Young Chul Jung

Medial prefrontal default-mode hypoactivity affecting trait physical anhedonia in schizophrenia

Anhedonia, as a deficit symptom, may be associated with default-mode hypofrontality in schizophrenia. To explore whether trait anhedonia in schizophrenia pertains to altered hypofrontal resting state brain function, resting state metabolic activities were compared and correlated with the Physical and Social Anhedonia Scale scores in 29 patients with schizophrenia and 21 healthy controls using (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET). In patients with schizophrenia, Physical Anhedonia Scale scores showed a trend-level negative correlation with the hypoactive dorsomedial prefrontal metabolism while Positive and Negative Symptom Scale (PANSS) negative subscale scores positively correlated with hyperactive cerebellar metabolism. Voxelwise correlation analysis showed physical anhedonia correlates in resting state activities of the supplementary motor area, ventromedial and dorsolateral prefrontal cortex, insular gyrus, and the precuneus in patients with schizophrenia while no frontal metabolic correlates were found in healthy controls. The hypoactive dorsomedial prefrontal metabolism correlated with physical anhedonia-correlated resting state regional activities. These findings provide further evidence for the relation of functional hypofrontality to the deficit syndrome and possible involvement of the functional imbalance in the cortico-cerebellar-thalamic-cortical circuit in the resting state brain function of schizophrenia.

Shape deformation of the insula in schizophrenia.

Schizophrenia has been conceptualized to be a neurodevelopmental disorder. Neuroimaging evidence was generally findings of volumetric reductions in various brain structures. The shape analysis of the insula can uncover unique structural deformity in the neurodevelopmental disorder, which cannot be revealed from a simple volume measurement. The objective of this study was to demonstrate a subtle change of the insula in schizophrenia using our special shape analysis technique. Subjects were 23 patients with schizophrenia and 23 normal healthy subjects. A landmark-based structural and surface shape analysis of the insula was performed using high-spatial resolution magnetic resonance imaging. A characteristic finding was that the frontotemporal sides of the right insula were deformed in the patients with schizophrenia compared with normal controls. This deformation can be associated with abnormal development of the frontal and temporal lobes in schizophrenia.

Neural substrates associated with evaluative processing during co-activation of positivity and negativity: A PET investigation

Affective symmetries, such as the positivity offset and negativity bias, have been postulated to be attributable to distinct activation functions of the positive and negative affect systems. We investigated the neural substrates that are engaged when the positive and negative affect systems undergo parallel and integrative processing. Eleven subjects were scanned using H(2)(15)O PET during choosing the subjective feeling produced by a stimulation pair of pictures or words. Four different conditions were designed for contrast: pure positivity, pure negativity, positivity offset, and negativity bias. The dorsolateral prefrontal activation was associated with positivity offset and negativity bias condition, whereas the ventromedial prefrontal activation, together with limbic and subcortical activations, was associated with pure positivity and pure negativity condition. The results indicated that positivity offset and negativity bias are not merely due to asymmetric activations of the positive and negative systems, but integrative processing of higher neocortical levels is involved.

Shape deformation of the insula in alcoholics: Reduction of left-right asymmetry

We have investigated shape deformation of the insula to get a viewpoint of how chronic alcohol consumption affects the perisylvian region and compared the deformity pattern between the left and right hemisphere. A landmark-based structural and surface shape analysis of the insula was performed in 20 patients with alcohol dependence and 20 controls matched for age. The shape analysis revealed that the left and right insula follow distinct shape deformation patterns, which resulted in the reduction of left–right asymmetry. The shape deformity was most prominent in the central part of both insula. Our findings indicate that the right and left hemisphere are both affected but shows distinct patterns of deformation in alcohol dependence.

Disruption of orbitofronto-striatal functional connectivity underlies maladaptive persistent behaviors in alcohol-dependent patients.

