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Neural Regeneration Research Jan 2024Adult neurogenesis, the process of creating new neurons, involves the coordinated division, migration, and differentiation of neural stem cells. This process is... (Review)
Review
Adult neurogenesis, the process of creating new neurons, involves the coordinated division, migration, and differentiation of neural stem cells. This process is restricted to neurogenic niches located in two distinct areas of the brain: the subgranular zone of the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricle, where new neurons are generated and then migrate to the olfactory bulb. Neurogenesis has been thought to occur only during the embryonic and early postnatal stages and to decline with age due to a continuous depletion of neural stem cells. Interestingly, recent years have seen tremendous progress in our understanding of adult brain neurogenesis, bridging the knowledge gap between embryonic and adult neurogenesis. Here, we discuss the current status of adult brain neurogenesis in light of what we know about neural stem cells. In this notion, we talk about the importance of intracellular signaling molecules in mobilizing endogenous neural stem cell proliferation. Based on the current understanding, we can declare that these molecules play a role in targeting neurogenesis in the mature brain. However, to achieve this goal, we need to avoid the undesired proliferation of neural stem cells by controlling the necessary checkpoints, which can lead to tumorigenesis and prove to be a curse instead of a blessing or hope.
PubMed: 37488837
DOI: 10.4103/1673-5374.375317 -
EC Psychology and Psychiatry Jun 2023The aim of this study is to provide a comprehensive overview of spatial multiomics analysis, including its definition, processes, applications, significance and relevant...
The aim of this study is to provide a comprehensive overview of spatial multiomics analysis, including its definition, processes, applications, significance and relevant research in psychiatric disorders. To achieve this, a literature search was conducted, focusing on three major spatial omics techniques and their application to three common psychiatric disorders: Alzheimer's disease (AD), schizophrenia, and autism spectrum disorders. Spatial genomics analysis has revealed specific genes associated with neuropsychiatric disorders in certain brain regions. Spatial transcriptomics analysis has identified genes related to AD in areas such as the hippocampus, olfactory bulb, and middle temporal gyrus. It has also provided insight into the response to AD in mouse models. Spatial proteogenomics has identified autism spectrum disorder (ASD)-risk genes in specific cell types, while schizophrenia risk loci have been linked to transcriptional signatures in the human hippocampus. In summary, spatial multiomics analysis offers a powerful approach to understand AD pathology and other psychiatric diseases, integrating multiple data modalities to identify risk genes for these disorders. It is valuable for studying psychiatric disorders with high or low cellular heterogeneity and provides new insights into the brain nucleome to predict disease progression and aid diagnosis and treatment.
PubMed: 37424930
DOI: No ID Found -
Frontiers in Cellular Neuroscience 2023Translocator protein (TSPO), a 18 kDa protein found in the outer mitochondrial membrane, has historically been associated with the transport of cholesterol in highly... (Review)
Review
Translocator protein (TSPO), a 18 kDa protein found in the outer mitochondrial membrane, has historically been associated with the transport of cholesterol in highly steroidogenic tissues though it is found in all cells throughout the mammalian body. TSPO has also been associated with molecular transport, oxidative stress, apoptosis, and energy metabolism. TSPO levels are typically low in the central nervous system (CNS), but a significant upregulation is observed in activated microglia during neuroinflammation. However, there are also a few specific regions that have been reported to have higher TSPO levels than the rest of the brain under normal conditions. These include the dentate gyrus of the hippocampus, the olfactory bulb, the subventricular zone, the choroid plexus, and the cerebellum. These areas are also all associated with adult neurogenesis, yet there is no explanation of TSPO's function in these cells. Current studies have investigated the role of TSPO in microglia during neuron degeneration, but TSPO's role in the rest of the neuron lifecycle remains to be elucidated. This review aims to discuss the known functions of TSPO and its potential role in the lifecycle of neurons within the CNS.
PubMed: 37416505
DOI: 10.3389/fncel.2023.1210205 -
Scientific Reports Jun 2023Although the combination antiretroviral treatment (cART) has considerably lowered the risk of HIV associated dementia (HAD), the incidence of neurocognitive...
