Neural substrates of emotion as revealed by functional magnetic resonance imaging

Dual-Brain Psychology: A novel theory and treatment based on cerebral laterality and psychopathology

Dual-Brain Psychology is a theory and its clinical applications that come out of the author's clinical observations and from the Split-brain Studies. The theory posits, based on decades of rigorous, peer-reviewed experiments and clinical reports, that, in most patients, one brain's cerebral hemisphere (either left or right) when stimulated by simple lateral visual field stimulation, or unilateral transcranial photobiomodulation, reveals a dramatic change in personality such that stimulating one hemisphere evokes, as a trait, a personality that is more childlike and more presently affected by childhood maltreatments that are usually not presently appreciated but are the proximal cause of the patient's symptoms. The personality associated with the other hemisphere is much more mature, less affected by the traumas, and less symptomatic. The theory can be applied to in-depth psychotherapy in which the focus is on helping the troubled side to bear and process the traumas with the help of the therapist and the healthier personality. A person's symptoms can be evoked to aid the psychotherapy with hemispheric stimulation and the relationship between the dual personalities can be transformed from conflicted and sabotaging to cooperating toward overall health. Stimulating the positive hemisphere in most therapy patients rapidly relieves symptoms such as anxiety, depression, or substance cravings. Two randomized controlled trials used unilateral transcranial photobiomodulation to the positive hemisphere as a stand-alone treatment for opioid cravings and both revealed high effect sizes. The theory is supported by brain imaging and rTMS studies. It is the first psychological theory and application that comes out of and is supported by rigorous peer-reviewed experimentation.

Task-Dependent Effective Connectivity of the Reward Network During Food Cue-Reactivity: A Dynamic Causal Modeling Investigation

Neural reactivity to food cues may play a central role in overeating and excess weight gain. Functional magnetic resonance imaging (fMRI) studies have implicated regions of the reward network in dysfunctional food cue-reactivity, but neural interactions underlying observed patterns of signal change remain poorly understood. Fifty overweight and obese participants with self-reported cue-induced food craving viewed food and neutral cues during fMRI scanning. Regions of the reward network with significantly greater food versus neutral cue-reactivity were used to specify plausible models of task-related neural interactions underlying the observed blood oxygenation level-dependent (BOLD) signal, and a bi-hemispheric winning model was identified in a dynamic causal modeling (DCM) framework. Neuro-behavioral correlations are investigated with group factor analysis (GFA) and Pearson’s correlation tests. The ventral tegmental area (VTA), amygdalae, and orbitofrontal cortices (OFC) showed significant food cue-reactivity. DCM suggests these activations are produced by largely reciprocal dynamic signaling between these regions, with food cues causing regional disinhibition and an apparent shifting of activity to the right amygdala. Intrinsic self-inhibition in the VTA and right amygdala is negatively correlated with measures of food craving and hunger and right-amygdalar disinhibition by food cues is associated with the intensity of cue-induced food craving, but no robust cross-unit latent factors were identified between the neural group and behavioral or demographic variable groups. Our results suggest a rich array of dynamic signals drive reward network cue-reactivity, with the amygdalae mediating much of the dynamic signaling between the VTA and OFCs. Neuro-behavioral correlations suggest particularly crucial roles for the VTA, right amygdala, and the right OFC-amygdala connection but the more robust GFA identified no cross-unit factors, so these correlations should be interpreted with caution. This investigation provides novel insights into dynamic circuit mechanisms with etiologic relevance to obesity, suggesting pathways in biomarker development and intervention.

Individual Differences in Hemispheric Emotional Valence by Computerized Test Correlate with Lateralized Differences in Nucleus Accumbens, Hippocampal and Amygdala Volumes

Purpose

Conventional theories of hemispheric emotional valence (HEV) postulate fixed hemispheric differences in emotional processing. Schiffer’s dual brain psychology proposes that there are prominent individual differences with a substantial subset showing a reversed laterality pattern. He further proposed that hemispheric differences were more akin to differences in personality than in emotional processing. This theory is supported by findings that unilateral treatments, such as transcranial magnetic stimulation, are effective if they accurately target individual differences in laterality. The aim of this paper was to assess if a computer test of hemispheric emotional valence (CTHEV) could effectively identify individual differences in HEV and to ascertain if these individual differences were associated with underlying differences in brain structure and connectivity.

Patients and Methods

The CTHEV was administered to 50 (18 male/32 female) right-handed participants, aged 18–19 years, enrolled in a study assessing the neurobiological effects of childhood maltreatment. Based on a literature review, we determined whether CTHEV correlated with lateralized volumes of the nucleus accumbens, amygdala, hippocampus, and subgenual anterior cingulate as well as volume of the corpus callosum.

Results

CTHEV scores correlated with laterality indices of the nucleus accumbens (p = 0.00016), amygdala (p = 0.0138) and hippocampus (p = 0.031). A positive left hemispheric valence was associated with a larger left-sided nucleus accumbens and hippocampus and a smaller left amygdala. We identified four eigenvector network centrality DTI measures that predict CTHEV, most notably the left amygdala, and found that CTHEV results correlated with total and segment-specific corpus callosal volumes.

Conclusion

Individual differences in HEV can be readily assessed by computer test and correlate with differences in brain structure and connectivity that could provide a mechanistic understanding. These findings provide further support for a revised understanding of HEV and provide a tool that could be used to guide lateralized brain treatments.

Machine Learning Classification of Mild Traumatic Brain Injury Using Whole-Brain Functional Activity: A Radiomics Analysis

Objectives

To investigate the classification performance of support vector machine in mild traumatic brain injury (mTBI) from normal controls.

Methods

Twenty-four mTBI patients (15 males and 9 females; mean age, 38.88 ± 13.33 years) and 24 age and sex-matched normal controls (13 males and 11 females; mean age, 40.46 ± 11.4 years) underwent resting-state functional MRI examination. Seven imaging parameters, including amplitude of low-frequency fluctuation (ALFF), fractional amplitude of low-frequency fluctuation (fALFF), regional homogeneity (ReHo), degree centrality (DC), voxel-mirrored homotopic connectivity (VMHC), long-range functional connectivity density (FCD), and short-range FCD, were entered into the classification model to distinguish the mTBI from normal controls.

Results

The ability for any single imaging parameters to distinguish the two groups is lower than multiparameter combinations. The combination of ALFF, fALFF, DC, VMHC, and short-range FCD showed the best classification performance for distinguishing the two groups with optimal AUC value of 0.778, accuracy rate of 81.11%, sensitivity of 88%, and specificity of 75%. The brain regions with the highest contributions to this classification mainly include bilateral cerebellum, left orbitofrontal cortex, left cuneus, left temporal pole, right inferior occipital cortex, bilateral parietal lobe, and left supplementary motor area.

Conclusions

Multiparameter combinations could improve the classification performance of mTBI from normal controls by using the brain regions associated with emotion and cognition.

