Real-time fMRI of cortico-limbic brain activity during emotional processing

Effects of neuromodulation on cognitive and emotional responses to psychosocial stressors in healthy humans

Physiological and psychological stressors can exert wide-ranging effects on the human brain and behavior. Research has improved understanding of how the sympatho-adreno-medullary (SAM) and hypothalamic-pituitary-adrenocortical (HPA) axes respond to stressors and the differential responses that occur depending on stressor type. Although the physiological function of SAM and HPA responses is to promote survival and safety, exaggerated psychobiological reactivity can occur in psychiatric disorders. Exaggerated reactivity may occur more for certain types of stressors, specifically, psychosocial stressors. Understanding stressor effects and how the body regulates these responses can provide insight into ways that psychobiological reactivity can be modulated. Non-invasive neuromodulation is one way that responding to stressors may be altered; research into these interventions may provide further insights into the brain circuits that modulate stress reactivity. This review focuses on the effects of acute psychosocial stressors and how neuromodulation might be effective in altering stress reactivity. Although considerable research into stress interventions focuses on treating pathology, it is imperative to first understand these mechanisms in non-clinical populations; therefore, this review will emphasize populations with no known pathology and consider how these results may translate to those with psychiatric pathologies.

Motor dysfunction as research domain across bipolar, obsessive-compulsive and neurodevelopmental disorders

Although genuine motor abnormalities (GMA) are frequently found in schizophrenia, they are also considered as an intrinsic feature of bipolar, obsessive-compulsive, and neurodevelopmental disorders with early onset such as autism, ADHD, and Tourette syndrome. Such transnosological observations strongly suggest a common neural pathophysiology. This systematic review highlights the evidence on GMA and their neuroanatomical substrates in bipolar, obsessive-compulsive, and neurodevelopmental disorders. The data lends support for a common pattern contributing to GMA expression in these diseases that seems to be related to cerebello-thalamo-cortical, fronto-parietal, and cortico-subcortical motor circuit dysfunction. The identified studies provide first evidence for a motor network dysfunction as a correlate of early neurodevelopmental deviance prior to clinical symptom expression. There are also first hints for a developmental risk factor model of these mental disorders. An in-depth analysis of motor networks and related patho-(physiological) mechanisms will not only help promoting Research Domain Criteria (RDoC) Motor System construct, but also facilitate the development of novel psychopharmacological models, as well as the identification of neurobiologically plausible target sites for non-invasive brain stimulation.

What Can Different Motor Circuits Tell Us About Psychosis? An RDoC Perspective

Signs of motor dysfunction are evidenced across a range of psychiatric disorders including schizophrenia. Historically, these features have been neglected but emerging theoretical and methodological advancements have shed new light on the utility of considering movement abnormalities. Indeed, the National Institute of Mental Health Research Domain Criteria initiative has recently met to develop a Motor Systems Domain. This reflects a growing appreciation for the enhanced reliability and validity that can come along with evaluating disturbances relevant to psychiatric illnesses from multiple levels of analysis, and conceptualizing these domains with respect to the complexity of their role in a broader integrated system (ie, weighing contributions and interactions between the cognitive, affective, and motor domains). This article discusses motor behaviors and seeks to explain how research into basal ganglia, cerebellar, and cortico-motor circuit function/dysfunction, grounded in brain circuit-motor behavior relationships, can elucidate our understanding of pathophysiology, provide vital links to other key systems of interest, significantly improve identification and classification, and drive development of targeted individualized treatments.

Insight in Psychiatry and Neurology: State of the Art, and Hypotheses

In spite of the increasing number of studies on insight in psychiatry and also in neurology and psychology, its nature is still elusive. It encompasses at least three fundamental characteristics: the awareness of suffering from an illness, an understanding of the cause and source of this suffering, and an acknowledgment of the need for treatment. As such, insight is fundamental for patients' management, prognosis, and treatment. Not surprisingly, the majority of available data, which have been gathered on schizophrenia, show a relationship between low insight and poorer outcomes. For mood disorders, however, insight is associated with less positive results. For other psychiatric disorders, insight has rarely been investigated. In neurology, the impaired ability to recognize the presence of sensory, perceptual, motor, affective, or cognitive functioning-referred to as anosognosia-has been related to damage of specific brain regions. This article provides a comprehensive review of insight in different psychiatric and neurological disorders, with a special focus on brain areas and neurotransmitters that serve as the substrate for this complex phenomenon.

