Functional Neuroimaging Methods Research Articles

Examining functional Near-Infrared Spectroscopy as a tool to study brain function in bilinguals

There is increasing evidence that using more than one languages has significant effects on brain function. These effects have been observed in the developing, adult and aging brain, and have been suggested to have implications for cognitive and brain decline in bilinguals and multilinguals. Aside from extensive investigations with behavioral methods, such effects are now commonly investigated with functional neuroimaging methods, mostly functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG). A relatively underused method in the field is functional Near-Infrared Spectroscopy (fNIRS), which carries several advantages over more established methods, including being appropriate for use with infants and children, but also with older and diseased samples. This paper provides an overview of the method and an account of how it has been used in the field of bilingual cognition. It concludes with suggestions of how the method can be best utilized in future research, highlighting it as a method with a strong potential for updating existing theories on the effects of bilingualism on brain function.

An fMRI study of phrase structure and subject island violations.

In principle, functional neuroimaging provides uniquely informative data in addressing linguistic questions, because it can indicate distinct processes that are not apparent from behavioral data alone. This could involve adjudicating the source of unacceptability via the different patterns of elicited brain responses to different ungrammatical sentence types. However, it is difficult to interpret brain activations to syntactic violations. Such responses could reflect processes that have nothing intrinsically related to linguistic representations, such as domain-general executive function abilities. In order to facilitate the potential use of functional neuroimaging methods to identify the source of different syntactic violations, we conducted an fMRI experiment to identify the brain activation maps associated with two distinct syntactic violation types: phrase structure (created by inverting the order of two adjacent words within a sentence) and subject islands (created by extracting a wh-phrase out of an embedded subject). The comparison of these violations to control sentences surprisingly showed no indication of a generalized violation response, with almost completely divergent activation patterns. Phrase structure violations seemingly activated regions previously implicated in verbal working memory and structural complexity in sentence processing, whereas the subject islands appeared to activate regions previously implicated in conceptual-semantic processing, broadly defined. We review our findings in the context of previous research on syntactic and semantic violations using event-related potentials. Although our results suggest potentially distinct underlying mechanisms underlying phrase structure and subject island violations, our results are tentative and suggest important methodological considerations for future research in this area.

Investigating acoustic startle habituation and prepulse inhibition with silent functional MRI and electromyography in young, healthy adults.

Startle habituation and prepulse inhibition (PPI) are distinct measures of different sensory information processes, yet both result in the attenuation of the startle reflex. Identifying startle habituation and PPI neural mechanisms in humans has mostly evolved from acoustic-focused rodent models. Human functional magnetic resonance imaging (fMRI) studies have used tactile startle paradigms to avoid the confounding effects of gradient-related acoustic noise on auditory paradigms and blood-oxygen-level-dependent (BOLD) measures. This study aimed to examine the neurofunctional basis of acoustic startle habituation and PPI in humans with silent fMRI. Using silent fMRI and simultaneous electromyography (EMG) to measure startle, the neural correlates of acoustic short-term startle habituation and PPI [stimulus onset asynchronies (SOA) of 60 ms and 120 ms] were investigated in 42 healthy adults (28 females). To derive stronger inferences about brain-behaviour correlations at the group-level, models included EMG-assessed measures of startle habituation (regression slope) or PPI (percentage) as a covariate. A linear temporal modulator was modelled at the individual-level to characterise functional changes in neural activity during startle habituation. Over time, participants showed a decrease in startle response (habituation), accompanied by decreasing thalamic, striatal, insula, and brainstem activity. Startle habituation was associated with the linear temporal modulation of BOLD response amplitude in several regions, with thalamus, insula, and parietal lobe activity decreasing over time, and frontal lobe, dorsal striatum, and posterior cingulate activity increasing over time. The paradigm yielded a small amount of PPI (9-13%). No significant neural activity for PPI was detected. Startle habituation was associated with the thalamus, putamen, insula, and brainstem, and with linear BOLD response modulation in thalamic, striatal, insula, parietal, frontal, and posterior cingulate regions. These findings provide insight into the mediation and functional basis of the acoustic primary startle circuit. Instead, whilst reduced compared to conventional MRI, scanner noise may have disrupted prepulse detection and processing, resulting in low PPI and impacting our ability to map its neural signatures. Our findings encourage optimisation of the MRI environment for acoustic PPI-based investigations in humans. Combining EMG and functional neuroimaging methods shows promise for mapping short-term startle habituation in healthy and clinical populations.

