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Science (New York, N.Y.) Jan 2020In 1904, Richard Semon introduced the term "engram" to describe the neural substrate for storing memories. An experience, Semon proposed, activates a subset of cells... (Review)
Review
In 1904, Richard Semon introduced the term "engram" to describe the neural substrate for storing memories. An experience, Semon proposed, activates a subset of cells that undergo off-line, persistent chemical and/or physical changes to become an engram. Subsequent reactivation of this engram induces memory retrieval. Although Semon's contributions were largely ignored in his lifetime, new technologies that allow researchers to image and manipulate the brain at the level of individual neurons has reinvigorated engram research. We review recent progress in studying engrams, including an evaluation of evidence for the existence of engrams, the importance of intrinsic excitability and synaptic plasticity in engrams, and the lifetime of an engram. Together, these findings are beginning to define an engram as the basic unit of memory.
Topics: Animals; Brain; Brain Chemistry; Humans; Memory Disorders; Mental Recall; Neurons
PubMed: 31896692
DOI: 10.1126/science.aaw4325 -
International Journal of Environmental... Aug 2021This research involved the participation of 3036 Chinese students in the first and second years of senior high school. The adolescents were active users of TikTok. The...
This research involved the participation of 3036 Chinese students in the first and second years of senior high school. The adolescents were active users of TikTok. The mediating effect of depression, anxiety, and stress between TikTok use disorder and memory loss was investigated. A forward and backward digit span test was applied to measure memory loss. Structural equation modeling (SEM) was established, and SPSS Amos was used for analysis. The results show a partial mediation effect of depression and anxiety between TikTok use disorder and forward digit span. A partial mediation effect of depression, anxiety, and stress between TikTok use disorder and backward digit span is also shown. These results also show gender differences. Attention should be given to male students, who have more depression, anxiety, and stress than female students; they also have more memory loss.
Topics: Adolescent; Anxiety; Anxiety Disorders; Depression; Female; Humans; Male; Memory Disorders; Social Media
PubMed: 34444569
DOI: 10.3390/ijerph18168820 -
Continuum (Minneapolis, Minn.) Dec 2021This article provides a practical overview of the diagnostic process for patients with memory dysfunction through exploration of the anatomic, physiologic, and... (Review)
Review
PURPOSE OF THE REVIEW
This article provides a practical overview of the diagnostic process for patients with memory dysfunction through exploration of the anatomic, physiologic, and psychological aspects of human memory.
RECENT FINDINGS
As updated methods become available to neurologists, the ability to accurately identify and treat patients with memory disorders evolves. An appreciation of current concepts in the anatomic, physiologic, and psychological aspects of memory, combined with a rational application of everyday tools (such as clinical examination, bedside testing, standardized cognitive screening, and formal neuropsychological examination), allows the clinician to identify possible etiologies and track longitudinal changes in functional memory status. Recent findings regarding the interactions of limbic, anterior temporal, primary sensory, parietal, and dorsal prefrontal structures shed new light on the putative classifications of procedural and declarative memory and their subfunctions.
SUMMARY
An understanding of memory profiles pertaining to registration, encoding, consolidation, storage, and retrieval, as well as methods to assess those functions, facilitates the clinician's identification of underlying pathology and affected cerebral territories. The memory profile must be appreciated in the context of the entire individual, including possible confounds of comorbid conditions, psychiatric disorders, and normal healthy aging.
Topics: Humans; Memory Disorders; Mental Disorders; Neuropsychological Tests
PubMed: 34881726
DOI: 10.1212/CON.0000000000001020 -
Handbook of Clinical Neurology 2020Since the seminal work on the patient HM, who in his adulthood presented an acquired amnesic syndrome following the resection of the bilateral temporal lobe, other... (Review)
Review
Since the seminal work on the patient HM, who in his adulthood presented an acquired amnesic syndrome following the resection of the bilateral temporal lobe, other research has described several cases of isolated memory dysfunction in children. This chapter presents developmental and long-lasting memory disorders emerging from an organic or neurologic cause at birth or in infancy. More notably, we focus on developmental amnesic syndrome caused by neonatal bihippocampal damage and memory dysfunction caused by medial temporal developmental epilepsy. We describe these two pediatric populations and present the consequences of hippocampal/medial temporal lobe damage in the development of memory systems. We review episodic memory deficits in children with developmental amnesia and temporal lobe epilepsy and highlight their impact on new learning, personal memories, and independent life. Finally, we provide a brief overview of some of the insights and debates emerging from classic work and recent advances in the context of episodic memory dysfunction displayed by children with hippocampal/medial temporal lobe amnesia and propose new perspectives in child neuropsychology of memory, suggesting new avenues for more ecologic memory assessment and rehabilitation.