A novel dynamic brain network in arousal for brain states and emotion analysis

BACKGROUND

Brain network can be well used in emotion analysis to analyze the brain state of subjects. A novel dynamic brain network in arousal is proposed to analyze brain states and emotion with Electroencephalography (EEG) signals. New Method: Time factors is integrated to construct a dynamic brain network under high and low arousal conditions. The transfer entropy is adopted in the dynamic brain network. In order to ensure the authenticity of dynamics and connections, surrogate data are used for testing and analysis. Channel norm information features are proposed to optimize the data and evaluate the level of activity of the brain.

RESULTS

The frontal lobe, temporal lobe, and parietal lobe provide the most information about emotion arousal. The corresponding stimulation state is not maintained at all times. The number of active brain networks under high arousal conditions is generally higher than those under low arousal conditions. More consecutive networks show high activity under high arousal conditions among these active brain networks. The results of the significance analysis of the features indicates that there is a significant difference between high and low arousal. Comparison with Existing Method(s): Compared with traditional methods, the method proposed in this paper can analyze the changes of subjects' brain state over time in more detail. The proposed features can be used to quantify the brain network for accurate analysis.

CONCLUSIONS

The proposed dynamic brain network bridges the research gaps in lacking time resolution and arousal conditions in emotion analysis. We can clearly get the dynamic changes of the overall and local details of the brain under high and low arousal conditions. Furthermore, the active segments and brain regions of the subjects were quantified and evaluated by channel norm information.This method can be used to realize the feature extraction and dynamic analysis of the arousal dimension of emotional EEG, further explore the emotional dimension model, and also play an auxiliary role in emotional analysis.

A short review on emotion processing: a lateralized network of neuronal networks

Emotions are valenced mental responses and associated physiological reactions that occur spontaneously and automatically in response to internal or external stimuli, and can influence our behavior, and can themselves be modulated to a certain degree voluntarily or by external stimuli. They are subserved by large-scale integrated neuronal networks with epicenters in the amygdala and the hippocampus, and which overlap in the anterior cingulate cortex. Although emotion processing is accepted as being lateralized, the specific role of each hemisphere remains an issue of controversy, and two major hypotheses have been proposed. In the right-hemispheric dominance hypothesis, all emotions are thought to be processed in the right hemisphere, independent of their valence or of the emotional feeling being processed. In the valence lateralization hypothesis, the left is thought to be dominant for the processing of positively valenced stimuli, or of stimuli inducing approach behaviors, whereas negatively valenced stimuli, or stimuli inducing withdrawal behaviors, would be processed in the right hemisphere. More recent research points at the existence of multiple interrelated networks, each associated with the processing of a specific component of emotion generation, i.e., its generation, perception, and regulation. It has thus been proposed to move from hypotheses supporting an overall hemispheric specialization for emotion processing toward dynamic models incorporating multiple interrelated networks which do not necessarily share the same lateralization patterns.

The basal ganglia and the cerebellum in human emotion

The basal ganglia (BG) and the cerebellum historically have been relegated to a functional role in producing or modulating motor output. Recent research, however, has emphasized the importance of these subcortical structures in multiple functional domains, including affective processes such as emotion recognition, subjective feeling elicitation and reward valuation. The pathways through the thalamus that connect the BG and cerebellum directly to each other and with extensive regions of the cortex provide a structural basis for their combined influence on limbic function. By regulating cortical oscillations to guide learning and strengthening rewarded behaviors or thought patterns to achieve a desired goal state, these regions can shape the way an individual processes emotional stimuli. This review will discuss the basic structure and function of the BG and cerebellum and propose an updated view of their functional role in human affective processing.

The moderating role of sensory processing sensitivity in the link between stress and depression: A VBM study

This study examined whether components of sensory processing sensitivity (SPS) could moderate the effect of perceived stress on depressive symptoms and its neural substrates. In this study, 244 participants (181females) reported on their SPS, perceived stress, and experienced depressive symptoms, and subsequently underwent a resting-state functional magnetic resonance imaging (RS-fMRI) to explore the neural basis of their SPS characteristics. Behavioral results showed that, compared with individuals low in EOE (i.e., ease of excitation, a sub-dimension of SPS), those high in EOE were more likely to report depressive symptoms under stress. The VBM analysis indicated that EOE was significantly positively correlated with gray matter (GM) volumes of right cerebellum and negatively correlated with GM volumes of right dorsal anterior cingulate cortex (right dACC). Moreover, GM volumes of the two areas moderated the relation between stress and depression. These findings collectively suggest that the structural abnormalities in these regions might account for simulating and experiencing intense emotional reactions frequently among individuals with high EOE. Thus, the accumulation of these negative emotions in reaction to stress may lead to higher probabilities of experiencing depressive symptoms. Taken together, present study shed light on how stress interacted with sensory processing sensitivity to predict depression from the neural perspective.

Left and right hemispheric lateralization of the amygdala in pain

Hemispheric asymmetries within the brain have been identified across taxa and have been extensively studied since the early 19th century. Here, we discuss lateralization of a brain structure, the amygdala, and how this lateralization is reshaping how we understand the role of the amygdala in pain processing. The amygdala is an almond-shaped, bilateral brain structure located within the limbic system. Historically, the amygdala was known to have a role in the processing of emotions and attaching emotional valence to memories and other experiences. The amygdala has been extensively studied in fear conditioning and affect but recently has been shown to have an important role in processing noxious information and impacting pain. The amygdala is composed of multiple nuclei; of special interest is the central nucleus of the amygdala (CeA). The CeA receives direct nociceptive inputs from the parabrachial nucleus (PBN) through the spino-parabrachio-amygdaloid pathway as well as more highly processed cortical and thalamic input via the lateral and basolateral amygdala. Although the amygdala is a bilateral brain region, most data investigating the amygdala's role in pain have been generated from the right CeA, which has an overwhelmingly pro-nociceptive function across pain models. The left CeA has often been characterized to have no effect on pain modulation, a dampened pro-nociceptive function, or most recently an anti-nociceptive function. This review explores the current literature on CeA lateralization and the hemispheres' respective roles in the processing and modulation of different forms of pain.

Dogs can sense weak thermal radiation

The dog rhinarium (naked and often moist skin on the nose-tip) is prominent and richly innervated, suggesting a sensory function. Compared to nose-tips of herbivorous artio- and perissodactyla, carnivoran rhinaria are considerably colder. We hypothesized that this coldness makes the dog rhinarium particularly sensitive to radiating heat. We trained three dogs to distinguish between two distant objects based on radiating heat; the neutral object was about ambient temperature, the warm object was about the same surface temperature as a furry mammal. In addition, we employed functional magnetic resonance imaging on 13 awake dogs, comparing the responses to heat stimuli of about the same temperatures as in the behavioural experiment. The warm stimulus elicited increased neural response in the left somatosensory association cortex. Our results demonstrate a hitherto undiscovered sensory modality in a carnivoran species.

A Novel Treatment of Opioid Cravings With an Effect Size of .73 for Unilateral Transcranial Photobiomodulation Over Sham

BACKGROUND

Opioid use disorders (OUDs) are an epidemic causing catastrophic consequences to individuals, families, and society despite treatments including psychotherapy, substitution therapy or receptor blockers, and psychoeducation. We have developed a novel treatment that combines unilateral transcranial photobiomodulation (t-PBM) to the hemisphere with a more positive valence by Dual Brain Psychology (DBP).

