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Canonica T, Kidd EJ, Gibbins D, Lana-Elola E, Fisher EMC, Tybulewicz VLJ, Good M. Dissecting the contribution of human chromosome 21 syntenic regions to recognition memory processes in adult and aged mouse models of Down syndrome. Front Behav Neurosci 2024; 18:1428146. [PMID: 39050700 PMCID: PMC11266108 DOI: 10.3389/fnbeh.2024.1428146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Accepted: 06/24/2024] [Indexed: 07/27/2024] Open
Abstract
Background Trisomy of human chromosome 21 (Hsa21) results in a constellation of features known as Down syndrome (DS), the most common genetic form of intellectual disability. Hsa21 is orthologous to three regions in the mouse genome on mouse chromosome 16 (Mmu16), Mmu17 and Mmu10. We investigated genotype-phenotype relationships by assessing the contribution of these three regions to memory function and age-dependent cognitive decline, using three mouse models of DS, Dp1Tyb, Dp(17)3Yey, Dp(10)2Yey, that carry an extra copy of the Hsa21-orthologues on Mmu16, Mmu17 and Mmu10, respectively. Hypothesis Prior research on cognitive function in DS mouse models has largely focused on models with an extra copy of the Mmu16 region and relatively little is known about the effects of increased copy number on Mmu17 and Mmu10 on cognition and how this interacts with the effects of aging. As aging is is a critical contributor to cognitive and psychiatric changes in DS, we hypothesised that ageing would differentially impact memory function in Dp1Tyb, Dp(17)3Yey, and Dp(10)2Yey, models of DS. Methods Young (12-13 months and old (18-20 months mice Dp1Tyb, Dp(17)3Yey and Dp(10)2Yey mice were tested on a battery of object recognition memory test that assessed object novelty detection, novel location detection and associative object-in place memory. Following behavioral testing, hippocampal and frontal cortical tissue was analysed for expression of glutamatergic receptor proteins using standard immunoblot techniques. Results Young (12-13 months and old (18-20 months mice Dp1Tyb, Dp(17)3Yey and Dp(10)2Yey mice were tested on a battery of object recognition memory test that assessed object novelty detection, novel location detection and associative object-in place memory. Following behavioral testing, hippocampal and frontal cortical tissue was analysed for expression of glutamatergic receptor proteins using standard immunoblot techniques. Conclusion Our results show that distinct Hsa21-orthologous regions contribute differentially to cognitive dysfunction in DS mouse models and that aging interacts with triplication of Hsa21-orthologous genes on Mmu10.
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Affiliation(s)
- Tara Canonica
- School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Emma J. Kidd
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | | | | | - Elizabeth M. C. Fisher
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | | | - Mark Good
- School of Psychology, Cardiff University, Cardiff, United Kingdom
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Davidson TL, Stevenson RJ. Vulnerability of the Hippocampus to Insults: Links to Blood-Brain Barrier Dysfunction. Int J Mol Sci 2024; 25:1991. [PMID: 38396670 PMCID: PMC10888241 DOI: 10.3390/ijms25041991] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 01/25/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
The hippocampus is a critical brain substrate for learning and memory; events that harm the hippocampus can seriously impair mental and behavioral functioning. Hippocampal pathophysiologies have been identified as potential causes and effects of a remarkably diverse array of medical diseases, psychological disorders, and environmental sources of damage. It may be that the hippocampus is more vulnerable than other brain areas to insults that are related to these conditions. One purpose of this review is to assess the vulnerability of the hippocampus to the most prevalent types of insults in multiple biomedical domains (i.e., neuroactive pathogens, neurotoxins, neurological conditions, trauma, aging, neurodegenerative disease, acquired brain injury, mental health conditions, endocrine disorders, developmental disabilities, nutrition) and to evaluate whether these insults affect the hippocampus first and more prominently compared to other brain loci. A second purpose is to consider the role of hippocampal blood-brain barrier (BBB) breakdown in either causing or worsening the harmful effects of each insult. Recent research suggests that the hippocampal BBB is more fragile compared to other brain areas and may also be more prone to the disruption of the transport mechanisms that act to maintain the internal milieu. Moreover, a compromised BBB could be a factor that is common to many different types of insults. Our analysis indicates that the hippocampus is more vulnerable to insults compared to other parts of the brain, and that developing interventions that protect the hippocampal BBB may help to prevent or ameliorate the harmful effects of many insults on memory and cognition.
