-
Alcoholism, Clinical and Experimental... Jun 2020Marijuana and alcohol are both substances that, when used during pregnancy, may have profound effects on the developing fetus. There is evidence to suggest that both...
BACKGROUND
Marijuana and alcohol are both substances that, when used during pregnancy, may have profound effects on the developing fetus. There is evidence to suggest that both drugs have the capacity to affect working memory, one function of the hippocampal formation; however, there is a paucity of data on how perinatal exposure to alcohol or cannabis impacts the process of adult neurogenesis.
METHODS
This systematic review examines immunohistochemical data from adult rat and mouse models that assess perinatal alcohol or perinatal marijuana exposure. A comprehensive list of search terms was designed and used to search 3 separate databases. All results were imported to Mendeley and screened by 2 authors. Consensus was reached on a set of final papers that met the inclusion criteria, and their results were summarized.
RESULTS
Twelve papers were identified as relevant, 10 of which pertained to the effects of perinatal alcohol on the adult hippocampus, and 2 pertained to the effects of perinatal marijuana on the adult hippocampus. Cellular proliferation in the dentate gyrus was not affected in adult rats and mice exposed to alcohol perinatally. In general, perinatal alcohol exposure did not have a significant and reliable effect on the maturation and survival of adult born granule neurons in the dentate gyrus. In contrast, interneuron numbers appear to be reduced in the dentate gyrus of adult rats and mice exposed perinatally to alcohol. Perinatal marijuana exposure was also found to reduce inhibitory interneuron numbers in the dentate gyrus.
CONCLUSIONS
Perinatal alcohol exposure and perinatal marijuana exposure both act on inhibitory interneurons in the hippocampal formation of adult rats. These findings suggest simultaneous perinatal alcohol and marijuana exposure (SAM) may have a dramatic impact on inhibitory processes in the dentate gyrus.
Topics: Alcohol Drinking; Animals; Cannabinoid Receptor Agonists; Central Nervous System Depressants; Dentate Gyrus; Dronabinol; Ethanol; Female; Marijuana Use; Mice; Neurogenesis; Pregnancy; Pregnancy Complications; Prenatal Exposure Delayed Effects; Rats
PubMed: 32246781
DOI: 10.1111/acer.14332 -
Journal of Neurology May 2023To evaluate the difference of tau burden between patients with progressive supranuclear palsy (PSP) and healthy controls (HCs) or other neurodegenerative diseases using... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
To evaluate the difference of tau burden between patients with progressive supranuclear palsy (PSP) and healthy controls (HCs) or other neurodegenerative diseases using tau-positron emission tomography (PET) imaging.
METHODS
A systematic search on PubMed, Embase, and Web of Science databases was performed for tau-PET studies in PSP patients, up to April 1, 2022. Standardized mean differences (SMDs) of tau tracer uptake were calculated using random-effects models. Subgroup analysis based on the type of tau tracers, meta-regression, and sensitivity analysis were conducted.
RESULTS
Twenty-seven studies comprising 553 PSP, 626 HCs, and 406 other neurodegenerative diseases were included. Compared with HCs, PSP patients showed elevated tau binding in basal ganglia, midbrain, dentate nucleus, cerebellar white matter, and frontal lobe with decreasing SMD (SMD: 0.390-1.698). Compared with Parkinson's disease patients, increased tau binding was identified in the midbrain, basal ganglia, dentate nucleus, and frontal and parietal lobe in PSP patients with decreasing SMD (SMD: 0.503-1.853). PSP patients showed higher tau binding in the subthalamic nucleus (SMD = 1.351) and globus pallidus (SMD = 1.000), and lower binding in the cortex and parahippocampal gyrus than Alzheimer's disease patients (SMD: - 2.976 to - 1.018). PSP patients showed higher midbrain tau binding than multiple system atrophy patients (SMD = 1.269).
CONCLUSION
Tau PET imaging indicates different topography of tau deposition between PSP patients and HCs or other neurodegenerative disorders. The affinity and selectivity of tracers for 4R-tau and the off-target binding of tracers should be considered when interpreting the results.