Neuro-Epigenetic Indications of Acute Stress Response in Humans: The Case of MicroRNA-29c

Stress research has progressively become more integrative in nature, seeking to unfold crucial relations between the different phenotypic levels of stress manifestations. This study sought to unravel stress-induced variations in expression of human microRNAs sampled in peripheral blood mononuclear cells and further assess their relationship with neuronal and psychological indices. We obtained blood samples from 49 healthy male participants before and three hours after performing a social stress task, while undergoing functional magnetic resonance imaging (fMRI). A seed-based functional connectivity (FC) analysis was conducted for the ventro-medial prefrontal cortex (vmPFC), a key area of stress regulation. Out of hundreds of microRNAs, a specific increase was identified in microRNA-29c (miR-29c) expression, corresponding with both the experience of sustained stress via self-reports, and alterations in vmPFC functional connectivity. Explicitly, miR-29c expression levels corresponded with both increased connectivity of the vmPFC with the anterior insula (aIns), and decreased connectivity of the vmPFC with the left dorso-lateral prefrontal cortex (dlPFC). Our findings further revealed that miR-29c mediates an indirect path linking enhanced vmPFC-aIns connectivity during stress with subsequent experiences of sustained stress. The correlative patterns of miR-29c expression and vmPFC FC, along with the mediating effects on subjective stress sustainment and the presumed localization of miR-29c in astrocytes, together point to an intriguing assumption; miR-29c may serve as a biomarker in the blood for stress-induced functional neural alterations reflecting regulatory processes. Such a multi-level model may hold the key for future personalized intervention in stress psychopathology.

Fractional Diffusion Based Modelling and Prediction of Human Brain Response to External Stimuli

Human brain response is the result of the overall ability of the brain in analyzing different internal and external stimuli and thus making the proper decisions. During the last decades scientists have discovered more about this phenomenon and proposed some models based on computational, biological, or neuropsychological methods. Despite some advances in studies related to this area of the brain research, there were fewer efforts which have been done on the mathematical modeling of the human brain response to external stimuli. This research is devoted to the modeling and prediction of the human EEG signal, as an alert state of overall human brain activity monitoring, upon receiving external stimuli, based on fractional diffusion equations. The results of this modeling show very good agreement with the real human EEG signal and thus this model can be used for many types of applications such as prediction of seizure onset in patient with epilepsy.

The influence of μ-opioid and noradrenaline reuptake inhibition in the modulation of pain responsive neurones in the central amygdala by tapentadol in rats with neuropathy

Treatments for neuropathic pain are either not fully effective or have problematic side effects. Combinations of drugs are often used. Tapentadol is a newer molecule that produces analgesia in various pain models through two inhibitory mechanisms, namely central μ-opioid receptor (MOR) agonism and noradrenaline reuptake inhibition. These two components interact synergistically, resulting in levels of analgesia similar to opioid analgesics such as oxycodone and morphine, but with more tolerable side effects. The right central nucleus of the amygdala (CeA) is critical for the lateral spinal ascending pain pathway, regulates descending pain pathways and is key in the emotional-affective components of pain. Few studies have investigated the pharmacology of limbic brain areas in pain models. Here we determined the actions of systemic tapentadol on right CeA neurones of animals with neuropathy and which component of tapentadol contributes to its effect. Neuronal responses to multimodal peripheral stimulation of animals with spinal nerve ligation or sham surgery were recorded before and after two doses of tapentadol. After the higher dose of tapentadol either naloxone or yohimbine were administered. Systemic tapentadol resulted in dose-dependent decrease in right CeA neuronal activity only in neuropathy. Both naloxone and yohimbine reversed this effect to an extent that was modality selective.

