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Frontiers in Human Neuroscience 2022: It has been reported that type 2 diabetes (T2DM) is associated with olfactory identification (OI) impairments and cognitive decline. However, the relationship between...
: It has been reported that type 2 diabetes (T2DM) is associated with olfactory identification (OI) impairments and cognitive decline. However, the relationship between OI impairments and cognitive decline is largely unknown in T2DM patients. : Sixty-eight T2DM patients and 68 healthy controls underwent 3D-T1 MRI scans, olfactory and cognitive assessments. The cortical thickness of olfaction-related brain regions, olfactory and cognitive scores were compared between groups. Correlation analyses were carried out among cognition, olfaction, and cortical thickness of olfaction-related brain regions. : First, the cognitive and olfactory test scores of T2DM patients were lower than healthy subjects. Second, higher olfactory scores were associated with increased cortical thickness in the left parahippocampal gyrus and bilateral insula in T2DM. Third, higher olfactory scores were associated with higher cognitive performance in T2DM. Fourth, some cognitive performances were related to cortical thickness in the left parahippocampal gyrus and left insula in T2DM. : These findings indicated that olfactory dysfunction may be useful for future applications that attempt to predict cognitive decline or develop tailored therapies in T2DM patients.
PubMed: 35237139
DOI: 10.3389/fnhum.2022.773309 -
Cell & Bioscience May 2023Where the gene is expressed determines the function of the gene. Neuregulin 1 (Nrg1) encodes a tropic factor and is genetically linked with several neuropsychiatry...
BACKGROUND
Where the gene is expressed determines the function of the gene. Neuregulin 1 (Nrg1) encodes a tropic factor and is genetically linked with several neuropsychiatry diseases such as schizophrenia, bipolar disorder and depression. Nrg1 has broad functions ranging from regulating neurodevelopment to neurotransmission in the nervous system. However, the expression pattern of Nrg1 at the cellular and circuit levels in rodent brain is not full addressed.
METHODS
Here we used CRISPR/Cas9 techniques to generate a knockin mouse line (Nrg1) that expresses a P2A-Cre cassette right before the stop codon of Nrg1 gene. Since Cre recombinase and Nrg1 are expressed in the same types of cells in Nrg1 mice, the Nrg1 expression pattern can be revealed through the Cre-reporting mice or adeno-associated virus (AAV) that express fluorescent proteins in a Cre-dependent way. Using unbiased stereology and fluorescence imaging, the cellular expression pattern of Nrg1 and axon projections of Nrg1-positive neurons were investigated.
RESULTS
In the olfactory bulb (OB), Nrg1 is expressed in GABAergic interneurons including periglomerular (PG) and granule cells. In the cerebral cortex, Nrg1 is mainly expressed in the pyramidal neurons of superficial layers that mediate intercortical communications. In the striatum, Nrg1 is highly expressed in the Drd1-positive medium spiny neurons (MSNs) in the shell of nucleus accumbens (NAc) that project to substantia nigra pars reticulata (SNr). In the hippocampus, Nrg1 is mainly expressed in granule neurons in the dentate gyrus and pyramidal neurons in the subiculum. The Nrg1-expressing neurons in the subiculum project to retrosplenial granular cortex (RSG) and mammillary nucleus (MM). Nrg1 is highly expressed in the median eminence (ME) of hypothalamus and Purkinje cells in the cerebellum.
CONCLUSIONS
Nrg1 is broadly expressed in mouse brain, mainly in neurons, but has unique expression patterns in different brain regions.
PubMed: 37147705
DOI: 10.1186/s13578-023-01032-4 -
Frontiers in Aging Neuroscience 2022Central anosmia is a potential marker of the prodrome and progression of Parkinson's disease (PD). Resting-state functional magnetic resonance imaging studies have shown...
INTRODUCTION
Central anosmia is a potential marker of the prodrome and progression of Parkinson's disease (PD). Resting-state functional magnetic resonance imaging studies have shown that olfactory dysfunction is related to abnormal changes in central olfactory-related structures in patients with early PD.
METHODS
This study, which was conducted at Guanyun People's Hospital, analyzed the resting-state functional magnetic resonance data using the functional covariance connection strength method to decode the functional connectivity between the white-gray matter in a Chinese population comprising 14 patients with PD and 13 controls.
RESULTS
The following correlations were observed in patients with PD: specific gray matter areas related to smell (i.e., the brainstem, right cerebellum, right temporal fusiform cortex, bilateral superior temporal gyrus, right Insula, left frontal pole and right superior parietal lobule) had abnormal connections with white matter fiber bundles (i.e., the left posterior thalamic radiation, bilateral posterior corona radiata, bilateral superior corona radiata and right superior longitudinal fasciculus); the connection between the brainstem [region of interest (ROI) 1] and right cerebellum (ROI2) showed a strong correlation. Right posterior corona radiation (ROI11) showed a strong correlation with part 2 of the Unified Parkinson's Disease Rating Scale, and right superior longitudinal fasciculus (ROI14) showed a strong correlation with parts 1, 2, and 3 of the Unified Parkinson's Disease Rating Scale and Hoehn and Yahr Scale.
