An fMRI-based investigation of the effects of odors on the functional connectivity network underlying the working memory.

In the human brain, the regions responsible for emotion processing, motivation, and memory are heavily influenced by olfaction, whose neural pathway is directly exposed to the outer world. In this study, we used fMRI to examine how different olfactory conditions might affect the functional connectivity circuit underlying working memory in the brain. To this end, 30 adults (aged 20-35), 13 males and 17 females, with high educational levels were chosen. Participants were screened for potential olfactory issues before undergoing the Sniffin' sticks test, which was part of the inclusion criteria. Before imaging, each participant was given the required level of training and was then asked to complete four olfactory tests involving pleasant and unpleasant odors, air, and null stimulation. The results of Seed-based analysis suggested a function connection between the inferior parietal region and the left frontal pole region upon olfactory stimulation with vanilla scent in contrast to null stimulation in this comparison, ROI-based analysis revealed an inverse synchronous among the entorhinal cortex, orbitofrontal cortex, and dorsolateral prefrontal cortex (dlPFC). Both dlPFC and hippocampus were involved in olfactory discrimination between two different stimulants. Our findings indicate the presence of inverse correlations between several regions associated with olfaction and working memory, with pleasant scents leaving a stronger impact on the working memory-related areas, particularly the inferior parietal region.

Intra and inter-regional functional connectivity of the human brain due to Task-Evoked fMRI Data classification through CNN & LSTM.

BACKGROUND AND PURPOSE: Olfaction is an early marker of neurodegenerative disease. Standard olfactory function is essential due to the importance of olfaction in human life. The psychophysical evaluation assesses the olfactory function commonly. It is patient-reported, and results rely on the patient's answers and collaboration. However, methodological difficulties attributed to the psychophysical evaluation of olfactory-related cerebral areas led to limited assessment of olfactory function in the human brain. MATERIALS AND METHODS: The current study utilized clustering approaches to assess olfactory function in fMRI data and used brain activity to parcellate the brain with homogeneous properties. Deep neural network architecture based on ResNet convolutional neural networks (CNN) and Long Short-Term Model (LSTM) designed to classify healthy with olfactory disorders subjects. RESULTS: The fMRI result obtained by k-means unsupervised machine learning model was within the expected outcome and similar to those found with the conn toolbox in detecting active areas. There was no significant difference between the means of subjects and every subject. Proposing a CRNN deep learning model to classify fMRI data in two different healthy and with olfactory disorders groups leads to an accuracy score of 97 %. CONCLUSIONS: The K-means unsupervised algorithm can detect the active regions in the brain and analyze olfactory function. Classification results prove the CNN-LSTM architecture using ResNet provides the best accuracy score in olfactory fMRI data. It is the first attempt conducted on olfactory fMRI data in detail until now.

Treatment of verb tense inflection and sentence production in Persian individuals with agrammatism.

Production of verb morphology, especially tense inflection, is usually impaired in individuals with agrammatism. There have been relatively few studies on treatment of verb tense inflection in agrammatic aphasia. In this study we adapted ACTION (a linguistically motivated treatment) to Persian language, to treat the production of regular and irregular verbs separately in sentence context. A single-subject multiple-baseline across behaviors design was used to establish the treatment effect. Using a non-probable convenience sampling, four Persian agrammatic patients with Broca's aphasia resulting from cerebrovascular accident (CVA) were recruited for this study. Two participants received treatment first for regular verbs (Phase 1, 4 weeks), and then for irregular verbs (Phase 2, 4 weeks). The other two participants received treatment in reverse order. In the final phase of treatment (Phase 3, 4 weeks), all 4 participants underwent a sentence construction treatment. All participants showed improvement in the production of trained tenses. Treatment also generalized to production of untrained regular verbs while generalization to irregular verbs was modest. Furthermore, improvement was found on narrative scores (e.g. MLU) after treatment. These findings suggest that Persian individuals with agrammatism could be trained to correctly apply temporal information to verb inflection in elicited speech.

The brain functional connectivity alterations in traumatic patients with olfactory disorder after low-level laser therapy demonstrated by fMRI.