Amplitude-integrated electroencephalography showed no differences in cerebral activity between preterm singletons and twins in the first 4 weeks of life.

Genetic influences on cerebral activity have been described previously, but data are scarce in preterms. We aimed to investigate whether a genetic influence causes amplitude-integrated electroencephalography (aEEG) signals to differ between singletons and twin preterm newborns. This was a retrospective single-centre study conducted at Innsbruck Medical University Hospital, Austria. Preterm infants born before 32 weeks of gestation between 6 November 2010 and 6 December 2022 were eligible for the study. The aEEG was analysed for the total maturation score, its component scores and the number of sleep-wake cycles per hour. We enrolled 240 preterm twin infants (57.5% male) with a mean gestational age of 30 (range: 24-32) weeks and a mean birth weight of 1324 (range: 600-2116) grams. We compared 240 singleton matched preterms. No differences were found between preterm singletons and twin preterm infants regarding the total maturation and component scores, or the number of sleep-wake cycles. aEEG showed no difference between monozygotic and dizygotic twins. Compared to singletons, twin infants born preterm showed no differences in aEEG signals in the first 4 weeks of life. Future studies should include more complex non-invasive functional neuroimaging methods to gain more insight into this important topic.

A novel restrainer device for acquistion of brain images in awake rats

Functional neuroimaging methods like fMRI and PET are vital in neuroscience research, but require that subjects remain still throughout the scan. In animal research, anesthetic agents are typically applied to facilitate the acquisition of high-quality data with minimal motion artifact. However, anesthesia can have profound effects on brain metabolism, selectively altering dynamic neural networks and confounding the acquired data. To overcome the challenge, we have developed a novel head fixation device designed to support awake rat brain imaging. A validation experiment demonstrated that the device effectively minimizes animal motion throughout the scan, with mean absolute displacement and mean relative displacement of 0.0256 (SD: 0.001) and 0.009 (SD: 0.002), across eight evaluated subjects throughout fMRI image acquisition (total scanning time per subject: 31 min, 12 s). Furthermore, the awake scans did not induce discernable stress to the animals, with stable physiological parameters throughout the scan (Mean HR: 344, Mean RR: 56, Mean SpO2: 94 %) and unaltered serum corticosterone levels (p = 0.159). In conclusion, the device presented in this paper offers an effective and safe method of acquiring functional brain images in rats, allowing researchers to minimize the confounding effects of anesthetic use.

Возможности и перспективы технологии функциональной ближней инфракрасной спектроскопии у пациентов, нуждающихся в высокотехнологичном слухопротезировании

One of the most notable features of auditory prosthetics at the present stage of development is the close interdisciplinary interaction of related medical, scientific, and social specialties. The solution of practical problems in audiology has long gone beyond the range of selecting a method of acoustic or electrical amplification. The priorities in decision making have increasingly shifted from purely engineering efficiency toward improving the quality of life in general. A personalized approach to choosing optimal solutions for each specific case inevitably led specialists to study the cognitive potential and neurophysiological characteristics of the patient. That is why various methods of functional neuroimaging are increasingly being introduced into the scientific and practical activities of an audiologist. Functional near infrared spectroscopy (fNIRS) is considered one of the youngest and most promising technologies. It allows us to research the metabolic activity of the cerebral cortex, which is an important source of feedback when working with sensory functions of the body. The potential of its use can vary from evaluating the effectiveness of measures already taken to solving complex controversial issues of selecting patients for high-tech treatment methods, which do not always remain regulated in methodological documents: the choice of prosthetics, the expediency of performing cochlear implantation in patients with ambiguous indications and contraindications, assessment of rehabilitation potential in neurological comorbidity, etc. In this article, we have tried to systematize and reflect the relevant aspects of the use of fNIRS for audiology patients with a description of the essence of the method, its comparison with alternative methods of functional imaging such as functional magnetic resonance imaging, electroencephalography, magnetoencephalography, positron emission tomography.