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Affiliation(s)
- Terry L. Davidson
- Department of Neuroscience, Center for Neuroscience and Behavior, American University, 4400 Massachusetts Avenue, NW, Washington, DC 20016, USA
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Hamadelseed O, Chan MKS, Wong MBF, Skutella T. Distinct neuroanatomical and neuropsychological features of Down syndrome compared to related neurodevelopmental disorders: a systematic review. Front Neurosci 2023; 17:1225228. [PMID: 37600012 PMCID: PMC10436105 DOI: 10.3389/fnins.2023.1225228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
Objectives We critically review research findings on the unique changes in brain structure and cognitive function characteristic of Down syndrome (DS) and summarize the similarities and differences with other neurodevelopmental disorders such as Williams syndrome, 22q11.2 deletion syndrome, and fragile X syndrome. Methods We conducted a meta-analysis and systematic literature review of 84 studies identified by searching PubMed, Google Scholar, and Web of Science from 1977 to October 2022. This review focuses on the following issues: (1) specific neuroanatomic and histopathological features of DS as revealed by autopsy and modern neuroimaging modalities, (2) language and memory deficits in DS, (3) the relationships between these neuroanatomical and neuropsychological features, and (4) neuroanatomic and neuropsychological differences between DS and related neurodevelopmental syndromes. Results Numerous post-mortem and morphometric neuroimaging investigations of individuals with DS have reported complex changes in regional brain volumes, most notably in the hippocampal formation, temporal lobe, frontal lobe, parietal lobe, and cerebellum. Moreover, neuropsychological assessments have revealed deficits in language development, emotional regulation, and memory that reflect these structural changes and are more severe than expected from general cognitive dysfunction. Individuals with DS also show relative preservation of multiple cognitive, linguistic, and social domains compared to normally developed controls and individuals with other neurodevelopmental disorders. However, all these neurodevelopment disorders exhibit substantial heterogeneity among individuals. Conclusion People with Down syndrome demonstrate unique neurodevelopmental abnormalities but cannot be regarded as a homogenous group. A comprehensive evaluation of individual intellectual skills is essential for all individuals with neurodevelopment disorders to develop personalized care programs.
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Affiliation(s)
- Osama Hamadelseed
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Mike K. S. Chan
- EW European Wellness Academy GmbH, Edenkoben, Germany
- Baden R&D Laboratories GmbH, Edenkoben, Germany
| | - Michelle B. F. Wong
- EW European Wellness Academy GmbH, Edenkoben, Germany
- Baden R&D Laboratories GmbH, Edenkoben, Germany
- Stellar Biomolecular Research GmbH, Edenkoben, Germany
| | - Thomas Skutella
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
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Zhao L, Xiong X, Liu L, Liang Q, Tong R, Feng X, Bai L, Shi J. Recent research and development of DYRK1A inhibitors. CHINESE CHEM LETT 2022. [DOI: 10.1016/j.cclet.2021.10.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lovos A, Bottrill K, Sakhon S, Nyhuis C, Egleson E, Luongo A, Murphy M, Thurman AJ, Abbeduto L, Lee NR, Hughes K, Edgin J. Circadian Sleep-Activity Rhythm across Ages in Down Syndrome. Brain Sci 2021; 11:brainsci11111403. [PMID: 34827402 PMCID: PMC8615672 DOI: 10.3390/brainsci11111403] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/05/2021] [Accepted: 10/17/2021] [Indexed: 11/16/2022] Open