BACKGROUND: Low-level laser therapy (LLLT) has been clinically accepted to accelerate the nerve regeneration process after a nerve injury or transection. We aimed to investigate the neuronal basis and the influence of LLLT on brain functional networks in traumatic patients with olfactory dysfunction. METHODS: Twenty-four Patients with traumatic anosmia/hyposmia were exposed to pleasant olfactory stimuli during a block-designed fMRI session. After a 10-week period, patients as control group and patients who had completed the sessions of LLLT were invited for follow-up testing using the same fMRI protocol. Two-sample t-tests were conducted to explore group differences in activation responding to odorants (p-FDR-corrected <0.05). Differences of functional connectivity were compared between the two groups and the topological features of the olfactory network were calculated. Correlation analysis was performed between graph parameters and TDI score. RESULTS: Compared to controls, laser-treated patients showed increased activation in the cingulate, rectus gyrus, and some parts of the frontal gyrus. Shorter pathlength (p = 0.047) and increased local efficiency (p = 0.043) within the olfactory network, as well as decreased inter-network connectivity within the whole brain were observed in patients after laser surgery. Moreover, higher clustering and local efficiency were related to higher TDI score, as manifested in increased sensitivity to identify odors. CONCLUSIONS: The results support that low-level laser induces neural reorganization process and make new connections in the olfactory structures. Furthermore, the connectivity parameters may serve as potential biomarkers for traumatic anosmia or hyposmia by revealing the underlying neural mechanisms of LLLT.

Brain structural analysis in patients with post-traumatic anosmia: Voxel-based and surface-based morphometry.

PURPOSE AND BACKGROUND: Voxel-based morphometry (VBM) and surfaced-based morphometry (SBM) investigate the characteristics of gray matter (GM) in various diseases such as post-traumatic anosmia (PTA). This study uses SBM and VBM to examine neuroanatomical measurements of GM and its functional correlates in patients with PTA. METHODS: MRI images and olfactory test results were collected from 39 PTA patients and 39 healthy controls. Sniffin' Sticks test was used to assess olfactory function. GM structure was analyzed using CAT12 and FreeSurfer, and olfactory bulb (OB) volume and olfactory sulcus (OS) depth were calculated using 3D-Slicer. RESULTS: Anosmic patients showed lower scores in the Sniffin' Sticks olfactory test, as well as reduction of OB volume and OS depth compared to control subjects. In these patients, overlapping changes were found between the VBM and SBM findings in the areas with significant effects, in particular, orbitofrontal cortex, superior and middle frontal gyrus, superior and middle temporal gyrus, anterior cingulate cortex, and insular cortex. Using SBM, decreased cortical thickness clusters were located in inferior and superior parietal gyrus. Further analysis in the region of interest demonstrated correlations between the orbitofrontal cortex and odor threshold score as well as the middle frontal gyrus and smell loss duration. CONCLUSION: These findings show that the morphological alterations in the OB, OS, and the central olfactory pathways might contribute to the pathogenic mechanism of olfactory dysfunction after head injury.

Quantitative Assessment of Resting-State Functional Connectivity MRI to Differentiate Amnestic Mild Cognitive Impairment, Late-Onset Alzheimer's Disease From Normal Subjects.