The interactions of the components of tapentadol are not limited to the synergy between the MOR and α₂-adrenoceptors seen at spinal levels, but are seen at this supraspinal site where suppression of responses may relate to the ability of the drug to alter affective components of pain.

Voluntary enhancement of neural signatures of affiliative emotion using FMRI neurofeedback

In Ridley Scott's film "Blade Runner", empathy-detection devices are employed to measure affiliative emotions. Despite recent neurocomputational advances, it is unknown whether brain signatures of affiliative emotions, such as tenderness/affection, can be decoded and voluntarily modulated. Here, we employed multivariate voxel pattern analysis and real-time fMRI to address this question. We found that participants were able to use visual feedback based on decoded fMRI patterns as a neurofeedback signal to increase brain activation characteristic of tenderness/affection relative to pride, an equally complex control emotion. Such improvement was not observed in a control group performing the same fMRI task without neurofeedback. Furthermore, the neurofeedback-driven enhancement of tenderness/affection-related distributed patterns was associated with local fMRI responses in the septohypothalamic area and frontopolar cortex, regions previously implicated in affiliative emotion. This demonstrates that humans can voluntarily enhance brain signatures of tenderness/affection, unlocking new possibilities for promoting prosocial emotions and countering antisocial behavior.

A graphics processing unit accelerated motion correction algorithm and modular system for real-time fMRI

Real-time functional magnetic resonance imaging (rt-fMRI) has recently gained interest as a possible means to facilitate the learning of certain behaviors. However, rt-fMRI is limited by processing speed and available software, and continued development is needed for rt-fMRI to progress further and become feasible for clinical use. In this work, we present an open-source rt-fMRI system for biofeedback powered by a novel Graphics Processing Unit (GPU) accelerated motion correction strategy as part of the BioImage Suite project ( www.bioimagesuite.org ). Our system contributes to the development of rt-fMRI by presenting a motion correction algorithm that provides an estimate of motion with essentially no processing delay as well as a modular rt-fMRI system design. Using empirical data from rt-fMRI scans, we assessed the quality of motion correction in this new system. The present algorithm performed comparably to standard (non real-time) offline methods and outperformed other real-time methods based on zero order interpolation of motion parameters. The modular approach to the rt-fMRI system allows the system to be flexible to the experiment and feedback design, a valuable feature for many applications. We illustrate the flexibility of the system by describing several of our ongoing studies. Our hope is that continuing development of open-source rt-fMRI algorithms and software will make this new technology more accessible and adaptable, and will thereby accelerate its application in the clinical and cognitive neurosciences.

The neural bases of uninstructed negative emotion modulation

Although numerous neuroimaging studies have examined what happens when individuals are instructed to regulate their emotions, we rarely receive such instruction in everyday life. This study sought to examine what underlies uninstructed modulation of negative affect by examining neural responses when 'responding naturally' to negative stimuli-and for comparison-during instructed reappraisal of negative stimuli as well. Two analyses were conducted to identify how variability in negative affect related to neural responses when responding naturally. First, in a within-participant analysis, lower levels of self-reported negative affect on a given trial were associated with recruitment of dorsolateral and dorsomedial prefrontal cortex (PFC)-brain regions also active during instructed reappraisal-whereas higher levels of negative affect were associated with recruitment of the amygdala-a region that responded more strongly overall to negative than neutral stimuli. Second, in a between-participant analysis, lower levels of average self-reported negative affect were associated with recruitment of ventromedial PFC. These results suggest that uninstructed modulation of emotion involves a combination of two types of regulatory processes, with moment-to-moment modulation depending on prefrontal regions that support reappraisal and individual differences in modulation depending on ventromedial PFC, a region involved in fear extinction.

