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Brain, Behavior, & Immunity - Health Mar 2024COVID-19 remains a significant international public health concern. Yet, the mechanisms through which symptomatology emerges remain poorly understood. While SARS-CoV-2...
COVID-19 remains a significant international public health concern. Yet, the mechanisms through which symptomatology emerges remain poorly understood. While SARS-CoV-2 infection may induce prolonged inflammation within the central nervous system, the evidence primarily stems from limited small-scale case investigations. To address this gap, our study capitalized on longitudinal UK Biobank neuroimaging data acquired prior to and following COVID-19 testing (N = 416 including n = 224 COVID-19 cases; M = 58.6). Putative neuroinflammation was assessed in gray matter structures and white matter tracts using non-invasive Diffusion Basis Spectrum Imaging (DBSI), which estimates inflammation-related cellularity (DBSI-restricted fraction; DBSI-RF) and vasogenic edema (DBSI-hindered fraction; DBSI-HF). We hypothesized that COVID-19 case status would be associated with increases in DBSI markers after accounting for potential confound (age, sex, race, body mass index, smoking frequency, and data acquisition interval) and multiple testing. COVID-19 case status was not significantly associated with DBSI-RF (|β|'s < 0.28, p >0.05), but with greater DBSI-HF in left pre- and post-central gyri and right middle frontal gyrus (β's > 0.3, all p = 0.03). Intriguingly, the brain areas exhibiting increased putative vasogenic edema had previously been linked to COVID-19-related functional and structural alterations, whereas brain regions displaying subtle differences in cellularity between COVID-19 cases and controls included regions within or functionally connected to the olfactory network, which has been implicated in COVID-19 psychopathology. Nevertheless, our study might not have captured acute and transitory neuroinflammatory effects linked to SARS-CoV-2 infection, possibly due to symptom resolution before the imaging scan. Future research is warranted to explore the potential time- and symptom-dependent neuroinflammatory relationship with COVID-19.
PubMed: 38298902
DOI: 10.1016/j.bbih.2023.100722 -
Journal of Neural Engineering Feb 2024. This study presents a novel methodological approach for incorporating information related to the peripheral sympathetic response into the investigation of neural...
. This study presents a novel methodological approach for incorporating information related to the peripheral sympathetic response into the investigation of neural dynamics. Particularly, we explore how hedonic contextual olfactory stimuli influence the processing of neutral faces in terms of sympathetic response, event-related potentials and effective connectivity analysis. The objective is to investigate how the emotional valence of odors influences the cortical connectivity underlying face processing and the role of face-induced sympathetic arousal in this visual-olfactory multimodal integration.. To this aim, we combine electrodermal activity (EDA) analysis and dynamic causal modeling to examine changes in cortico-cortical interactions.. The results reveal that stimuli arising sympathetic EDA responses are associated with a more negative N170 amplitude, which may be a marker of heightened arousal in response to faces. Hedonic odors, on the other hand, lead to a more negative N1 component and a reduced the vertex positive potential when they are unpleasant or pleasant. Concerning connectivity, unpleasant odors strengthen the forward connection from the inferior temporal gyrus (ITG) to the middle temporal gyrus, which is involved in processing changeable facial features. Conversely, the occurrence of sympathetic responses after a stimulus is correlated with an inhibition of this same connection and an enhancement of the backward connection from ITG to the fusiform face gyrus.. These findings suggest that unpleasant odors may enhance the interpretation of emotional expressions and mental states, while faces capable of eliciting sympathetic arousal prioritize identity processing.
Topics: Odorants; Facial Recognition; Galvanic Skin Response; Emotions; Evoked Potentials; Facial Expression; Electroencephalography
PubMed: 38290158
DOI: 10.1088/1741-2552/ad2403 -
Frontiers in Neuroscience 2023
PubMed: 38249580
DOI: 10.3389/fnins.2023.1307844 -
Epilepsy & Behavior : E&B Feb 2024To characterize a profile for patients with tumor-related epilepsy presenting olfactory auras.
OBJECTIVES
To characterize a profile for patients with tumor-related epilepsy presenting olfactory auras.