Abstract
Across all ages, individuals with Down syndrome (DS) experience high rates of sleep problems as well as cognitive impairments. This study sought to investigate whether circadian rhythm disruption was also experienced by people with DS and whether this kind of sleep disorder may be correlated with cognitive performance. A cross-sectional study of 101 participants (58 with DS, 43 with typical development) included individuals in middle childhood (6–10 years old), adolescence (11–18 years old), and young adulthood (19–26 years old). Sleep and markers of circadian timing and robustness were calculated using actigraphy. Cognitive and behavioral data were gathered via a novel touchscreen battery (A-MAPTM, Arizona Memory Assessment for Preschoolers and Special Populations) and parent questionnaire. Results indicated that children and adolescents with DS slept the same amount as peers with typical development, but significant group differences were seen in phase timing. The circadian robustness markers, interdaily stability and intradaily variability of sleep-wake rhythms, were healthiest for children regardless of diagnostic group and worst for adults with DS. Amplitude of the 24-h activity profile was elevated for all individuals with DS. In analyses of the correlations between sleep quality, rhythms, and cognition in people with DS, interdaily stability was positively correlated with reaction time and negatively correlated with verbal and scene recall, a finding that indicates increased stability may paradoxically correlate with poorer cognitive outcomes. Further, we found no relations with sleep efficiency previously found in preschool and adult samples. Therefore, the current findings suggest that a thorough examination of sleep disorders in DS must take into account age as well as circadian robustness to better understand sleep-cognitive correlations in this group.
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Affiliation(s)
- Annalysa Lovos
- Department of Psychology, School of Mind, Brain and Behavior, College of Science, The University of Arizona, Tucson, AZ 85721, USA; (K.B.); (E.E.); (A.L.); (J.E.)
- Correspondence:
| | - Kenneth Bottrill
- Department of Psychology, School of Mind, Brain and Behavior, College of Science, The University of Arizona, Tucson, AZ 85721, USA; (K.B.); (E.E.); (A.L.); (J.E.)
| | - Stella Sakhon
- Statistics Department, Los Angeles Valley College, Van Nuys, Los Angeles, CA 91401, USA;
| | - Casandra Nyhuis
- College of Medicine, Pennsylvania State University, Hershey, PA 17033, USA;
| | - Elizabeth Egleson
- Department of Psychology, School of Mind, Brain and Behavior, College of Science, The University of Arizona, Tucson, AZ 85721, USA; (K.B.); (E.E.); (A.L.); (J.E.)
| | - Alison Luongo
- Department of Psychology, School of Mind, Brain and Behavior, College of Science, The University of Arizona, Tucson, AZ 85721, USA; (K.B.); (E.E.); (A.L.); (J.E.)
| | - Melanie Murphy
- Department of Physiology and Buiphysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA;
| | - Angela John Thurman
- Department of Psychiatry and Behavioral Sciences and MIND Institute, University of California Davis Health, Sacramento, CA 95817, USA; (A.J.T.); (L.A.)
| | - Leonard Abbeduto
- Department of Psychiatry and Behavioral Sciences and MIND Institute, University of California Davis Health, Sacramento, CA 95817, USA; (A.J.T.); (L.A.)
| | - Nancy Raitano Lee
- Department of Psychological and Brain Sciences, Drexel University, Philadelphia, PA 19104, USA;
| | | | - Jamie Edgin
- Department of Psychology, School of Mind, Brain and Behavior, College of Science, The University of Arizona, Tucson, AZ 85721, USA; (K.B.); (E.E.); (A.L.); (J.E.)