Comparative assessment of cerebral perfusion and metabolism in patients with Alzheimer’s disease and vascular cognitive disorders

BACKGROUND: The high medical and social significance of the problem determines the necessity of the earliest nosological diagnostics of the cognitive disorders. Functional neuroimaging methods such as single-photon emission computed tomography and positron emission tomography play an important role in the early differential diagnosis, allowing to estimate perfusion and metabolism of the cerebral tissue.
 AIM: To perform a comparative analysis of perfusion and metabolic abnormalities in different cerebral structures of patients with Alzheimer’s disease and vascular cognitive disorders in small cerebral vessels disease.
 MATERIALS AND METHODS: Single-photon emission computed tomography was performed in 13 patients with Alzheimer’s disease and in 21 patients with vascular cognitive disorders; positron emission tomography with 18F-FDG was performed in 17 patients with Alzheimer’s disease and in 15 patients with vascular cognitive disorders.
 RESULTS: Patterns of perfusion and metabolic abnormalities differ in patients with Alzheimer’s disease and vascular cognitive disorders. In patients with vascular cognitive disorders due to cerebral small vessels disease, a distinctive feature was a combination of hypoperfusion in subcortical structures, especially in the caudate nucleus and thalamus, with hypoperfusion in the deep parts of the frontal lobe. In Alzheimer’s disease, bilateral pronounced perfusion abnormalities in the parietal and temporal cortex were the most characteristic. Patterns of metabolic disturbances were similar to patterns of perfusion disturbances in different variants of cognitive disorders, but metabolic disturbances were more widespread. Рositron emission tomography was more informative in diagnosing patients with Alzheimer’s disease compared to single photon emission computed tomography. More pronounced perfusion and metabolic disorders were observed in patients with more severe cognitive disorders. Perfusion disturbances in the area of subcortical structures can be considered as an early marker of cognitive impairment development in patients with small vessel disease.
 CONCLUSION: Single photon emission computed tomography has sufficient sensitivity and specificity when examining patients with vascular cognitive disorders, while positron emission tomography is more preferable when examining patients with Alzheimer-type dementia.

65 Neuroscience in the Everyday World: Lateralization of Brain Activity During Dual-Task Walking

Objective:Functional near-infrared spectroscopy (fNIRS) is a non-invasive functional neuroimaging method that takes advantage of the optical properties of hemoglobin to provide an indirect measure of brain activation via task-related relative changes in oxygenated hemoglobin (HbO). Its advantage over fMRI is that fNIRS is portable and can be used while walking and talking. In this study, we used fNIRS to measure brain activity in prefrontal and motor region of interests (ROIs) during single- and dual-task walking, with the goal of identifying neural correlates.Participants and Methods:Nineteen healthy young adults [mean age=25.4 (SD=4.6) years; 14 female] engaged in five tasks: standing single-task cognition (serial-3 subtraction); single-task walking at a self-selected comfortable speed on a 24.5m oval-shaped course (overground walking) and on a treadmill; and dual-task cognition+walking on the same overground course and treadmill (8 trials/condition: 20 seconds standing rest, 30 seconds task). Performance on the cognitive task was quantified as the number of correct subtractions, number of incorrect subtractions, number of self-corrected errors, and percent accuracy over the 8 trials. Walking speed (m/sec) was recorded for all walking conditions. fNIRS data were collected on a system consisting of 16 sources, 15 detectors, and 8 short-separation detectors in the following ROIs: right and left lateral frontal (RLF, LLF), right and left medial frontal (RMF, LMF), right and left medial superior frontal (RMSF, LMSF), and right and left motor (RM, LM). Lateral and medial refer to ROIs’ relative positions on lateral prefrontal cortex. fNIRS data were analyzed in Homer3 using a spline motion correction and the iterative weighted least squares method in the general linear model. Correlations between the cognitive/speed variables and ROI HbO data were applied using a Bonferroni adjustment for multiple comparisons.Results:Subjects with missing cognitive data were excluded from analyses, resulting in sample sizes of 18 for the single-task cognition, dual-task overground walking, and dual-task treadmill walking conditions. During dual-task overground walking, there was a significant positive correlation between walking speed and relative change in HbO in RMSF [r(18)=.51, p<.05] and RM [r(18)=.53, p<.05)]. There was a significant negative correlation between total number of correct subtractions and relative change in HbO in LMSF ([r(18)=-.75, p<.05] and LM [r(18)=-.52, p<.05] during dual-task overground walking. No other significant correlations were identified.Conclusions:These results indicate that there is lateralization of the cognitive and motor components of overground dual-task walking. The right hemisphere appears to be more active the faster people walk during the dual-task. By contrast, the left hemisphere appears to be less active when people are working faster on the cognitive task (i.e., serial-3 subtraction). The latter results suggest that automaticity of the cognitive task (i.e., more total correct subtractions) is related to decreased brain activity in the left hemisphere. Future research will investigate whether there is a change in cognitive automaticity over trials and if there are changes in lateralization patterns in neurodegenerative disorders that are known to differentially affect the hemispheres (e.g., Parkinson’s disease).

