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Journal of Neural Engineering Oct 2021The emotional response to olfactory stimuli implies the activation of a complex cascade of events triggered by structures lying in the limbic system. However, little is...
The emotional response to olfactory stimuli implies the activation of a complex cascade of events triggered by structures lying in the limbic system. However, little is known about how this activation is projected up to cerebral cortex and how different cortical areas dynamically interact each other.In this study, we acquired EEG from human participants performing a passive odor-perception task with odorants conveying positive, neutral and negative valence. A novel methodological pipeline integrating global field power (GFP), independent component analysis (ICA), dipole source localization was applied to estimate effective connectivity in the challenging scenario of single-trial low-synchronized stimulation.We identified the brain network and the neural paths, elicited at different frequency bands, i.e.θ(4-7Hz),α(8-12Hz)andβ(13-30Hz), involved in odor valence processing. This brain network includes the orbitofrontal cortex (OFC), the cingulate gyrus (CgG), the superior temporal gyrus (STG), the posterior cingulate cortex/precuneus (PCC/PCu) and the parahippocampal gyrus (PHG). It was analyzed using a time-varying multivariate autoregressive model to resolve time-frequency causal interactions. Specifically, the OFC acts as the main node for odor perception and evaluation of pleasant and unpleasant stimuli, whereas no specific path was observed for a neutral stimulus.The results introduce new evidences on the role of the OFC during hedonic perception and underpin its specificity during the odor valence assessment. Our findings suggest that, after the odor onset different, bidirectional interactions occur between the OFC and other brain regions associated with emotion recognition/categorization and memory according to the stimulus valence. This outcome unveils how the hedonic olfactory network dynamically changes based on odor valence.
Topics: Brain; Cerebral Cortex; Humans; Magnetic Resonance Imaging; Olfactory Perception; Smell
PubMed: 34547740
DOI: 10.1088/1741-2552/ac28d2 -
Brain Topography May 2020Patients with anosmia exhibit structural and functional brain abnormalities. The present study explored changes in brain white matter (WM) in non-neurodegenerative...
Patients with anosmia exhibit structural and functional brain abnormalities. The present study explored changes in brain white matter (WM) in non-neurodegenerative anosmia using diffusion-tensor-based network analysis. Twenty patients with anosmia and sixteen healthy controls were recruited in the cross-sectional, case-control study. Participants underwent olfactory tests (orthonasal and retronasal), neuropsychological assessment (cognitive function and depressive symptoms) and diffusion tensor imaging measurement. Tract-Based Spatial Statistics, graph theoretical analysis and Network-Based Statistics were used to explore the white matter. There was no significant difference in fractional anisotropy (FA) between patients and controls. In global network topological properties comparisons, patients exhibited higher γ and λ levels than controls, and both groups satisfied the criteria of small-world (σ > 1). In local network topological properties, patients had reduced betweenness, degree and efficiency (global and local), as well as increased shortest path length and cluster coefficient in olfactory-related brain areas (anterior cingulum, lenticular nucleus, putamen, hippocampus, amygdala, caudate nucleus, orbito-frontal gyrus). Olfactory threshold scores and the retronasal score were negatively correlated with γ and λ, and the retronasal score was positively correlated with FA values in certain WM tracts, i.e. middle cerebellar peduncle, right inferior cerebellar peduncle, left inferior cerebellar peduncle, right cerebral peduncle, left cerebral peduncle, left cingulum (cingulate gyrus), right cingulum (hippocampus), superior fronto-occipital fasciculus, and, left tapetum. Patients with anosmia demonstrated relevant WM network dysfunction though their structural integrity remained intact. Their retronasal olfaction deficits revealed to be more strongly associated with WM alterations compared with orthonasal olfactory scores.
Topics: Anisotropy; Anosmia; Brain; Case-Control Studies; Cross-Sectional Studies; Diffusion Tensor Imaging; Humans
PubMed: 32297077
DOI: 10.1007/s10548-020-00769-2 -
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 -
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 -
Progress in Neurobiology Jan 2023The amygdala and orbitofrontal cortex have been implicated in emotion. To understand these regions better in humans, their effective connectivity with 360 cortical...