- Sonoran University Center for Excellence in Developmental Disabilities (UCEDD), University of Arizona, Farmington, CT 06032, USA
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6
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Nadel L. Some implications of postnatal hippocampal development. Hippocampus 2021; 32:98-107. [PMID: 34133050 DOI: 10.1002/hipo.23369] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/24/2021] [Accepted: 05/26/2021] [Indexed: 11/09/2022]
Abstract
It is well established that in most species, the hippocampus shows extensive postnatal development. This delayed maturation has a number of implications, which can be thought of in three categories. First, the late maturation has the direct effect of depriving the developing organism of at least some of the functions of the hippocampus, in particular place learning, context coding and in humans, episodic memory. Second, such learning that does occur very early in life, prior to hippocampal maturation, will largely bear the imprint and properties of those brain systems that, unlike the hippocampus, are fully functional early in life. Third, the active state of development of hippocampus in the first weeks and months of life render this structure susceptible to disruption by environmental and/or chromosomal factors. In this article, I discuss my efforts, with many colleagues over the past 40 years, to understand each of these implications.
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Affiliation(s)
- Lynn Nadel
- Cognitive Science Program and Department of Psychology, University of Arizona, Tucson, Arizona, USA
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7
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Koenig KA, Oh SH, Stasko MR, Roth EC, Taylor HG, Ruedrich S, Wang ZI, Leverenz JB, Costa ACS. High resolution structural and functional MRI of the hippocampus in young adults with Down syndrome. Brain Commun 2021; 3:fcab088. [PMID: 33977271 PMCID: PMC8100000 DOI: 10.1093/braincomms/fcab088] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 02/19/2021] [Accepted: 03/22/2021] [Indexed: 11/29/2022] Open
Abstract
Down syndrome is the phenotypic consequence of trisomy 21, with clinical presentation including both neurodevelopmental and neurodegenerative components. Although the intellectual disability typically displayed by individuals with Down syndrome is generally global, it also involves disproportionate deficits in hippocampally-mediated cognitive processes. Hippocampal dysfunction may also relate to Alzheimer’s disease-type pathology, which can appear in as early as the first decade of life and becomes universal by age 40. Using 7-tesla MRI of the brain, we present an assessment of the structure and function of the hippocampus in 34 individuals with Down syndrome (mean age 24.5 years ± 6.5) and 27 age- and sex-matched typically developing healthy controls. In addition to increased whole-brain mean cortical thickness and lateral ventricle volumes (P < 1.0 × 10−4), individuals with Down syndrome showed selective volume reductions in bilateral hippocampal subfields cornu Ammonis field 1, dentate gyrus, and tail (P < 0.005). In the group with Down syndrome, bilateral hippocampi showed widespread reductions in the strength of functional connectivity, predominately to frontal regions (P < 0.02). Age was not related to hippocampal volumes or functional connectivity measures in either group, but both groups showed similar relationships of age to whole-brain volume measures (P < 0.05). Finally, we performed an exploratory analysis of a subgroup of individuals with Down syndrome with both imaging and neuropsychological assessments. This analysis indicated that measures of spatial memory were related to mean cortical thickness, total grey matter volume and right hemisphere hippocampal subfield volumes (P < 0.02). This work provides a first demonstration of the usefulness of high-field MRI to detect subtle differences in structure and function of the hippocampus in individuals with Down syndrome, and suggests the potential for development of MRI-derived measures as surrogate markers of drug efficacy in pharmacological studies designed to investigate enhancement of cognitive function.