Non-Invasive Mapping of the Neuronal Networks of Language.

This review consists of three main sections. In the first, the Introduction, the main theories of the neuronal mediation of linguistic operations, derived mostly from studies of the effects of focal lesions on linguistic performance, are summarized. These models furnish the conceptual framework on which the design of subsequent functional neuroimaging investigations is based. In the second section, the methods of functional neuroimaging, especially those of functional Magnetic Resonance Imaging (fMRI) and of Magnetoencephalography (MEG), are detailed along with the specific activation tasks employed in presurgical functional mapping. The reliability of these non-invasive methods and their validity, judged against the results of the invasive methods, namely, the "Wada" procedure and Cortical Stimulation Mapping (CSM), is assessed and their use in presurgical mapping is justified. In the third and final section, the applications of fMRI and MEG in basic research are surveyed in the following six sub-sections, each dealing with the assessment of the neuronal networks for (1) the acoustic and phonological, (2) for semantic, (3) for syntactic, (4) for prosodic operations, (5) for sign language and (6) for the operations of reading and the mechanisms of dyslexia.

B - 61 Increased Cortical Efficiency in the Absence of Behavioral Improvement on Working Memory Task Revealed by Functional Near-Infrared Spectroscopy.

Functional near-infrared spectroscopy (fNIRS) is a non-invasive functional neuroimaging method that indirectly measures cortical activation via task-related changes in oxygenated hemoglobin (HbO). We used fNIRS during a working memory task to assess learning effect over time by assessing brain activity (fNIRS signal) and task performance. We hypothesized that in later blocks of the task, learning (better accuracy) would be correlated to less increase in HbO in prefrontal regions, indicating improved cognitive efficiency. Eighteen healthy adults [mean age = 24.9 (SD = 4.2); 14 female] engaged in 8 blocks of serial-3 subtraction for 30seconds each followed by 20seconds of rest. fNIRS data were collected in 8 cortical regions of interest (ROI) broadly covering the frontal lobe. fNIRS signal in each ROI and task-performance data were compared for the first 4 and last 4 blocks to examine learning. fNIRS signal was significantly greater for the first 4 than last 4 blocks (z = -2.1, p < 0.05) in only the right dorsolateral prefrontal cortex ROI. No learning effects appeared for any task-performance variables. These results indicate a dissociation between brain activity and task performance during a working memory task in healthy adults. There was less activity in the right dorsolateral prefrontal cortex during later than earlier trials, indicating an increase in this region's efficiency, without a change in task performance. The results suggest that fNIRS may be sensitive to change in brain activity before it appears clinically, which may be useful in studying people with conditions such as preclinical Alzheimer's disease, and in assessing subtle effects of interventions.