Topics: Humans; Supranuclear Palsy, Progressive; tau Proteins; Basal Ganglia; Parkinson Disease; Positron-Emission Tomography
PubMed: 36633672
DOI: 10.1007/s00415-022-11556-3 -
CNS Neuroscience & Therapeutics Feb 2024Amyotrophic lateral sclerosis (ALS) is a progressive motor and extra-motor neurodegenerative disease. This systematic review aimed to examine MRI biomarkers and... (Review)
Review
BACKGROUND AND OBJECTIVE
Amyotrophic lateral sclerosis (ALS) is a progressive motor and extra-motor neurodegenerative disease. This systematic review aimed to examine MRI biomarkers and neuropsychological assessments of the hippocampal and parahippocampal regions in patients with ALS.
METHODS
A systematic review was conducted in the Scopus and PubMed databases for studies published between January 2000 and July 2023. The inclusion criteria were (1) MRI studies to assess hippocampal and parahippocampal regions in ALS patients, and (2) studies reporting neuropsychological data in patients with ALS.
RESULTS
A total of 46 studies were included. Structural MRI revealed hippocampal atrophy, especially in ALS-FTD, involving specific subregions (CA1, dentate gyrus). Disease progression and genetic factors impacted atrophy patterns. Diffusion tensor imaging (DTI) showed increased mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and decreased fractional anisotropy (FA) in the hippocampal tracts and adjacent regions, indicating loss of neuronal and white matter integrity. Functional MRI (fMRI) revealed reduced functional connectivity (FC) between the hippocampus, parahippocampus, and other regions, suggesting disrupted networks. Perfusion MRI showed hypoperfusion in parahippocampal gyri. Magnetic resonance spectroscopy (MRS) found changes in the hippocampus, indicating neuronal loss. Neuropsychological tests showed associations between poorer memory and hippocampal atrophy or connectivity changes. CA1-2, dentate gyrus, and fimbria atrophy were correlated with worse memory.
CONCLUSIONS
The hippocampus and the connected regions are involved in ALS. Hippocampal atrophy disrupted connectivity and metabolite changes correlate with cognitive and functional decline. Specific subregions can be particularly affected. The hippocampus is a potential biomarker for disease monitoring and prognosis.
Topics: Humans; Diffusion Tensor Imaging; Amyotrophic Lateral Sclerosis; Neurodegenerative Diseases; Frontotemporal Dementia; Magnetic Resonance Imaging; Hippocampus; Biomarkers; Neuropsychological Tests; Atrophy
PubMed: 38334254
DOI: 10.1111/cns.14578 -
Journal of Psychiatry & Neuroscience :... 2023Hippocampal disturbances are important in the pathophysiology of both schizophrenia and major depressive disorder (MDD). Imaging studies have shown selective volume... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Hippocampal disturbances are important in the pathophysiology of both schizophrenia and major depressive disorder (MDD). Imaging studies have shown selective volume deficits across hippocampal subfields in both disorders. We aimed to investigate whether these volumetric alterations in hippocampal subfields are shared or divergent across disorders.
METHODS
We searched PubMed and Embase from database inception to May 8, 2021. We identified MRI studies in patients with schizophrenia, MDD or both, in which hippocampal subfield volumes were measured. We excluded nonoriginal, animal or postmortem studies, and studies that used other imaging modalities or overlapping data. We conducted a network meta-analysis to estimate and contrast alterations in subfield volumes in the 2 disorders.
RESULTS
We identified 45 studies that met the initial criteria for systematic review, of which 15 were eligible for network metaanalysis. Compared to healthy controls, patients with schizophrenia had reduced volumes in the bilateral cornu ammonis (CA) 1, granule cell layer of the dentate gyrus, subiculum, parasubiculum, molecular layer, hippocampal tail and hippocampus-amygdala transition area (HATA); in the left CA4 and presubiculum; and in the right fimbria. Patients with MDD had decreased volumes in the left CA3 and CA4 and increased volumes in the right HATA compared to healthy controls. The bilateral parasubiculum and right HATA were smaller in patients with schizophrenia than in patients with MDD.
LIMITATIONS
We did not investigate medication effects because of limited information. Study heterogeneity was noteworthy in direct comparisons between patients with MDD and healthy controls.