MATERIALS AND METHODS
We conducted a monocentric, retrospective study on patients who underwent surgery in the Neurosurgery Unit of Udine University Hospital (Udine, Italy), between the 1st of January 2010 and the 1st of January 2019, for primary brain tumors (PBTs) involving the temporal lobe and the insula. All patients were affected by tumor-related epilepsy; the study group presented olfactory auras as well. We collected neuroradiological, neuropsychological and neurophysiological data from patients' medical charts.
RESULTS
The subtraction analysis of MRI data shows maximum lesion overlay in left olfactory cortex, left and right hippocampus, left amygdala, right rolandic operculum, right inferior frontal gyrus and right middle temporal gyrus. The presence of olfactory auras did not influence seizure outcome (p = 0.500) or tumor recurrence after surgery (p = 0.185). The type of auras (elementary vs. complex), also, did not influence seizure control (p = 0.222).
DISCUSSION
In presence of olfactory auras, anterior and mesial temporal regions are mainly involved, such as olfactory cortex, amygdala, and anterior hippocampus, together with right rolandic operculum, right inferior frontal gyrus and right middle temporal gyrus, suggesting their possible role in the genesis of olfactory auras. Post-surgical seizure outcome and disease relapse are not influenced by neither the presence nor the type of olfactory auras.
CONCLUSIONS
Olfactory auras are rare event, however they may be often underestimated by the patients and under-investigated by the clinicians, even when their occurrence can represent a useful localizing tool.
Topics: Humans; Epilepsy, Temporal Lobe; Odorants; Retrospective Studies; Epilepsy; Seizures; Neoplasms; Magnetic Resonance Imaging; Recurrence; Electroencephalography
PubMed: 38242066
DOI: 10.1016/j.yebeh.2024.109642 -
Journal of Anatomy May 2024Structural asymmetries of brain regions associated with lateralised functions have been extensively studied. However, there are fewer morphometric analyses of...
Structural asymmetries of brain regions associated with lateralised functions have been extensively studied. However, there are fewer morphometric analyses of asymmetries of the gyri and sulci of the entire cortex. The current study assessed cortical asymmetries in a sample of healthy adults (N = 175) from an admixed population from South America. Grey matter volume and surface area of 66 gyri and sulci were quantified on T1 magnetic resonance images. The departure from zero of the differences between left and right hemispheres (L-R), a measure of directional asymmetry (DA), the variance of L-R, and an index of fluctuating asymmetry (FA) were evaluated for each region. Significant departures from perfect symmetry were found for most cortical gyri and sulci. Regions showed leftward asymmetry at the population level in the frontal lobe and superior lateral parts of the parietal lobe. Rightward asymmetry was found in the inferior parietal, occipital, frontopolar, and orbital regions, and the cingulate (anterior, middle, and posterior-ventral). Despite this general pattern, several sulci showed the opposite DA compared to the neighbouring gyri, which remarks the need to consider the neurobiological differences in gyral and sulcal development in the study of structural asymmetries. The results also confirm the absence of DA in most parts of the inferior frontal gyrus and the precentral region. This study contributes with data on populations underrepresented in the databases used in neurosciences. Among its findings, there is agreement with previous results obtained in populations of different ancestry and some discrepancies in the middle frontal and medial parietal regions. A significant DA not reported previously was found for the volume of long and short insular gyri and the central sulcus of the insula, frontomarginal, transverse frontopolar, paracentral, and middle and posterior parts of the cingulate gyrus and sulcus, gyrus rectus, occipital pole, and olfactory sulcus, as well as for the volume and area of the transverse collateral sulcus and suborbital sulcus. Also, several parcels displayed significant variability in the left-right differences, which can be partially attributable to developmental instability, a source of FA. Moreover, a few gyri and sulci displayed ideal FA with non-significant departures from perfect symmetry, such as subcentral and posterior cingulate gyri and sulci, inferior frontal and fusiform gyri, and the calcarine, transverse collateral, precentral, and orbital sulci. Overall, these results show that asymmetries are ubiquitous in the cerebral cortex.
Topics: Adult; Humans; Gray Matter; Cerebral Cortex; Frontal Lobe; Gyrus Cinguli; Magnetic Resonance Imaging; South America
PubMed: 38183319
DOI: 10.1111/joa.14001 -
NPJ Parkinson's Disease Jan 2024In Parkinson's disease (PD), and other α-synucleinopathies, α-synuclein (α-Syn) aggregates form a myriad of conformational and truncational variants. Most antibodies...