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Affiliation(s)
- Katherine A Koenig
- Imaging Sciences, Imaging Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Se-Hong Oh
- Imaging Sciences, Imaging Institute, Cleveland Clinic, Cleveland, OH 44195, USA.,Department of Biomedical Engineering, Hankuk University of Foreign Studies, Yongin 449-791, Republic of Korea
| | - Melissa R Stasko
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Elizabeth C Roth
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - H Gerry Taylor
- Abigail Wexner Research Institute at Nationwide Children's Hospital, and Department of Pediatrics, The Ohio State University, Columbus, OH 43215, USA
| | - Stephen Ruedrich
- Department of Psychiatry, University Hospitals, Cleveland, OH 44106, USA
| | - Z Irene Wang
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - James B Leverenz
- Lou Ruvo Center for Brain Health, Neurological Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Alberto C S Costa
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, USA.,Department of Psychiatry, University Hospitals, Cleveland, OH 44106, USA
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Chang P, Bush D, Schorge S, Good M, Canonica T, Shing N, Noy S, Wiseman FK, Burgess N, Tybulewicz VLJ, Walker MC, Fisher EMC. Altered Hippocampal-Prefrontal Neural Dynamics in Mouse Models of Down Syndrome. Cell Rep 2020; 30:1152-1163.e4. [PMID: 31995755 PMCID: PMC6996020 DOI: 10.1016/j.celrep.2019.12.065] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 10/02/2019] [Accepted: 12/17/2019] [Indexed: 01/26/2023] Open
Abstract
Altered neural dynamics in the medial prefrontal cortex (mPFC) and hippocampus may contribute to cognitive impairments in the complex chromosomal disorder Down syndrome (DS). Here, we demonstrate non-overlapping behavioral differences associated with distinct abnormalities in hippocampal and mPFC electrophysiology during a canonical spatial working memory task in three partially trisomic mouse models of DS (Dp1Tyb, Dp10Yey, and Dp17Yey) that together cover all regions of homology with human chromosome 21 (Hsa21). Dp1Tyb mice show slower decision-making (unrelated to the gene dose of DYRK1A, which has been implicated in DS cognitive dysfunction) and altered theta dynamics (reduced frequency, increased hippocampal-mPFC coherence, and increased modulation of hippocampal high gamma); Dp10Yey mice show impaired alternation performance and reduced theta modulation of hippocampal low gamma; and Dp17Yey mice are not significantly different from the wild type. These results link specific hippocampal and mPFC circuit dysfunctions to cognitive deficits in DS models and, importantly, map them to discrete regions of Hsa21.
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Affiliation(s)
- Pishan Chang
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK; Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Daniel Bush
- UCL Institute of Cognitive Neuroscience, UCL Queen Square Institute of Neurology, University College London WC1N 3AZ, UK
| | - Stephanie Schorge
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Mark Good
- School of Psychology, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Tara Canonica
- School of Psychology, College of Biomedical and Life Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Nathanael Shing
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Suzanna Noy
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Frances K Wiseman
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Neil Burgess
- UCL Institute of Cognitive Neuroscience, UCL Queen Square Institute of Neurology, University College London WC1N 3AZ, UK
| | - Victor L J Tybulewicz
- Francis Crick Institute, London NW1 1AT, UK; Department of Medicine, Imperial College, London W12 0NN, UK
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK.
| | - Elizabeth M C Fisher
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
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Edgin JO, Liu Y, Hughes K, Spanò G, Clark CAC. The "eyes have it," but when in development?: The importance of a developmental perspective in our understanding of behavioral memory formation and the hippocampus. Hippocampus 2019; 30:815-828. [PMID: 31465140 DOI: 10.1002/hipo.23149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 07/31/2019] [Accepted: 08/03/2019] [Indexed: 11/11/2022]
Abstract
Lynn Nadel has been a trailblazer in memory research for decades. In just one example, Nadel and Zola-Morgan [Infantile amnesia, In Infant memory, Springer, Boston, MA, 1984, pp. 145-172] were the first to present the provocative notion that the extended development of the hippocampus may underlie the period of infantile amnesia. In this special issue of Hippocampus to honor Lynn Nadel, we review some of his major contributions to the field of memory development, with an emphasis on his observations that behavioral memory assessments follow an uneven, yet protracted developmental course. We present data emphasizing this point from memory-related eye movements [Hannula & Ranganath, Neuron, 2009, 63(5), 592-599]. Eye tracking is a sensitive behavioral measure, allowing for an indication of memory function even without overt responses, which is seemingly ideal for the investigation of memory in early childhood or in other nonverbal populations. However, the behavioral manifestation of these eye movements follows a U-shaped trajectory-and one that must be understood before these indictors could be broadly used as a marker of memory. We examine the change in preferential looking time to target stimuli in school-aged children and adults, and compare these eye movement responses to explicit recall measures. Our findings indicate change in the nature and timing of these eye movements in older children, causing us to question how 6-month-old infants may produce eye movements that initially appear to have the same properties as those measured in adulthood. We discuss these findings in the context of our current understanding of memory development, particularly the period of infantile amnesia.