BACKGROUND: Alzheimer disease (AD) is a neurological disorder with brain network dysfunction. Investigation of the brain network functional connectivity (FC) alterations using resting-state functional MRI (rs-fMRI) can provide valuable information about the brain network pattern in early AD diagnosis. PURPOSE: To quantitatively assess FC patterns of resting-state brain networks and graph theory metrics (GTMs) to identify potential features for differentiation of amnestic mild cognitive impairment (aMCI) and late-onset AD from normal. STUDY TYPE: Prospective. SUBJECTS: A total of 14 normal, 16 aMCI, and 13 late-onset AD. FIELD STRENGTH/SEQUENCE: A 3.0 T; rs-fMRI: single-shot 2D-EPI and T1-weighted structure: MPRAGE. ASSESSMENT: By applying bivariate correlation coefficient and Fisher transformation on the time series of predefined ROIs' pairs, correlation coefficient matrixes and ROI-to-ROI connectivity (RRC) were extracted. By thresholding the RRC matrix (with a threshold of 0.15), a graph adjacency matrix was created to compute GTMs. STATISTICAL TESTS: Region of interest (ROI)-based analysis: parametric multivariable statistical analysis (PMSA) with a false discovery rate using (FDR)-corrected P < 0.05 cluster-level threshold together with posthoc uncorrected P < 0.05 connection-level threshold. Graph-theory analysis (GTA): P-FDR-corrected < 0.05. One-way ANOVA and Chi-square tests were used to compare clinical characteristics. RESULTS: PMSA differentiated AD from normal, with a significant decrease in FC of default mode, salience, dorsal attention, frontoparietal, language, visual, and cerebellar networks. Furthermore, significant increase in overall FC of visual and language networks was observed in aMCI compared to normal. GTA revealed a significant decrease in global-efficiency (28.05 < 45), local-efficiency (22.98 < 24.05), and betweenness-centrality (14.60 < 17.39) for AD against normal. Moreover, a significant increase in local-efficiency (33.46 > 24.05) and clustering-coefficient (25 > 20.18) were found in aMCI compared to normal. DATA CONCLUSION: This study demonstrated resting-state FC potential as an indicator to differentiate AD, aMCI, and normal. GTA revealed brain integration and breakdown by providing concise and comprehensible statistics. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Brain Tumor Segmentation using Hierarchical Combination of Fuzzy Logic and Cellular Automata.

Background: Magnetic resonance (MR) image is one of the most important diagnostic tools for brain tumor detection. Segmentation of glioma tumor region in brain MR images is challenging in medical image processing problems. Precise and reliable segmentation algorithms can be significantly helpful in the diagnosis and treatment planning. Methods: In this article, a novel brain tumor segmentation method is introduced as a postsegmentation module, which uses the primary segmentation method's output as input and makes the segmentation performance values better. This approach is a combination of fuzzy logic and cellular automata (CA). Results: The BraTS online dataset has been used for implementing the proposed method. In the first step, the intensity of each pixel is fed to a fuzzy system to label each pixel, and at the second step, the label of each pixel is fed to a fuzzy CA to make the performance of segmentation better. This step repeated while the performance saturated. The accuracy of the first step was 85.8%, but the accuracy of segmentation after using fuzzy CA was obtained to 99.8%. Conclusion: The practical results have shown that our proposed method could improve the brain tumor segmentation in MR images significantly in comparison with other approaches.

Reorganizing brain structure through olfactory training in post-traumatic smell impairment: An MRI study.

PURPOSE AND BACKGROUND: Post-traumatic olfactory dysfunction (PTOD), mostly caused by head injury, is thought to be associated with changes in the structure and function of the brain olfactory processing areas. Training and repeated exposure to odorants lead to enhanced olfactory capability. This study investigated the effects of a 16-weeks olfactory training (OT) on olfactory function and brain structure. METHODS: Twenty-five patients with PTOD were randomly divided in three groups: (1) 9 control patients who did not receive any training, (2) 9 patients underwent classical OT by 4 fixed odors, and (3) 7 patients underwent modified OT coming across 4 sets of 4 different odors sequentially. Before and after the training period, all patients performed olfactory function tests and structural magnetic resonance imaging (MRI). Sniffin' Sticks test was used to assess olfactory function. MRI data were analyzed using voxel-based morphometry and surface-based morphometry. RESULTS: Both trained groups showed a considerable recovery of olfactory function, especially in odor identification. MRI data analysis revealed that the classical OT leads to increases in cortical thickness/density of several brain regions, including the right superior and middle frontal gyrus, and bilateral cerebellums. In addition, the modified OT yielded a lower extent of cortical measures in the right orbital frontal cortex and right insular. Following modified OT, a positive correlation was observed between the odor identification and the right orbital frontal cortex. CONCLUSION: Both olfactory training methods can improve olfactory function and that the improvement is associated with changes in the structure of olfactory processing areas of the brain.

Effects of olfactory training on resting­state effective connectivity in patients with posttraumatic olfactory dysfunction.