METHODS

We used a randomized, double blind, placebo-controlled protocol in which 22 patients with significant opioid cravings and a history of recent or current OUD attended three 1-h weekly sessions. After baseline measures of opioid craving and other psychometrics, subjects received two unilateral t-PBM applications (810 nm CW LED, 250 mW/cm², 60 J/cm², 4 min) or a sham (foil-covered LED) at F3 or F4. Prior to any treatment we used two tests to determine which hemisphere was more associated with a negative outlook and cravings and treated that side before the more positive hemisphere. Primary outcome measure was an opioid craving scale (OCS). Secondary outcomes were weekly Hamilton Depression (HDRS) and Anxiety (HARS) Rating Scales prior to treatments and at follow-up.

RESULTS

Immediately after treatment the OCS improved significantly for both the sham and active treatments, but one week later the active treatment showed a 51.0% (SD 33.7) decrease in OCS while a week after the sham treatments there was a decrease of only 15.8% (SD 35.0) (by Wilcoxon Sign Rank Test, p = 0.004) and by a mixed model it was p = 0.0071. The effect size for the differences between active and sham was 0.73. For the active treatment from before and after treatment the effect size was 1.51 and for the sham, 0.45. The HDRS improved from a baseline of 15.1 to 8.8 (SD 10.3) a week after the active treatment and to 13.3 (SD 12.9) after the sham (p = 0.0071). HARS improved from 14.7 to 8.0 (SD 13.2) after the active treatments and to 14.3 (SD 16.0) after the sham, p = 0.08. Active treatment of the positive hemisphere after the negative hemisphere significantly improved the OCS, but there was no significant difference after the sham treatment. One patient complained of 2 h of abdominal bloating and dropped out; no other adverse effects were observed.

DISCUSSION

Unilateral t-PBM to the hemisphere with a more positive hemispheric emotional valence was an effective and safe treatment for opioid cravings as well as for depression and anxiety. Our results also lend support to the underlying premises of DBP.

Reducing negative affect with anodal transcranial direct current stimulation increases memory performance in young-but not in elderly-individuals

Affect can directly influence memory storage and retrieval, which offers the opportunity to improve memory performance by changing affective responses. A promising target is the left dorsolateral prefrontal cortex (dlPFC), as it is functionally involved in both affect and memory. This study explores whether anodal transcranial direct current stimulation (tDCS) to the left dlPFC improves memory retrieval through the reduction of negative affect and if this interacts with age. We randomly assigned 94 healthy individuals (n = 43 young, n = 51 elderly) to either sham or active tDCS during encoding of a verbal episodic memory task. Participants completed two questionnaires assessing affective states pre- and post-stimulation. They had to recall items unexpectedly 20 min after encoding and to name which feelings were associated with this free recall. We applied mediation models to explore the relation between tDCS, change in affect, and memory retrieval. In young participants, the reduction of negative affect via anodal tDCS fully mediated the increase in memory retrieval (R² = 57%; p < 0.001); that is, a stronger reduction of negative affect via tDCS led to better memory performance. We did not observe these effects in the elderly. Our study provides a further link between affect and memory: as increased activity in the dlPFC is crucial for successfully coping with affective interference, anodal tDCS seems to help preventing irrelevant negative thoughts, thus foster attention allocation. Studies applying anodal tDCS to the left dlPFC in healthy young participants should consider changes in affect when interpreting the effect of stimulation on memory performance.

The Role of the Cerebellum in Skin-Picking Disorder

Previous research indicated that the cerebellum is involved in psychopathologies with body-focused repetitive behaviors. The present study investigated whether patients with a diagnosis of skin-picking disorder (SPD) also show altered cerebellar structure and function. Structural as well as functional MRI data from 30 SPD patients and 31 controls were analyzed. The fMRI approach compared cerebellar activity and connectivity between the two groups during scratching and caressing of a small skin area on the arm. Relative to controls, SPD patients were characterized by reduced gray matter volumes in the left cerebellar lobules V and VI. During picking (relative to caressing), SPD patients displayed increased activation of the left crus I, which showed enhanced coupling with the left ventrolateral prefrontal cortex (VLPFC). This study provides the first evidence that SPD patients display structural as well as functional abnormalities in specific subregions of the cerebellum related to motor (V) and affective-cognitive functions (VI, crus I). The SPD-related altered cerebellar connectivity with an area implicated in affect control (VLPFC) fits nicely to the model of pathological skin picking as a maladaptive emotion regulation strategy.

Structural and functional neuroimaging studies in generalized anxiety disorder: a systematic review

OBJECTIVES

Brain imaging studies carried out in patients suffering from generalized anxiety disorder (GAD) have contributed to better characterize the pathophysiological mechanisms underlying this disorder. The present study reviews the available functional and structural brain imaging evidence on GAD, and suggests further strategies for investigations in this field.

METHODS

A systematic literature review was performed in PubMed, PsycINFO, and Google Scholar, aiming to identify original research evaluating GAD patients with the use of structural and functional magnetic resonance imaging as well as diffusion tensor imaging.

RESULTS

The available studies have shown impairments in ventrolateral and dorsolateral prefrontal cortex, anterior cingulate, posterior parietal regions, and amygdala in both pediatric and adult GAD patients, mostly in the right hemisphere. However, the literature is often tentative, given that most studies have employed small samples and included patients with comorbidities or in current use of various medications. Finally, different methodological aspects, such as the type of imaging equipment used, also complicate the generalizability of the findings.

CONCLUSIONS

Longitudinal neuroimaging studies with larger samples of both juvenile and adult GAD patients, as well as at risk individuals and unaffected relatives, should be carried out in order to shed light on the specific biological signature of GAD.

Microstructural Changes in Patients With Parkinson's Disease Comorbid With REM Sleep Behaviour Disorder and Depressive Symptoms

The diagnosis of Parkinson's disease (PD) is currently anchored on clinical motor symptoms, which appear more than 20 years after initiation of the neurotoxicity. Extra-nigral involvement in the onset of PD with probable nonmotor manifestations before the development of motor signs, lead us to the preclinical (asymptomatic) or prodromal stages of the disease (various nonmotor or subtle motor signs). REM sleep behavior disorder (RBD) and depression are established prodromal clinical markers of PD and predict worse motor and cognitive outcomes. Nevertheless, taken by themselves, these markers are not yet claimed to be practical in identifying high-risk individuals. Combining promising markers may be helpful in a reliable diagnosis of early PD. Therefore, we aimed to detect neural correlates of RBD and depression in 93 treatment-naïve and non-demented early PD by means of diffusion MRI connectometry. Comparing four groups of PD patients with or without comorbid RBD and/or depressive symptoms with each other and with 31 healthy controls, we found that these two non-motor symptoms are associated with lower connectivity in several white matter tracts including the cerebellar peduncles, corpus callosum and long association fibers such as cingulum, fornix, and inferior longitudinal fasciculus. For the first time, we were able to detect the involvement of short association fibers (U-fibers) in PD neurodegenerative process. Longitudinal studies on larger sample groups are needed to further investigate the reported associations.