Topics: Amnesia; Hippocampus; Humans; Memory Disorders; Memory, Episodic; Neuropsychological Tests; Temporal Lobe
PubMed: 32977899
DOI: 10.1016/B978-0-444-64148-9.00008-9 -
The Lancet. Psychiatry Feb 2020Cognitive symptoms are common, and yet many who seek help for cognitive symptoms neither have, nor go on to develop, dementia. A proportion of these people are likely to...
Cognitive symptoms are common, and yet many who seek help for cognitive symptoms neither have, nor go on to develop, dementia. A proportion of these people are likely to have functional cognitive disorders, a subtype of functional neurological disorders, in which cognitive symptoms are present, associated with distress or disability, but caused by functional alterations rather than degenerative brain disease or another structural lesion. In this Review, we have systematically examined the prevalence and clinical associations of functional cognitive disorders, and related phenotypes, within the wider cognitive disorder literature. Around a quarter of patients presenting to memory clinics received diagnoses that might indicate the presence of functional cognitive disorders, which were associated with affective symptoms, negative self-evaluation, negative illness perceptions, non-progressive symptom trajectories, and linguistic and behavioural differences during clinical interactions. Those with functional cognitive disorder phenotypes are at risk of iatrogenic harm because of misdiagnosis or inaccurate prediction of future decline. Further research is imperative to improve diagnosis and identify effective treatments for functional cognitive disorders, and better understanding these phenotypes will also improve the specificity of diagnoses of prodromal degenerative brain disease.
Topics: Affective Symptoms; Attitude to Health; Cognition Disorders; Humans; Medically Unexplained Symptoms; Memory Disorders
PubMed: 31732482
DOI: 10.1016/S2215-0366(19)30405-5 -
Continuum (Minneapolis, Minn.) Dec 2021This article provides a definition of and introduction to cognitive rehabilitation. It discusses different approaches to cognitive rehabilitation (ie, restorative,... (Review)
Review
PURPOSE OF REVIEW
This article provides a definition of and introduction to cognitive rehabilitation. It discusses different approaches to cognitive rehabilitation (ie, restorative, compensatory, and metacognitive). It also reviews types of memory impairment and how they can be distinguished to improve treatment design and implementation.
RECENT FINDINGS
Neural plasticity as a biological substrate for functional changes from cognitive rehabilitation is an exciting new area of research.
SUMMARY
This article provides a high-level review of cognitive rehabilitation and presents a complex case example.
Topics: Cognition; Humans; Memory Disorders
PubMed: 34881731
DOI: 10.1212/CON.0000000000001075 -
The American Journal of Psychiatry Aug 2022Neuropsychiatric symptoms of dementia (NPS) are a group of noncognitive symptoms that occur in over 90% of individuals with dementia. NPS seem to result from a complex... (Review)
Review
Neuropsychiatric symptoms of dementia (NPS) are a group of noncognitive symptoms that occur in over 90% of individuals with dementia. NPS seem to result from a complex interaction among various biological, psychosocial, and environmental factors, and they are associated with greater morbidity and mortality, higher caregiver burden and burnout, high risk of nursing home placement, and increased cost of care for patients with dementia. Use of standardized assessment tools like the Neuropsychiatric Inventory can assist with qualifying and quantifying NPS. In this review, the authors evaluate the evidence for efficacy and safety of nonpharmacological and pharmacological interventions for treating NPS, mostly based on published meta-analyses. Commonly prescribed medications include atypical antipsychotics, acetylcholinesterase inhibitors, memantine, antidepressants, and mood stabilizers. There are also limited data on cannabinoids, repetitive transcranial magnetic stimulation, and ECT in individuals with NPS. Available evidence indicates that several nonpharmacological interventions are beneficial in the management of NPS and are recommended as first-line treatments. Pharmacotherapy should be reserved for the treatment of more severe or refractory NPS or where nonpharmacological management is not feasible. Atypical antipsychotics have shown mostly modest benefit in reducing NPS, and their use is limited by their adverse effect profiles. Recent investigations suggest potential strategies for preventing or at least reducing the risk of dementia and NPS. The authors conclude with brief guidelines for clinical practice as well as future research.