The amygdala and orbitofrontal cortex have been implicated in emotion. To understand these regions better in humans, their effective connectivity with 360 cortical regions was measured in 171 humans from the Human Connectome Project, and complemented with functional connectivity and diffusion tractography. The human amygdala has effective connectivity from few cortical regions compared to the orbitofrontal cortex: primarily from auditory cortex A5 and the related superior temporal gyrus and temporal pole regions; the piriform (olfactory) cortex; the lateral orbitofrontal cortex 47m; somatosensory cortex; the hippocampus, entorhinal cortex, perirhinal cortex, and parahippocampal TF; and from the cholinergic nucleus basalis. The amygdala has effective connectivity to the hippocampus, entorhinal and perirhinal cortex; to the temporal pole; and to the lateral orbitofrontal cortex. The orbitofrontal cortex has effective connectivity from gustatory, olfactory, and temporal visual, auditory and pole cortex, and to the pregenual anterior and posterior cingulate cortex, hippocampal system, and prefrontal cortex, and provides for rewards and punishers to be used in reported emotions, and memory and navigation to goals. Given the paucity of amygdalo-neocortical connectivity in humans, it is proposed that the human amygdala is involved primarily in autonomic and conditioned responses via brainstem connectivity, rather than in reported (declarative) emotion.
Topics: Humans; Prefrontal Cortex; Amygdala; Hippocampus; Emotions; Entorhinal Cortex; Neural Pathways
PubMed: 36442728
DOI: 10.1016/j.pneurobio.2022.102385 -
The International Journal of... Aug 2018Olfactory dysfunction (ODF) has been reported in patients with neuromyelitis optica (NMO) and multiple sclerosis (MS). However, the comparison of olfactory function and...
OBJECTIVES
Olfactory dysfunction (ODF) has been reported in patients with neuromyelitis optica (NMO) and multiple sclerosis (MS). However, the comparison of olfactory function and olfactory-related gray matter (GM) between patients with NMO and MS needed to be further elucidated.
MATERIALS AND METHODS
Thirty-seven patients with NMO and 37 with MS were enrolled. Olfactory function was evaluated with a Japanese T&T olfactometer test kit, and the neuroanatomical features of olfactory-related GM were assessed using voxel-based morphometry.
RESULTS
Olfactory deficits were found in 51.4% of patients with NMO and 40.5% of patients with MS. Patients with NMO with ODF had significantly smaller olfactory bulbs than patients with MS with ODF (p = 0.031). Olfactory-related GM atrophy was found in patients with NMO in several regions of the right orbitofrontal cortex and right superior frontal gyrus; in patients with MS, reduced GM volume was found in the right parahippocampal gyrus and piriform cortex (p < 0.05, cluster size > 200 voxels).
CONCLUSIONS
Olfactory deficits are common in both NMO and MS. However, the neuroanatomical features related to olfactory deficits differ greatly between the two diseases.
Topics: Adult; Disability Evaluation; Female; Humans; Japan; Magnetic Resonance Imaging; Male; Middle Aged; Multiple Sclerosis; Neuromyelitis Optica; Olfaction Disorders; Olfactory Bulb; Sensory Thresholds; Severity of Illness Index
PubMed: 29297712
DOI: 10.1080/00207454.2018.1424152 -
Biochemical and Biophysical Research... Jul 2021Kin of irregular chiasm-like 3 (Kirrel3), a member of the immunoglobulin superfamily, is expressed in the central nervous system during development and in adulthood. It...
Kin of irregular chiasm-like 3 (Kirrel3), a member of the immunoglobulin superfamily, is expressed in the central nervous system during development and in adulthood. It has been reported that Kirrel3 is involved in the axonal fasciculation in the olfactory bulb, the neuronal migration in the pontine nucleus, and the synapse formation in the hippocampal neurons in mice. Although KIRREL3 mutations have been implicated in autism spectrum disorder and intellectual disability in humans, the comprehensive expression pattern of Kirrel3 in the adult brain is not fully understood. To better visualize Kirrel3 expression pattern and to gain insight into the role of Kirrel3 in the brain, we investigated the expression of Kirrel3 in the adult brain of Kirrel3-heterozygous (Kirrel3) mice, in which Kirrel3-expressing cells could be identified by the expression of β-galactosidase (β-gal) in the nucleus of cells. The strong expression of β-gal was observed in the hippocampus, cerebral cortex, olfactory bulb, amygdala, thalamus, and cerebellum. In the hippocampus, β-gal was detected in the dentate gyrus and in the ventral parts of CA1 and CA3, which are known to be involved in the social recognition memory. Within the cerebral cortex, many cells with β-gal expression were observed in the olfactory area and auditory area. In the striatum, neurons with β-gal expression were mainly observed in the ventral striatum. Expression of β-gal was observed in all layers in the cerebellum and olfactory bulb, except for the olfactory nerve layer. Double-immunofluorescence staining of β-galactosidase with neuronal markers revealed that β-gal expression was exclusively detected in neurons. These results suggest that Kirrel3 may be involved in the maintenance of neuronal networks, such as the maintenance of synaptic connectivity and plasticity in the motor, sensory, and cognitive circuits of adult brain.
