Visual integration difficulties in a 9-year-old girl with Turner syndrome: parallel verbal disabilities?

Turner syndrome (TS) is a genetic disorder in females that arises from the loss of X chromosome material. Affected individuals demonstrate a characteristic neuropsychological profile of strengths in verbal processing and weaknesses in visuospatial processing, consistent with the Nonverbal Learning Disabilities syndrome. Previous research has described a wide range of visuospatial deficits in TS; however, their verbal abilities are less extensively studied. The present paper describes the processing difficulties of a 9-year-old girl with TS who demonstrated problems in integrating details of a complex visual display and using organizational terms to describe visual scenes or events. Her specific cognitive disabilities were thought to underlie some of the social and behavioral problems she was currently experiencing. Her pattern of results is consonant with the neuropsychological pattern that others have attributed to right hemisphere dysfunction and/or white matter abnormality.

Dissociating attention deficits in children with ADHD and congenital hypothyroidism using multiple CPTs.

Recent studies suggest that children with different etiologies of attention disorder also differ as to the types of errors they make on attention tasks. Because these errors are reflective of the core deficits underlying their attention problems, we sought to compare error patterns in children with different attention disorders. Studied were 144 children aged 7-12 years, 43 with attention deficit hyperactivity disorder (ADHD), 35 with congenital hypothyroidism (CH), and 68 controls. Two variations of the continuous performance task (CPT) that differed in demands on inhibitory control and memory were used. One variation, the CPT:A-not-X task, required subjects to observe a continuous stream of letters shown at different rates on the computer screen and respond to all stimuli except "X". The other variation, the CPT:AX task, required them to respond whenever a specified combination of letter such as "A" followed by "X" appeared on the screen. On the CPT:A-not-X task, children with ADHD differed from controls in commission errors, signifying difficulty with inhibitory control, whereas children with CH differed in perceptual sensitivity or signal detection. Although the CH and ADHD groups both performed more poorly than controls on the CPT:AX task, children with CH made more errors to the first stimulus item, suggesting a problem holding information in memory, whereas children with ADHD made more errors to the second item, suggesting impulsivity. These results therefore signify the utility of these tasks in identifying the different mechanisms underlying the specific attention deficits of different groups of children.

Neurophysiological correlates of verbal and nonverbal short-term memory in children: repetition of words and faces.

The neurophysiological correlates of verbal and nonverbal memory have been extensively studied in adults, but comparable investigations of children are limited. A memory paradigm that is well established with adults is the repetition task, which finds a positive shift in the ERP waveform in response to repeated items, called the "repetition effect." This is thought to represent the brain's memory trace for previously seen information and is reported predominantly at midline frontal and parietal electrodes. We recorded ERPs in thirteen 11- to 14-year old children during repetition tasks of words and faces. Performance was better and ERP latencies shorter for the word than the face task. Although a repetition effect similar to adults was seen at parietal electrodes with increased positivity to repeated items, increased negativity was observed at frontal electrodes; this suggests that the neural substrates of recognition memory continue to develop beyond 11 to 14 years of age. The demonstration of a repetition effect in children provides a basis for studying the neural correlates of specific childhood memory deficits.