CONCLUSION
The volumes of multiple hippocampal subfields are selectively altered in patients with schizophrenia and MDD, with overlap and differentiation in subfield alterations across disorders. Rigorous head-to-head studies are needed to validate our findings.
Topics: Humans; Depressive Disorder, Major; Network Meta-Analysis; Schizophrenia; Hippocampus; Magnetic Resonance Imaging; Organ Size
PubMed: 36750240
DOI: 10.1503/jpn.220086 -
Hippocampus Sep 2017The generation of new neurons in the hippocampus of adult mammals has become a widely accepted phenomenon, but the functional significance of the adult neurogenesis in... (Meta-Analysis)
Meta-Analysis Review
The generation of new neurons in the hippocampus of adult mammals has become a widely accepted phenomenon, but the functional significance of the adult neurogenesis in the hippocampus is not fully understood. One of the main hypotheses currently investigated suggests that neurogenesis contributes to pattern separation in the dentate gyrus. Many behavioral studies were conducted aiming to test this hypothesis using rodents as animal model. In those studies, researches ablated neurogenesis in the animals and subsequently evaluate them in tests of behavioral pattern separation, that is, behaviors that are thought to rely on the computational process of pattern separation. The results of these studies are varied, with most supporting a role for neurogenesis in pattern separation, but some others not. To address this controversy we performed a systematic review and meta-analysis of studies evaluating the effect of neurogenesis ablation on behavioral pattern separation. Analysis results indicated that most of the literature in the topic is surprisingly consistent and, although there are two studies with divergent results, the bulk of the literature supports an effect of hippocampal neurogenesis on behavioral pattern separation. We discuss those findings in light of other behavioral effects of hippocampal neurogenesis ablation, limitations of behavioral data and other lines of evidence about the effect of hippocampal neurogenesis in the dentate gyrus.
Topics: Animals; Databases, Bibliographic; Hippocampus; Humans; Neurogenesis; Neurons
PubMed: 28597491
DOI: 10.1002/hipo.22746 -
Frontiers in Physiology 2023Studies have shown that exercise increases angiogenesis and perfusion in the hippocampus, activates neurogenesis in the dentate gyrus and increases synaptic plasticity,...
Studies have shown that exercise increases angiogenesis and perfusion in the hippocampus, activates neurogenesis in the dentate gyrus and increases synaptic plasticity, as well as increases the complexity and number of dendritic spines, all of which promote memory function and protect against cognitive decline. Flavonoids are gaining attention as antioxidants in health promotion due to their rich phenolic content, particularly for their modulating role in the treatment of neurodegenerative diseases. Despite this, there has been no comprehensive review of cognitive improvement supplemented with flavonoid and prescribed with exercise or a combination of the two interventions has been conducted. The purpose of this review is to determine whether a combined intervention produces better results when given together than when given separately. Relevant articles assessing the effect of physical exercise, flavonoid or in combination on cognitive related biomarkers and neurobehavioral assessments within the timeline of January 2011 until June 2023 were searched using three databases; PubMed, PROQUEST and SCOPUS. A total of 705 articles were retrieved and screened, resulting in 108 studies which are in line with the objective of the current study were included in the analysis. The selected studies have shown significant desired effect on the chosen biomarkers and neurobehavioral assessments. identifier: [CRD42021271001].
PubMed: 37664425
DOI: 10.3389/fphys.2023.1216948 -
Hippocampus Jun 2016To systematically review the characteristics, validity and outcome measures of tasks that have been described in the literature as assessing pattern separation and... (Review)
Review
To systematically review the characteristics, validity and outcome measures of tasks that have been described in the literature as assessing pattern separation and pattern completion in humans. Electronic databases were searched for articles. Parameters for task validity were obtained from two reviews that described optimal task design factors to evaluate pattern separation and pattern completion processes. These were that pattern separation should be tested during an encoding task using abstract, never-before-seen visual stimuli, and pattern completion during a retrieval task using partial cues; parametric alteration of the degree of interference of stimuli or degradation of cues should be used to generate a corresponding gradient in behavioral output; studies should explicitly identify the specific memory domain under investigation (sensory/perceptual, temporal, spatial, affect, response, or language) and account for the contribution of other potential attributes involved in performance of the task. A systematic, qualitative assessment of validity in relation to these parameters was performed, along with a review of general validity and task outcome measures. Sixty-two studies were included. The majority of studies investigated pattern separation and most tasks were performed on young, healthy adults. Pattern separation and pattern completion were most frequently tested during a retrieval task using familiar or recognizable visual stimuli and cues. Not all studies parametrically altered the degree of stimulus interference or cue degradation, or controlled for potential confounding factors. This review found evidence that some of the parameters for task validity have been followed in some human studies of pattern separation and pattern completion, but no study was judged to have adequately met all the parameters for task validity. The contribution of these parameters and other task design factors towards an optimal behavioral paradigm is discussed and recommendations for future research are made. © 2015 Wiley Periodicals, Inc.