Changes in cerebellar functional connectivity and autonomic regulation in cancer patients treated with the Neuro Emotional Technique for traumatic stress symptoms

PURPOSE

A growing number of research studies have implicated the cerebellum in emotional processing and regulation, especially with regard to negative emotional memories. However, there currently are no studies showing functional changes in the cerebellum as a result of treatment for traumatic stress symptoms. The Neuro Emotional Technique (NET) is an intervention designed to help improve symptoms related to traumatic stress using an integrative approach that combines emotional, cognitive, and motor processing, with a particular focus on autonomic nervous system regulation. In this study, we evaluated whether the NET intervention alters functional connectivity in the brain of patients with traumatic stress symptoms associated with a cancer-related event. We hypothesized that the NET intervention would reduce emotional and autonomic reactivity and that this would correlate with connectivity changes between the cerebellum and limbic structures as well as the brain stem.

METHODS

We enrolled patients with a prior cancer diagnosis who experienced distressing cancer-related memories associated with traumatic stress symptoms of at least 6 months in duration. Participants were randomized to either the NET intervention or a waitlist control. To evaluate the primary outcome of neurophysiological effects, all participants received resting-state functional blood oxygen level-dependent (BOLD) magnetic resonance imaging (rs-fMRI) before and after the NET intervention. In addition, autonomic reactivity was measured using heart rate response to the traumatic stimulus. Pre/post comparisons were performed between the NET and control groups.

RESULTS

The results demonstrated significant changes in the NET group, as compared to the control group, in the functional connectivity between the cerebellum (including the vermis) and the amygdala, parahippocampus, and brain stem. Likewise, participants receiving the NET intervention had significant reductions in autonomic reactivity based on heart rate response to the traumatic stimulus compared to the control group.

CONCLUSIONS

This study is an initial step towards establishing a neurological signature of treatment effect for the NET intervention. Specifically, functional connectivity between the cerebellum and the amygdala and prefrontal cortex appear to be associated with a reduction in autonomic reactivity in response to distressing cancer-related memories.

IMPLICATIONS FOR CANCER SURVIVORS

This study contributes to the understanding of possible mechanisms by which interventions like NET may help reduce emotional distress in cancer patients who suffer from traumatic stress symptoms.

Priming the Secure Attachment Schema Affects the Emotional Face Processing Bias in Attachment Anxiety: An fMRI Research

Our study explored how priming with a secure base schema affects the processing of emotional facial stimuli in individuals with attachment anxiety. We enrolled 42 undergraduate students between 18 and 27 years of age, and divided them into two groups: attachment anxiety and attachment secure. All participants were primed under two conditions, the secure priming using references to the partner, and neutral priming using neutral references. We performed repeated attachment security priming combined with a dual-task paradigm and functional magnetic resonance imaging. Participants’ reaction times in terms of responding to the facial stimuli were also measured. Attachment security priming can facilitate an individual’s processing of positive emotional faces; for instance, the presentation of the partner’s name was associated with stronger activities in a wide range of brain regions and faster reaction times for positive facial expressions in the subjects. The current finding of higher activity in the left-hemisphere regions for secure priming rather than neutral priming is consistent with the prediction that attachment security priming triggers the spread of the activation of a positive emotional state. However, the difference in brain activity during processing of both, positive and negative emotional facial stimuli between the two priming conditions appeared in the attachment anxiety group alone. This study indicates that the effect of attachment secure priming on the processing of emotional facial stimuli could be mediated by chronic attachment anxiety. In addition, it highlights the association between higher-order processes of the attachment system (secure attachment schema priming) and early-stage information processing system (attention), given the increased attention toward the effects of secure base schema on the processing of emotion- and attachment-related information among the insecure population. Thus, the following study has applications in providing directions for clinical treatment of mood disorders in attachment anxiety.

Emotion processing in early blind and sighted individuals

OBJECTIVE

Emotion processing is known to be mediated by a complex network of cortical and subcortical regions with evidence of specialized hemispheric lateralization within the brain. In light of prior evidence indicating that lateralization of cognitive functions (such as language) may depend on normal visual development, we investigated whether the lack of prior visual experience would have an impact on the development of specialized hemispheric lateralization in emotional processing.

METHOD

We addressed this issue by comparing performance in early blind and sighted controls on a dichotic listening task requiring the detection of specific emotional vocalizations (i.e., suggestive of happiness or sadness) presented independently to either ear.

RESULTS

Consistent with previous studies, we found that sighted individuals showed enhanced detection of positive vocalizations when presented in the right ear (i.e., processed within the left hemisphere) and negative vocalizations when presented in the left ear (i.e., right hemisphere). It is interesting to note that although blind individuals were as accurate as sighted controls in detecting the valance of the vocalization, performance was not consistent with any pattern of specialized hemispheric lateralization.

CONCLUSIONS

Overall, these results suggest that although the lack of prior visual experience may not lead to impaired emotion processing performance, the underlying neurophysiological substrate (i.e., degree of special hemispheric lateralization) may depend on normal visual development. (PsycINFO Database Record

Dorsomedial prefrontal cortex and cerebellar contribution to in-group attitudes: a transcranial magnetic stimulation study

We tend to express more positive judgments and behaviors toward individuals belonging to our own group compared to other (out-) groups. In this study, we assessed the role of the cerebellum and of the dorsomedial prefrontal cortex (dmPFC) - two regions critically implicated in social cognition processes - in mediating implicit valenced attitudes toward in-group and out-group individuals. To this aim, we used transcranial magnetic stimulation (TMS) in combination with a standard attitude priming task, in which Caucasian participants had to categorize the valence of a series of adjectives primed by either an in-group or an out-group face. In two behavioral experiments, we found an in-group bias (i.e. faster categorization of positive adjectives when preceded by in-group faces) but no evidence of an out-group bias. Interestingly, TMS over both the dmPFC and over the (right) cerebellum significantly interfered with the modulation exerted by group membership on adjective valence classification, abolishing the in-group bias observed at baseline. Overall, our data suggest that both the dmPFC and the cerebellum play a causal role in mediating implicit social attitudes.

Brain Lateralization of Emotional Processing: Historical Roots and a Future Incorporating “Dominance”

This article provides a review of research on the hemispheric specialization in emotional processing during the past 40 years and the theoretical models derived from the conceptual analysis of these results. The publications reviewed here were collected to better appreciate the cortical lateralization of emotional perception (visual and auditory), expression (facial and prosodic), and experience. Four major models of emotional processing are discussed—the Right Hemisphere, Valence, Approach-Withdrawal, and Behavioral Inhibition System–Behavioral Activation System models. Observing the relative merits and limitations of these models, a new direction for exploration is offered. Specifically, to better appreciate the strength and direction (i.e., approach versus withdrawal) of experienced emotions, it is recommended that state “dominance” be evaluated in the context of asymmetrical activation of left-frontal (dominance) versus right-frontal (submission) brain regions.

