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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 -
Brain Sciences Apr 2023Alzheimer's disease (AD) is associated with the abnormal connection of functional networks. Olfactory impairment occurs in early AD; therefore, exploring alterations in...
Alzheimer's disease (AD) is associated with the abnormal connection of functional networks. Olfactory impairment occurs in early AD; therefore, exploring alterations in olfactory-related regions is useful for early AD diagnosis. We combined the graph theory of local brain network topology with olfactory performance to analyze the differences in AD brain network characteristics. A total of 23 patients with AD and 18 normal controls were recruited for resting-state functional magnetic resonance imaging (fMRI), clinical neuropsychological examinations and the University of Pennsylvania Smell Identification Test (UPSIT). Between-group differences in the topological properties of the local network were compared. Pearson correlations were explored based on differential brain regions and olfactory performance. Statistical analysis revealed a correlation of the degree of cognitive impairment with olfactory recognition function. Local node topological properties were significantly altered in many local brain regions in the AD group. The nodal clustering coefficients of the bilateral temporal pole: middle temporal gyrus (TPOmid), degree centrality of the left insula (INS.L), degree centrality of the right middle temporal gyrus (MTG.R), and betweenness centrality of the left middle temporal gyrus (MTG.L) were related to olfactory performance. Alterations in local topological properties combined with the olfactory impairment can allow early identification of abnormal olfactory-related regions, facilitating early AD screening.
PubMed: 37190596
DOI: 10.3390/brainsci13040631 -
Brain Sciences Mar 2023Much is known about the effect of odors on mood, cognition and behavior, but little is known about the relationship between odors and well-being. We investigated the...
Much is known about the effect of odors on mood, cognition and behavior, but little is known about the relationship between odors and well-being. We investigated the neural processing of odors with different degrees of association with well-being (WB) through two large independent datasets. The study encompassed pre-testing and fMRI. During pre-testing, 100 and 80 (studies 1 and 2) young, healthy subjects participated, rating intensity, valence, and WB association for 14 (study 1) and 8 (study 2) different odors. Pre-testing resulted in the selection of two odors with high WB association (WB-associated) and two odors with lower WB association (neutral odors) for each study. Odors were delivered intranasally to the subjects who underwent fMRI scanning (44 and 41 subjects, respectively, for studies 1 and 2). We assessed brain activity for subjects when they experienced WB-associated versus neutral odors. In study 1, WB-associated odors showed increased activation in the right angular gyrus whereas in study 2, increased activity in the left angular gyrus existed, together with increased activity in the anterior cingulate cortex and posterior orbitofrontal cortex. The increased activity of higher-order cognitive and emotional regions during the processing of WB-associated odors in the two independent studies suggests a role of odors in influencing individual well-being. Moreover, the consistent activation of the angular gyrus might suggest its key role in shifting attention toward relevant emotional stimuli.
PubMed: 37190541
DOI: 10.3390/brainsci13040576 -
Cells Apr 2023In the mammalian brain, neurogenesis is maintained throughout adulthood primarily in two typical niches, the subgranular zone (SGZ) of the dentate gyrus and the... (Review)
Review
In the mammalian brain, neurogenesis is maintained throughout adulthood primarily in two typical niches, the subgranular zone (SGZ) of the dentate gyrus and the subventricular zone (SVZ) of the lateral ventricles and in other nonclassic neurogenic areas (e.g., the amygdala and striatum). During prenatal and early postnatal development, neural stem cells (NSCs) differentiate into neurons and migrate to appropriate areas such as the olfactory bulb where they integrate into existing neural networks; these phenomena constitute the multistep process of neurogenesis. Alterations in any of these processes impair neurogenesis and may even lead to brain dysfunction, including cognitive impairment and neurodegeneration. Here, we first summarize the main properties of mammalian neurogenic niches to describe the cellular and molecular mechanisms of neurogenesis. Accumulating evidence indicates that neurogenesis plays an integral role in neuronal plasticity in the brain and cognition in the postnatal period. Given that neurogenesis can be highly modulated by a number of extrinsic and intrinsic factors, we discuss the impact of extrinsic (e.g., alcohol) and intrinsic (e.g., hormones) modulators on neurogenesis. Additionally, we provide an overview of the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to persistent neurological sequelae such as neurodegeneration, neurogenic defects and accelerated neuronal cell death. Together, our review provides a link between extrinsic/intrinsic factors and neurogenesis and explains the possible mechanisms of abnormal neurogenesis underlying neurological disorders.