Topics: Discrimination, Psychological; Hippocampus; Humans; Recognition, Psychology
PubMed: 26663362
DOI: 10.1002/hipo.22561 -
Neuropsychologia Jul 2014In this systematic review and meta-analysis, we explore how the time scale of practice affects patterns of brain activity associated with motor skill acquisition.... (Meta-Analysis)
Meta-Analysis Review
In this systematic review and meta-analysis, we explore how the time scale of practice affects patterns of brain activity associated with motor skill acquisition. Fifty-eight studies that involved skill learning with healthy participants (117 contrasts) met inclusion criteria. Two meta-contrasts were coded: decreases: peak coordinates that showed decreases in brain activity over time; increases: peak coordinates that showed increases in activity over time. Studies were grouped by practice time scale: short (≤1 h; 25 studies), medium (>1 and ≤24 h; 18 studies), and long (>24h to 5 weeks; 17 studies). Coordinates were analyzed using Activation Likelihood Estimation to show brain areas that were consistently activated for each contrast. Across time scales, consistent decreases in activity were shown in prefrontal and premotor cortex, the inferior parietal lobules, and the cerebellar cortex. Across the short and medium time scales there were consistent increases in supplementary and primary motor cortex and dentate nucleus. At the long time scale, increases were seen in posterior cingulate gyrus, primary motor cortex, putamen, and globus pallidus. Comparisons between time scales showed that increased activity in M1 at medium time scales was more spatially consistent across studies than increased activity in M1 at long time scales. Further, activity in the striatum (viz. putamen and globus pallidus) was consistently more rostral in the medium time scale and consistently more caudal in the long time scale. These data support neurophysiological models that posit that both a cortico-cerebellar system and a cortico-striatal system are active, but at different time points, during motor learning, and suggest there are associative/premotor and sensorimotor networks active within each system.
Topics: Brain; Brain Mapping; Humans; Learning; Motor Skills; Neural Pathways; Neuroimaging; Time Factors
PubMed: 24831923
DOI: 10.1016/j.neuropsychologia.2014.05.001 -
Pharmacological Reports : PR Apr 2016Lithium has been used in modern psychiatry for more than 65 years, constituting a cornerstone for the long-term treatment of bipolar disorder. A number of biological... (Review)
Review
Lithium has been used in modern psychiatry for more than 65 years, constituting a cornerstone for the long-term treatment of bipolar disorder. A number of biological properties of lithium have been discovered, including its hematological, antiviral and neuroprotective effects. In this article, a systematic review of the effect of lithium on hematopoietic, mesenchymal and neural stem cells is presented. The beneficial effects of lithium on the level of hematopoietic stem cells (HSC) and growth factors have been reported since 1970s. Lithium improves homing of stem cells, the ability to form colonies and HSC self-renewal. Lithium also exerts a favorable influence on the proliferation and maintenance of mesenchymal stem cells (MSC). Studies on the effect of lithium on neurogenesis have indicated an increased proliferation of progenitor cells in the dentate gyrus of the hippocampus and enhanced mitotic activity of Schwann cells. This may be connected with the neuroprotective and neurotrophic effects of lithium, reflected in an improvement in synaptic plasticity promoting cell survival and inhibiting apoptosis. In clinical studies, lithium treatment increases cerebral gray matter, mainly in the frontal lobes, hippocampus and amygdala. Recent findings also suggest that lithium may reduce the risk of dementia and exert a beneficial effect in neurodegenerative diseases. The most important mediators and signaling pathways of lithium action are the glycogen synthase kinase-3 and Wnt/β-catenin pathways. Recently, to study of bipolar disorder pathogenesis and the mechanism of lithium action, the induced pluripotent stem cells (iPSC) obtained from bipolar patients have been used.