Topics: Acetylcholinesterase; Antidepressive Agents; Antipsychotic Agents; Dementia; Humans; Memory Disorders
PubMed: 35921394
DOI: 10.1176/appi.ajp.20220508 -
Nature Communications Mar 2021Aberrant regulation of microRNAs (miRNAs) has been implicated in the pathogenesis of Alzheimer's disease (AD), but most abnormally expressed miRNAs found in AD are not...
Aberrant regulation of microRNAs (miRNAs) has been implicated in the pathogenesis of Alzheimer's disease (AD), but most abnormally expressed miRNAs found in AD are not regulated by synaptic activity. Here we report that dysfunction of miR-135a-5p/Rock2/Add1 results in memory/synaptic disorder in a mouse model of AD. miR-135a-5p levels are significantly reduced in excitatory hippocampal neurons of AD model mice. This decrease is tau dependent and mediated by Foxd3. Inhibition of miR-135a-5p leads to synaptic disorder and memory impairments. Furthermore, excess Rock2 levels caused by loss of miR-135a-5p plays an important role in the synaptic disorder of AD via phosphorylation of Ser726 on adducin 1 (Add1). Blocking the phosphorylation of Ser726 on Add1 with a membrane-permeable peptide effectively rescues the memory impairments in AD mice. Taken together, these findings demonstrate that synaptic-related miR-135a-5p mediates synaptic/memory deficits in AD via the Rock2/Add1 signaling pathway, illuminating a potential therapeutic strategy for AD.
Topics: Alzheimer Disease; Animals; Cells, Cultured; Cytoskeletal Proteins; Disease Models, Animal; Hippocampus; Male; Maze Learning; Memory Disorders; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; MicroRNAs; Neurons; Phosphorylation; Signal Transduction; Synapses; rho-Associated Kinases; tau Proteins; Mice
PubMed: 33771994
DOI: 10.1038/s41467-021-22196-y -
Journal of the Neurological Sciences Jun 2020Acute amnestic syndromes are usually rare clinical events occurring in emergency situations. Etiological diagnosis can be challenging and underlying causes diverse. They... (Review)
Review
Acute amnestic syndromes are usually rare clinical events occurring in emergency situations. Etiological diagnosis can be challenging and underlying causes diverse. They can be transient and totally reversible, or accompanied by other neurological symptoms resulting in serious and irreversible brain damage. Pathophysiology of these syndromes mainly corresponds to structural or functional alteration of memory circuits, including those in the hippocampus. One of the most frequent forms is transient global amnesia (TGA), characterized by sudden onset of anterograde amnesia lasting less than 24 hours, in the absence of other neurological signs or symptoms. Another acute and transient memory disorder is transient epileptic amnesia (TEA), due to focal crisis activity. Stroke injuries occurring at strategic memory-related sites can also present as sudden episodes of amnesia. In addition to neurological etiologies, amnesia may be a symptom of a psychiatric disorder (dissociative amnesia). Traumatic brain injuries, autoimmune encephalitis and acute toxic metabolic disorders can also cause amnesia and should be included among the differential diagnoses. In this review, we summarize the most relevant clinical findings in acute amnestic syndromes, and discuss the different ancillary tests needed to establish a correct diagnosis and management as well the best treatment options. Relevant anatomical and pathophysiological aspects underlying these conditions will be also be presented.
Topics: Amnesia; Amnesia, Transient Global; Brain Injuries; Humans; Memory; Syndrome
PubMed: 32203745
DOI: 10.1016/j.jns.2020.116781 -
Psychology, Health & Medicine Aug 2022It is found that overgeneral Autobiographic Memory (AM) disturbance is related to affective disorder such as depression. This article reviewed the conception and... (Review)
Review
It is found that overgeneral Autobiographic Memory (AM) disturbance is related to affective disorder such as depression. This article reviewed the conception and mechanism of overgeneral AM, which including Affection Regulation, Functional Avoidance, Capture & Rumination, Impaired Executive Control and the CaR-FA-X model. The relationship between depression and overgeneral AM is also reviewed, in both adult and adolescent patients, overgeneral AM is a risk factor of depressive disorder and AM deficits might be trait-like in depressive patients.
Topics: Adolescent; Adult; Depression; Executive Function; Humans; Memory Disorders; Memory, Episodic; Mood Disorders
PubMed: 33870813
DOI: 10.1080/13548506.2021.1916954