Although the combination antiretroviral treatment (cART) has considerably lowered the risk of HIV associated dementia (HAD), the incidence of neurocognitive impairments (NCI) has not decreased likely due to the insidious and slow progressive nature of HIV infection. Recent studies showed that the resting-state functional magnetic resonance imaging (rs-fMRI) is a prominent technique in helping the non-invasive analysis of neucognitive impairment. Our study is to explore the neuroimaging characteristics among people living with HIV (PLWH) with or without NCI in terms of cerebral regional and neural network by rs-fMRI, based on the hypothesis that HIV patients with and without NCI have independent brain imaging characteristics. 33 PLWH with NCI and 33 PLWH without NCI, recruited from the Cohort of HIV-infected associated Chronic Diseases and Health Outcomes, Shanghai, China (CHCDO) which was established in 2018, were categorized into the HIV-NCI and HIV-control groups, respectively, based on Mini-Mental State Examination (MMSE) results. The two groups were matched in terms of sex, education and age. Resting-state fMRI data were collected from all participants to analyze the fraction amplitude of low-frequency fluctuation (fALFF) and functional connectivity (FC) to assess regional and neural network alterations in the brain. Correlations between fALFF/FC values in specific brain regions and clinical characteristics were also examined. The results showed increased fALFF values in the bilateral calcarine gyrus, bilateral superior occipital gyrus, left middle occipital gyrus, and left cuneus in the HIV-NCI group compared to the HIV-control group. Additionally, increased FC values were observed between the right superior occipital gyrus and right olfactory cortex, bilateral gyrus rectus, and right orbital part of the middle frontal gyrus in the HIV-NCI group. Conversely, decreased FC values were found between the left hippocampus and bilateral medial prefrontal gyrus, as well as bilateral superior frontal gyrus. The study concluded that abnormal spontaneous activity in PLWH with NCI primarily occurred in the occipital cortex, while defects in brain networks were mostly associated with the prefrontal cortex. The observed changes in fALFF and FC in specific brain regions provide visual evidence to enhance our understanding of the central mechanisms underlying the development of cognitive impairment in HIV patients.
Topics: Humans; Magnetic Resonance Imaging; HIV Infections; Brain Mapping; China; Brain; AIDS Dementia Complex
PubMed: 37365237
DOI: 10.1038/s41598-023-37493-3 -
Acta Radiologica (Stockholm, Sweden :... Sep 2023Bipolar disorder (BD) is a mental health disorder.
BACKGROUND
Bipolar disorder (BD) is a mental health disorder.
PURPOSE
To investigate the peripheric and central olfactory measurements in patients with BD using magnetic resonance imaging (MRI).
MATERIAL AND METHODS
This study was conducted retrospectively. Group 1 consisted of 27 euthymic patients with BD (14 men, 13 women) and Group 2 consisted of 27 healthy controls (14 men, 13 women). Olfactory bulb (OB) volume and olfactory sulcus (OS) depth (peripheric), and corpus amygdala and insular gyrus area (central) measurements were performed using cranial MRI.
RESULTS
OB volume and OS depth value of the bipolar group were lower than the control group, but there were no significant differences between the groups ( > 0.05). The corpus amygdala and left insular gyrus area of the bipolar group were significantly lower than those in the control group ( < 0.05). There were positive correlations between OB volumes and OS depths, the insular gyrus areas, and the corpus amygdala areas ( < 0.05). As the number of depressive episodes and duration of illness increased in bipolar patients, the depth of the sulcus decreased ( < 0.05).
CONCLUSION
In the present study a correlation was detected between OB volumes and the structures, known as emotional processing (e.g. insular gyrus area, corpus amygdala), and clinical features. Accordingly, new treatment techniques, such as olfactory training, may be considered an option in the treatment of such patients with BD.
Topics: Male; Humans; Female; Bipolar Disorder; Olfaction Disorders; Retrospective Studies; Smell; Amygdala; Magnetic Resonance Imaging
PubMed: 37312533
DOI: 10.1177/02841851231179174 -
Cortex; a Journal Devoted To the Study... Aug 2023Lemon fragrance is known for its stimulating properties, but its mechanisms of action are not well known yet. This study aimed to examine the effect of lemon essential...