Parkinson’s disease. Focus on early stages

The review presents current data on the peculiarities of the neurodegenerative process in the early stages of Parkinson’s disease (PD) and considers the hypothesis of the presence of body-first and brain-first subtypes of the disease onset. The earliest manifestations of the disease include symptoms such as parasomnia, constipation, hyposmia, anxiety-depressive disorder, daytime sleepiness, color perception changes, cognitive dysfunction, and mild motor manifestations. The diagnosis of PD can be made when characteristic motor manifestations occur: hypokinesia, rest tremor, muscle rigidity. Substantia nigra ultrasound, magnetic resonance imaging in SWI mode, and functional neuroimaging methods are used as confirmatory methods. The approach to the treatment of early stages of PD is age dependent. Patients over 70 years of age are recommended to start therapy with levodopa; younger patients – with dopamine receptor agonists (ADR), amantadines, MAO-B inhibitors. The mechanisms of ADR action, the possibility of their influence on the motor and non-motor symptoms of PD are analyzed. A special place is given to piribedil, which, due to the dual mechanism of action, has a positive effect on cognitive functions, depression, apathy, as well as a minimal effect on daytime sleepiness.

Assessing blood oxygen level-dependent signal variability as a biomarker of brain injury in sport-related concussion.

Mild traumatic brain injury is a complex neurological disorder of significant concern among athletes who play contact sports. Athletes who sustain sport-related concussion typically undergo physical examination and neurocognitive evaluation to determine injury severity and return-to-play status. However, traumatic disruption to neurometabolic processes can occur with minimal detectable anatomic pathology or neurocognitive alteration, increasing the risk that athletes may be cleared for return-to-play during a vulnerable period and receive a repetitive injury. This underscores the need for sensitive functional neuroimaging methods to detect altered cerebral physiology in concussed athletes. The present study compared the efficacy of Immediate Post-concussion Assessment and Cognitive Testing composite scores and whole-brain measures of blood oxygen level-dependent signal variability for classifying concussion status and predicting concussion symptomatology in healthy, concussed and repetitively concussed athletes, assessing blood oxygen level-dependent signal variability as a potential diagnostic tool for characterizing functional alterations to cerebral physiology and assisting in the detection of sport-related concussion. We observed significant differences in regional blood oxygen level-dependent signal variability measures for concussed athletes but did not observe significant differences in Immediate Post-concussion Assessment and Cognitive Testing scores of concussed athletes. We further demonstrate that incorporating measures of functional brain alteration alongside Immediate Post-concussion Assessment and Cognitive Testing scores enhances the sensitivity and specificity of supervised random forest machine learning methods when classifying and predicting concussion status and post-concussion symptoms, suggesting that alterations to cerebrovascular status characterize unique variance that may aid in the detection of sport-related concussion and repetitive mild traumatic brain injury. These results indicate that altered blood oxygen level-dependent variability holds promise as a novel neurobiological marker for detecting alterations in cerebral perfusion and neuronal functioning in sport-related concussion, motivating future research to establish and validate clinical assessment protocols that can incorporate advanced neuroimaging methods to characterize altered cerebral physiology following mild traumatic brain injury.

Exploring the Frontiers of Neuroimaging: A Review of Recent Advances in Understanding Brain Functioning and Disorders.

Neuroimaging has revolutionized our understanding of brain function and has become an essential tool for researchers studying neurological disorders. Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are two widely used neuroimaging techniques to review changes in brain activity. fMRI is a noninvasive technique that uses magnetic fields and radio waves to produce detailed brain images. An EEG is a noninvasive technique that records the brain's electrical activity through electrodes placed on the scalp. This review overviews recent developments in noninvasive functional neuroimaging methods, including fMRI and EEG. Recent advances in fMRI technology, its application to studying brain function, and the impact of neuroimaging techniques on neuroscience research are discussed. Advances in EEG technology and its applications to analyzing brain function and neural oscillations are also highlighted. In addition, advanced courses in neuroimaging, such as diffusion tensor imaging (DTI) and transcranial electrical stimulation (TES), are described, along with their role in studying brain connectivity, white matter tracts, and potential treatments for schizophrenia and chronic pain. Application. The review concludes by examining neuroimaging studies of neurodevelopmental and neurological disorders such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), Alzheimer's disease (AD), and Parkinson's disease (PD). We also described the role of transcranial direct current stimulation (tDCS) in ASD, ADHD, AD, and PD. Neuroimaging techniques have significantly advanced our understanding of brain function and provided essential insights into neurological disorders. However, further research into noninvasive treatments such as EEG, MRI, and TES is necessary to continue to develop new diagnostic and therapeutic strategies for neurological disorders.