DISCUSSION
The characteristics of olfactory-related brain networks can be potentially used as neuroimaging biomarkers for characterizing PD states. In the future, dynamic testing of olfactory function may help improve the accuracy and specificity of olfactory dysfunction in the diagnosis of neurodegenerative diseases.
PubMed: 36688163
DOI: 10.3389/fnagi.2022.1071520 -
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 -
Molecular Autism Apr 2024This meta-analysis aimed to explore the most robust findings across numerous existing resting-state functional imaging and voxel-based morphometry (VBM) studies on the... (Meta-Analysis)
Meta-Analysis
BACKGROUND
This meta-analysis aimed to explore the most robust findings across numerous existing resting-state functional imaging and voxel-based morphometry (VBM) studies on the functional and structural brain alterations in individuals with autism spectrum disorder (ASD).
METHODS
A whole-brain voxel-wise meta-analysis was conducted to compare the differences in the intrinsic functional activity and gray matter volume (GMV) between individuals with ASD and typically developing individuals (TDs) using Seed-based d Mapping software.
RESULTS
A total of 23 functional imaging studies (786 ASD, 710 TDs) and 52 VBM studies (1728 ASD, 1747 TDs) were included. Compared with TDs, individuals with ASD displayed resting-state functional decreases in the left insula (extending to left superior temporal gyrus [STG]), bilateral anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC), left angular gyrus and right inferior temporal gyrus, as well as increases in the right supplementary motor area and precuneus. For VBM meta-analysis, individuals with ASD displayed decreased GMV in the ACC/mPFC and left cerebellum, and increased GMV in the left middle temporal gyrus (extending to the left insula and STG), bilateral olfactory cortex, and right precentral gyrus. Further, individuals with ASD displayed decreased resting-state functional activity and increased GMV in the left insula after overlapping the functional and structural differences.
CONCLUSIONS
The present multimodal meta-analysis demonstrated that ASD exhibited similar alterations in both function and structure of the insula and ACC/mPFC, and functional or structural alterations in the default mode network (DMN), primary motor and sensory regions. These findings contribute to further understanding of the pathophysiology of ASD.
Topics: Humans; Autism Spectrum Disorder; Brain; Cerebral Cortex; Gray Matter; Gyrus Cinguli; Magnetic Resonance Imaging
PubMed: 38576034
DOI: 10.1186/s13229-024-00593-6 -
Brain Sciences Oct 2016Fetal alcohol exposure (FAE) alters hippocampal cell numbers in rodents and primates, and this may be due, in part, to a reduction in the number or migration of neuronal...
Fetal alcohol exposure (FAE) alters hippocampal cell numbers in rodents and primates, and this may be due, in part, to a reduction in the number or migration of neuronal progenitor cells. The olfactory bulb exhibits substantial postnatal cellular proliferation and a rapid turnover of newly formed cells in the rostral migratory pathway, while production and migration of postnatal neurons into the dentate gyrus may be more complex. The relatively small size of the olfactory bulb, compared to the hippocampus, potentially makes this structure ideal for a rapid analysis. This study used the St. Kitts vervet monkey () to (1) investigate the normal developmental sequence of post-natal proliferation in the olfactory bulb and dentate gyrus and (2) determine the effects of naturalistic prenatal ethanol exposure on proliferation at three different ages (neonate, five months and two years). Using design-based stereology, we found an age-related decrease of actively proliferating cells in the olfactory bulb and dentate gyrus for both control and FAE groups. Furthermore, at the neonatal time point, the FAE group had fewer actively proliferating cells as compared to the control group. These data are unique with respect to fetal ethanol effects on progenitor proliferation in the primate brain and suggest that the olfactory bulb may be a useful structure for studies of cellular proliferation.
PubMed: 27801790
DOI: 10.3390/brainsci6040052 -
Cellular and Molecular Life Sciences :... May 2012The adult brain most probably reaches its highest degree of plasticity with the lifelong generation and integration of new neurons in the hippocampus and olfactory... (Review)
Review
The adult brain most probably reaches its highest degree of plasticity with the lifelong generation and integration of new neurons in the hippocampus and olfactory system. Neural precursor cells (NPCs) residing both in the subgranular zone of the dentate gyrus and in the subventricular zone of the lateral ventricles continuously generate neurons that populate the dentate gyrus and the olfactory bulb, respectively. The regulation of NPC proliferation in the adult brain has been widely investigated in the past few years. Yet, the intrinsic cell cycle machinery underlying NPC proliferation remains largely unexplored. In this review, we discuss the cell cycle components that are involved in the regulation of NPC proliferation in both neurogenic areas of the adult brain.