Real-time fMRI pattern decoding and neurofeedback using FRIEND: an FSL-integrated BCI toolbox

The demonstration that humans can learn to modulate their own brain activity based on feedback of neurophysiological signals opened up exciting opportunities for fundamental and applied neuroscience. Although EEG-based neurofeedback has been long employed both in experimental and clinical investigation, functional MRI (fMRI)-based neurofeedback emerged as a promising method, given its superior spatial resolution and ability to gauge deep cortical and subcortical brain regions. In combination with improved computational approaches, such as pattern recognition analysis (e.g., Support Vector Machines, SVM), fMRI neurofeedback and brain decoding represent key innovations in the field of neuromodulation and functional plasticity. Expansion in this field and its applications critically depend on the existence of freely available, integrated and user-friendly tools for the neuroimaging research community. Here, we introduce FRIEND, a graphic-oriented user-friendly interface package for fMRI neurofeedback and real-time multivoxel pattern decoding. The package integrates routines for image preprocessing in real-time, ROI-based feedback (single-ROI BOLD level and functional connectivity) and brain decoding-based feedback using SVM. FRIEND delivers an intuitive graphic interface with flexible processing pipelines involving optimized procedures embedding widely validated packages, such as FSL and libSVM. In addition, a user-defined visual neurofeedback module allows users to easily design and run fMRI neurofeedback experiments using ROI-based or multivariate classification approaches. FRIEND is open-source and free for non-commercial use. Processing tutorials and extensive documentation are available.

Function in the human connectome: task-fMRI and individual differences in behavior

The primary goal of the Human Connectome Project (HCP) is to delineate the typical patterns of structural and functional connectivity in the healthy adult human brain. However, we know that there are important individual differences in such patterns of connectivity, with evidence that this variability is associated with alterations in important cognitive and behavioral variables that affect real world function. The HCP data will be a critical stepping-off point for future studies that will examine how variation in human structural and functional connectivity play a role in adult and pediatric neurological and psychiatric disorders that account for a huge amount of public health resources. Thus, the HCP is collecting behavioral measures of a range of motor, sensory, cognitive and emotional processes that will delineate a core set of functions relevant to understanding the relationship between brain connectivity and human behavior. In addition, the HCP is using task-fMRI (tfMRI) to help delineate the relationships between individual differences in the neurobiological substrates of mental processing and both functional and structural connectivity, as well as to help characterize and validate the connectivity analyses to be conducted on the structural and functional connectivity data. This paper describes the logic and rationale behind the development of the behavioral, individual difference, and tfMRI batteries and provides preliminary data on the patterns of activation associated with each of the fMRI tasks, at both group and individual levels.

Processing of emotional distraction is both automatic and modulated by attention: evidence from an event-related fMRI investigation

Traditionally, emotional stimuli have been thought to be automatically processed via a bottom-up automatic "capture of attention" mechanism. Recently, this view has been challenged by evidence that emotion processing depends on the availability of attentional resources. Although these two views are not mutually exclusive, direct evidence reconciling them is lacking. One limitation of previous investigations supporting the traditional or competing views is that they have not systematically investigated the impact of emotional charge of task-irrelevant distraction in conjunction with manipulations of attentional demands. Using event-related fMRI, we investigated the nature of emotion-cognition interactions in a perceptual discrimination task with emotional distraction by manipulating both the emotional charge of the distracting information and the demands of the main task. Our findings show that emotion processing is both automatic and modulated by attention, but emotion and attention were only found to interact when finer assessments of emotional charge (comparison of most vs. least emotional conditions) were considered along with an effective manipulation of processing load (high vs. low). The study also identified brain regions reflecting the detrimental impact of emotional distraction on performance as well as regions involved in coping with such distraction. Activity in the dorsomedial pFC and ventrolateral pFC was linked to a detrimental impact of emotional distraction, whereas the dorsal ACC and lateral occipital cortex were involved in helping with emotional distraction. These findings demonstrate that task-irrelevant emotion processing is subjective to both the emotional content of distraction and the level of attentional demand.