Brain Connectivity: A Journal of Clinical Neurology, Neuroscience, &amp; Neuroimaging Advancing the Field of Neurology

Brain Connectivity: A Journal of Clinical Neurology, Neuroscience, &amp; Neuroimaging Advancing the Field of Neurology

Neural mechanisms underlying peripheral facial nerve palsy: A protocol for systematic review and meta-analysis of neuroimaging studies

Peripheral facial nerve palsy is a general term used to describe diseases that cause lower motor neuron lesions in the facial nerve. The most common cause of peripheral facial nerve palsy is idiopathic Bell's palsy (BP), accounting for 60% to 70% of all peripheral facial nerve palsy cases. Idiopathic BP is found in various medical conditions, such as ischemia, viral infection, and neuroinflammation; however, the specific pathophysiology remains unclear. Neuroimaging techniques help understand the neural mechanisms underlying various neurological disorders. In recent years, several studies have applied functional neuroimaging to investigate alterations of brain function in BP patients. However, the results have been inconsistent due to differences in methodology and quality. Moreover, systematic reviews of studies on functional neuroimaging for BP are insufficient. Therefore, the present study aims to verify the neural mechanisms of brain alterations and draw conclusions about the functional reorganization in patients with BP. This review includes all suitable studies published on or before October 31, 2022. A thorough search will be conducted using the following databases: MEDLINE, Cochrane Library, Excerpta Medica Database (EMBASE), China Knowledge Resource Integrated Database (CNKI), Korean Medical database (KMBASE), Korean Studies Information Service System (KISS). Clinical studies of BP using functional neuroimaging will be selected. We will apply a coordinate-based meta-analysis because most individual neuroimaging studies provide their results as coordinates in the standard space. The primary outcomes will include the types of functional neuroimaging methods and alterations of brain function in BP patients. The secondary outcomes will include the information about clinical measurement of the disease. Study selection, data extraction, and risk of bias assessment will be conducted. If possible, heterogeneity tests, data synthesis, and subgroup analyses will be conducted. The study will analyze the alterations in brain activity and worsening of clinical symptoms caused by idiopathic BP. The aim of this study is to investigate functional reorganization of brain alterations in patients with BP. This review will improve the understanding of the neural mechanisms of BP based on the most recent publications through extensive data retrieval. If sufficient data are collected, a sensitivity analysis is performed to verify the robustness of the conclusions.

Effects of Deployment Traumatic Brain Injury on the Functional Connectome

<h3>Research Objectives</h3> To determine if the context in which a mild TBI is acquired (deployment or non-deployment) affects complex brain function, as indicated by changes to the functional connectome. <h3>Design</h3> Cross-sectional observational cohort. <h3>Setting</h3> Veterans Affairs Medical Center. <h3>Participants</h3> 181 Iraq/Afghanistan combat Veterans (n = 74 with deployment-related mild TBI; M years since injury = 11.0, SD = 4.1). Moderate to severe TBI was exclusionary. <h3>Interventions</h3> None. <h3>Main Outcome Measures</h3> The Mid-Atlantic MIRECC Assessment of Traumatic Brain Injury (MMA-TBI) assessed lifetime history and severity of TBI. The Clinician Administered PTSD Scale – 5 (CAPS-5) evaluated current and lifetime PTSD diagnosis and severity. Functional connectomes were created from brain activity measured using magnetoencephalography (MEG), a non-invasive functional neuroimaging method. <h3>Results</h3> Linear regression adjusting for relevant covariates demonstrated a significant (FDR corrected p < .05) association between deployment mild TBI with reduced Global Efficiency and degree of the K-Core. Non-deployment mild TBI was significantly associated with a reduced number of modules. The interaction between deployment and non-deployment mild TBI was significantly associated with increased mean and mode frequency at which connections occur. <h3>Conclusions</h3> Results demonstrate distinct effects of mild TBI sustained in a deployment versus non-deployment context on the functional brain connectome. This is consistent with prior findings demonstrating differential effects in other areas including psychiatric diagnosis/severity, pain, sleep, and cognitive function. Participants were an average of 11 years post-injury, suggesting these represent chronic effects of mild TBI, rather than changes associated with acute effects of the injury. Overall, these findings add to the growing body of evidence suggesting the effects of mild TBI acquired during deployment are different and longer lasting than injuries acquired in a non-deployment context. <h3>Author(s) Disclosures</h3> No competing financial or conflicts of interest exist.

