Suicide is a complex phenomenon resulting from interactions between individual vulnerabilities and socio-environmental factors. The current review primarily focuses on research into the serotonin system, hypothalamic-pituitary-adrenal axis, neurotrophic factors, lipid metabolism, and functional neuroimaging studies. It has been found that dysfunctions in the serotonin system, hypothalamic-pituitary-adrenal axis abnormalities, and low brain-derived neurotrophic factor and cholesterol levels may be linked to suicide. Additionally, recent neuroimaging studies have suggested that structural and functional abnormalities in brain areas related to cognitive and emotional regulation may be associated with suicide. More research incorporating advanced methodological approaches may shed further light on the neurobiological basis of suicide.
Brain ; Brain-Derived Neurotrophic Factor ; Cholesterol ; Functional Neuroimaging ; Lipid Metabolism ; Nerve Growth Factors ; Neurobiology ; Neuroimaging ; Pituitary-Adrenal System ; Serotonin ; Suicide

BACKGROUND/AIMS: Functional dyspepsia (FD) remains a great clinical challenge since the FD subtypes, defined by Rome III classification, still have heterogeneous pathogenesis. Previous studies have shown notable differences in visceral sensation processing in the CNS in FD compared to healthy subjects (HS). However, the role of CNS in the pathogenesis of each FD subtype has not been recognized. METHODS: Twenty-eight FD patients, including 10 epigastric pain syndrome (EPS), 9 postprandial distress syndrome (PDS), and 9 mixed-type, and 10 HS, were enrolled. All subjects underwent a proximal gastric perfusion water load test and the regional brain activities during resting state and water load test were investigated by functional magnetic resonance imaging. RESULTS: For regional brain activities during the resting state and water load test, each FD subtype was significantly different from HS (P < 0.05). Focusing on EPS and PDS, the regional brain activities of EPS were stronger than PDS in the left paracentral lobule, right inferior frontal gyrus pars opercularis, postcentral gyrus, precuneus, insula, parahippocampal gyrus, caudate nucleus, and bilateral cingulate cortices at the resting state (P < 0.05), and stronger than PDS in the left inferior temporal and fusiform gyri during the water load test (P < 0.05). CONCLUSIONS: Compared to HS, FD subtypes had different regional brain activities at rest and during water load test, whereby the differences displayed distinct manifestations for each subtype. Compared to PDS, EPS presented more significant differences from HS at rest, suggesting that the abnormality of central visceral pain processing could be one of the main pathogenesis mechanisms for EPS.
Brain ; Broca Area ; Caudate Nucleus ; Classification ; Dyspepsia ; Functional Neuroimaging ; Healthy Volunteers ; Humans ; Magnetic Resonance Imaging ; Parahippocampal Gyrus ; Parietal Lobe ; Perfusion ; Prefrontal Cortex ; Sensation ; Somatosensory Cortex ; Visceral Pain ; Water

Alzheimer's disease (AD) is a debilitating syndrome with cognitive decline and impairment in daily activities. Although clinical assessment forms the basis for diagnosing AD, structural and functional brain imaging tools have been known to enhance accuracy of differential diagnosis and prognosis prediction by presenting structural and functional signatures for AD. Associated with the important role of brain imaging in diagnosing and treating AD, brain imaging has been recommended in the current diagnostic guidelines of AD. Visual rating scales, a cost-effective diagnostic tool, have been known to assess atrophy and functional changes in patients with cognitive impairment as accurate as quantitative assessment. In this regard, visual rating scales for brain imaging interpretation could be useful in clinical settings. In this review, we interpret structural and functional brain imaging results with standardized visual rating scales, and review recent findings concerning brain imaging tools for differential diagnosing and predicting prognosis of AD.
Alzheimer Disease ; Atrophy ; Brain ; Cognition Disorders ; Diagnosis, Differential ; Functional Neuroimaging ; Humans ; Magnetic Resonance Imaging ; Neuroimaging ; Positron-Emission Tomography ; Prognosis ; Weights and Measures

