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Journal of Neurological Surgery. Part... Oct 2021We investigated the effects of vitamin D deficiency in the peripheral and central smell regions by magnetic resonance imaging (MRI). This retrospective study...
We investigated the effects of vitamin D deficiency in the peripheral and central smell regions by magnetic resonance imaging (MRI). This retrospective study included 29 patients (12 males, 17 females) with 25-dihydroxy vitamin D3 [25(OH) D ] deficiency (group 1) and 34 subjects without 25(OH) D deficiency (14 males, 20 females) (group 2). Using cranial MRIs, the peripheral (olfactory bulb [OB] volume and olfactory sulcus [OS] depth) and central (insular gyrus and corpus amygdala) smell regions were evaluated. The OB volume and OS depth values of the 25(OH) D3 deficiency group were significantly lower than those of the control group ( < 0.05). For the central smell regions, the insular gyrus and corpus amygdala areas of the 25(OH) D3 deficiency group were nonsignificantly lower than those in the control group ( > 0.05). There were positive correlations between OB volumes, OS depths, and insular gyrus and corpus amygdala areas bilaterally in the 25(OH) D3 deficiency group separately and in all subjects (groups 1 and 2) ( < 0.05). In the 25(OH) D3 deficiency group, as the 25(OH) D3 values became lower, the insular gyrus area values decreased bilaterally ( < 0.05). In females, the corpus amygdala area values were lower than in males ( < 0.05). Since vitamin D3 deficiency affected the peripheral and central smell regions negatively, we recommend evaluating patients' vitamin D levels as a health policy to prevent vitamin D3 deficiency-related cranial smell region problems. Moreover, sunlight exposure is very important to increase vitamin D levels, and the public should be informed about this topic.
PubMed: 34513566
DOI: 10.1055/s-0040-1722227 -
Frontiers in Allergy 2022Currently, clinical assessment of olfaction is largely reliant on subjective methods that require patient participation. The objective method for measuring olfaction,...
IMPORTANCE
Currently, clinical assessment of olfaction is largely reliant on subjective methods that require patient participation. The objective method for measuring olfaction, using electroencephalogram (EEG) readings, can be supplemented with the improved temporal resolution of magnetoencephalography (MEG) for olfactory measurement that can delineate cortical and peripheral olfactory loss. MEG provides high temporal and spatial resolution which can enhance our understanding of central olfactory processing compared to using EEG alone.
OBJECTIVE
To determine the feasibility of building an in-house portable olfactory stimulator paired with electrophysiological neuroimaging technique with MEG to assess olfaction in the clinical setting.
DESIGN SETTING AND PARTICIPANTS
This proof-of-concept study utilized a paired MEG-olfactometer paradigm to assess olfaction in three normosmic participants. We used a two-channel olfactory stimulator to deliver odorants according to a programmed stimulus-rest paradigm. Two synthetic odorants: 2% phenethyl alcohol (rose) and 0.5% amyl acetate (banana) were delivered in increasing increments of time followed by periods of rest. Cortical activity was measured a 306-channel MEG system.
MAIN OUTCOMES AND MEASURES
Primary outcome measure was the relative spectral power for each frequency band, which was contrasted between rest and olfactory stimulation.
RESULTS
Compared to rest, olfactory stimulation produced a 40% increase in relative alpha power within the olfactory cortex bilaterally with both odorants. A 25%-30% increase in relative alpha power occurred in the left orbitofrontal cortex and precentral gyrus with phenethyl alcohol stimulation but not amyl acetate.
CONCLUSION AND RELEVANCE
In this proof-of-concept study, we demonstrate the feasibility of olfactory measurement an olfactometer-MEG paradigm. We found that odorant-specific cortical signatures can be identified using this paradigm, setting the basis for further investigation of this system as a prognostic tool for olfactory loss.
PubMed: 36698377
DOI: 10.3389/falgy.2022.1019265 -
The International Journal of... Sep 2017Evidence for olfactory dysfunction in schizophrenia has been firmly established. However, in the typical understanding of schizophrenia, olfaction is not recognized to...