Surface-Based Display of Volume-Averaged Cerebellar Imaging Data

The paper presents a flat representation of the human cerebellum, useful for visualizing functional imaging data after volume-based normalization and averaging across subjects. Instead of reconstructing individual cerebellar surfaces, the method uses a white- and grey-matter surface defined on volume-averaged anatomical data. Functional data can be projected along the lines of corresponding vertices on the two surfaces. The flat representation is optimized to yield a roughly proportional relationship between the surface area of the 2D-representation and the volume of the underlying cerebellar grey matter. The map allows users to visualize the activation state of the complete cerebellar grey matter in one concise view, equally revealing both the anterior-posterior (lobular) and medial-lateral organization. As examples, published data on resting-state networks and task-related activity are presented on the flatmap. The software and maps are freely available and compatible with most major neuroimaging packages.

The dynamic opponent relativity model: an integration and extension of capacity theory and existing theoretical perspectives on the neuropsychology of arousal and emotion

Arousal theory as discussed within the present paper refers to those mechanisms and neural systems involved in central nervous system activation and more specifically the systems involved in cortical activation. Historical progress in the evolution of arousal theory has led to a better understanding of the functional neural systems involved in arousal or activation processes and ultimately contributed much to our current theories of emotion. Despite evidence for the dynamic interplay between the left and right cerebral hemispheres, the concepts of cerebral balance and dynamic activation have been emphasized in the neuropsychological literature. A conceptual model is proposed herein that incorporates the unique contributions from multiple neuropsychological theories of arousal and emotion. It is argued that the cerebral hemispheres may play oppositional roles in emotion partially due to the differences in their functional specializations and in their persistence upon activation. In the presence of a threat or provocation, the right hemisphere may activate survival relevant responses partially derived from hemispheric specializations in arousal and emotional processing, including the mobilization of sympathetic drive to promote heightened blood pressure, heart rate, glucose mobilization and respiratory support necessary for the challenge. Oppositional processes and mechanisms are discussed, which may be relevant to the regulatory control over the survival response; however, the capacity of these systems is necessarily limited. A limited capacity mechanism is proposed, which is familiar within other physiological systems, including that providing for the prevention of muscular damage under exceptional demand. This capacity theory is proposed, wherein a link may be expected between exceptional stress within a neural system and damage to the neural system. These mechanisms are proposed to be relevant to emotion and emotional disorders. Discussion is provided on the possible role of currently applied therapeutic interventions for emotional disorders.

Which Cheek did the Resurrected Jesus Turn?

Secular portraits are likely to show more of the left than right side of the face (hemiface). Prior research has shown that emotions are more strongly expressed by the left hemiface. In addition, the valence theory of emotion proposes that the right hemisphere is dominant for mediating negative emotions, and the left hemisphere for positive emotions. Since religious art depicting a scene such as the Resurrection of Jesus is more likely to be associated with positive emotions, we postulated that there would be a significant smaller percentage number of artistic works of the Resurrection that reveal the left side of the face of Jesus than in those art works portraying the Crucifixion. Thus, we analyzed artistic portrayals of the Resurrection of Jesus and compared them to the artistic scenes of the Crucifixion. This analysis revealed that the left side of the face of Jesus is less commonly depicted in portraits of the Resurrection than the Crucifixion. In addition, both the right hemiface, and forward-facing faces were also more commonly portrayed in painting of the Resurrection than the Crucifixion. Whereas this right-left hemiface, Resurrection-Crucifixion dichotomy may be related to right-left hemispheric difference in the mediation of emotional valence other factors such as agency, action-intention, and biblical text may have influenced these differences.

Impaired corticopontocerebellar tracts underlie pseudobulbar affect in motor neuron disorders

OBJECTIVE

The objectives of the study were (1) to determine the prevalence and characteristics of pseudobulbar affect (PBA) in patients with primary lateral sclerosis (PLS) and amyotrophic lateral sclerosis (ALS) in an outpatient clinic population, and (2) to test the hypothesis that damage of inputs to the cerebellum, leading to cerebellar dysmodulation, is associated with PBA.

METHODS

Chart review of all patients with PLS and ALS seen between 2000 and 2013. The examining neurologist documented the presence or absence of PBA in 87 patients. Forty-seven patients also had diffusion tensor imaging (DTI) studies. Tract-based spatial statistics were used to compare DTI of patients with and without PBA to identify altered white matter tracts associated with PBA.

RESULTS

Thirty-one of 50 patients with PLS and 12 of 37 patients with ALS had PBA. Psychiatric/emotional assessment found congruence between mood and affect during episodes, but excessive magnitude of the response. DTI studies of 25 PLS and 22 ALS patient brains showed reduced fractional anisotropy of the corticospinal and callosal white matter tracts in all patients. Patients with PBA additionally had increased mean diffusivity of white matter tracts underlying the frontotemporal cortex, the transverse pontine fibers, and the middle cerebellar peduncle.

CONCLUSIONS

PBA is common in PLS. Imaging findings showing disruption of corticopontocerebellar pathways support the hypothesis that PBA can be viewed as a "dysmetria" of emotional expression resulting from cerebellar dysmodulation.

Neurochemical properties of the synapses between the parabrachial nucleus-derived CGRP-positive axonal terminals and the GABAergic neurons in the lateral capsular division of central nucleus of amygdala

The lateral capsular division of central nucleus of amygdala (CeC) contains neurons using γ-amino butyric acid (GABA) as the predominant neurotransmitter and expresses abundant calcitonin gene-related peptide (CGRP)-positive terminals. However, the relationship between them has not been revealed yet. Using GAD67-green fluorescent protein (GFP) knock-in mouse, we investigated the neurochemical features of synapses between CGRP-positive terminals and GABAergic neurons within CeC and the potential involvement of CGRP1 receptor by combining fluorescent in situ hybridization for CGRP1 receptor mRNA with immunofluorescent histochemistry for GFP and CGRP. The ultrastructures of these synapses were investigated with pre-embedding electron microscopy for GFP and CGRP. We found that some GABAergic neurons in the CeC received parabrachial nucleus (PBN) derived CGRP innervations and some of these GABAergic neurons can be activated by subcutaneous injection of formalin. Moreover, more than 90 % GABAergic neurons innervated by CGRP-positive terminal also express CGRP1 receptor mRNA. The CGRP-positive fibers made symmetric synapses onto the GABAergic somata, and asymmetric synapses onto the GABA-LI dendritic shafts and spines. This study provides direct ultrastructural evidences for the synaptic contacts between CGRP-positive terminals and GABAergic neurons within the CeC, which may underlie the pain-related neural pathway from PBN to CeC and be involved in the chronic pain modulation.

A meta-analysis of cerebellar contributions to higher cognition from PET and fMRI studies

A growing interest in cerebellar function and its involvement in higher cognition have prompted much research in recent years. Cerebellar presence in a wide range of cognitive functions examined within an increasing body of neuroimaging literature has been observed. We applied a meta-analytic approach, which employed the activation likelihood estimate method, to consolidate results of cerebellar involvement accumulated in different cognitive tasks of interest and systematically identified similarities among the studies. The current analysis included 88 neuroimaging studies demonstrating cerebellar activations in higher cognitive domains involving emotion, executive function, language, music, timing and working memory. While largely consistent with a prior meta-analysis by Stoodley and Schmahmann ([2009]: Neuroimage 44:489-501), our results extended their findings to include music and timing domains to provide further insights into cerebellar involvement and elucidate its role in higher cognition. In addition, we conducted inter- and intradomain comparisons for the cognitive domains of emotion, language, and working memory. We also considered task differences within the domain of verbal working memory by conducting a comparison of the Sternberg with the n-back task, as well as an analysis of the differential components within the Sternberg task. Results showed a consistent cerebellar presence in the timing domain, providing evidence for a role in time keeping. Unique clusters identified within the domain further refine the topographic organization of the cerebellum.