Functional neuroimaging studies have revealed the importance of the role of cognitive and psychological factors and the dysregulation of the brain-gut axis in functional gastrointestinal disorder patients. Although only a small number of neuroimaging studies have been conducted in functional gastrointestinal disorder patients, and despite the fact that the neuroimaging technique requires a high level of knowledge, the technique still has a great deal of potential. The application of functional magnetic resonance imaging (fMRI) technique in functional gastrointestinal disorders should provide novel methods of diagnosing and treating patients. In this review, basic knowledge and technical/practical issues of fMRI will be introduced to clinicians.
Brain ; Functional Neuroimaging ; Gastrointestinal Diseases* ; Humans ; Magnetic Resonance Imaging* ; Neuroimaging ; Psychology

Empathy is the ability to identify with or make a vicariously experience of another person's feelings or thoughts based on memory and/or self-referential mental simulation. The default mode network in particular is related to self-referential empathy. In order to elucidate the possible neural mechanisms underlying empathy, we investigated the functional connectivity of the default mode network in subjects from a general population. Resting state functional magnetic resonance imaging data were acquired from 19 low-empathy subjects and 18 medium-empathy subjects. An independent component analysis was used to identify the default mode network, and differences in functional connectivity strength were compared between the two groups. The low-empathy group showed lower functional connectivity of the medial prefrontal cortex and anterior cingulate cortex (Brodmann areas 9 and 32) within the default mode network, compared to the medium-empathy group. The results of the present study suggest that empathy is related to functional connectivity of the medial prefrontal cortex/anterior cingulate cortex within the default mode network. Functional decreases in connectivity among low-empathy subjects may reflect an impairment of self-referential mental simulation.
Empathy ; Functional Neuroimaging ; Gyrus Cinguli ; Magnetic Resonance Imaging ; Memory ; Prefrontal Cortex

Cerebellar circuitry is important to controlling and modifying motor activity. It conducts the coordination and correction of errors in muscle contractions during active movements. Therefore, cerebrovascular lesions of the cerebellum or its pathways can cause diverse movement disorders, such as action tremor, Holmes' tremor, palatal tremor, asterixis, and dystonia. The pathophysiology of abnormal movements after stroke remains poorly understood. However, due to the current advances in functional neuroimaging, it has recently been described as changes in functional brain networks. This review describes the clinical features and pathophysiological mechanisms in different types of movement disorders following cerebrovascular lesions in the cerebellar circuits.
Brain ; Cerebellum ; Cerebrovascular Disorders ; Dyskinesias ; Dystonia ; Functional Neuroimaging ; Motor Activity ; Movement Disorders* ; Muscle Contraction ; Stroke ; Tremor

A growing body of evidence supports that Internet gaming disorder (IGD) is considered as ‘behavioral addiction’ with neurobiological alterations. We have reviewed previous research into the clinical and neurobiological features of IGD, and suggest a flowchart for the comprehensive evaluation of IGD. Several self-rating screening tests based on Diagnostic and Statistical Manual of Mental Disorder, 5th edition (DSM-5) IGD criteria were developed. IGD is often comorbid with depressive disorder, social anxiety disorder, attention deficit/hyperactivity disorder (ADHD), and smartphone addiction. Individuals with IGD are prone to act impulsively and make risky decisions, especially in response to game-related cues. Functional neuroimaging results have shown altered functional activities in prefrontal cortex, cingulate cortex, superior temporal gyrus and nucleus accumbens (NAc). Structural neuroimaging demonstrated gray matter volume changes in prefrontal cortex and NAc, while showing white matter integrity disruption in thalamus and posterior cingulate cortex. There are few evidences on the attribution of specific genes to IGD. To evaluate IGD comprehensively, self-rating scales based on DSM-5 are useful, but a diagnostic interview by a clinician is more helpful to assess functional impairments of IGD. Presence of psychiatric comorbidities such as depressive disorder, social anxiety disorder, ADHD, and smartphone addiction should be evaluated. Neurocognitive tests that assess impulsivity, decision-making under risk, and cue-reactivity are helpful when planning individualized IGD treatment.
Anxiety Disorders ; Comorbidity ; Cues ; Depressive Disorder ; Functional Neuroimaging ; Gray Matter ; Gyrus Cinguli ; Immunoglobulin D ; Impulsive Behavior ; Internet* ; Mass Screening ; Mental Disorders ; Neuroimaging ; Nucleus Accumbens ; Prefrontal Cortex ; Smartphone ; Software Design ; Temporal Lobe ; Thalamus ; Weights and Measures ; White Matter

