Consideration on neuroimaging and functional diagnosis in cerebrovascular disorder

The electroencephalogram(EEG) has been one of the important clinical examination in cerebrovascular disorder(CVD). Since X-ray computed tomography(CT) was introduced in the 1970's, the numbers of EEG examination decreased in Japan. In the present, the diagnosis of acute CVD is done by neuroimaging examinations which generally are CT, magnetic resonance imaging(MRI) and at times, single photon emission computed tomography(SPECT). But EEG examination is necessary for estimate of brain function in acute and/or chronic CVD. Only EEG examination is able to confirm epileptic seizure, sleep-wake disorder and disturbance of consciousness. alpha-coma and spindle coma are peculiar disturbance of consciousness and appear in acute CVD. REM sleep behavior disorder(RBD) sometimes appear in chronic CVD. The characteristic of RBD is violent or injurious behavior during REM sleep. Polysomnography demonstrates abnormal REM sleep without loss of atonia. Both neuroimaging and functional diagnosis have been to perform to estimate in CVD same as in the other central nervous disorders.     

Neuroanatomy and neurophysiology in schizophrenia

Schizophrenia is a major mental disorder, characterized by their set of symptoms, including hallucinatory-delusional symptoms, thought disorder, emotional flattening, and social withdrawal. Since 1980s, advances in neuroimaging and neurophysiological techniques have provided tremendous merits for investigations into schizophrenia as a brain disorder. In this article, we first overviewed neuroanatomical studies using structural magnetic resonance imaging (s-MRI), MR spectroscopy (MRS), and postmortem brains, followed by neurophysiological studies using event-related potentials (ERPs) and magnetoencephalography (MEG), in patients with schizophrenia. Evidences from these studies suggest that schizophrenia is a chronic brain disorder, structurally and functionally affecting various cortical and subcortical regions involved in cognitive, emotional, and motivational aspects of human behavior. Second, we reviewed recent investigations into neurobiological basis for schizophrenic symptoms (auditory hallucinations and thought disorder) using these indices as well as hemodynamic assessments such as positron emission tomography (PET) and functional MRI (f-MRI). Finally, we addressed the issue of the heterogeneity of schizophrenia from the neurobiological perspective, in relation to the neuroanatomical and neurophysiological measures.     

Interoceptive sensitivity in anxiety and anxiety disorders: An overview and integration of neurobiological findings

Interoceptive sensitivity, particularly regarding heartbeat, has been suggested to play a pivotal role in the pathogenesis of anxiety and anxiety disorders. This review provides an overview of methods which are frequently used to assess heartbeat perception in clinical studies and summarizes presently available results referring to interoceptive sensitivity with respect to heartbeat in anxiety-related traits (anxiety sensitivity, state/trait anxiety), panic disorder and other anxiety disorders. In addition, recent neurobiological studies of neuronal activation correlates of heartbeat perception using positron emission tomography (PET), functional magnetic resonance imaging (fMRI) or electroencephalographic (EEG) techniques are presented. Finally, possible clinical and therapeutic implications (e.g., beta-blockers, biofeedback therapy, cognitive interventions and interoceptive exposure) of the effects of heartbeat perception on anxiety and the anxiety disorders and the potential use of interoceptive sensitivity as an intermediate phenotype of anxiety disorders in future neurobiological and genetic studies are discussed.     

Recent advances in investigations into brain function and its clinical application

Recent advances in investigations into brain function and its clinical application are described. The investigations were divided into three method groups consisting of the examinations of; 1) brain electric activity; 2) imaging techniques on activated brain tissue; and 3) collation of the metabolic information on the area of brain focused on. The first group included electroencephalogram(EEG), dipole tracing(DT) and magnetoencephalogram(MEG). The second one, single photon emission computed tomography(SPECT), positron emission tomography(PET) and functional magnetic resonance imaging(fMRI), and the third, magnetic resonance spectrometry(MRS). Here I overview these examinations and report some cases diagnosed with these technologies.     