Overview of functional magnetic resonance imaging

Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) depicts changes in deoxyhemoglobin concentration consequent to task-induced or spontaneous modulation of neural metabolism. Since its inception in 1990, this method has been widely employed in thousands of studies of cognition for clinical applications such as surgical planning, for monitoring treatment outcomes, and as a biomarker in pharmacologic and training programs. More recently, attention is turning to the use of pattern classification and other statistical methods to draw increasingly complex inferences about cognitive brain states from fMRI data. This article reviews the methods, challenges, and future of fMRI.

Real-time functional MRI using pseudo-continuous arterial spin labeling

The first implementation of real-time acquisition and analysis of arterial spin labeling-based functional magnetic resonance imaging time series is presented in this article. The implementation uses a pseudo-continuous labeling scheme followed by a spiral k-space acquisition trajectory. Real-time reconstruction of the images, preprocessing, and regression analysis of the functional magnetic resonance imaging data were implemented on a laptop computer interfaced with the MRI scanner. The method allows the user to track the current raw data, subtraction images, and the cumulative t-statistic map overlaid on a cumulative subtraction image. The user is also able to track the time course of individual time courses and interactively selects a region of interest as a nuisance covariate. The pulse sequence allows the user to adjust acquisition and labeling parameters while observing their effect on the image within two successive pulse repetition times. This method is demonstrated by two functional imaging experiments: a simultaneous finger-tapping and visual stimulation paradigm, and a bimanual finger-tapping task.

Self-reports of interoceptive responses during stress and drug cue-related experiences in cocaine- and alcohol-dependent individuals

Cocaine dependence is associated with neuroadaptations in stress and reward pathways that could alter stress and drug-related experiences and associated interoceptive sensations and result in enhanced craving states. Subjective interoceptive emotional and physiological responses experienced in stressful and drug cue situations were examined in abstinent cocaine-dependent individuals. Fifty-six treatment engaged cocaine-dependent patients with comorbid alcohol abuse or dependence were interviewed to identify personal stressful, drug cue, and neutral situations using a scene construction questionnaire (SCQ) that includes an emotional and physiological response checklist. Using this checklist, subjects identified emotional and bodily sensations that they recently experienced in the stress- and drug-related scenarios. Kappa coefficients indicated fair to moderate but significant degree of concordance in heart (p < .01), perspiration (p < .05), stomach (p < .05), and blood flow (p < .01) sensations for both stress and drug cue scenarios, while the McNemar change test indicated differential endorsement of interoceptive responses in stress and drug cue situations for breathing (p < .05), stomach (p < .05), tension (p < .05), and chest (p < .05) sensations, and for sad (p < .01), anger (p < .01), and excitement (p < .01) responses. Increased heartbeat and tension, tears, and anger urges were most commonly endorsed in the stress scenarios (between 50% and 79%), whereas butterflies in stomach, increased heartbeat and tension, jittery, restless, and warm excitement (53%-73%) were the most frequently endorsed sensations in the drug cue-related experiences. These self-reported sensations comprise both general arousal and specific interoceptive responses pertaining to stress or drug cue-related experiences in cocaine dependence, with potential value in guiding treatments targeting craving reduction.

FMRI brain-computer interface: a tool for neuroscientific research and treatment

Brain-computer interfaces based on functional magnetic resonance imaging (fMRI-BCI) allow volitional control of anatomically specific regions of the brain. Technological advancement in higher field MRI scanners, fast data acquisition sequences, preprocessing algorithms, and robust statistical analysis are anticipated to make fMRI-BCI more widely available and applicable. This noninvasive technique could potentially complement the traditional neuroscientific experimental methods by varying the activity of the neural substrates of a region of interest as an independent variable to study its effects on behavior. If the neurobiological basis of a disorder (e.g., chronic pain, motor diseases, psychopathy, social phobia, depression) is known in terms of abnormal activity in certain regions of the brain, fMRI-BCI can be targeted to modify activity in those regions with high specificity for treatment. In this paper, we review recent results of the application of fMRI-BCI to neuroscientific research and psychophysiological treatment.