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Affiliation(s)
- Jamie O Edgin
- Department of Psychology, University of Arizona, Tucson, Arizona
| | - Yating Liu
- Department of Psychology, University of Arizona, Tucson, Arizona
| | - Katharine Hughes
- Department of Psychology, University of Arizona, Tucson, Arizona
| | - Goffredina Spanò
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Caron A C Clark
- Department of Educational Psychology, University of Nebraska, Lincoln, Nebraska
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REM sleep in naps differentially relates to memory consolidation in typical preschoolers and children with Down syndrome. Proc Natl Acad Sci U S A 2018; 115:11844-11849. [PMID: 30373840 DOI: 10.1073/pnas.1811488115] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Sleep is recognized as a physiological state associated with learning, with studies showing that knowledge acquisition improves with naps. Little work has examined sleep-dependent learning in people with developmental disorders, for whom sleep quality is often impaired. We examined the effect of natural, in-home naps on word learning in typical young children and children with Down syndrome (DS). Despite similar immediate memory retention, naps benefitted memory performance in typical children but hindered performance in children with DS, who retained less when tested after a nap, but were more accurate after a wake interval. These effects of napping persisted 24 h later in both groups, even after an intervening overnight period of sleep. During naps in typical children, memory retention for object-label associations correlated positively with percent of time in rapid eye movement (REM) sleep. However, in children with DS, a population with reduced REM, learning was impaired, but only after the nap. This finding shows that a nap can increase memory loss in a subpopulation, highlighting that naps are not universally beneficial. Further, in healthy preschooler's naps, processes in REM sleep may benefit learning.
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Sakhon S, Edwards K, Luongo A, Murphy M, Edgin J. Small Sets of Novel Words Are Fully Retained After 1-Week in Typically Developing Children and Down Syndrome: A Fast Mapping Study. J Int Neuropsychol Soc 2018; 24:955-965. [PMID: 30375315 PMCID: PMC6211816 DOI: 10.1017/s1355617718000450] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVES Down syndrome (DS) is a population with known hippocampal impairment, with studies showing that individuals with DS display difficulties in spatial navigation and remembering arbitrary bindings. Recent research has also demonstrated the importance of the hippocampus for novel word-learning. Based on these data, we aimed to determine whether individuals with DS show deficits in learning new labels and if they may benefit from encoding conditions thought to be less reliant on hippocampal function (i.e., through fast mapping). METHODS In the current study, we examined immediate, 5-min, and 1-week delayed word-learning across two learning conditions (e.g., explicit encoding vs. fast mapping). These conditions were examined across groups (twenty-six 3- to 5-year-old typically developing children and twenty-six 11- to 28-year-old individuals with DS with comparable verbal and nonverbal scores on the Kaufman Brief Intelligence Test - second edition) and in reference to sleep quality. RESULTS Both individuals with and without DS showed retention after a 1-week delay, and the current study found no benefit of the fast mapping condition in either group contrary to our expectations. Eye tracking data showed that preferential eye movements to target words were not present immediately but emerged after 1-week in both groups. Furthermore, sleep measures collected via actigraphy did not relate to retention in either group. CONCLUSIONS This study presents novel data on long-term knowledge retention in reference to sleep patterns in DS and adds to a body of knowledge helping us to understand the processes of word-learning in typical and atypically developing populations. (JINS, 2018, 24, 955-965).