Topics: Animals; Cell Proliferation; Hematopoietic Stem Cells; Hippocampus; Humans; Lithium; Mesenchymal Stem Cells; Neural Stem Cells; Neurogenesis
PubMed: 26922521
DOI: 10.1016/j.pharep.2015.09.005 -
Experimental Neurology Jul 2023Cerebral palsy (CP) is a neurodevelopmental disorder caused by damage to the immature brain. CP is considered the main cause of physical disability in childhood. Studies... (Meta-Analysis)
Meta-Analysis Review
Therapeutic advances for treating memory impairments in perinatal brain injuries with implications for cerebral palsy: a systematic review and meta-analysis of preclinical studies.
Cerebral palsy (CP) is a neurodevelopmental disorder caused by damage to the immature brain. CP is considered the main cause of physical disability in childhood. Studies have shown that memory function and emotional behaviour are significantly impaired in CP. Current thought is that interventions for neuromotor damaged play a prominent role, but neglects the memory acquisition problems that affect the functioning and quality of life of these children. This systematic review aims to map and analyse pre-clinical interventions used to treat memory formation problems resulting from CP. For this, a search was carried out in the Pubmed, Web of Science, Scopus and Lilacs databases. Then, eligibility, extraction date and evaluation of the methodological quality of the studies were determined. 52 studies were included in this review, and 27 were included in a meta-analysis. Assessing memory performance as a primary outcome, and structural and biochemical changes in the hippocampus as a secondary outcome. CP models were reported to be induced by hypoxia-ischemia, oxygen deprivation and liposaccharide (LPS) exposure, resulting in impairments in the formation of short-term and long-term memory in adult life. A reduction in escape latency and dwell time were observed in the target quadrant as well as an increase in the time needed for the rodents to find the platform in the Morris Water Maze (MWM). Brain injuries during the perinatal period are considered an insult that negatively impacts hippocampus maturation and causes impairment in memory formation in adult life. Some studies reported that regions of the hippocampus such as the dentate gyrus and cornu ammonis 1 were impaired in CP, noting an increase in oxidative stress enzymes and pro-inflammatory cytokines, associated with a reduction in BDNF and neurogenesis levels. These were reported to cause a reduction in the number of neurons and the volume of the hippocampus, in addition to an increase in astrogliosis and apoptosis of neurons and difficulties in forming new memories similar to those that occur in children with CP. Interventions that reduced neuroinflammation and the presence of free radicals were highlighted as a therapy for the memory disturbance present in CP. Preclinical studies registered treatments with oxygen interventions, resveratrol and erythropoietin, which were able to reduce the damage to the hippocampus and promote improvements in memory and behaviour. In the meta-analysis of selected studies, we observed favorable results, through effect size, for the use of oxygen interventions (SDM -6.83 95% CI [-7.91, -5.75], Z = 12.38, p = 0.03; I2 = 71%), erythropoietin (SDM -3.16 95% CI [-4.27, -2.05], Z = 5.58, p = 0.002; I2 = 82%) and resveratrol (SDM -2.42 95% CI [-3.19, - 1.66], Z = 6.21, p = 0.01; I2 = 77%), stimulating plastic responses in the hippocampus and facilitating the memory formation, with these presenting positive effects in general (SDM -2.84 95% CI [-3.10, -2.59], Z = 22.00; p < 0.00001; I2 = 92.9%). These studies demonstrate possible avenues of intervention for memory alterations in experimental models of early brain injuries, highlighting promising interventions that can facilitate the maturation of the hippocampus and memory formation and, consequently, minimize functional problems that arise during development.
Topics: Humans; Cerebral Palsy; Quality of Life; Resveratrol; Hippocampus; Memory Disorders; Brain Injuries; Erythropoietin
PubMed: 37068620
DOI: 10.1016/j.expneurol.2023.114411