The neurocircuitry of fear, stress, and anxiety disorders

Anxiety disorders are a significant problem in the community, and recent neuroimaging research has focused on determining the brain circuits that underlie them. Research on the neurocircuitry of anxiety disorders has its roots in the study of fear circuits in animal models and the study of brain responses to emotional stimuli in healthy humans. We review this research, as well as neuroimaging studies of anxiety disorders. In general, these studies have reported relatively heightened amygdala activation in response to disorder-relevant stimuli in post-traumatic stress disorder, social phobia, and specific phobia. Activation in the insular cortex appears to be heightened in many of the anxiety disorders. Unlike other anxiety disorders, post-traumatic stress disorder is associated with diminished responsivity in the rostral anterior cingulate cortex and adjacent ventral medial prefrontal cortex. Additional research will be needed to (1) clarify the exact role of each component of the fear circuitry in the anxiety disorders, (2) determine whether functional abnormalities identified in the anxiety disorders represent acquired signs of the disorders or vulnerability factors that increase the risk of developing them, (3) link the findings of functional neuroimaging studies with those of neurochemistry studies, and (4) use functional neuroimaging to predict treatment response and assess treatment-related changes in brain function.

Excitatory neurotransmitters in brain regions in interictal migraine patients

OBJECTIVE

To examine biochemical differences in the anterior cingulate cortex (ACC) and insula during the interictal phase of migraine patients. We hypothesized that there may be differences in levels of excitatory amino acid neurotransmitters and/or their derivatives in migraine group based on their increased sensitivity to pain.

METHODS

2D J-resolved proton magnetic resonance spectroscopy (1H-MRS) data were acquired at 4.0 Tesla (T) from the ACC and insula in 10 migraine patients (7 women, 3 men, age 43 +/- 11 years) and 8 age gender matched controls (7 women, 3 men, age 41 +/- 9 years).

RESULTS

Standard statistical analyses including analysis of variance (ANOVA) showed no significant metabolite differences between the two subject cohorts in the ACC nor the insula. However, linear discriminant analysis (LDA) introduced a clear separation between subject cohorts based on N-acetyl aspartylglutamate (NAAG) and glutamine (Gln) in the ACC and insula.

CONCLUSION

These results are consistent with glutamatergic abnormalities in the ACC and insula in migraine patients during their interictal period compared to healthy controls. An alteration in excitatory amino acid neurotransmitters and their derivatives may be a contributing factor for migraineurs for a decrease in sensitivity for migraine or a consequence of the chronic migraine state. Such findings, if extrapolated to other regions of the brain would offer new opportunities to modulate central system as interictal or preemptive medications in these patients.

Applications of real-time fMRI

For centuries people have aspired to understand and control the functions of the mind and brain. It has now become possible to image the functioning of the human brain in real time using functional MRI (fMRI), and thereby to access both sides of the mind-brain interface--subjective experience (that is, one's mind) and objective observations (that is, external, quantitative measurements of one's brain activity)--simultaneously. Developments in neuroimaging are now being translated into many new potential practical applications, including the reading of brain states, brain-computer interfaces, communicating with locked-in patients, lie detection, and learning control over brain activation to modulate cognition or even treat disease.

Functional grouping and cortical-subcortical interactions in emotion: a meta-analysis of neuroimaging studies

We performed an updated quantitative meta-analysis of 162 neuroimaging studies of emotion using a novel multi-level kernel-based approach, focusing on locating brain regions consistently activated in emotional tasks and their functional organization into distributed functional groups, independent of semantically defined emotion category labels (e.g., "anger," "fear"). Such brain-based analyses are critical if our ways of labeling emotions are to be evaluated and revised based on consistency with brain data. Consistent activations were limited to specific cortical sub-regions, including multiple functional areas within medial, orbital, and inferior lateral frontal cortices. Consistent with a wealth of animal literature, multiple subcortical activations were identified, including amygdala, ventral striatum, thalamus, hypothalamus, and periaqueductal gray. We used multivariate parcellation and clustering techniques to identify groups of co-activated brain regions across studies. These analyses identified six distributed functional groups, including medial and lateral frontal groups, two posterior cortical groups, and paralimbic and core limbic/brainstem groups. These functional groups provide information on potential organization of brain regions into large-scale networks. Specific follow-up analyses focused on amygdala, periaqueductal gray (PAG), and hypothalamic (Hy) activations, and identified frontal cortical areas co-activated with these core limbic structures. While multiple areas of frontal cortex co-activated with amygdala sub-regions, a specific region of dorsomedial prefrontal cortex (dmPFC, Brodmann's Area 9/32) was the only area co-activated with both PAG and Hy. Subsequent mediation analyses were consistent with a pathway from dmPFC through PAG to Hy. These results suggest that medial frontal areas are more closely associated with core limbic activation than their lateral counterparts, and that dmPFC may play a particularly important role in the cognitive generation of emotional states.