Topics: Animals; Brain; Cell Nucleus; Membrane Proteins; Mice; Mice, Transgenic; beta-Galactosidase
PubMed: 34062388
DOI: 10.1016/j.bbrc.2021.05.063 -
Neurology(R) Neuroimmunology &... Mar 2022This [F]fluorodeoxyglucose (FDG) PET study evaluates the accuracy of semiquantitative measurement of putaminal hypermetabolism in identifying anti-leucine-rich,...
BACKGROUND AND OBJECTIVES
This [F]fluorodeoxyglucose (FDG) PET study evaluates the accuracy of semiquantitative measurement of putaminal hypermetabolism in identifying anti-leucine-rich, glioma-inactivated-1 (LGI1) protein autoimmune encephalitis (AE). In addition, the extent of brain dysmetabolism, their association with clinical outcomes, and longitudinal metabolic changes after immunotherapy in LGI1-AE are examined.
METHODS
FDG-PET scans from 49 age-matched and sex-matched subjects (13 in LGI1-AE group, 15 in non-LGI1-AE group, 11 with Alzheimer disease [AD], and 10 negative controls [NCs]) and follow-up scans from 8 patients with LGI1 AE on a median 6 months after immunotherapy were analyzed. Putaminal standardized uptake value ratios (SUVRs) normalized to global brain (P-SUVRg), thalamus (P/Th), and midbrain (P/Mi) were evaluated for diagnostic accuracy. SUVRg was applied for all other analyses.
RESULTS
P-SUVRg, P/Th, and P/Mi were higher in LGI1-AE group than in non-LGI1-AE group, AD group, and NCs (all < 0.05). P/Mi and P-SUVRg differentiated LGI1-AE group robustly from other groups (areas under the curve 0.84-0.99). Mediotemporal lobe (MTL) SUVRg was increased in both LGI1-AE and non-LGI1-AE groups when compared with NCs (both < 0.05). SUVRg was decreased in several frontoparietal regions and increased in pallidum, caudate, pons, olfactory, and inferior occipital gyrus in LGI1-AE group when compared with that in NCs (all < 0.05). In LGI1-AE group, both MTL and putaminal hypermetabolism were reduced after immunotherapy. Normalization of regional cortical dysmetabolism associated with clinical improvement at the 6- and 20-month follow-up.
DISCUSSION
Semiquantitative measurement of putaminal hypermetabolism with FDG-PET may be used to distinguish LGI1-AE from other pathologies. Metabolic abnormalities in LGI1-AE extend beyond putamen and MTL into other subcortical and cortical regions. FDG-PET may be used in evaluating disease evolution in LGI1-AE.
CLASSIFICATION OF EVIDENCE
This study provides Class II evidence that semiquantitative measures of putaminal metabolism on PET can differentiate patients with LGI1-AE from patients without LGI1-AE, patients with AD, or NCs.
Topics: Adolescent; Adult; Aged; Alzheimer Disease; Autoantibodies; Cerebral Cortex; Demyelinating Autoimmune Diseases, CNS; Electroencephalography; Encephalitis; Female; Follow-Up Studies; Humans; Intracellular Signaling Peptides and Proteins; Magnetic Resonance Imaging; Male; Mesencephalon; Middle Aged; Positron-Emission Tomography; Putamen; Retrospective Studies; Young Adult
PubMed: 35091466
DOI: 10.1212/NXI.0000000000001136