Facial memory deficits in children with fetal alcohol spectrum disorders.

Prenatal exposure to alcohol may lead to a range of neurobehavioral effects, including impaired learning and memory. Although children with fetal alcohol spectrum disorders (FASD) exhibit both verbal and nonverbal memory impairments, their memory for faces has not been as thoroughly investigated and the extent literature provides inconsistent results. The aim of the current study was to determine whether difficulties in face memory exist in children with FASD and whether the difficulties are mediated by task demands. To address this, we used two measures of immediate and delayed facial recognition memory, the Children's Memory Scale (CMS) and Test of Memory and Learning (TOMAL). Compared to typically developing controls, children with FASD showed memory deficits on all tests and were more likely to perform in a clinically significant range. As well, children performed more poorly on the CMS compared to TOMAL, a finding consistent with the greater difficulty of the CMS task. Our results are consistent with our hypothesis that children with FASD show impairment in facial memory, particularly on demanding memory tasks.

Visuospatial associative memory and hippocampal functioning in congenital hypothyroidism.

Congenital hypothyroidism is a pediatric endocrine disorder caused by insufficient endogenous thyroid hormone production. Children with congenital hypothyroidism have difficulties with episodic memory and abnormalities in hippocampal structure, suggesting deficient hippocampal functioning. To assess hippocampal activation in adolescents with congenital hypothyroidism (N = 14; age range, 11.5-14.7 years) compared with controls (N = 15; age range, 11.2-15.5 years), a functional magnetic resonance imaging visuospatial memory task was used. In this task, participants had to decide if object pairings were novel or were previously studied or if object pairs were in the same location as they were at study or had switched locations. Despite no group differences in task performance, adolescents with congenital hypothyroidism showed both increased magnitude of hippocampal activation relative to controls and bilateral hippocampal activation when only the left was observed in controls. Furthermore, the increased activation in the congenital hypothyroidism group was correlated with the severity of the hypothyroidism experienced early in life. These results suggest that perinatal deprivation of thyroid hormone has longstanding effects on hippocampal function and may account for memory problems experienced by adolescents with congenital hypothyroidism.

Effects of prenatal alcohol exposure on hippocampal volume, verbal learning, and verbal and spatial recall in late childhood.

Children with prenatal alcohol exposure (PAE) show deficits in verbal learning and spatial memory, as well as abnormal hippocampal development. The relationship between their memory and neuroanatomic impairments, however, has not been directly explored. Given that the hippocampus is integral for the synthesis and retrieval of learned information and is particularly vulnerable to the teratogenic effects of alcohol, we assessed whether reduced learning and recall abilities in children with fetal alcohol spectrum disorders (FASDs) are associated with abnormal hippocampal volumes. Nineteen children with FASDs and 18 typically developing controls aged 9 to 15 years were assessed for verbal learning and verbal and spatial recall and underwent structural magnetic resonance imaging. Images were analyzed for total intracranial volume and for right and left hippocampal volumes. Results revealed smaller left hippocampi and poorer verbal learning and verbal and spatial recall performance in children with FASDs than controls, as well as positive correlations between selective memory indices and hippocampal volumes only in the FASD group. Additionally, hippocampal volumes increased significantly with age in controls only, suggesting that PAE may be associated with long-term abnormalities in hippocampal development that may contribute to impaired verbal learning and verbal and spatial recall.

Re-exposure to studied items at test does not influence false recognition.

In two experiments, we investigated whether re-exposure to previously studied items at test affects false recognition in the DRM paradigm. Furthermore, we examined whether exposure to the critical lure at test influences memory for subsequently presented study items. In Experiment 1, immediately following each studied DRM list, participants were given a recognition test. The tests were constructed such that the number of studied items preceding the critical lure varied from zero to five. Neither false recognition for critical lures nor accurate memory for studied items was affected by this manipulation. In Experiment 2, we replicated this pattern of results under speeded conditions at test. Both experiments confirm that exposure to previously studied items at test does not affect true or false recognition in the DRM paradigm. This pattern strongly suggests that retrieval processes do not influence false recognition in the DRM paradigm.