Functional Neuroanatomy and Sleep‐Disordered Breathing: Implications for Autonomic Regulation

A major concern with sleep‐disordered breathing conditions, which include obstructive sleep apnea (OSA), central apnea, and congenital central hypoventilation syndrome (CCHS), is the high incidence of accompanying autonomic dysfunction and metabolic disorders. Patients with OSA show exaggerated sympathetic tone, leading to hypertension, cardiac arrhythmia, profuse sweating, impaired cerebral perfusion, and stroke. In addition, OSA appears in 86% of obese Type II diabetic patients, suggesting common deleterious processes. Autonomic deficiencies also appear in CCHS patients, who are often hypoglycemic. The impaired autonomic control may stem from injury to central sympathetic and parasympathetic regulatory areas resulting from apnea‐related inflammation, hypoxia, or perfusion‐related consequences in OSA, and genetic mutation repercussions in CCHS. Disturbed sleep organization from apnea arousals may also disrupt hormonal release. Brain areas affected in both OSA and CCHS include cortical and limbic regions that influence hypothalamic‐regulated sympathetic control and hormone release, essential for glycemic regulation, as well as parasympathetic nuclei influencing the pancreas and other viscera, and raphé serotonergic sites, important for thermal and vascular regulation. Brain injury and altered functional responses appear in OSA and CCHS, assessed with magnetic resonance imaging techniques, in areas which show regional gray matter loss, alterations of free water within tissue, loss of axonal integrity, and disruption of functional responses to autonomic and ventilatory challenges. Evaluation of neural injury and distortion in functional signals to autonomic challenges in localized brain areas can provide insights into common pathological mechanisms for dysregulation of hormonal release and autonomic processes in sleep‐disordered breathing and metabolic disorders. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

Morphometric and functional connectivity changes in the brain of patients with obstructive sleep apnea: A meta‐analysis

Existing evidence for brain morphometric changes and functional connectivity alterations in patients with obstructive sleep apnea is mixed. The current study aimed to meta‐analyse the neuroimaging data, and thus synthesize a brain map showing locations with morphometric and functional connectivity differences between patients with obstructive sleep apnea and controls. Published studies to 2018 were retrieved and included into the analysis if they reported such between‐group differences using voxel‐based morphometry or resting‐state functional magnetic resonance imaging, and reported the results in the form of brain coordinates based on whole‐brain analysis. Twelve voxel‐based morphometry and seven resting‐state functional magnetic resonance imaging studies that comprised a total of 1,113 participants fulfilled the inclusion criteria. Compared with healthy controls, patients with obstructive sleep apnea had reduced resting‐state connectivity in the right anterior cingulate and larger grey matter volume in the right insula. Patients with obstructive sleep apnea do have morphometric and resting‐state connectivity alterations in the brain. These neural correlates may help explain the effects of obstructive sleep apnea on the emotion, cognition and quality of life of patients, and may be used in future for evaluating its treatment outcome.     

Active consciousness and the prefrontal cortex: a working-memory approach

Biological studies of human consciousness based on recent neuroimaging experiments, i.e., functional magnetic resonance imaging (fMRI) and positron emission tomography (PET), were reviewed from the viewpoint of different functions of consciousness. A biological hierarchy of consciousness structured in three levels, i.e., arousal, awareness and self-consciousness, was reviewed in connection with working memory. We found that the dorsolateral prefrontal cortex (PFC), anterior cingulate cortex, medial PFC, and parieto-temporal junction area play a crucial role in social cognition involving estimation of the mental states of other people. The ventrolateral PFC plays a role in language-based rehearsal/imitation in connection with a mirror system. Frontal pole and orbitofrontal areas are also likely to contribute to generation of self function, reward expectancy and internal planning of goal-directed behavior. Interestingly, we found that these various PFC and related areas strongly contribute to active consciousness based on the working memory system. Furthermore, we have shown that a theory-of-mind approach could be closely related to higher cognitive functions involved in working memory, which has a meta-recognition processes during mentalization.     