Automatic autism spectrum disorder detection using artificial intelligence methods with MRI neuroimaging: A review.

Autism spectrum disorder (ASD) is a brain condition characterized by diverse signs and symptoms that appear in early childhood. ASD is also associated with communication deficits and repetitive behavior in affected individuals. Various ASD detection methods have been developed, including neuroimaging modalities and psychological tests. Among these methods, magnetic resonance imaging (MRI) imaging modalities are of paramount importance to physicians. Clinicians rely on MRI modalities to diagnose ASD accurately. The MRI modalities are non-invasive methods that include functional (fMRI) and structural (sMRI) neuroimaging methods. However, diagnosing ASD with fMRI and sMRI for specialists is often laborious and time-consuming; therefore, several computer-aided design systems (CADS) based on artificial intelligence (AI) have been developed to assist specialist physicians. Conventional machine learning (ML) and deep learning (DL) are the most popular schemes of AI used for diagnosing ASD. This study aims to review the automated detection of ASD using AI. We review several CADS that have been developed using ML techniques for the automated diagnosis of ASD using MRI modalities. There has been very limited work on the use of DL techniques to develop automated diagnostic models for ASD. A summary of the studies developed using DL is provided in the Supplementary Appendix. Then, the challenges encountered during the automated diagnosis of ASD using MRI and AI techniques are described in detail. Additionally, a graphical comparison of studies using ML and DL to diagnose ASD automatically is discussed. We suggest future approaches to detecting ASDs using AI techniques and MRI neuroimaging.

Structural language impairment in Autism Spectrum Disorder versus Loss of Autism Diagnosis: Behavioral and neural characteristics

This study probed for structural language impairment using behavioral and functional neuroimaging methods in individuals with Autism Spectrum Disorder (ASD) and those diagnosed with ASD in childhood who no longer meet criteria for ASD, referred to as Loss of Autism Diagnosis (LAD1). Participants were drawn from Fein et al. (2013): ASD (n = 35), LAD (n = 31), and Neurotypical (NT; n = 34). Criteria for structural language impairment were: Scores ≤ 82 on Clinical Evaluation of Language Fundamentals-4 (CELF) Core Language, an omnibus measure of language; and scores ≤ 7 on CELF Recalling Sentences, a clinical marker of structural language impairment. Task-based fMRI examined lateralization of significantly activated language-related brain regions in groups with structural language impairment (LI2) versus normal-range language (LN3), collapsed across ASD, LAD1, and NT status. Results showed no ASD versus LAD group differences in the proportion of participants with structural language impairment according to either metric (Recalling Sentences or Core Language). Functional MRI results indicated greater left hemisphere lateralization within significantly activated regions in the LI2 group. Structural language abilities were not meaningfully associated with either social abilities or lifetime ADHD symptoms in LI2 subgroups, further suggesting the presence of structural language impairment. Findings indicate the presence of persistent structural language difficulty even in the absence of ASD symptoms in some individuals within the LAD1 group and unique patterns of language-related neural specialization for language function in LI2 relative to LN3.