In Parkinson's disease (PD), and other α-synucleinopathies, α-synuclein (α-Syn) aggregates form a myriad of conformational and truncational variants. Most antibodies used to detect and quantify α-Syn in the human brain target epitopes within the C-terminus (residues 96-140) of the 140 amino acid protein and may fail to capture the diversity of α-Syn variants present in PD. We sought to investigate the heterogeneity of α-Syn conformations and aggregation states in the PD human brain by labelling with multiple antibodies that detect epitopes along the entire length of α-Syn. We used multiplex immunohistochemistry to simultaneously immunolabel tissue sections with antibodies mapping the three structural domains of α-Syn. Discrete epitope-specific immunoreactivities were visualised and quantified in the olfactory bulb, medulla, substantia nigra, hippocampus, entorhinal cortex, middle temporal gyrus, and middle frontal gyrus of ten PD cases, and the middle temporal gyrus of 23 PD, and 24 neurologically normal cases. Distinct Lewy neurite and Lewy body aggregate morphologies were detected across all interrogated regions/cases. Lewy neurites were the most prominent in the olfactory bulb and hippocampus, while the substantia nigra, medulla and cortical regions showed a mixture of Lewy neurites and Lewy bodies. Importantly, unique N-terminus immunoreactivity revealed previously uncharacterised populations of (1) perinuclear, (2) glial (microglial and astrocytic), and (3) neuronal lysosomal α-Syn aggregates. These epitope-specific N-terminus immunoreactive aggregate populations were susceptible to proteolysis via time-dependent proteinase K digestion, suggesting a less stable oligomeric aggregation state. Our identification of unique N-terminus immunoreactive α-Syn aggregates adds to the emerging paradigm that α-Syn pathology is more abundant and complex in human brains with PD than previously realised. Our findings highlight that labelling multiple regions of the α-Syn protein is necessary to investigate the full spectrum of α-Syn pathology and prompt further investigation into the functional role of these N-terminus polymorphs.
PubMed: 38167744
DOI: 10.1038/s41531-023-00614-w -
BioEssays : News and Reviews in... Mar 2024The anterior cingulate cortex (ACC) is a complex and continually evolving brain region that remains a primary focus of research due to its multifaceted functions.... (Review)
Review
The anterior cingulate cortex (ACC) is a complex and continually evolving brain region that remains a primary focus of research due to its multifaceted functions. Various studies and analyses have significantly advanced our understanding of how the ACC participates in a wide spectrum of memory and cognitive processes. However, despite its strong connections to brain areas associated with hippocampal and olfactory neurogenesis, the functions of the ACC in regulating postnatal and adult neurogenesis in these regions are still insufficiently explored. Investigating the intricate involvement of the ACC in neurogenesis could enhance our comprehension of essential aspects of brain plasticity. This involvement stems from its complex circuitry with other relevant brain regions, thereby exerting both direct and indirect impacts on the neurogenesis process. This review sheds light on the promising significance of the ACC in orchestrating postnatal and adult neurogenesis in conditions related to memory, cognitive behavior, and associated disorders.
Topics: Gyrus Cinguli; Brain; Hippocampus; Neurogenesis
PubMed: 38135889
DOI: 10.1002/bies.202300160 -
Behavioral and Brain Functions : BBF Dec 2023Parosmia is a qualitative olfactory dysfunction presenting as "distorted odor perception" in presence of an odor source. Aim of this study was to use resting state...
OBJECTIVE
Parosmia is a qualitative olfactory dysfunction presenting as "distorted odor perception" in presence of an odor source. Aim of this study was to use resting state functional connectivity to gain more information on the alteration of olfactory processing at the level of the central nervous system level.
METHODS
A cross sectional study was performed in 145 patients with parosmia (age range 20-76 years; 90 women). Presence and degree of parosmia was diagnosed on the basis of standardized questionnaires. Participants also received olfactory testing using the "Sniffin' Sticks". Then they underwent resting state scans using a 3 T magnetic resonance imaging scanner while fixating on a cross.