The present study investigated if and how the smell training scheme affects resting­state effective connectivity. We focused on connectivity among brain regions that participate in olfactory­related processes, including the piriform cortex, amygdala, orbitofrontal cortex (OFC), insula, and cingulate cortex. Sixteen patients with posttraumatic olfactory dysfunctions between the ages of 18 and 36 years participated in this study. Olfactory performance of subjects was evaluated using the Sniffin' Sticks test kit and then, resting­state functional magnetic resonance imaging (fMRI) was performed. Of the 16 participants, 8 underwent olfactory training for 16 weeks and the remaining 8 did not receive the treatment (the control group). After 16 weeks, participants in both groups underwent the same procedure (smell testing and the MRI examination). Olfactory performance scores were compared between groups using an independent samples t­test. Spectral dynamic causal modeling was applied to resting­state fMRI data to identify alterations in effective connectivity due to the smell training. We found that patients in the treatment group improved in the odor discrimination task and overall olfactory function as compared to the control group. Compared to the control group, patients in the treatment group had increased self­inhibitory connectivity of the OFC and increased excitatory connectivity from the cingulate cortex to the insula. Moreover, the excitatory connectivity from the OFC to the cingulate cortex was found to be weaker following the olfactory training scheme. This study shows that a smell training scheme can cause changes in resting­state effective connectivity parameters that can be attributed to improvements in the odor discrimination task.

A multimodal MR-compatible olfactometer with real-time controlling capability.

Design of an MR-compatible and computer-controlled odour stimuli system is essential in the studies of human olfactory function. Olfactometers are used to deliver odours to the subjects in an objective manner. We present a portable, computer-controlled eight channels olfactometer able to stimulate olfaction by employing liquid odorant stimuli. We used a high-pressure pump to generate medical grade airflow. After passing through solenoid valve-controlled odour reservoirs, odorant stimulus is conveyed to the nasal mask. The odour delivery delay of the device was measured using photo-ionisation detectors. To assess the application of the designed olfactometer, an fMRI experiment was done with 9 healthy subjects. Two odour stimuli (Vanillin and Rose) were presented to each subject in an alternating block design task of odour and non-odour conditions. The response time of each subject was gathered using the response box. Group analysis revealed a significant BOLD signal change in some regions of olfactory and trigeminal networks including the orbitofrontal cortex, insula, inferior frontal gyrus, hippocampus, cingulate gyrus and piriform cortex. The odour delivery delay measured by photo-ionisation detector was 190 ms, and the subjects' response showed 205 ms for the Vanillin and 243 ms for the Rose odour stimuli. Our portable MR-compatible olfactometer as a stimulation device is capable of creating adequate stimulation suitable for olfactory fMRI experiments.

The neural basis of hazard perception differences between novice and experienced drivers - An fMRI study.

The neural mechanisms underlying hazard perception are poorly understood as to how experience leads to better driving skills. In this study we used functional magnetic resonance imaging (fMRI) to examine experience-related changes in brain activation during hazard perception task between novice and aged drivers. Additionally, region of interest (ROI) and seed-to-voxel analyses were conducted to examine experience-related functional connectivity changes during visual attention and saliency networks between novice (n=15, age 22.13 ± 3.38 years years) and experienced (n=16, age 41.44 ± 5.83 years) drivers. Experienced drivers had significantly lower hazard perception reaction time (1.32 ± 1.09 s) and miss rates (11.42 ± 8.36 %) compared to the novice (3.58 ± 1.45 s and 39.67 ± 15.72 %, respectively). Blood oxygen level dependent (BOLD) activation increased in occipital, parietal and frontal areas when executing hazard perception task in both groups. In general, during the task execution, experienced drivers showed greater activation in the occipital lobe, supramarginal gyrus (SMG), right anterior insular cortex (AIC), anterior cingulate cortex (ACC) and cerebellar regions compared to the novice drivers indicating more efficient visual attention and decision-making process during hazard perception task. Seed based functional analyses during the hazard perception task revealed greater connectivity between the ACC and the entire salience network (visual attention network) in the experienced group. Additionally, ACC had higher functional connectivity with the right frontal eye field (FEF), bilateral intraparietal sulcus (IPS) and lateral occipital areas in the experienced group. Our results suggest that better hazard perception in the experienced drivers is due to increase in the activation of executive attention regions and higher functional connectivity between bilateral occipital cortices and salience network. In conclusion, better hazard perception is highly dependent on emotional awareness, perception of motion velocity, spatial representation of the environment and executing control.