Methods on Skull Stripping of MRI Head Scan Images—a Review

The high resolution magnetic resonance (MR) brain images contain some non-brain tissues such as skin, fat, muscle, neck, and eye balls compared to the functional images namely positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI) which usually contain relatively less non-brain tissues. The presence of these non-brain tissues is considered as a major obstacle for automatic brain image segmentation and analysis techniques. Therefore, quantitative morphometric studies of MR brain images often require a preliminary processing to isolate the brain from extra-cranial or non-brain tissues, commonly referred to as skull stripping. This paper describes the available methods on skull stripping and an exploratory review of recent literature on the existing skull stripping methods.     

Renewal of the neurophysiology of language: functional neuroimaging

Functional neuroimaging methods have reached maturity. It is now possible to start to build the foundations of a physiology of language. The remarkable number of neuroimaging studies performed so far illustrates the potential of this approach, which complements the classical knowledge accumulated on aphasia. Here we attempt to characterize the impact of the functional neuroimaging revolution on our understanding of language. Although today considered as neuroimaging techniques, we refer less to electroencephalography and magnetoencephalography studies than to positron emission tomography and functional magnetic resonance imaging studies, which deal more directly with the question of localization and functional neuroanatomy. This review is structured in three parts. 1) Because of their rapid evolution, we address technical and methodological issues to provide an overview of current procedures and sketch out future perspectives. 2) We review a set of significant results acquired in normal adults (the core of functional imaging studies) to provide an overview of language mechanisms in the "standard" brain. Single-word processing is considered in relation to input modalities (visual and auditory input), output modalities (speech and written output), and the involvement of "central" semantic processes before sentence processing and nonstandard language (illiteracy, multilingualism, and sensory deficits) are addressed. 3) We address the influence of plasticity on physiological functions in relation to its main contexts of appearance, i.e., development and brain lesions, to show how functional imaging can allow fine-grained approaches to adaptation, the fundamental property of the brain. In closing, we consider future developments for language research using functional imaging.     

Obstructive sleep apnea syndrome caused by uncommon tumors of the upper aerodigestive tract

Obstructive sleep apnea syndrome (OSAS) is always caused by anatomic abnormalities, including nasal cavity, pharynx, and neuromuscular dysfunctions, leading to airway narrowing. OSAS associated with a mass in the aerodigestive tract is rare. In the present study, we report OSAS caused by 9 cases of preoperative uncommon tumors in the aerodigestive tract. Two tumors in the parapharyngeal space were pleomorphic adenoma, one oropharyngeal tumor was mucoepidermoid carcinoma, one tumor in the right tonsil was schwannoma, and five tumors were non-Hodgkin’s lymphoma (NHL). Of the five NHL cases, one in the nasopharynx was diffuse large B-cell lymphoma, two were mantle cell lymphoma, one was chronic lymphocytic leukemia/small lymphocytic lymphoma, and one was NHL. Tumors in the aerodigestive tract should be considered in the differential diagnosis of OSAS upon exacerbation of snoring or sudden gasping. Further examinations should be performed, including a routine workup (computed tomography (CT) and magnetic resonance imaging) and positron emission tomography/CT.     

Clinical and neuroimaging findings in MOGAD–MRI and OCT

Myelin oligodendrocyte glycoprotein antibody‐associated disorders (MOGAD) are rare in both children and adults, and have been recently suggested to be an autoimmune neuroinflammatory group of disorders that are different from aquaporin‐4 autoantibody‐associated neuromyelitis optica spectrum disorder and from classic multiple sclerosis. In‐vivo imaging of the MOGAD patient central nervous system has shown some distinguishing features when evaluating magnetic resonance imaging of the brain, spinal cord and optic nerves, as well as retinal imaging using optical coherence tomography. In this review, we discuss key clinical and neuroimaging characteristics of paediatric and adult MOGAD. We describe how these imaging techniques may be used to study this group of disorders and discuss how image analysis methods have led to recent insights for consideration in future studies.     