Reading and controlling human brain activation using real-time functional magnetic resonance imaging

Understanding how to control how the brain's functioning mediates mental experience and the brain's processing to alter cognition or disease are central projects of cognitive and neural science. The advent of real-time functional magnetic resonance imaging (rtfMRI) now makes it possible to observe the biology of one's own brain while thinking, feeling and acting. Recent evidence suggests that people can learn to control brain activation in localized regions, with corresponding changes in their mental operations, by observing information from their brain while inside an MRI scanner. For example, subjects can learn to deliberately control activation in brain regions involved in pain processing with corresponding changes in experienced pain. This may provide a novel, non-invasive means of observing and controlling brain function, potentially altering cognitive processes or disease.

The neurocircuitry of obsessive-compulsive disorder and disgust

Recent evidence from human research has indicated that discrete regions of the brain control different basic emotions. Whether the recognition and formulation of emotions truly stem from compartmentalized systems or arise from a multidimensional framework has yet to be elucidated, however. Disgust is a basic emotion that has been hypothesized to constitute an evolutionary function of contamination and disease avoidance. Disgust involves the appraisal of objects and events for their potential role in contamination, and OCD conceivably involves a dysfunction of this appraisal process. Disgust sensitivity has been shown to be positively correlated with OCD and to significantly predict contamination fear. Likewise, functional imaging studies of OCD patients with contamination concerns demonstrate activation of the same neural regions with disgust-inducing pictures as symptom relevant stimuli. Therefore, the neurocircuits involved in disgust processing may be relevant to OCD and, in particular, the contamination subtype. This review focuses on describing what is known to date concerning the neurocircuitry of disgust, and its relevance to the apparent neurocircuitry of OCD.

Beyond threat: amygdala reactivity across multiple expressions of facial affect

The amygdala has been consistently isolated as a key neural substrate for processing facial displays of affect. Recent evidence from human lesion and functional neuroimaging studies have begun to challenge the notion that the amygdala is reserved for signals of threat (fear/anger). We performed a 4 T fMRI study in which 20 subjects viewed a contemporary set of photographs displaying 6 different facial expressions (fearful, disgusted, angry, sad, neutral, happy) while performing a task with minimal cognitive demand. Across subjects, the left amygdala was activated by each face condition separately, and its response was not selective for any particular emotion category. These results challenge the notion that the amygdala has a specialized role in processing certain emotions and suggest that the amygdala may have a more general-purpose function in processing salient information from faces.

Self-regulation of local brain activity using real-time functional magnetic resonance imaging (fMRI)

Functional magnetic resonance imaging (fMRI) measures the blood oxygen level-dependent (BOLD) signal related to neuronal activity. So far, this technique has been limited by time-consuming data analysis impeding on-line analysis. In particular, no brain-computer interface (BCI) was available which provided on-line feedback to learn physiological self-regulation of the BOLD signal. Recently, studies have shown that fMRI feedback is feasible and facilitates voluntary control of brain activity. Here we review these studies to make the fMRI feedback methodology accessible to a broader scientific community such as researchers concerned with functional brain imaging and the neurobiology of learning. Methodological and conceptual limitations were substantially reduced by artefact control, sensitivity improvements, real-time algorithms, and adapted experimental designs. Physiological self-regulation of the local BOLD response is a new paradigm for cognitive neuroscience to study brain plasticity and the functional relevance of regulated brain areas by modification of behaviour. Voluntary control of abnormal activity in circumscribed brain areas may even be applied as psychophysiological treatment.