Investigating the mechanisms behind extensive death in human cancer cells following nanoparticle assisted photo-thermo-radiotherapy.

We have recently reported the synthesis and characterization of gold-coated iron oxide nanoparticle and demonstrated such a nanoparticle (Au@Fe2O3 NP) was able to significantly enhance the lethal effects of photo-thermo-radiotherapy. The purpose of this study was to determine the mechanisms behind such an enhancement by investigating the changes induced in cancer cell viability, proliferation, and morphology as well as monitoring the alteration of some genes which play important role in the process of cell death. Using MTT assay and transmission electron microscopy (TEM), the KB cells viability and morphology were assessed after treating with various combinations of NPs, photothermal therapy (PTT), and radiotherapy (RT). Clonogenic assay was used to assess the proliferation ability of treated KB cells. Nanoparticle internalization into the cells was investigated by TEM and inductively coupled plasma (ICP). During the treatment procedures, temperature changes were monitored using an IR-camera. Furthermore, the changes occurred in Bax, BCL2 and HSP70 genes expression level were measured using real-time PCR. The results showed that combination of NP, PTT, and RT caused more cell death compared to PTT or RT alone. Following such a combination therapy, massive cell injury was detected. We also observed an extensive increase in Bax/Bcl2 ratio and HSP70 expression for the KB cells treated by combination therapy procedure. Our results showed that massive cell injury and apoptosis induction are the main reasons of extensive cell death observed in cancer cells when a nanoparticle assisted photo-thermo-radiotherapy procedure is applied.

Differentiation of human mesenchymal stem cells (MSC) to dopaminergic neurons: A comparison between Wharton's Jelly and olfactory mucosa as sources of MSCs.

The generation of dopaminergic neurons from stem cells is a potential therapeutic approach to treat neurodegenerative disorders, such as Parkinson's disease. The current study aims to investigate the potential of two different types of mesenchymal stem cells derived from human Wharton's jelly and nasal cavity for differentiation into dopaminergic neurons. The differentiation capacities of both cell types were evaluated using real-time PCR, immunocytochemistry, flow cytometry and HPLC. Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) are noted for their capability to differentiate into mesodermal and non-mesodermal cells, including neurons. However, it was demonstrated that having the same neuroectodermal origin as the nervous system, the olfactory ectomesenchymal stem cells (OE-MSCs) expressed the neural marker MAP2 as well as dopaminergic markers such as tyrosine hydroxylase (TH), dopamine transporter (DAT) and PITX3 to a greater extent than the WJ-MSCs both at the level of mRNA and protein. Furthermore, quantitative flow cytometric evaluation of these markers at 12 days post-induction supported the above-mentioned results. Finally, the assessment of the functionality of differentiated cells and their ability to synthesize dopamine measured by HPLC revealed that the OE-MSC-derived dopaminergic cells released almost the same amount of dopamine as that secreted by WJ-MSC-derived cells. Thus it showed the difference in their functionality to be negligible. Overall, it may be concluded that higher proliferation and differentiation capacity of OE-MSCs, along with their easier harvestability and autologous transplantability compared with WJ-MSCs, makes them a better cell source for stem cell therapy of neurodegenerative disorders which are caused by degeneration of dopaminergic neurons.

Real-time mapping of heat generation and distribution in a laser irradiated agar phantom loaded with gold nanoparticles using MR temperature imaging.