Lemon fragrance is known for its stimulating properties, but its mechanisms of action are not well known yet. This study aimed to examine the effect of lemon essential oil inhalation on healthy participants' alertness level and their neural correlates using magnetic resonance imaging (MRI). Twenty-one healthy men underwent functional MRI scans in different conditions: a resting state condition, a condition where they were exposed to passive lemon smelling (alternating exposure to lemon and breathing fresh air), and a control condition without lemon fragrance diffusion -the order of the last two conditions being randomized. Alertness levels were assessed immediately after each condition using the Karolinska Sleepiness Scale. Voxel-wise whole-brain global functional connectivity and graph theory analyses were computed to investigate brain functional connectivity and network topology alterations. After lemon fragrance inhalation, we observed a higher level of alertness as compared to resting state -but not compared to control condition. During lemon fragrance inhalation, we found increased global functional connectivity in the thalamus, paralleled by decreased global connectivity in several cortical regions such as precuneus, postcentral and precentral gyrus, lateral occipital cortex and paracingulate gyrus. Graph theory analysis revealed increased network integration in cortical regions typically involved in olfaction and emotion processing such as olfactory bulb, hypothalamus and thalamus, while decreased network segregation in several regions of the posterior part of the brain during olfaction as compared to resting state. The present findings suggest that lemon essential oil inhalation could increase the level of alertness.
Topics: Male; Humans; Brain; Brain Mapping; Magnetic Resonance Imaging; Attention; Thalamus
PubMed: 37285762
DOI: 10.1016/j.cortex.2023.04.012 -
ACS Chemical Neuroscience Jun 2023The functional and developmental unit of neurogenesis is neural stem cells (NSCs). These NSCs have self-renewal capacity and produce new neurons throughout life in... (Review)
Review
The functional and developmental unit of neurogenesis is neural stem cells (NSCs). These NSCs have self-renewal capacity and produce new neurons throughout life in different neurogenic niche. Neurogenesis in adult brain is associated with synaptic plasticity, learning, and memory in dentate gyrus (DG) of hippocampus and olfactory bulb. Remarkably, weakened neurogenesis has been viewed before the onset of different pathological hallmarks of neurological disorders. In this review, we have provided evidence which implicates impaired neurogenesis as a culprit in age associated neurological disorders with greater emphasis on Alzheimer's disease (AD). Moreover, an insight about the molecular and cellular regulation linked with altered neurogenesis in young and aging brain has also been discussed. This review further summarizes the therapeutic strategies for targeting the manipulation of the neural stem cell pool and factors affecting the pool involved in AD.
Topics: Adult; Humans; Alzheimer Disease; Hippocampus; Neural Stem Cells; Neurogenesis; Neurons
PubMed: 37261380
DOI: 10.1021/acschemneuro.3c00119 -
Journal of Clinical Medicine May 2023The efficacy of electroconvulsive therapy (ECT) in the treatment of adolescents with treatment-refractory depression is still unsatisfactory, and the individual...
OBJECTS
The efficacy of electroconvulsive therapy (ECT) in the treatment of adolescents with treatment-refractory depression is still unsatisfactory, and the individual differences are large. It is not clear which factors are related to the treatment effect. Resting-state fMRI may be a good tool to predict the clinical efficacy of this treatment, and it is helpful to identify the most suitable population for this treatment.
METHODS
Forty treatment-refractory depression adolescents were treated by ECT and evaluated using HAMD and BSSI scores before and after treatment, and were then divided into a treatment response group and a non-treatment group according to the reduction rate of the HAMD scale. We extracted the ALFF, fALFF, ReHo, and functional connectivity of patients as predicted features after a two-sample -test and LASSO to establish and evaluate a prediction model of ECT in adolescents with treatment-refractory depression.
RESULTS
Twenty-seven patients achieved a clinical response; symptoms of depression and suicidal ideation were significantly improved after treatment with ECT, which was reflected in a significant decrease in the scores of HAMD and BSSI ( < 0.001). The efficacy was predicted by ALFF, fALFF, ReHo, and whole-brain-based functional connectivity. We found that models built on a subset of features of ALFF in the left insula, fALFF in the left superior parietal gyrus, right superior parietal gyrus, and right angular, and functional connectivity between the left superior frontal gyrus, dorsolateral-right paracentral lobule, right middle frontal gyrus, orbital part-left cuneus, right olfactory cortex-left hippocampus, left insula-left thalamus, and left anterior cingulate gyrus-right hippocampus to have the best predictive performance (AUC > 0.8).