Frequency of narcolepsy symptoms and other sleep disorders in narcoleptic patients and their first-degree relatives

Narcolepsy is a rare neurological sleep disorder affecting around 0.05% of the general population. Genetic factors are known to have an important role in narcolepsy. However, because of its very low prevalence, it is difficult to have groups of comparison between first-degree relatives and general population subjects in order to identify a specific spectrum of disorders in these families. Consequently, from 157 Italian patients with narcolepsy, 263 first-degree relatives were recruited, two refused to participate. These family members were compared with a matched group of 1071 subjects selected from a sample of 3970 subjects representative of the general population of Italy (46 million inhabitants). Finally, 68 spouses of narcoleptic patients were used to assess for possible role of environmental factors. All subjects were interviewed by telephone using the Sleep-EVAL system. Nineteen cases of narcolepsy were discovered among the first-degree relatives of 17 probands (10.8%). Compared with the general population subjects, the relative risk of narcolepsy among female first-degree relatives was of 54.4 and of 105.1 among male first-degree relatives. First-degree relatives were also at higher risk for idiopatic hypersomnia (OR: 23.0), obstructive sleep apnea syndrome (OR: 6.8), adjustment sleep disorder (OR: 4.0), insufficient sleep syndrome (OR: 7.0), circadian rhythm disorders (OR: 2.5), REM behavior disorder (OR: 4.4), and sleep talking (OR: 2.0). The vulnerability to sleep disorders is very high in first-degree relatives and the link with different expressivity and severity of hypersomnia can be confirmed.     

Intolerance of uncertainty correlates with insula activation during affective ambiguity

Intolerance of uncertainty (IU), or the increased affective response to situations with uncertain outcomes, is an important component process of anxiety disorders. Increased IU is observed in panic disorder (PD), obsessive compulsive disorder (OCD) and generalized anxiety disorder (GAD), and is thought to relate to dysfunctional behaviors and thought patterns in these disorders. Identifying what brain systems are associated with IU would contribute to a comprehensive model of anxiety processing, and increase our understanding of the neurobiology of anxiety disorders. Here, we used a behavioral task, Wall of Faces (WOFs), during functional magnetic resonance imaging (fMRI), which probes both affect and ambiguity, to examine the neural circuitry of IU in 14 (10 females) college age (18.8 years) subjects. All subjects completed the Intolerance of Uncertainty Scale (IUS), Anxiety Sensitivity Index (ASI), and a measure of neuroticism (i.e. the NEO-N). IUS scores but neither ASI nor NEO-N scores, correlated positively with activation in bilateral insula during affective ambiguity. Thus, the experience of IU during certain types of emotion processing may relate to the degree to which bilateral insula processes uncertainty. Previously observed insula hyperactivity in anxiety disorder individuals may therefore be directly linked to altered processes of uncertainty.     

Neuroimaging and ADHD: fMRI,PET, DTI Findings,and Methodological Limitations

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by pervasive and developmentally inappropriate levels of inattention, impulsivity, and hyperactivity. There is no conclusive cause of ADHD although a number of etiologic theories have been advanced. Research across neuroanatomical, neurochemical, and genetic disciplines collectively support a physiological basis for ADHD and, within the past decade, the number of neuroimaging studies concerning ADHD has increased exponentially. The current selective review summarizes research findings concerning ADHD using functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and diffusion tensor imaging (DTI). Although these technologies and studies offer promise in helping to better understand the physiologic underpinnings of ADHD, they are not without methodological problems, including inadequate sensitivity and specificity for psychiatric disorders. Consequently, neuroimaging technology, in its current state of development, should not be used to inform clinical practice.     

