Visual perception and frontal lobe in intellectual disabilities: a study with evoked potentials and neuropsychology

Visual-Motor Integration in Children With Mild Intellectual Disability: A Meta-Analysis

Visual-motor integration (VMI) skills, defined as the coordination of fine motor and visual perceptual abilities, are a very good indicator of a child's overall level of functioning. Research has clearly established that children with intellectual disability (ID) have deficits in VMI skills. This article presents a meta-analytic review of 10 research studies involving 652 children with mild ID for which a VMI skills assessment was also available. We measured the standardized mean difference (Hedges' g) between scores on VMI tests of these children with mild ID and either typically developing children's VMI test scores in these studies or normative mean values on VMI tests used by the studies. While mild ID is defined in part by intelligence scores that are two to three standard deviations below those of typically developing children, the standardized mean difference of VMI differences between typically developing children and children with mild ID in this meta-analysis was 1.75 (95% CI [1.11, 2.38]). Thus, the intellectual and adaptive skill deficits of children with mild ID may be greater (perhaps especially due to their abstract and conceptual reasoning deficits) than their relative VMI deficits. We discuss the possible meaning of this relative VMI strength among children with mild ID and suggest that their stronger VMI skills may be a target for intensive academic interventions as a means of attenuating problems in adaptive functioning.

Individual differences in response speed and accuracy are associated to specific brain activities of two interacting systems

The study investigates the neurocognitive stages involved in the speed-accuracy trade-off (SAT). Contrary to previous approach, we did not manipulate speed and accuracy instructions: participants were required to be fast and accurate in a go/no-go task, and we selected post-hoc the groups based on the subjects' spontaneous behavioral tendency. Based on the reaction times, we selected the fast and slow groups (Speed-groups), and based on the percentage of false alarms, we selected the accurate and inaccurate groups (Accuracy-groups). The two Speed-groups were accuracy-matched, and the two Accuracy-groups were speed-matched. High density electroencephalographic (EEG) and stimulus-locked analyses allowed us to observe group differences both before and after the stimulus onset. Long before the stimulus appearance, the two Speed-groups showed different amplitude of the Bereitschaftspotential (BP), reflecting the activity of the supplementary motor area (SMA); by contrast, the two Accuracy-groups showed different amplitude of the prefrontal negativity (pN), reflecting the activity of the right prefrontal cortex (rPFC). In addition, the post-stimulus event-related potential (ERP) components showed differences between groups: the P1 component was larger in accurate than inaccurate group; the N1 and N2 components were larger in the fast than slow group; the P3 component started earlier and was larger in the fast than slow group. The go minus no-go subtractive wave enhancing go-related processing revealed a differential prefrontal positivity (dpP) that peaked at about 330 ms; the latency and the amplitude of this peak were associated with the speed of the decision process and the efficiency of the stimulus-response mapping, respectively. Overall, data are consistent with the view that speed and accuracy are processed by two interacting but separate neurocognitive systems, with different features in both the anticipation and the response execution phases.

Reorganization and stability for motor and language areas using cortical stimulation: case example and review of the literature

The cerebral organization of language in epilepsy patients has been studied with invasive procedures such as Wada testing and electrical cortical stimulation mapping and more recently with noninvasive neuroimaging techniques, such as functional MRI. In the setting of a chronic seizure disorder, clinical variables have been shown to contribute to cerebral language reorganization underscoring the need for language lateralization and localization procedures. We present a 14-year-old pediatric patient with a refractory epilepsy disorder who underwent two neurosurgical resections of a left frontal epileptic focus separated by a year. He was mapped extraoperatively through a subdural grid using cortical stimulation to preserve motor and language functions. The clinical history and extensive workup prior to surgery is discussed as well as the opportunity to compare the cortical maps for language, motor, and sensory function before each resection. Reorganization in cortical tongue sensory areas was seen concomitant with a new zone of ictal and interictal activity in the previous tongue sensory area. Detailed neuropsychological data is presented before and after any surgical intervention to hypothesize about the extent of reorganization between epochs. We conclude that intrahemispheric cortical plasticity does occur following frontal lobe resective surgery in a teenager with medically refractory seizures.

Long-term visual functioning after eclampsia

OBJECTIVE

Complete neurocognitive recovery after eclampsia has been questioned with the expression of neurocognitive deficits by affected women and demonstration of cerebral white matter lesions on magnetic resonance imaging years after eclampsia. We hypothesized that formerly eclamptic women may experience impaired vision-related quality of life (QOL) and visual field loss as a result of the presence of such lesions in the cerebral visual areas.

METHODS

Using the National Eye Institute Visual Function Questionnaire-39/Nederlands questionnaire, vision-related QOL was compared between formerly eclamptic women and control participants after normotensive pregnancies. Furthermore, in formerly eclamptic women, visual fields were assessed using automated perimetry, and presence of white matter lesions was evaluated using cerebral magnetic resonance imaging. Presence of a relationship between these lesions and National Eye Institute Visual Function Questionnaire-39/Nederlands scores was estimated.

RESULTS

Forty-seven formerly eclamptic women and 47 control participants participated 10.1±5.2 and 11.5±7.8 years after their index pregnancy, respectively. Composite scores and 4 out of 12 National Eye Institute Visual Function Questionnaire-39/Nederlands subscale scores were significantly lower in formerly eclamptic women than in control participants (P<.01 for composite scores). This could not be explained by visual field loss, because all formerly eclamptic women who underwent perimetry (n=43) demonstrated intact visual fields. White matter lesions were present in 35.7% of formerly eclamptic women who underwent magnetic resonance imaging (n=42) and were associated with lower vision-related QOL scores (P<.05 for composite scores).

CONCLUSION

Formerly eclamptic women express lower vision-related QOL than control participants, which seemed at least partly related to the presence of white matter lesions. However, such women do not have unconscious visual field loss. Vision-related QOL impairment expressed by formerly eclamptic women may therefore be related to problems with higher-order visual functions.

LEVEL OF EVIDENCE

II.