Identifying mixed Lewy body and Alzheimer’s disease pathologies using functional neuroimaging

AbstractBackgroundLewy body dementia (LBD) and Alzheimer’s disease (AD) are the two most common neurodegenerative causes of dementia. Autopsy studies report many cases with these clinical diagnoses having mixed pathology with alpha‐synuclein, tau and amyloid proteinopathies. There is limited research in trying to distinguish these potential mixed pathology conditions prior to death. We used functional neuroimaging methods including FDG PET, amyloid PET, and DaTscan SPECT to evaluate clinically diagnosed subjects with dementia with Lewy bodies (DLB), AD and PD to investigate how often potential mixed pathologies could be present.MethodEighteensubjects (all Caucasian, male/female ratio 15:3) so far were recruited from Ohio State University Memory Disorder and Movement Disorder Clinics in this currently enrolling study. Subjects were diagnosed based on standard clinical criteria for DLB, PD and AD by fellowship trained cognitive and movement disorders faculty. Cognitive testing including Mini‐Mental State Examination (MMSE) and Self‐Administered Gerocognitive Examination (SAGE) were performed. Neuroimaging evaluations performed by neuroradiology faculty were blinded to clinical diagnosis.ResultNine subjects with clinical diagnosis of Lewy body disease (5 DLB and 4 PD) and nine subjects with clinical diagnosis AD were compared. The Lewy body subjects were 71.3 ± 7.4 years old, MMSE 22.3 ± 5.4, and SAGE 9.7 ± 4.8. AD subjects were 67.1 ± 9.6 years old, MMSE 18.6 ± 5.2, and SAGE 9.0 ± 5.2. One subject (11%) of the clinical AD cases showed mixed LBD and AD features, one subject (11%) of the clinical AD cases was negative for amyloid with normal DaTscan uptake, two subjects (40%) of the clinical DLB cases showed mixed LBD and AD features, one subject (20%) of the clinical DLB cases was positive for amyloid with normal DaTscan uptake, and all four subjects with clinical PD showed neuroimaging findings consistent with PD.ConclusionBased on functional neuroimaging, 21% of clinically diagnosed AD or DLB subjects had evidence of potential mixed pathologies and 14% were misdiagnosed. Although the sample size is small, functional neuroimaging studies revealed possibly incomplete or incorrect diagnoses in about one third of subjects clinically diagnosed by subspecialists using standard clinical diagnostic criteria. Larger studies are required to confirm these findings.

521 - The link between olfactory dysfunction and dementia: the road so far.

Dementia is characterized by the presence of progressive cognitive impairment losses in the individual’s social and occupational activities. Its etiological diagnosis has therapeutic and prognostic implications. Although its definitive diagnosis depends on neuropathological analysis, detailed anamnesis, physical and neuropsychological tests; biochemical and neuroimaging exams may enable a greater accuracy. Technological innovations using structural and functional neuroimaging methods, as well as biology and molecular genetics techniques, have presented perspectives for the early diagnosis of dementias, particularly Alzheimer’s disease (AD). However, such techniques burden the diagnostic investigation, making its practice unfeasible most the times. The probable link between neurodegenerative diseases and impaired olfactory dysfunction has long been studied. It is suggested that smell tests can be used in dementia’s early detection and differential diagnosis, reducing costs and facilitating the establishment of appropriate treatment. In order to verify the validity of this information, a medical literature search was carried out in may 2021 using PubMed and Cochrane Library, including the terms “olfaction” and “olfactory dysfunction” combined individually with “neurodegenerative disorder”, “dementia” and “Alzheimer’s disease”. Only systematic reviews and meta-analyses written in English from 1991 to 2021 were included. Results show that olfactory impairment in neurodegenerative diseases worsens progressively as patients progress from mild cognitive impairment to AD. It suggests that odor tests could potentially identify AD in the preclinical stages. Although, rigorously designed longitudinal cohort studies are necessary to clarify the value of olfactory identification testing in predicting the onset of AD and its value as an early marker of cognitive decline. In addition, AD patients are more impaired on odor identification and recognition tasks and Parkinson’s Disease (PD) patients on odor detection thresholds tasks, what suggests that PD patients are more impaired on low-level perceptual olfactory tasks whereas AD patients are more strongly impaired on higher-order olfactory tasks involving specific cognitive processes. The results suggest smell tests are a cheaper, simpler to apply and a promising weapon for detecting individuals at risk of dementia.