the idea that form and motion integration mechanisms are functionally delayed or attenuated in WS. Form coherence thresholds for both static and dynamic Glass patterns in WS were similar to those of 4-5year old children, younger than what is predicted by mental age. Dynamic presentation of Glass patterns improved thresholds to the same degree as typical participants. Motion coherence thresholds in WS were similar to those of mental age matches. These data pose constraints on the dorsal vulnerability hypothesis, and refine our understanding of the relationship between form and motion processing in development.

Longitudinal assessment of intellectual abilities of children with Williams syndrome: multilevel modeling of performance on the Kaufman Brief Intelligence Test-Second Edition

Multilevel modeling was used to address the longitudinal stability of standard scores (SSs) measuring intellectual ability for children with Williams syndrome (WS). Participants were 40 children with genetically confirmed WS who completed the Kaufman Brief Intelligence Test-Second Edition (KBIT-2; A. S. Kaufman & N. L. Kaufman, 2004 ) 4-7 times over a mean of 5.06 years. Mean age at first assessment was 7.44 years (range  =  4.00-13.97 years). On average, KBIT-2 Composite IQ, Verbal SS, and Nonverbal SS were stable from 4 to 17 years, although there were significant individual differences in intercept (Composite IQ, Verbal SS, Nonverbal SS) and slope (Composite IQ, Nonverbal SS). Maternal education was significantly related to Verbal SS intercept. No significant sex differences were found. Implications for studies of genotype/phenotype correlations in WS are discussed.