CONCLUSIONS
The local brain function in the insula, superior parietal gyrus, and angular gyrus as well as characteristic changes in the functional connectivity of cortical-limbic circuits may serve as potential markers for efficacy judgment of ECT and help to provide optimized individual treatment strategies for adolescents with depression and suicidal ideation in the early stages of treatment.
PubMed: 37240663
DOI: 10.3390/jcm12103556 -
Journal of Alzheimer's Disease : JAD 2023Olfactory identification dysfunction (OID) might be an early sign of amnestic mild cognitive impairment (aMCI). However, odor hedonics, the ability to perceive odor...
Characteristics of Odor Identification and Hedonics and Their Association with Piriform Cortex-Based Resting-State Functional Connectivity in Amnestic Mild Cognitive Impairment.
BACKGROUND
Olfactory identification dysfunction (OID) might be an early sign of amnestic mild cognitive impairment (aMCI). However, odor hedonics, the ability to perceive odor pleasantness, is neglected. Also, the neural substrate of OID remains unclear.
OBJECTIVE
To explore the characteristics of odor identification and hedonics in aMCI and examine the potential neural correlates of OID by analyzing olfactory functional connectivity (FC) patterns in MCI.
METHODS
Forty-five controls and 83 aMCI patients were examined. The Chinese smell identification test was used to assess olfaction. Global cognition, memory, and social cognition were assessed. Resting-state functional networks associated with olfactory cortex seeds were compared between the cognitively normal (CN) and aMCI groups, as well as between aMCI subgroups by the degree of OID.
RESULTS
Compared to controls, aMCI patients had a significant deficit in olfactory identification, mainly reflected in the identification of pleasant and neutral odors. aMCI patients also rated pleasant and neutral odors much lower than controls. A positive correlation between olfaction and social cognition was found in aMCI. The seed-based FC analysis found that aMCI patients had higher FC between the right orbitofrontal cortex and right frontal lobe/middle frontal gyrus than controls. Subgroup analysis showed that, compared to aMCI without OID, aMCI with severe OID had abnormal FC in the bilateral piriform region.
CONCLUSION
Our results suggest that OID in aMCI primarily refers to the identification of pleasant and neutral odors. The FC alterations in bilateral orbitofrontal cortex and piriform cortices might contribute to the impairment in odor identification.
Topics: Humans; Odorants; Piriform Cortex; Magnetic Resonance Imaging; Cognitive Dysfunction; Olfactory Cortex
PubMed: 37212099
DOI: 10.3233/JAD-221163 -
European Archives of... Oct 2023In a previous neuroimaging study, patients with taste loss showed stronger activations in gustatory cortices compared to people with normal taste function during taste...
PURPOSE
In a previous neuroimaging study, patients with taste loss showed stronger activations in gustatory cortices compared to people with normal taste function during taste stimulations. The aim of the current study was to examine whether there are changes in central-nervous functional connectivity in patients with taste loss.
METHODS
We selected 26 pairs of brain regions related to taste processing as our regions of interests (ROIs). Functional magnetic resonance imaging (fMRI) was used to measure brain responses in seven patients with taste loss and 12 healthy controls as they received taste stimulations (taste condition) and water (water condition). The data were analysed using ROI-to-ROI functional connectivity analysis (FCA).
RESULTS
We observed weaker functional connectivity in the patient group between the left and right orbitofrontal cortex in the taste condition and between the left frontal pole and the left superior frontal gyrus in the water condition.
CONCLUSION
These results suggested that patients with taste loss experience changes of functional connectivity between brain regions not only relevant to taste processing but also to cognitive functions. While further studies are needed, fMRI might be helpful in diagnosing taste loss as an additional tool in exceptional cases.
Topics: Humans; Pilot Projects; Ageusia; Brain Mapping; Brain; Magnetic Resonance Imaging; Taste Disorders
PubMed: 37198301
DOI: 10.1007/s00405-023-08019-4