BACKGROUND
Evidence for olfactory dysfunction in schizophrenia has been firmly established. However, in the typical understanding of schizophrenia, olfaction is not recognized to contribute to or interact with the illness. Despite the solid presence of olfactory dysfunction in schizophrenia, its relation to the rest of the illness remains largely unclear. Here, we aimed to examine functional connectivity of the olfactory bulb, olfactory tract, and piriform cortices and isolate the network that would account for the altered olfaction in schizophrenia.
METHODS
We examined the functional connectivity of these specific olfactory regions in order to isolate other brain regions associated with olfactory processing in schizophrenia. Using the resting state functional MRI data from the Center for Biomedical Research Excellence in Brain Function and Mental Illness, we compared 84 patients of schizophrenia and 90 individuals without schizophrenia.
RESULTS
The schizophrenia group showed disconnectivity between the anterior piriform cortex and the nucleus accumbens, between the posterior piriform cortex and the middle frontal gyrus, and between the olfactory tract and the visual cortices.
CONCLUSIONS
The current results suggest functional disconnectivity of olfactory regions in schizophrenia, which may account for olfactory dysfunction and disrupted integration with other sensory modalities in schizophrenia.
Topics: Adult; Brain Mapping; Case-Control Studies; Female; Frontal Lobe; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Middle Aged; Olfaction Disorders; Olfactory Bulb; Olfactory Pathways; Oxygen; Rest; Schizophrenia; Young Adult
PubMed: 28582529
DOI: 10.1093/ijnp/pyx045 -
Scientific Reports Aug 2023We aimed to investigate changes in olfactory bulb volume and brain network in the white matter (WM) in patients with persistent olfactory disfunction (OD) following...
We aimed to investigate changes in olfactory bulb volume and brain network in the white matter (WM) in patients with persistent olfactory disfunction (OD) following COVID-19. A cross-sectional study evaluated 38 participants with OD after mild COVID-19 and 24 controls, including Sniffin' Sticks identification test (SS-16), MoCA, and brain magnetic resonance imaging. Network-Based Statistics (NBS) and graph theoretical analysis were used to explore the WM. The COVID-19 group had reduced olfactory bulb volume compared to controls. In NBS, COVID-19 patients showed increased structural connectivity in a subnetwork comprising parietal brain regions. Regarding global network topological properties, patients exhibited lower global and local efficiency and higher assortativity than controls. Concerning local network topological properties, patients had reduced local efficiency (left lateral orbital gyrus and pallidum), increased clustering (left lateral orbital gyrus), increased nodal strength (right anterior orbital gyrus), and reduced nodal strength (left amygdala). SS-16 test score was negatively correlated with clustering of whole-brain WM in the COVID-19 group. Thus, patients with OD after COVID-19 had relevant WM network dysfunction with increased connectivity in the parietal sensory cortex. Reduced integration and increased segregation are observed within olfactory-related brain areas might be due to compensatory plasticity mechanisms devoted to recovering olfactory function.
Topics: Humans; Diffusion Tensor Imaging; Cross-Sectional Studies; COVID-19; Brain; White Matter; Magnetic Resonance Imaging
PubMed: 37558765
DOI: 10.1038/s41598-023-40115-7 -
The Journal of Neuroscience : the... Dec 2021Neural oscillations can couple networks of brain regions, especially at lower frequencies. The nasal respiratory rhythm, which elicits robust olfactory bulb...