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Affiliation(s)
- Stella Sakhon
- Department of Psychology, University of Arizona, Tucson,
Arizona
| | - Kelly Edwards
- Department of Psychology, University of Arizona, Tucson,
Arizona
| | - Alison Luongo
- Department of Psychology, University of Arizona, Tucson,
Arizona
| | - Melanie Murphy
- Department of Psychology, University of Arizona, Tucson,
Arizona
| | - Jamie Edgin
- Department of Psychology, University of Arizona, Tucson,
Arizona
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Abstract
OBJECTIVES As surprisingly little is known about the developing brain studied in vivo in youth with Down syndrome (DS), the current review summarizes the small DS pediatric structural neuroimaging literature and begins to contextualize existing research within a developmental framework. METHODS A systematic review of the literature was completed, effect sizes from published studies were reviewed, and results are presented with respect to the DS cognitive behavioral phenotype and typical brain development. RESULTS The majority of DS structural neuroimaging studies describe gross differences in brain morphometry and do not use advanced neuroimaging methods to provide nuanced descriptions of the brain. There is evidence for smaller total brain volume (TBV), total gray matter (GM) and white matter, cortical lobar, hippocampal, and cerebellar volumes. When reductions in TBV are accounted for, specific reductions are noted in subregions of the frontal lobe, temporal lobe, cerebellum, and hippocampus. A review of cortical lobar effect sizes reveals mostly large effect sizes from early childhood through adolescence. However, deviance is smaller in adolescence. Despite these smaller effects, frontal GM continues to be largely deviant in adolescence. An examination of age-frontal GM relations using effect sizes from published studies and data from Lee et al. (2016) reveals that while there is a strong inverse relationship between age and frontal GM volume in controls across childhood and adolescence, this is not observed in DS. CONCLUSIONS Further developmentally focused research, ideally using longitudinal neuroimaging, is needed to elucidate the nature of the DS neuroanatomic phenotype during childhood and adolescence. (JINS, 2018, 24, 966-976).
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Godfrey M, Lee NR. Memory profiles in Down syndrome across development: a review of memory abilities through the lifespan. J Neurodev Disord 2018; 10:5. [PMID: 29378508 PMCID: PMC5789527 DOI: 10.1186/s11689-017-9220-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 11/21/2017] [Indexed: 12/30/2022] Open
Abstract
Down syndrome (DS) is associated with a variety of cognitive impairments, notably memory impairments. Due to the high prevalence rates of early-onset dementia associated with DS, it is imperative to understand the comprehensive development of memory impairments beginning in childhood and into adulthood, as this may help researchers identify precursors of dementia at earlier stages of development and pinpoint targets for memory intervention. The current paper provides a systematic, developmentally focused review of the nature of memory difficulties in DS across the lifespan. Specifically, this review summarizes what is known about long-term, short-term, and working memory abilities (distinguishing between verbal and nonverbal modalities) in DS, compared to both mental age-matched typically developing peers and individuals with other forms of intellectual disability (ID) at three developmental stages (i.e., preschool, adolescence, and adulthood). Additionally, this review examines the degree of impairment reported relative to typically developing mental age-matched peers in the existing literature by examining effect size data across memory domains as a function of age. With few exceptions, memory abilities were impaired across the lifespan compared to mental age-matched typically developing peers. Relative to other groups with ID, research findings are mixed. Our review of the literature identified a scarcity of memory studies in early childhood, particularly for STM and WM. In adulthood, research was limited in the LTM and WM domains and very little research has compared memory abilities in older adults with DS to those with typical development. Looking to the future, longitudinal studies could provide a better understanding of the developmental trajectory of memory abilities in DS, and the possible associations between memory abilities and real-world functioning. This research could ultimately inform interventions to improve independence and overall quality of life for those with DS and their families.
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Affiliation(s)
- Mary Godfrey
- Department of Psychology, Drexel University, 3141 Chestnut Street, Stratton 119, Philadelphia, PA, 19104, USA.
| | - Nancy Raitano Lee
- Department of Psychology, Drexel University, 3141 Chestnut Street, Stratton 119, Philadelphia, PA, 19104, USA
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