Ha ha! versus aha! a direct comparison of humor to nonhumorous insight for determining the neural correlates of mirth

While humor typically involves a surprising discovery, not all discoveries are perceived as humorous or lead to a feeling of mirth. Is there a difference in the neural signature of humorous versus nonhumorous discovery? Subjects viewed drawings that were uninterpretable until a caption was presented that provided either: 1) a nonhumorous interpretation (or insight) of an object from an unusual or partial view (UV) or 2) a humorous interpretation (HU) of the image achieved by linking remote and unexpected concepts. fMRI activation elicited by the UV captions was a subset of that elicited by the humorous HU captions, with only the latter showing activity in the temporal poles and temporo-occipital junction (linking remote concepts), and medial prefrontal cortex (unexpected reward). Mirth may be a consequence of the linking of remote ideas producing high-and unexpected-activation in association and classical reward areas. We suggest that this process is mediated by opioid activity as part of a system rewarding attention to novel information.

Excitability of motor cortices as a function of emotional sounds

We used transcranial magnetic stimulation (TMS) to clarify how non-verbal emotionally-characterized sounds modulate the excitability of the corticospinal motor tract (CST). While subjects were listening to sounds (monaurally and binaurally), single TMS pulses were delivered to either left or right primary motor cortex (M1), and electromyographic activities were recorded from the contralateral abductor pollicis brevis muscle. We found a significant increase in CST excitability in response to unpleasant as compared to neutral sounds. The increased excitability was lateralized as a function of stimulus valence: Unpleasant stimuli resulted in a significantly higher facilitation of motor potentials evoked in the left hemisphere, while pleasant stimuli yielded a greater CST excitability in the right one. Furthermore, TMS induced higher motor evoked potentials when listening to unpleasant sounds with the left than with the right ear. Taken together, our findings provide compelling evidence for an asymmetric modulation of CST excitability as a function of emotional sounds along with ear laterality.

Abnormalities of cortical-limbic-cerebellar white matter networks may contribute to treatment-resistant depression: a diffusion tensor imaging study

BACKGROUND

White matter abnormalities can cause network dysfunction that underlies major depressive disorder (MDD). Diffusion tensor imaging (DTI) is used to examine the neural connectivity and integrity of the white matter. Previous studies have implicated frontolimbic neural networks in the pathophysiology of MDD. Approximately 30% of MDD patients demonstrate treatment-resistant depression (TRD). However, the neurobiology of TRD remains unclear.

METHODS

We used a voxel-based analysis method to analyze DTI data in young patients with TRD (n = 30; 19 males, 11 females) compared with right-handed, age- and sex-matched healthy volunteers (n = 25; 14 males, 11 females).

RESULTS

We found a significant decrease in fractional anisotropy (FA) (corrected, cluster size >50) in the left middle frontal gyrus (peak coordinates [-18 46-14]), left limbic lobe uncus (peak coordinates [-18 2-22]), and right cerebellum posterior lobe (peak coordinates [26-34 -40]). There was no increase in FA in any brain region in patients. We also found a significant negative correlation between mean regional FA values in the three areas and Beck Depression Inventory symptom scores.

CONCLUSIONS

We found significant differences in white matter FA in the frontal lobe, limbic lobe and cerebellum between TRD patients and controls. These data suggest that abnormalities of cortical-limbic-cerebellar white matter networks may contribute to TRD in young patients.

Neural correlates of the behavioral-autonomic interaction response to potentially threatening stimuli

Subjective assessment of emotional valence is typically associated with both brain activity and autonomic arousal. Accurately assessing emotional salience is particularly important when perceiving threat. We sought to characterize the neural correlates of the interaction between behavioral and autonomic responses to potentially threatening visual and auditory stimuli. Twenty-five healthy male subjects underwent fMRI scanning whilst skin conductance responses (SCR) were recorded. One hundred and eighty pictures, sentences, and sounds were assessed as “harmless” or “threatening.” Individuals' stimulus-locked, phasic SCRs and trial-by-trial behavioral assessments were entered as regressors into a flexible factorial design to establish their separate autonomic and behavioral neural correlates, and convolved to examine psycho-autonomic interaction (PAI) effects. Across all stimuli, “threatening,” compared with “harmless” behavioral assessments were associated with mainly frontal and precuneus activation with specific within-modality activations including bilateral parahippocampal gyri (pictures), bilateral anterior cingulate cortex (ACC) and frontal pole (sentences), and right Heschl's gyrus and bilateral temporal gyri (sounds). Across stimulus modalities SCRs were associated with activation of parieto-occipito-thalamic regions, an activation pattern which was largely replicated within-modality. In contrast, PAI analyses revealed modality-specific activations including right fusiform/parahippocampal gyrus (pictures), right insula (sentences), and mid-cingulate gyrus (sounds). Phasic SCR activity was positively correlated with an individual's propensity to assess stimuli as “threatening.” SCRs may modulate cognitive assessments on a “harmless–threatening” dimension, thereby modulating affective tone and hence behavior.

Equivalent brain SPECT perfusion changes underlying therapeutic efficiency in pharmacoresistant depression using either high-frequency left or low-frequency right prefrontal rTMS

BACKGROUND

Functional neuroimaging studies have suggested similar mechanisms underlying antidepressant effects of distinct therapeutics.

OBJECTIVE

This study aimed to determine and compare functional brain patterns underlying the antidepressant response of 2 distinct protocols of repetitive transcranial magnetic stimulation (rTMS).

METHODS

99mTc-ECD SPECT was performed before and after rTMS of dorsolateral prefrontal cortex in 61 drug-resistant right-handed patients with major depression, using high frequency (10Hz) left-side stimulation in 33 patients, and low frequency (1Hz) right-side stimulation in 28 patients. Efficiency of rTMS response was defined as at least 50% reduction of the baseline Beck Depression Inventory score. We compared the whole-brain voxel-based brain SPECT changes in perfusion after rTMS, between responders and non-responders in the whole sample (p<0.005, uncorrected), and separately in the subgroup of patients with left- and right-stimulation.

RESULTS

Before rTMS, the left- and right-prefrontal stimulation groups did not differ from clinical data and brain SPECT perfusion. rTMS efficiency (evaluated on % of responders) was statistically equivalent in the two groups of patients. In the whole-group of responder patients, a perfusion decrease was found after rTMS, in comparison to non-responders, within the left perirhinal cortex (BA35, BA36). This result was secondarily confirmed separately in the two subgroups, i.e. after either left stimulation (p=0.017) or right stimulation (p<0.001), without significant perfusion differences between these two subgroups.