Tinnitus is an auditory phantom characterized by the perception of sound without the presence of an external acoustical source. The peripheral auditory system is considered to contribute to the initiation of tinnitus but only explains the severity and distress level to a limited degree. The neuropsychological models of tinnitus have been developed to explain the pathophysiology of tinnitus as a malfunctioning feedforward/feedback signal in the central neural system including the auditory brainstem, limbic system, auditory cortices, and other anatomical features. Functional neuroimaging techniques have been introduced in recent decades and have provided non-invasive tools to assess the working human brain in vivo. Researchers have found these techniques valuable in examining the neural correlates of tinnitus and have been able to not only support the neuropsychological model but to expand it. Though neuroimaging studies on tinnitus only began in 1990s, they have been increasing exponentially in number. In this review, we investigate the current state of functional neuroimaging studies on tinnitus in humans. The characteristics of commonly used functional neuroimaging techniques including positron emission tomography (PET), functional magnetic resonance imaging (fMRI), electroencephalography (EEG) and magnetoencephalography (MEG) are also discussed. We briefly review recent studies on the tinnitus-brain relationship that have used those research tools.
Brain ; Brain Stem ; Electroencephalography ; Functional Neuroimaging ; Humans ; Limbic System ; Magnetic Resonance Imaging ; Magnetoencephalography ; Neuroimaging ; Positron-Emission Tomography ; Tinnitus*

Psychophysiological and functional neuroimaging studies have frequently and consistently shown that emotional information can be processed outside of the conscious awareness. Non-conscious processing comprises automatic, uncontrolled, and fast processing that occurs without subjective awareness. However, how such non-conscious emotional processing occurs in patients with various psychiatric disorders requires further examination. In this article, we reviewed and discussed previous studies on the non-conscious emotional processing in patients diagnosed with anxiety disorder, schizophrenia, bipolar disorder, and depression, to further understand how non-conscious emotional processing varies across these psychiatric disorders. Although the symptom profile of each disorder does not often overlap with one another, these patients commonly show abnormal emotional processing based on the pathology of their mood and cognitive function. This indicates that the observed abnormalities of emotional processing in certain social interactions may derive from a biased mood or cognition process that precedes consciously controlled and voluntary processes. Since preconscious forms of emotional processing appear to have a major effect on behaviour and cognition in patients with these disorders, further investigation is required to understand these processes and their impact on patient pathology.
Anxiety Disorders ; Bias (Epidemiology) ; Bipolar Disorder ; Cognition ; Depression ; Functional Neuroimaging ; Humans ; Interpersonal Relations ; Pathology ; Psychopathology* ; Schizophrenia

Neuro-otologic symptoms such as dizziness, hearing loss, or tinnitus give rise to peripheral change-induced neuroplasticity or central pathology-induced structural or functional changes. In this regard, functional neuroimaging modalities such as positron emission tomography (PET), functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), quantitative electroencephalography (qEEG), or functional near infrared spectroscopy have provided researchers with possibility to observe neuro-otologic disease-induced central functional changes. Among these methods, PET and fMRI are advantageous over qEEG or MEG with regard to spatial resolution, while qEEG and MEG are advantageous over PET or fMRI with regard to temporal resolution. Also, fMRI or MEG is not suitable for patients with implanted devices, whereas PET is not ideal for repetitive measures due to radiation hazard. In other words, as these modalities are complementary to one another, researchers should choose optimum imaging modality on a case by case basis. Hereinafter, representative functional neuroimaging modalities and their application to neuro-otologic research will be summarized.
Dizziness ; Electroencephalography ; Functional Neuroimaging ; Hearing Loss ; Humans ; Magnetic Resonance Imaging ; Magnetoencephalography ; Neuronal Plasticity ; Neurotology ; Positron-Emission Tomography ; Spectrum Analysis ; Tinnitus