Functional neuroimaging findings in healthy middle-aged adults at risk of Alzheimer’s disease

It is well established that the neurodegenerative process of Alzheimer's disease (AD) begins many years before symptom onset. This preclinical phase provides a crucial time-window for therapeutic intervention, though this requires biomarkers that could evaluate the efficacy of future disease-modification treatments in asymptomatic individuals. The last decade has witnessed a proliferation of studies characterizing the temporal sequence of the earliest functional and structural brain imaging changes in AD. These efforts have focused on studying individuals who are highly vulnerable to develop AD, such as those with familial genetic mutations, susceptibility genes (i.e. apolipoprotein epsilon-4 allele), and/or a positive family history of AD. In this paper, we review the rapidly growing literature of functional imaging changes in cognitively intact individuals who are middle-aged: positron emission tomography (PET) studies of amyloid deposition, glucose metabolism, as well as arterial spin labeling (ASL), task-dependent, resting-state functional magnetic resonance imaging (fMRI) and magnetic resonance spectroscopy (MRS) studies. The prevailing evidence points to early brain functional changes in the relative absence of cognitive impairment and structural atrophy, although there is marked variability in the directionality of the changes, which could, in turn, be related to antagonistic pleiotropy early in life. A common theme across studies relates to the spatial extent of these changes, most of which overlap with brain regions that are implicated in established AD. Notwithstanding several methodological caveats, functional imaging techniques could be preferentially sensitive to the earliest events of AD pathology prior to macroscopic grey matter loss and clinical manifestations of AD. We conclude that while these techniques have great potential to serve as biomarkers to identify at-risk individuals, more longitudinal studies with greater sample size and robust correction for multiple comparisons are still warranted to establish their utility.     

Comparison of blood-oxygen-level-dependent functional magnetic resonance imaging and near-infrared spectroscopy recording during functional brain activation in patients with stroke and brain tumors

Blood-oxygen-level-dependent contrast functional magnetic resonance imaging (BOLD-fMRI) has been used to perform functional imaging in brain disorders such as stroke and brain tumors. However, recent studies have revealed that BOLD-fMRI does not image activation areas correctly in such patients. To clarify the characteristics of the evoked cerebral blood oxygenation (CBO) changes occurring in stroke and brain tumors, we have been comparing near-infrared spectroscopy (NIRS) and BOLD-fMRI recording during functional brain activation in these patients. We review our recent studies and related functional imaging studies on the brain disorders. In the primary sensorimotor cortex (PSMC) on the nonlesion side, the motor task consistently caused a decrease of deoxyhemoglobin (deoxy-Hb) with increases of oxyhemoglobin (oxy-Hb) and total hemoglobin (t-Hb), which is consistent with the evoked CBO response observed in normal adults. BOLD-fMRI demonstrated robust activation areas on the nonlesion side. In stroke patients, severe cerebral ischemia (i.e., misery perfusion) caused an increase of deoxy-Hb during the task, associated with increases of oxy-Hb and t-Hb, in the PSMC on the lesion side. In addition, the activation volume of BOLD-fMRI was significantly reduced on the lesion side. The BOLD signal did not change in some areas of the PSMC on the lesion side, but it tended to decrease in other areas during the tasks. In brain tumors, BOLD-fMRI clearly demonstrated activation areas in the PSMC on the lesion side in patients who displayed a normal evoked CBO response. However, the activation volume on the lesion side was significantly reduced in patients who exhibited an increase of deoxy-Hb during the task. In both stroke and brain tumors, false-negative activations (i.e., marked reductions of activation volumes) in BOLD imaging were associated with increases of deoxy-Hb, which could cause a reduction in BOLD signal. BOLD-fMRI investigations of patients with brain disorders should be performed while giving consideration to atypical evoked CBO changes.     