CONCLUSIONS

These data show that distinct successful rTMS protocols induce equivalent brain functional changes associated to antidepressive efficiency, consisting to a remote brain limbic activity decrease within the left perirhinal cortex. However, these results will have to be confirmed in a double-blind randomized trial using a sham control group.

Hemispheric asymmetry for affective stimulus processing in healthy subjects--a fMRI study

Background

While hemispheric specialization of language processing is well established, lateralization of emotion processing is still under debate. Several conflicting hypotheses have been proposed, including right hemisphere hypothesis, valence asymmetry hypothesis and region-specific lateralization hypothesis. However, experimental evidence for these hypotheses remains inconclusive, partly because direct comparisons between hemispheres are scarce.

Methods

The present fMRI study systematically investigated functional lateralization during affective stimulus processing in 36 healthy participants. We normalized our functional data on a symmetrical template to avoid confounding effects of anatomical asymmetries. Direct comparison of BOLD responses between hemispheres was accomplished taking two approaches: a hypothesis-driven region of interest analysis focusing on brain areas most frequently reported in earlier neuroimaging studies of emotion; and an exploratory whole volume analysis contrasting non-flipped with flipped functional data using paired t-test.

Results

The region of interest analysis revealed lateralization towards the left in the medial prefrontal cortex (BA 10) during positive stimulus processing; while negative stimulus processing was lateralized towards the right in the dorsolateral prefrontal cortex (BA 9 & 46) and towards the left in the amygdala and uncus. The whole brain analysis yielded similar results and, in addition, revealed lateralization towards the right in the premotor cortex (BA 6) and the temporo-occipital junction (BA 19 & 37) during positive stimulus processing; while negative stimulus processing showed lateralization towards the right in the temporo-parietal junction (BA 37,39,42) and towards the left in the middle temporal gyrus (BA 21).

Conclusion

Our data suggests region-specific functional lateralization of emotion processing. Findings show valence asymmetry for prefrontal cortical areas and left-lateralized negative stimulus processing in subcortical areas, in particular, amygdala and uncus.

The cerebellum and cognition: evidence from functional imaging studies

Evidence for a role of the human cerebellum in cognitive functions comes from anatomical, clinical and neuroimaging data. Functional neuroimaging reveals cerebellar activation during a variety of cognitive tasks, including language, visual-spatial, executive, and working memory processes. It is important to note that overt movement is not a prerequisite for cerebellar activation: the cerebellum is engaged during conditions which either control for motor output or do not involve motor responses. Resting-state functional connectivity data reveal that, in addition to networks underlying motor control, the cerebellum is part of "cognitive" networks with prefrontal and parietal association cortices. Consistent with these findings, regional differences in activation patterns within the cerebellum are evident depending on the task demands, suggesting that the cerebellum can be broadly divided into functional regions based on the patterns of anatomical connectivity between different regions of the cerebellum and sensorimotor and association areas of the cerebral cortex. However, the distinct contribution of the cerebellum to cognitive tasks is not clear. Here, the functional neuroimaging evidence for cerebellar involvement in cognitive functions is reviewed and related to hypotheses as to why the cerebellum is active during such tasks. Identifying the precise role of the cerebellum in cognition-as well as the mechanism by which the cerebellum modulates performance during a wide range of tasks-remains a challenge for future investigations.

Altered regional homogeneity in post-traumatic stress disorder: a resting-state functional magnetic resonance imaging study

OBJECTIVE

Little is known about the brain systems that contribute to vulnerability to post-traumatic stress disorder (PTSD). Comparison of the resting-state patterns of intrinsic functional synchronization, as measured by functional magnetic resonance imaging (fMRI), between groups with and without PTSD following a traumatic event can help identify the neural mechanisms of the disorder and targets for intervention.

METHODS

Fifty-four PTSD patients and 72 matched traumatized subjects who experienced the 2008 Sichuan earthquake were imaged with blood oxygen level-dependent (BOLD) fMRI and analyzed using the measure of regional homogeneity (ReHo) during the resting state.

RESULTS

PTSD patients presented enhanced ReHo in the left inferior parietal lobule and right superior frontal gyrus, and reduced ReHo in the right middle temporal gyrus and lingual gyrus, relative to traumatized individuals without PTSD.

CONCLUSION

Our findings showed that abnormal brain activity exists under resting conditions in PTSD patients who had been exposed to a major earthquake. Alterations in the local functional connectivity of cortical regions are likely to contribute to the neural mechanisms underlying PTSD.

Resting-state functional connectivity of the vermal and hemispheric subregions of the cerebellum with both the cerebral cortical networks and subcortical structures

The human cerebellum is a heterogeneous structure, and the pattern of resting-state functional connectivity (rsFC) of each subregion has not yet been fully characterized. We aimed to systematically investigate rsFC pattern of each cerebellar subregion in 228 healthy young adults. Voxel-based analysis revealed that several subregions showed similar rsFC patterns, reflecting functional integration; however, different subregions displayed distinct rsFC patterns, representing functional segregation. The same vermal and hemispheric subregions showed either different patterns or different strengths of rsFCs with the cerebrum, and different subregions of lobules VII and VIII displayed different rsFC patterns. Region of interest (ROI)-based analyses also confirmed these findings. Specifically, strong rsFCs were found: between lobules I-VI and vermal VIIb-IX and the visual network; between hemispheric VI, VIIb, VIIIa and the auditory network; between lobules I-VI, VIII and the sensorimotor network; between lobule IX, vermal VIIIb and the default-mode network; between lobule Crus I, hemispheric Crus II and the fronto-parietal network; between hemispheric VIIb, VIII and the task-positive network; between hemispheric VI, VIIb, VIII and the salience network; between most cerebellar subregions and the thalamus; between lobules V, VIIb and the midbrain red nucleus; between hemispheric Crus I, Crus II, vermal VIIIb, IX and the caudate nucleus; between lobules V, VI, VIIb, VIIIa and the pallidum and putamen; and between lobules I-V, hemispheric VIII, IX and the hippocampus and amygdala. These results confirm the existence of both functional integration and segregation among cerebellar subregions and largely improve our understanding of the functional organization of the human cerebellum.

How the emotional content of discourse affects language comprehension

Emotion effects on cognition have often been reported. However, only few studies investigated emotional effects on subsequent language processing, and in most cases these effects were induced by non-linguistic stimuli such as films, faces, or pictures. Here, we investigated how a paragraph of positive, negative, or neutral emotional valence affects the processing of a subsequent emotionally neutral sentence, which contained either semantic, syntactic, or no violation, respectively, by means of event-related brain potentials (ERPs). Behavioral data revealed strong effects of emotion; error rates and reaction times increased significantly in sentences preceded by a positive paragraph relative to negative and neutral ones. In ERPs, the N400 to semantic violations was not affected by emotion. In the syntactic experiment, however, clear emotion effects were observed on ERPs. The left anterior negativity (LAN) to syntactic violations, which was not visible in the neutral condition, was present in the negative and positive conditions. This is interpreted as reflecting modulatory effects of prior emotions on syntactic processing, which is discussed in the light of three alternative or complementary explanations based on emotion-induced cognitive styles, working memory, and arousal models. The present effects of emotion on the LAN are especially remarkable considering that syntactic processing has often been regarded as encapsulated and autonomous.