Neural oscillations can couple networks of brain regions, especially at lower frequencies. The nasal respiratory rhythm, which elicits robust olfactory bulb oscillations, has been linked to episodic memory, locomotion, and exploration, along with widespread oscillatory coherence. The piriform cortex is implicated in propagating the olfactory-bulb-driven respiratory rhythm, but this has not been tested explicitly in the context of both hippocampal theta and nasal respiratory rhythm during exploratory behaviors. We investigated systemwide interactions during foraging behavior, which engages respiratory and theta rhythms. Local field potentials from the olfactory bulb, piriform cortex, dentate gyrus, and CA1 of hippocampus, primary visual cortex, and nasal respiration were recorded simultaneously from male rats. We compared interactions among these areas while rats foraged using either visual or olfactory spatial cues. We found high coherence during foraging compared with home cage activity in two frequency bands that matched slow and fast respiratory rates. Piriform cortex and hippocampus maintained strong coupling at theta frequency during periods of slow respiration, whereas other pairs showed coupling only at the fast respiratory frequency. Directional analysis shows that the modality of spatial cues was matched to larger influences in the network by the respective primary sensory area. Respiratory and theta rhythms also coupled to faster oscillations in primary sensory and hippocampal areas. These data provide the first evidence of widespread interactions among nasal respiration, olfactory bulb, piriform cortex, and hippocampus in awake freely moving rats, and support the piriform cortex as an integrator of respiratory and theta activity. Recent studies have shown widespread interactions between the nasally driven respiratory rhythm and neural oscillations in hippocampus and neocortex. With this study, we address how the respiratory rhythm interacts with ongoing slow brain rhythms across olfactory, hippocampal, and visual systems in freely moving rats. Patterns of network connectivity change with behavioral state, with stronger interactions at fast and slow respiratory frequencies during foraging as compared with home cage activity. Routing of interactions between sensory cortices depends on the modality of spatial cues present during foraging. Functional connectivity and cross-frequency coupling analyses suggest strong bidirectional interactions between olfactory and hippocampal systems related to respiration and point to the piriform cortex as a key area for mediating respiratory and theta rhythms.
Topics: Animals; Cues; Exploratory Behavior; Male; Olfactory Perception; Piriform Cortex; Rats; Rats, Long-Evans; Respiratory Physiological Phenomena; Spatial Behavior; Theta Rhythm; Visual Perception
PubMed: 34667070
DOI: 10.1523/JNEUROSCI.0719-21.2021 -
European Journal of Nuclear Medicine... May 2022Hyposmia is a common feature of COVID-19 and Parkinson's disease (PD). As parkinsonism has been reported after COVID-19, a link has been hypothesized between SARS-CoV2...
PURPOSE
Hyposmia is a common feature of COVID-19 and Parkinson's disease (PD). As parkinsonism has been reported after COVID-19, a link has been hypothesized between SARS-CoV2 infection and PD. We aimed to evaluate brain metabolic correlates of isolated persistent hyposmia after mild-to-moderate COVID-19 and to compare them with metabolic signature of hyposmia in drug-naïve PD patients.
METHODS
Forty-four patients who experienced hyposmia after SARS-COV2 infection underwent brain [F]-FDG PET in the first 6 months after recovery. Olfaction was assessed by means of the 16-item "Sniffin' Sticks" test and patients were classified as with or without persistent hyposmia (COVID-hyposmia and COVID-no-hyposmia respectively). Brain [F]-FDG PET of post-COVID subgroups were compared in SPM12. COVID-hyposmia patients were also compared with eighty-two drug-naïve PD patients with hyposmia. Multiple regression analysis was used to identify correlations between olfactory test scores and brain metabolism in patients' subgroups.
RESULTS
COVID-hyposmia patients (n = 21) exhibited significant hypometabolism in the bilateral gyrus rectus and orbitofrontal cortex with respect to COVID-non-hyposmia (n = 23) (p < 0.002) and in middle and superior temporal gyri, medial/middle frontal gyri, and right insula with respect to PD-hyposmia (p < 0.012). With respect to COVID-hyposmia, PD-hyposmia patients showed hypometabolism in inferior/middle occipital gyri and cuneus bilaterally. Olfactory test scores were directly correlated with metabolism in bilateral rectus and medial frontal gyri and in the right middle temporal and anterior cingulate gyri in COVID-hyposmia patients (p < 0.006) and with bilateral cuneus/precuneus and left lateral occipital cortex in PD-hyposmia patients (p < 0.004).
CONCLUSION
Metabolic signature of persistent hyposmia after COVID-19 encompasses cortical regions involved in olfactory perception and does not overlap metabolic correlates of hyposmia in PD.