Gold nanoparticles (AuNPs) have shown potential strength in photothermal therapy of cancer. Several techniques have been developed to investigate local heat generation by AuNPs. However, a sensitive thermal imaging technology with high temporal resolution, minimum invasiveness and high spatial resolution is still lacking. In this research study, by using magnetic resonance thermal imaging (MRTI), we reported a technique for monitoring of heat generation and distribution in an AuNPs loaded agar phantom irradiated by laser. Three different agar phantoms with various AuNPs concentrations (0, 8 and 16 µg/ml) were produced and studied. The phantoms were exposed to an external laser [532 nm; 4 min] under MRTI. For real-time temperature monitoring, we employed the theory of proton resonance frequency (PRF) shift. Infrared (IR) camera was employed to measure the actual temperature of each point on the surface of irradiated agar gel. Finally, the correlation between the temperatures obtained by IR camera and MRTI was evaluated. We observed that temperature of the gels loaded by AuNPs at concentration of 0, 8 and 16 µg/ml reached 27.2, 37.8, 45 °C with a total area of heat distribution of 94.98, 452.16, and 907.34 mm2 (from the point of irradiation). During the process of laser irradiation, we observed: (i) a significant rise in temperature, (ii) a dependency between the rate of temperature rise and concentration of AuNPs, and (iii) a direct correlation between temperature change and MR image phase. In addition, statistical analysis showed that the variation of temperatures measured by IR camera and temperatures computed by MRTI had acceptable correlation (R > 0.9). In conclusion, MRTI has a good sensitivity and precision that can be employed for nano-photothermal therapy planning and may be considered for real-time mapping of heat generation and distribution in a laser irradiated tissue loaded by AuNPs.

Differentiation of neural crest stem cells from nasal mucosa into motor neuron-like cells.

Cell transplantation is a potential therapeutic approach for repairing neuropathological and neurodegenerative disorders of central nervous system by replacing the degenerated cells with new ones. Among a variety of stem cell candidates to provide these new cells, olfactory ectomesenchymal stem cells (OE-MSCs) have attracted a great attention due to their neural crest origin, easy harvest, high proliferation, and autologous transplantation. Since there is no report on differentiation potential of these cells into motor neuron-like cells, we evaluated this potential using Real-time PCR, flowcytometry and immunocytochemistry after the treatment with differentiation cocktail containing retinoic acid and Sonic Hedgehog. Immunocytochemistry staining of the isolated OE-MSCs demonstrated their capability to express nestin and vimentin, as the two markers of primitive neuroectoderm. The motor neuron differentiation of OE-MSCs resulted in changing their morphology into bipolar cells with high expression of motor neuron markers of ChAT, Hb-9 and Islet-1 at the level of mRNA and protein. Consequently, we believe that the OE-MSCs have great potential to differentiate into motor neuron-like cells and can be an ideal stem cell source for the treatment of motor neuron-related disorders of central nervous system.

Changes in Effective Connectivity Network Patterns in Drug Abusers, Treated With Different Methods.

INTRODUCTION: Various treatment methods for drug abusers will result in different success rates. This is partly due to different neural assumptions and partly due to various rate of relapse in abusers because of different circumstances. Investigating the brain activation networks of treated subjects can reveal the hidden mechanisms of the therapeutic methods. METHODS: We studied three groups of subjects: heroin abusers treated with abstinent based therapy (ABT) method, heroin abusers treated with Methadone Maintenance Therapy (MMT) method, and a control group. They were all scanned with functional magnetic resonance imaging (fMRI), using a 6-block task, where each block consisted of the rest-craving-rest-neutral sequence. Using the dynamic causal modeling (DCM) algorithm, brain effective connectivity network (caused by the drug craving stimulation) was quantified for all groups. In this regard, 4 brain areas were selected for this analysis based on previous findings: ventromedial prefrontal cortex (VMPFC), dorsolateral prefrontal cortex (DLPFC), amygdala, and ventral striatum. RESULTS: Our results indicated that the control subjects did not show significant brain activations after craving stimulations, but the two other groups showed significant brain activations in all 4 regions. In addition, VMPFC showed higher activations in the ABT group compared to the MMT group. The effective connectivity network suggested that the control subjects did not have any direct input from drug-related cue indices, while the other two groups showed reactions to these cues. Also, VMPFC displayed an important role in ABT group. In encountering the craving pictures, MMT subjects manifest a very simple mechanism compared to other groups. CONCLUSION: This study revealed an activation network similar to the emotional and inhibitory control networks observed in drug abusers in previous works. The results of DCM analysis also support the regulatory role of frontal regions on bottom regions. Furthermore, this study demonstrates the different effective connectivity patterns after drug abuse treatment and in this way helps the experts in the field.