Hemispheric asymmetry in the processing of negative and positive words: a divided field study

Research on the lateralisation of brain functions for emotion has yielded different results as a function of whether it is the experience, expression, or perceptual processing of emotion that is examined. Further, for the perception of emotion there appear to be differences between the processing of verbal and nonverbal stimuli. The present research examined the hemispheric asymmetry in the processing of verbal stimuli varying in emotional valence. Participants performed a lexical decision task for words varying in affective valence (but equated in terms of arousal) that were presented briefly to the right or left visual field. Participants were significantly faster at recognising positive words presented to the right visual field/left hemisphere. This pattern did not occur for negative words (and was reversed for high arousal negative words). These results suggest that the processing of verbal stimuli varying in emotional valence tends to parallel hemispheric asymmetry in the experience of emotion.

Analysis of cortical thickness in narcolepsy patients with cataplexy

STUDY OBJECTIVES

To investigate differences in cortical thickness in narcolepsy patients with cataplexy and control subjects.

DESIGN

Cortical thickness was measured using a 3-D surface-based method that enables more accurate measurement in deep sulci and localized regional mapping.

SETTING

University hospital.

PATIENTS AND PARTICIPANTS

We enrolled 28 patients with narcolepsy and cataplexy and 33 age-and sex-matched control subjects.

INTERVENTIONS

Cortical thickness was measured using a direct method for calculating the distance between corresponding vertices from inner and outer cortical surfaces.

MEASUREMENTS AND RESULTS

We normalized cortical surfaces using 2-D surface registration and performed diffusion smoothing to reduce the variability of folding patterns and to increase the power of the statistical analysis. Localized cortical thinning in narcolepsy patients with cataplexy was found in orbitofrontal gyri, dorsolateral and medial prefrontal cortexes, insula, cingulate gyri, middle and inferior temporal gyri, and inferior parietal lobule of the right and left hemispheres at the level of a false discovery rate P<0.05. No significant local increases in cortical thickness were observed in narcolepsy patients. A significant negative correlation was observed between the narcolepsy patients' scores on the Epworth Sleepiness Scale and the cortical thickness of the left supramarginal gyrus.

CONCLUSIONS

Cortical thinning in narcolepsy patients with cataplexy in localized anatomic brain regions may serve as a possible neuroanatomic mechanism of the disturbances in attention, memory, emotion, and sleepiness.

Emotional scenes and facial expressions elicit different psychophysiological responses

We examined if emotional faces elicit physiological responses similar to pictures of emotional scenes. Forty one students viewed emotional scenes (negative, neutral, and positive) and emotional faces (angry, neutral, and happy). Heart rate, orbicularis oculi and electrodermal activity were measured continuously, and the startle reflex was elicited. Although the patterns of valence and arousal ratings were comparable, physiological response patterns differed. For scenes we replicated the valence-specific modulation of the startle response, heart rate deceleration, and the arousal-related modulation of the electrodermal response. In contrast, for faces we found valence-specific modulation only for the electrodermal response, but the startle and heart rate deceleration were modulated by arousal. Although arousal differences may account for some differences in physiological responding this shows that not all emotional material that is decoded similarly leads to the same psychophysiological output.

An fMRI study of intra-individual functional topography in the human cerebellum

Neuroimaging studies report cerebellar activation during both motor and non-motor paradigms, and suggest a functional topography within the cerebellum. Sensorimotor tasks activate the anterior lobe, parts of lobule VI, and lobule VIII, whereas higher-level tasks activate lobules VI and VII in the posterior lobe. To determine whether these activation patterns are evident at a single-subject level, we conducted functional magnetic resonance imaging (fMRI) during five tasks investigating sensorimotor (finger tapping), language (verb generation), spatial (mental rotation), working memory (N-back), and emotional processing (viewing images from the International Affective Picture System). Finger tapping activated the ipsilateral anterior lobe (lobules IV-V) as well as lobules VI and VIII. Activation during verb generation was found in right lobules VII and VIIIA. Mental rotation activated left-lateralized clusters in lobules VII-VIIIA, VI-Crus I, and midline VIIAt. The N-back task showed bilateral activation in right lobules VI-Crus I and left lobules VIIB-VIIIA. Cerebellar activation was evident bilaterally in lobule VI while viewing arousing vs. neutral images. This fMRI study provides the first proof of principle demonstration that there is topographic organization of motor execution vs. cognitive/emotional domains within the cerebellum of a single individual, likely reflecting the anatomical specificity of cerebro-cerebellar circuits underlying different task domains. Inter-subject variability of motor and non-motor topography remains to be determined.

Emotional perception: meta-analyses of face and natural scene processing

Functional imaging studies of emotional processing typically contain neutral control conditions that serve to remove simple effects of visual perception, thus revealing the additional emotional process. Here we seek to identify similarities and differences across 100 studies of emotional face processing and 57 studies of emotional scene processing, using a coordinate-based meta-analysis technique. The overlay of significant meta-analyses resulted in extensive overlap in clusters, coupled with offset and unique clusters of reliable activity. The area of greatest overlap is the amygdala, followed by regions of medial prefrontal cortex, inferior frontal/orbitofrontal cortex, inferior temporal cortex, and extrastriate occipital cortex. Emotional face-specific clusters were identified in regions known to be involved in face processing, including anterior fusiform gyrus and middle temporal gyrus, and emotional scene studies were uniquely associated with lateral occipital cortex, as well as pulvinar and the medial dorsal nucleus of the thalamus. One global result of the meta-analysis reveals that a class of visual stimuli (faces vs. scenes) has a considerable impact on the resulting emotion effects, even after removing the basic visual perception effects through subtractive contrasts. Pure effects of emotion may thus be difficult to remove for the particular class of stimuli employed in an experimental paradigm. Whether a researcher chooses to tightly control the various elements of the emotional stimuli, as with posed face photographs, or allow variety and environmental realism into their evocative stimuli, as with natural scenes, will depend on the desired generalizability of their results.

fMRI BOLD response in high-risk college students (Part 1): during exposure to alcohol, marijuana, polydrug and emotional picture cues

AIM

This functional magnetic resonance imaging (fMRI) study examined reactivity to alcohol, polydrug, marijuana and emotional picture cues in students who were referred to a college alcohol and drug assistance program.

METHODS

The fMRI data of 10 participants (5 females; 5 males) were collected while they viewed standardized emotional and appetitive cues.

RESULTS

Positive and negative emotional cues produced greater activity than neutral cues in the expected brain areas. Compared with neutral cues, alcohol cues produced greater brain activation in the right insula, left anterior cingulate, left caudate and left prefrontal cortex (Z = 2.01, 1.86, 1.82, 1.81, respectively; P < 0.05). Drug cues produced significantly greater left prefrontal activity compared with neutral cues, with polydrug cues activating the right insula and marijuana cues activating left anterior cingulate.

CONCLUSIONS

Students at-risk for alcohol abuse showed neural reactivity to alcohol cues in four brain regions, which is consistent with their greater use of alcohol. Insula activation to appetitive cues may be an early marker of risk for progression to alcohol/drug abuse.