Topics: Anosmia; COVID-19; Fluorodeoxyglucose F18; Humans; Olfaction Disorders; Parkinson Disease; RNA, Viral; SARS-CoV-2; Smell
PubMed: 34984501
DOI: 10.1007/s00259-021-05666-9 -
BMC Cancer Apr 2012According to a fundamental law of radiobiology ("Law of Bergonié and Tribondeau", 1906), the brain is a paradigm of a highly differentiated organ with low mitotic... (Review)
Review
BACKGROUND
According to a fundamental law of radiobiology ("Law of Bergonié and Tribondeau", 1906), the brain is a paradigm of a highly differentiated organ with low mitotic activity, and is thus radio-resistant. This assumption has been challenged by recent evidence discussed in the present review.
RESULTS
Ionizing radiation is an established environmental cause of brain cancer. Although direct evidence is lacking in contemporary fluoroscopy due to obvious sample size limitation, limited follow-up time and lack of focused research, anecdotal reports of clusters have appeared in the literature, raising the suspicion that brain cancer may be a professional disease of interventional cardiologists. In addition, although terminally differentiated neurons have reduced or mild proliferative capacity, and are therefore not regarded as critical radiation targets, adult neurogenesis occurs in the dentate gyrus of the hippocampus and the olfactory bulb, and is important for mood, learning/memory and normal olfactory function, whose impairment is a recognized early biomarker of neurodegenerative diseases. The head doses involved in radiotherapy are high, usually above 2 Sv, whereas the low-dose range of professional exposure typically involves lifetime cumulative whole-body exposure in the low-dose range of < 200 mSv, but with head exposure which may (in absence of protection) arrive at a head equivalent dose of 1 to 3 Sv after a professional lifetime (corresponding to a brain equivalent dose around 500 mSv).
CONCLUSIONS
At this point, a systematic assessment of brain (cancer and non-cancer) effects of chronic low-dose radiation exposure in interventional cardiologists and staff is needed.
Topics: Brain; Brain Neoplasms; Cardiology; Cognition; Dose-Response Relationship, Radiation; Eye; Eye Neoplasms; Health Personnel; Humans; Neoplasms, Radiation-Induced; Occupational Diseases; Occupational Exposure; Radiation Injuries
PubMed: 22540409
DOI: 10.1186/1471-2407-12-157 -
The World Journal of Biological... Feb 2023Olfactory dysfunction is reproducibly reported in psychotic disorders, particularly in association with negative symptoms. The superior frontal gyrus (SFG) has been...
OBJECTIVES
Olfactory dysfunction is reproducibly reported in psychotic disorders, particularly in association with negative symptoms. The superior frontal gyrus (SFG) has been frequently studied in patients with psychotic disorders, in particular with their associations with negative symptoms. The relationship between olfactory functions and brain structure has been studied in healthy controls (HCs). Nevertheless, the studies with patients with psychotic disorders are limited. Here we report the olfactory-brain relationship in a first episode psychosis (FEP) cohort through both hypothesis-driven (centred on the SFG) and data-driven approaches.
METHODS
Using data from 88 HCs and 76 FEP patients, we evaluated the correlation between olfactory functions and structural/resting-state functional magnetic resonance imaging (MRI) data.
RESULTS
We found a significant correlation between the left SFG volume and odour discrimination in FEP patients, but not in HCs. We also observed a significant correlation between rs-fMRI connectivity involving the left SFG and odour discrimination in FEP patients, but not in HCs. The data-driven approach didn't observe any significant correlations, possibly due to insufficient statistical power.
CONCLUSION
The left SFG may be a promising brain region in the context of olfactory dysfunction and negative symptoms in FEP.
Topics: Humans; Schizophrenia; Magnetic Resonance Imaging; Psychotic Disorders; Brain; Olfaction Disorders
PubMed: 35678361
DOI: 10.1080/15622975.2022.2082526 -
Frontiers in Human Neuroscience 2021Although emerging evidence has implicated structural/functional abnormalities of patients with Autism Spectrum Disorder(ASD), definitive neuroimaging markers remain...