The use of cerebral blood flow as an index of neuronal activity in functional neuroimaging: experimental and pathophysiological considerations

Over recent years, activation studies that have been undertaken using brain imaging techniques, such as functional magnetic resonance imaging, positron emission tomography or near infrared spectroscopy, have greatly improved our knowledge of the functional anatomy of the brain. Nevertheless, activation studies do not directly quantify the variations of synaptic transmission (neuronal activity) but detect it indirectly either through the visualisation of changes in cerebral blood flow, oxidative or glycolytic metabolism (for positron emission tomography), or through the measurement of a global index that is dependent on both cerebral blood flow and oxidative metabolism (for functional magnetic resonance imaging and near infrared spectroscopy). Such approaches are based on the concept of a tight parallelism — termed coupling — between variations in neuronal activity, metabolism and cerebral blood flow. However, several “uncoupled” situations between these parameters have been reported over the last decade through experimental, pharmacological and pathophysiological studies. The aim of this review is to focus on these data that have to be taken into account for the interpretation of the results obtained in activation paradigms.     

阻塞性睡眠呼吸暂停的脑血流灌注成像研究进展

阻塞性睡眠呼吸暂停（OSA）是一种常见的睡眠呼吸障碍,可致局部脑血流量改变,脑血流灌注成像对于评估OSA严重程度及预后进展具有重要意义。目前应用于评估OSA患者脑血流灌注的成像技术主要包括单光子发射计算机断层显像、磁共振脑血流灌注成像等。本研究旨在对脑血流灌注成像技术在OSA的研究进展进行综述,客观分析各脑血流灌注技术的优势和局限,以期提高各技术在OSA的早期筛查、评价疾病严重程度以及预后进展的临床适用性,并展望未来研究方向和提出目前潜在的挑战。     

Decreased brain activation during a working memory task at rested baseline is associated with vulnerability to sleep deprivation

STUDY OBJECTIVE: To examine whether differences in patterns of brain activation under baseline conditions relate to the differences in sleep-deprivation vulnerability. DESIGN: Using blood oxygenation level dependent (BOLD) functional magnetic resonance imaging, we scanned 33 healthy young men while they performed the Sternberg working memory task following a normal night of sleep and again following 30 hours of sleep deprivation. From this initial group, based on their Sternberg working memory task performance, we found 10 subjects resilient to sleep deprivation (sleep deprivation-resilient group) and then selected 10 age- and education-matched subjects vulnerable to sleep deprivation (sleep deprivation-vulnerable group). SETTING: Inpatient General Clinical Research Center and outpatient functional magnetic resonance imaging center. PATIENTS OR PARTICIPANTS: Data from 10 young men (mean age 27.8 +/- 1.7 years) in the sleep deprivation-resilient group and 10 young men (mean age 28.2 +/- 1.9 years) in the sleep deprivation-vulnerable group were included in the final analyses. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: We compared functional magnetic resonance imaging BOLD signal at rested baseline and sleep deprivation states in the 2 groups. As hypothesized, following sleep deprivation, both groups showed significant decreases in global brain activation compared to their rested group baseline. At rested baseline and in the sleep-deprivation state, the sleep deprivation-resilient group had significantly more brain activation than did the sleep deprivation-vulnerable group. There were also differences in functional circuits within and between groups in response to sleep deprivation. CONCLUSIONS: These preliminary data suggest that patterns of brain activation during the Sternberg working memory task at the rested baseline and the sleep-deprivation state, differ across individuals as a function of their sleep-deprivation vulnerability.     

Inhibitory deficits in Tourette's syndrome

A developmental approach to the study of psychopathology can broaden understanding of a wide variety of complex psychological disorders. This article reviews research on Tourette's syndrome (TS), a developmental disorder characterized by unwanted motor and vocal tics. Over the past decade, knowledge of the neurobiology and pathophysiology of TS has progressed rapidly. The application of brain imaging techniques, primarily magnetic resonance imaging, to the study of Tourette's has increased knowledge of structural and functional deficits in brain areas associated with behavioral and psychological disturbances in the disorder. By reviewing some of this work, we will describe one way in which knowledge of brain function in TS has both informed and been informed by a developmental science approach. In particular, we will consider the extent to which the cognitive and emotional development of persons with TS may be affected by specific neurobiological characteristics of the disorder.