Topics: Animals; Humans; Adult; COVID-19; SARS-CoV-2; Neurogenesis; Neurons; Neural Stem Cells; Mammals
PubMed: 37174685
DOI: 10.3390/cells12091285 -
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 Neuroscience 2023Myopia is one of the major public health problems worldwide. However, the exact pathogenesis of myopia remains unclear. This study proposes using voxel-based morphometry...
BACKGROUND
Myopia is one of the major public health problems worldwide. However, the exact pathogenesis of myopia remains unclear. This study proposes using voxel-based morphometry (VBM) to investigate potential morphological alterations in gray matter volume (GMV) in form-deprivation myopia (FDM) rats.
METHODS
A total of 14 rats with FDM (FDM group) and 15 normal controls (NC group) underwent high-resolution magnetic resonance imaging (MRI). Original T2 brain images were analyzed using VBM method to identify group differences in GMV. Following MRI examination, all rats were perfused with formalin, and immunohistochemical analysis of NeuN and c-fos levels was performed on the visual cortex.
RESULTS
In the FDM group, compared to the NC group, significantly decreased GMVs were found in the left primary visual cortex, left secondary visual cortex, right subiculum, right cornu ammonis, right entorhinal cortex and bilateral molecular layer of the cerebellum. Additionally, significantly increased GMVs were found in the right dentate gyrus, parasubiculum, and olfactory bulb.
CONCLUSIONS
Our study revealed a positive correlation between mGMV and the expression of c-fos and NeuN in the visual cortex, suggesting a molecular relationship between cortical activity and macroscopic measurement of visual cortex structural plasticity. These findings may help elucidate the potential neural pathogenesis of FDM and its relationship to changes in specific brain regions.
PubMed: 37144093
DOI: 10.3389/fnins.2023.1113578 -
European Review For Medical and... Apr 2023The aim of this study was to investigate central smell centers with cranial magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) in COVID-19.
OBJECTIVE
The aim of this study was to investigate central smell centers with cranial magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI) in COVID-19.
PATIENTS AND METHODS
This retrospective study evaluated cranial MRI images of 54 adults. The experimental group (Group 1), consisting of 27 patients with positive COVID-19 real-time polymerase chain reaction (RT-PCR) assays, was compared to the control group (Group 2), comprising 27 healthy controls without COVID-19. The apparent diffusion coefficient (ADC) values were measured in the corpus amygdala, thalamus, and insular gyrus in both groups.
RESULTS
Thalamus ADC values of the COVID-19 group were significantly lower compared to the control group bilaterally. However, no differences were found in the insular gyrus and corpus amygdala ADC values between the two groups. Positive correlations were observed between the insular gyrus and corpus amygdala ADC values and the thalamus ADC values. Insular gyrus ADC values (right) were higher in females. Left insular gyrus and corpus amygdala ADC values were higher in COVID-19 patients with smell loss. Right insular gyrus and left corpus amygdala ADC values were lower in COVID-19 patients with lymphopenia.
CONCLUSIONS
Diffusion restriction in olfactory areas can be considered an obvious indicator that the COVID-19 virus affects and damages the immune system at the neuronal level. Given the urgency and lethality of the current pandemic, acute onset odor loss should be considered a high suspicion-adhesive index for patients with SARS-CoV-2 infection. Therefore, the sense of smell should be considered and evaluated simultaneously with other neurological symptoms. DWI should be widely used as an early imaging method for central nervous system (CNS) infections, especially in relation to COVID-19.