Although emerging evidence has implicated structural/functional abnormalities of patients with Autism Spectrum Disorder(ASD), definitive neuroimaging markers remain obscured due to inconsistent or incompatible findings, especially for structural imaging. Furthermore, brain differences defined by statistical analysis are difficult to implement individual prediction. The present study has employed the machine learning techniques under the unified framework in neuroimaging to identify the neuroimaging markers of patients with ASD and distinguish them from typically developing controls(TDC). To enhance the interpretability of the machine learning model, the study has processed three levels of assessments including model-level assessment, feature-level assessment, and biology-level assessment. According to these three levels assessment, the study has identified neuroimaging markers of ASD including the opercular part of bilateral inferior frontal gyrus, the orbital part of right inferior frontal gyrus, right rolandic operculum, right olfactory cortex, right gyrus rectus, right insula, left inferior parietal gyrus, bilateral supramarginal gyrus, bilateral angular gyrus, bilateral superior temporal gyrus, bilateral middle temporal gyrus, and left inferior temporal gyrus. In addition, negative correlations between the communication skill score in the Autism Diagnostic Observation Schedule (ADOS_G) and regional gray matter (GM) volume in the gyrus rectus, left middle temporal gyrus, and inferior temporal gyrus have been detected. A significant negative correlation has been found between the communication skill score in ADOS_G and the orbital part of the left inferior frontal gyrus. A negative correlation between verbal skill score and right angular gyrus and a significant negative correlation between non-verbal communication skill and right angular gyrus have been found. These findings in the study have suggested the GM alteration of ASD and correlated with the clinical severity of ASD disease symptoms. The interpretable machine learning framework gives sight to the pathophysiological mechanism of ASD but can also be extended to other diseases.
PubMed: 35273484
DOI: 10.3389/fnhum.2021.765517 -
Frontiers in Cellular Neuroscience 2015Adult neurogenesis has been convincingly demonstrated in two regions of the mammalian brain: the sub-granular zone (SGZ) of the dentate gyrus (DG) in the hippocampus,... (Review)
Review
Adult neurogenesis has been convincingly demonstrated in two regions of the mammalian brain: the sub-granular zone (SGZ) of the dentate gyrus (DG) in the hippocampus, and the sub-ventricular zone (SVZ) of the lateral ventricles (LV). SGZ newborn neurons are destined to the granular cell layer (GCL) of the DG, while new neurons from the SVZ neurons migrate rostrally into the olfactory bulb (OB). The process of adult neurogenesis persists throughout life and is supported by a pool of neural stem cells (NSCs), which reside in a unique and specialized microenvironment known as "neurogenic niche". Neurogenic niches are structured by a complex organization of different cell types, including the NSC-neuron lineage, glial cells and vascular cells. Thus, cell-to-cell communication plays a key role in the dynamic modulation of homeostasis and plasticity of the adult neurogenic process. Specific cell-cell contacts and extracellular signals originated locally provide the necessary support and regulate the balance between self-renewal and differentiation of NSCs. Furthermore, extracellular signals originated at distant locations, including other brain regions or systemic organs, may reach the niche through the cerebrospinal fluid (CSF) or the vasculature and influence its nature. The role of several secreted molecules, such as cytokines, growth factors, neurotransmitters, and hormones, in the biology of adult NSCs, has been systematically addressed. Interestingly, in addition to these well-recognized signals, a novel type of intercellular messengers has been identified recently: the extracellular vesicles (EVs). EVs, and particularly exosomes, are implicated in the transfer of mRNAs, microRNAs (miRNAs), proteins and lipids between cells and thus are able to modify the function of recipient cells. Exosomes appear to play a significant role in different stem cell niches such as the mesenchymal stem cell niche, cancer stem cell niche and pre-metastatic niche; however, their roles in adult neurogenic niches remain virtually unexplored. This review focuses on the current knowledge regarding the functional relationship between cellular and extracellular components of the adult SVZ and SGZ neurogenic niches, and the growing evidence that supports the potential role of exosomes in the physiology and pathology of adult neurogenesis.
PubMed: 26834560
DOI: 10.3389/fncel.2015.00501