RESULTS
Whole brain analyses revealed reduced functional connectivity in salience as well as executive control networks. Region of interest-based analyses also supported reduced functional connectivity measures between primary and secondary olfactory eloquent areas (temporal pole, supramarginal gyrus and right orbitofrontal cortex; dorso-lateral pre-frontal cortex and the right piriform cortex).
CONCLUSIONS
Participants with parosmia exhibited a reduced information flow between memory, decision making centers, and primary and secondary olfactory areas.
Topics: Humans; Female; Young Adult; Adult; Middle Aged; Aged; Cross-Sectional Studies; Olfaction Disorders; Smell; Brain; Magnetic Resonance Imaging
PubMed: 38115149
DOI: 10.1186/s12993-023-00225-8 -
Genesis (New York, N.Y. : 2000) Feb 2024A wide variety of CreER driver lines are available for genetic manipulation of adult-born neurons in the mouse brain. These tools have been instrumental in studying fate...
A wide variety of CreER driver lines are available for genetic manipulation of adult-born neurons in the mouse brain. These tools have been instrumental in studying fate potential, migration, circuit integration, and morphology of the stem cells supporting lifelong neurogenesis. Despite a wealth of tools, genetic manipulation of adult-born neurons for circuit and behavioral studies has been limited by poor specificity of many driver lines targeting early progenitor cells and by the inaccessibility of lines selective for later stages of neuronal maturation. We sought to address these limitations by creating a new CreER driver line targeted to the endogenous mouse doublecortin locus as a marker of fate-specified neuroblasts and immature neurons. Our new model places a T2A-CreER cassette immediately downstream of the Dcx coding sequence on the X chromosome, allowing expression of both Dcx and CreER proteins in the endogenous spatiotemporal pattern for this gene. We demonstrate that the new mouse line drives expression of a Cre-dependent reporter throughout the brain in neonatal mice and in known neurogenic niches of adult animals. The line has been deposited with the Jackson Laboratory and should provide an accessible tool for studies targeting fate-restricted neuronal precursors.
Topics: Mice; Animals; Mice, Transgenic; Neurons; Neural Stem Cells; Neurogenesis; Brain
PubMed: 38102875
DOI: 10.1002/dvg.23584 -
Psychiatry Research. Neuroimaging Jan 2024Studies from animal models and clinical trials of blood and cerebrospinal fluid have proposed that blood-brain barrier (BBB) dysfunction in depression (MDD). But there...
BACKGROUND
Studies from animal models and clinical trials of blood and cerebrospinal fluid have proposed that blood-brain barrier (BBB) dysfunction in depression (MDD). But there are no In vivo proves focused on BBB dysfunction in MDD patients. The present study aimed to identify whether there was abnormal BBB permeability, as well as the association with clinical status in MDD patients using dynamic contrast-enhanced magnetic resonance (DCE-MRI) imaging.
METHODS
Patients with MDD and healthy adults were recruited and underwent DCE-MRI and structural MRI scans. The mean volume transfer constant (K) values were calculated for a quantitative assessment of BBB leakage. For each subject, the mean K values were calculated for the whole gray matter, white matter, and 90 brain regions of the anatomical automatic labeling template (AAL). The differences in K values between patients and controls and between treated and untreated patients were compared.
RESULTS
23 MDD patients (12 males and 11 females, mean age 28.09 years) and 18 healthy controls (HC, 8 males and 10 females, mean age 30.67 years) were recruited in the study. We found that the K values in the olfactory, caudate, and thalamus were higher in MDD patients compared to healthy controls (p<0.05). The K values in the orbital lobe, anterior cingulate gyrus, putamen, and thalamus in treated patients were lower than the patients never treated. There were positive correlations between HAMD total score with K values in whole brain WM, hippocampus and thalamus. The total HAMA score was positively correlated with the K of hippocampus.
CONCLUSION
These findings supported a link between blood-brain barrier leakage and depression and symptom severity. The results also suggested a role for non-invasive DCE-MRI in detecting blood-brain barrier dysfunction in depression patients.
Topics: Male; Adult; Female; Animals; Humans; Blood-Brain Barrier; Depressive Disorder, Major; Magnetic Resonance Imaging; Brain; Contrast Media; Permeability
PubMed: 38061159
DOI: 10.1016/j.pscychresns.2023.111761