Topics: Adult; Animals; Brain; Cell Cycle; Cyclin-Dependent Kinases; Cyclins; Humans; Mice; Models, Neurological; Neural Stem Cells; Neurogenesis
PubMed: 22068613
DOI: 10.1007/s00018-011-0880-6 -
Current Opinion in Neurobiology Aug 2010Neural stem cells (NSCs) in the adult brain continuously supply new neurons to the hippocampal dentate gyrus (DG) and the olfactory bulb (OB). Recent studies indicate...
Neural stem cells (NSCs) in the adult brain continuously supply new neurons to the hippocampal dentate gyrus (DG) and the olfactory bulb (OB). Recent studies indicate that the progression from neural precursor cells (NPCs) to mature neurons is tightly controlled by coordinate cell-intrinsic programs and external signals within the neurogenic niche. In this review, we summarize both classes of regulatory factors involved in distinct stages of adult neurogenesis, including proliferation and lineage differentiation of NSCs, migration of neuroblasts and integration of newborn neurons. A full understanding of the wide variety of signaling pathways will ultimately provide precise targets for therapeutic applications.
Topics: Animals; Brain; Cell Differentiation; Cell Movement; Neural Stem Cells; Neurogenesis; Signal Transduction; Transcription Factors
PubMed: 20471243
DOI: 10.1016/j.conb.2010.04.010 -
Scientific Reports Sep 2020To investigate the changes and clinical significance of brain structural abnormalities in patients with Meige syndrome and related depressive symptoms. We...
To investigate the changes and clinical significance of brain structural abnormalities in patients with Meige syndrome and related depressive symptoms. We retrospectively analysed clinical data, imaging examinations, and Hamilton Depression Rating scale scores in 46 patients with Meige syndrome from January 2017 to January 2019. We compared the Meige syndrome group with the healthy control group, and the definite depression group with the non-definite depression group. Voxel-based morphometry (VBM) was used to compare grey matter (GM) volumes. We conducted two-sample t-tests corrected for subject age and gender. We tested at a level of significance of p < 0.001 with a false discovery rate (FDR) correction. VBM demonstrated decreased GM volume (p < 0.001 and cluster size > 50 voxels) in the left hemisphere in the middle frontal orbital gyrus, temporal pole (superior temporal gyrus) and insula and in the right hemisphere in the temporal pole (middle temporal gyrus), precuneus, inferior parietal, inferior temporal and olfactory cortices in the Meige syndrome group. Comparing VBM-MRI measures in Meige syndrome patients with and without depression, decreased GM volume was found in the left hemisphere in the cuneus and hippocampus and in the right hemisphere in the angular gyrus, middle frontal gyrus and middle occipital gyrus in the definite depression group. Unlike other dystonia studies that have suggested an involvement of the basal ganglia and motor cortex in the pathophysiology of the disorder , we believe that the precuneus is involved in the development of Meige syndrome. Additionally, our findings suggest that the hippocampus plays a role in the pathogenesis of depression in patients with Meige syndrome.
Topics: Aged; Female; Gray Matter; Humans; Magnetic Resonance Imaging; Male; Meige Syndrome; Middle Aged; Motor Cortex; Retrospective Studies
PubMed: 32884000
DOI: 10.1038/s41598-020-71479-9 -
Current Opinion in Neurobiology Feb 2008New neurons are continuously generated in the dentate gyrus of the mammalian hippocampus and in the subventricular zone of the lateral ventricles throughout life. The... (Review)
Review
New neurons are continuously generated in the dentate gyrus of the mammalian hippocampus and in the subventricular zone of the lateral ventricles throughout life. The origin of these new neurons is believed to be from multipotent adult neural stem cells. Aided by new methodologies, significant progress has been made in the characterization of neural stem cells and their development in the adult brain. Recent studies have also begun to reveal essential extrinsic and intrinsic molecular mechanisms that govern sequential steps of adult neurogenesis in the hippocampus and subventricular zone/olfactory bulb, from proliferation and fate specification of neural progenitors to maturation, navigation, and synaptic integration of the neuronal progeny. Future identification of molecular mechanisms and physiological functions of adult neurogenesis will provide further insight into the plasticity and regenerative capacity of the mature central nervous system.
Topics: Animals; Cell Differentiation; Cell Lineage; Cell Movement; Dentate Gyrus; Humans; Lateral Ventricles; Neurons; Olfactory Bulb; Stem Cells; Telencephalon
PubMed: 18514504
DOI: 10.1016/j.conb.2008.04.001