A sleep schedule incorporating naps benefits the transformation of hierarchical knowledge.

STUDY OBJECTIVES: The learning brain establishes schemas (knowledge structures) that benefit subsequent learning. We investigated how sleep and having a schema might benefit initial learning followed by rearranged and expanded memoranda. We concurrently examined the contributions of sleep spindles and slow-wave sleep to learning outcomes. METHODS: Fifty-three adolescents were randomly assigned to an 8 h Nap schedule (6.5 h nocturnal sleep with a 90-minute daytime nap) or an 8 h No-Nap, nocturnal-only sleep schedule. The study spanned 14 nights, simulating successive school weeks. We utilized a transitive inference task involving hierarchically ordered faces. Initial learning to set up the schema was followed by rearrangement of the hierarchy (accommodation) and hierarchy expansion (assimilation). The expanded sequence was restudied. Recall of hierarchical knowledge was tested after initial learning and at multiple points for all subsequent phases. As a control, both groups underwent a No-schema condition where the hierarchy was introduced and modified without opportunity to set up a schema. Electroencephalography accompanied the multiple sleep opportunities. RESULTS: There were main effects of Nap schedule and Schema condition evidenced by superior recall of initial learning, reordered and expanded memoranda. Improved recall was consistently associated with higher fast spindle density but not slow-wave measures. This was true for both nocturnal sleep and daytime naps. CONCLUSION: A sleep schedule incorporating regular nap opportunities compared to one that only had nocturnal sleep benefited building of robust and flexible schemas, facilitating recall of the subsequently rearranged and expanded structured knowledge. These benefits appear to be strongly associated with fast spindles. CLINICAL TRIAL REGISTRATION: NCT04044885 (https://clinicaltrials.gov/ct2/show/NCT04044885).

Schema-driven memory benefits boost transitive inference in older adults.

Age-related cognitive deficits may be diminished by tapping into prior knowledge structures. We investigated age-related differences in the formation and updating of schemas and examined whether the memory benefits of recently acquired schemas would be preserved in older adults. Data were collected from 60 older adults (M = 66.2, SD = 9.3 years) and 59 adolescents recruited from Singapore's top schools (M = 16.6, SD = 0.9 years) who learnt the age hierarchy of six galaxies to criterion by viewing neighboring pairs one at a time, for example A-B, D-E, C-D, enabling the formation of a schema via transitive inference (i.e., if B > C and C > D then B > D). Once learning reached criterion, two new sets of galaxies were presented: one comprising four galaxies from the schema intercalated with four new galaxies (schema condition) and the other comprising eight unfamiliar galaxies (no schema condition). Participants were then tested on both neighboring pairs (noninference) and inference pairs: (B-D, B-E, C-E). Compared with adolescents, older adults required a significantly higher number of learning blocks to successfully form a schema. Nonetheless, the acquired schema significantly aided relational memory and facilitated the making of novel inferences in older adults. This schema benefit was particularly pronounced in supporting novel inferences, boosting performance in older adults to levels comparable with adolescents (59% vs. 61%). These results suggest that older adults can effectively form new schemas with extended practice. Schema-driven memory benefits are preserved with aging and appear to mitigate age-related memory deficits, optimizing cognitive performance in making novel inferences. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Tumors of the Central Nervous System: An 18-Year Retrospective Review in a Tertiary Pediatric Referral Center.

OBJECTIVE: Few studies exist on the demographics and trends of pediatric central nervous system (CNS) tumors in Iran. In this study, we retrospectively reviewed all cases with confirmed CNS tumors admitted to Mofid Pediatric Hospital, Tehran, Iran during the last 18 years. MATERIALS & METHODS: Data on gender, age of diagnosis, pathologic classification and tumor location were extracted from the available medical records. We used the last version of International Classification of Childhood Cancer. RESULT: Overall, 258 (81.9%) brain tumors and 57 (18.1%) spinal tumors were identified. Our subjects comprised of 147 (46.7%) female and 168 (53.3%) male children. More male dominancy was observed in brain tumors with a male to female ratio of 1.2 compared with 1.03 of spinal tumors. Malignant CNS tumors were most common in 1-4 yr age group. The four most common brain tumors in our subjects were astrocytomas, medulloblastoma, ependymoma and craniopharyngioma. Overall, 53.1% of the brain tumors were supratentorial. Gliomas, PNET and neuroblastma were the most frequent primary spinal tumors in our study. We observed an increasing trend for both brain and spinal tumors that was moreremarkable in the last 5 years. CONCLUSION: Our results are comparable with similar single center studies on CNS tumors during childhood. The observed disparities could be attributed to the single center nature of our study and geographical, environmental and racial variations in pediatric CNS tumors. The increasing trend of both brain and spinal tumors could warrant further investigations at provincial and national levels to investigate probable contributing environmental risk factors.

Survey on childhood solid malignant tumors in cases admitted to mofid pediatric hospital from 1996-2010: a single-center study.

BACKGROUND: As children comprise a considerable proportion of our population, the importance of local epidemiologic research and geographic and racial differences can't be disputed on childhood malignancies. METHODS: In this descriptive retrospective study, we extensively reviewed the medical records of patients younger than 15 years of age, diagnosed with solid malignant tumors, from 1996 to 2010, using the last version of International Classification of Childhood Cancers. RESULTS: In our study the order of incidence of solid malignancies was relatively similar to the other national studies, with lymphomas and Central Nervous System (CNS) tumors as the most common, followed by Sympathetic Nervous System (SNS) tumors, soft tissue sarcomas and renal tumors. The peak age of diagnosis was between 1 and 4 years old. In our study, the overall male to female ratio was 1.38, with a trend towards male dominance in the older age groups. We also observed a disturbing trend of childhood solid malignancies. The total number of cases almost doubled from 2009(54(6.9%)) to 2010(96(12.2%)) .This trend was particularly detected in CNS and SNS tumors. Further analysis showed that malignant CNS tumors had played a more pronounced role in this change. CONCLUSION: Changes in trends of some tumor categories have illustrated a desperate need to further research in regional and national levels. Also the gathered data can be used to make more accurate programs for a better control of cancer and to help policymakers to allocate more evidence-based resource for hospitals.