Topics: Adult; Female; Humans; Smell; Insular Cortex; Retrospective Studies; COVID-19; SARS-CoV-2; Diffusion Magnetic Resonance Imaging; Thalamus; Amygdala
PubMed: 37070924
DOI: 10.26355/eurrev_202304_31954 -
Cerebral Cortex (New York, N.Y. : 1991) Jun 2023Prefrontal cortical maturation coincides with adolescent transitions in social engagement, suggesting that it influences social development. The anterior cingulate...
Prefrontal cortical maturation coincides with adolescent transitions in social engagement, suggesting that it influences social development. The anterior cingulate cortex (ACC) is important for social interaction, including ACC outputs to the basolateral amygdala (BLA). However, little is known about ACC-BLA sensitivity to the social environment and if this changes during maturation. Here, we used brief (2-hour) isolation to test the immediate impact of changing the social environment on the ACC-BLA circuit and subsequent shifts in social behavior of adolescent and adult rats. We found that optogenetic inhibition of the ACC during brief isolation reduced isolation-driven facilitation of social interaction across ages. Isolation increased activity of ACC-BLA neurons across ages, but altered the influence of ACC on BLA activity in an age-dependent manner. Isolation reduced the inhibitory impact of ACC stimulation on BLA neurons in a frequency-dependent manner in adults, but uniformly suppressed ACC-driven BLA activity in adolescents. This work identifies isolation-driven alterations in an ACC-BLA circuit, and the ACC itself as an essential region sensitive to social environment and regulates its impact on social behavior in both adults and adolescents.
Topics: Rats; Male; Animals; Basolateral Nuclear Complex; Prefrontal Cortex; Gyrus Cinguli; Neurons; Olfactory Cortex
PubMed: 37032624
DOI: 10.1093/cercor/bhad124 -
Frontiers in Neuroscience 2023Structural and functional changes in the brain have been identified in individuals with medication-overuse headache (MOH) using MRI. However, it has not been clearly...
AIM
Structural and functional changes in the brain have been identified in individuals with medication-overuse headache (MOH) using MRI. However, it has not been clearly established whether neurovascular dysfunction occurs in MOH, which could be elucidated by examining neurovascular coupling (NVC) from the viewpoints of neuronal activity and cerebral blood flow. The aim of this study was to investigate potential alterations in NVC function of the brain in individuals with MOH using resting-state functional MRI (rs-fMRI) and 3D pseudo-continuous arterial spin labeling (3D PCASL) imaging techniques.
METHODS
A total of 40 patients with MOH and 32 normal controls (NCs) were recruited, and rs-fMRI and 3D PCASL data were obtained using a 3.0 T MR scanner. Standard preprocessing of the rs-fMRI data was performed to generate images representing regional homogeneity (ReHo), fractional amplitude of low-frequency fluctuation (fALFF), and degree centrality (DC); cerebral blood flow (CBF) images were generated using 3D PCASL sequence data. These functional maps were all normalized into Montreal Neurological Institute (MNI) space, and NVC was subsequently determined on the basis of Pearson correlation coefficients between the rs-fMRI maps (ReHo, fALFF, and DC) and CBF maps. The statistical significance of differences between the MOH and NC groups in terms of NVC in different brain regions was established -test. Further analysis was performed to examine correlations between NVC in the brain regions with NVC dysfunction and clinical variables among patients with MOH.
RESULTS
NVC mainly presented a negative correlation in patients with MOH and NCs. No significant difference between the two groups was detected in terms of average NVC over the entire gray matter area. However, several brain regions with significantly decreased NVC in patients with MOH compared to NCs were identified: the left orbital region of the superior frontal gyrus, the bilateral gyrus rectus, and the olfactory cortex ( < 0.05). A correlation analysis revealed that the DC of the brain regions with NVC dysfunction was significantly positively correlated with disease duration ( = 0.323, = 0.042), and DC-CBF connectivity was negatively correlated with VAS score ( = -0.424, = 0.035).
CONCLUSION
The current study demonstrated that cerebral NVC dysfunction occurs in patients with MOH, and the NVC technique could function as a new imaging biomarker in headache research.
PubMed: 37008219
DOI: 10.3389/fnins.2023.1139086