Noradrenaline mediates amygdala activation in men and women during encoding of emotional material

The amygdala is a pivotal structure in humans for encoding of emotional information, as shown by recent imaging studies. It is unknown which neurotransmitters are specifically involved in the human amygdala, although in animal studies noradrenaline was shown to be essential. In our study, participants received the betablocker propranolol (which blocks the noradrenergic response) or placebo when watching neutral to highly negative arousing pictures. Amygdala activation, monitored with functional magnetic resonance imaging (fMRI), increased with emotional intensity of the pictures under placebo condition. Betablockade selectively decreased amygdala activation for emotional pictures of the second highest category, but not for the highest or lower (neutral) category pictures. Two findings add to the existing knowledge in this area. First, the activation pattern in the amygdala under placebo condition shows a nonlinearity related to the emotional categories of the pictures. Second, propranolol disturbs this activation pattern in the amygdala. Explorations with respect to gender show a similar effect of betablockade on amygdala activation in both men and women, but a difference in its effect on long-term memory for emotional pictures. This study supports the hypothesis that the neurotransmitter noradrenaline also mediates amygdala activity in humans when processing emotional stimuli and that betablockers can disrupt the normal activation pattern in the amygdala.

Neural correlates of telling lies: a functional magnetic resonance imaging study at 4 Tesla

RATIONALE AND OBJECTIVE

Intentional deception (ie, lying) is a complex cognitive act, with important legal, moral, political, and economic implications. Prior studies have identified activation of discrete anterior frontal regions, such as the ventrolateral prefrontal cortex (VLPFC), dorsolateral prefrontal cortex (DLPFC), dorsal medial prefrontal cortex (DMPFC), and anterior cingulate cortex (ACC) during deception. To extend these findings, we used novel real-time functional magnetic resonance imaging (fMRI) technology to simulate a polygraph experience in order to evoke performance anxiety about generating lies, and sought to ascertain the neural correlates of deception.

MATERIALS AND METHODS

In this investigational fMRI study done with a 4-T scanner, we examined the neural correlates of lying in 14 healthy adult volunteers while they performed a modified card version of the Guilty Knowledge Test (GKT), with the understanding that their brain activity was being monitored in real time by the investigators conducting the study. The volunteers were instructed to attempt to generate Lies that would not evoke changes in their brain activity, and were told that their performance and brain responses were being closely monitored.

RESULTS

Subjects reported performance anxiety during the task. Deceptive responses were specifically associated with activation of the VLPFC, DLPFC, DMPFC, and superior temporal sulcus.

DISCUSSION

These findings suggest the involvement of discrete regions of the frontal cortex during lying, and that the neural substrates responsible for cognitive control of behavior may also be engaged during deception.

Neural correlates of internally-generated disgust via autobiographical recall: a functional magnetic resonance imaging investigation

Converging lines of evidence suggest the involvement of the insula and basal ganglia in the processing of disgust, an important primary emotion that guides the avoidance of potential physical contamination and disease. Prior human lesion and functional brain imaging studies have employed exteroceptive sensory stimuli such as facial expressions of disgust, and disgust-eliciting pictures. Thus, the neural substrates underlying the internal experience of disgust remain unknown. The present fMRI study examined the neural correlates of self-induced disgust aided by the recall and re-experience of personally salient life events. Subjects were scanned while they recalled and re-experienced either a recent situation that evoked intense disgust or a time-matched, equally vivid neutral/non-emotional event. Relative to the emotionally neutral condition, self-induced disgust was associated with activation of the insula, hippocampus, anterior and posterior cingulate cortex, basal ganglia, thalamus, and primary visual cortex. These findings suggest that areas previously associated with the perception of disgust (e.g., insula, basal ganglia) are also involved interoceptive experience of disgust.