Objective Alcohol dependence is characterized by persistent alcohol-seeking despite negative consequences. Previous studies suggest that maladaptive persistent behaviors reflect alcohol-induced brain changes that cause alterations in the cortico-striatal-limbic circuit. Methods Twenty one alcohol dependent patients and 24 age-matched healthy controls performed a decision-making task during functional MRI. We defined the medial orbitofrontal cortex (mOFC) as a region-of-interest and performed seed-based functional connectivity analysis. Results Healthy controls were more flexible in adapting an alternative behavioral strategy, which correlated with stronger mOFC-dorsal striatum functional connectivity. In contrast, alcohol dependent patients persisted to the first established behavioral strategy. The mOFC-dorsal striatum functional connectivity was impaired in the alcohol-dependent patients, but increased in correlation with the duration of abstinence. Conclusion Our findings support that the disruption of the mOFC-striatal circuitry contribute to the maldaptive persistent behaviors in alcohol dependent patients.

Neural evidence for emotional involvement in pathological alcohol craving

AIMSnReducing craving is a key to success in the treatment of alcohol dependence. The emotion circuit may be involved in pathological craving for alcohol. In this study, we investigated neural correlates of emotional involvement in craving in alcohol dependence.nnnMETHODSnThe study included 17 detoxified alcoholic patients and 25 social drinkers. We used functional magnetic resonance imaging to examine brain activation (blood oxygen level-dependent signals) while participants reported craving and emotion in response to visually presented, alcohol-related stimuli and emotional stimuli.nnnRESULTSnIn the craving-rating paradigm, negative emotional stimuli as well as alcohol cues activated craving-related brain regions in alcoholic patients. Activations of the inferior parietal lobule and dorsolateral prefrontal cortex by negative emotional stimuli were negatively correlated with craving; meanwhile limbic activation was positively correlated with craving. For the emotion paradigm, greater limbic activation was evident by alcohol-related stimuli in the alcohol-dependent group.nnnCONCLUSIONSnOur findings constitute neural evidence for emotional involvement in pathological craving for alcohol, underscoring the importance of emotion management in abstinent alcoholic patients for relapse prevention.

Brain mechanisms involved in processing unreal perceptions

Individuals sometimes experience an illusory or hallucinatory perception. This unreal perception is usually resolved after the individual recognizes that the perception was not real. In this study, we investigated the brain mechanisms involved in the process to an illusory or hallucinatory perception through obtaining insight into unreality. We used a novel and intuitive paradigm designed by combining functional magnetic resonance imaging and augmented reality technology to simulate visual illusory stimuli that mimic hallucinations during brain scanning. The results showed various brain activations, predominantly in the amygdala in the early phase, the medial frontal cortex and the occipitotemporal junction in the middle phase, and the thalamus in the late phase, which correlated with a subjects proneness to hallucinating. These activations may correspond to a responding stage for a perception-based immediate emotional reaction, a monitoring stage for integration and recalibration to ascertain that the perception was not real, and a resolving stage for controlling the information and finally settling it, respectively. Our paradigm and findings may be useful in understanding the mechanisms for discriminating and coping with hallucinatory perceptions.

Bright illumination reduces parietal EEG alpha activity during a sustained attention task

The influence of the illumination condition on our cognitive-performance seems to be more critical in the modern life, wherein, most people work in an office under a specific illumination condition. However, neurophysiological changes in a specific illumination state and their cognitive interpretation still remain unclear. Thereby, in the present study, the effect of different illumination conditions on the same cognitive performance was evaluated particularly by EEG wavelet analyses. During a sustained attention task, we observed that the higher illumination condition yielded significantly lower parietal tonic electroencephalogram (EEG) alpha activity before the presentation of the probe digit and longer reaction times, than that of the other illumination conditions. Although previous studies suggest that lower prestimulus EEG alpha activity is related to higher performance in an upcoming task, the reduced prestimulus alpha activity under higher illumination was associated with delayed reaction times in the present study. Presumably, the higher background illumination condition seems to be too bright for normal attentional processing and distracted participants attention during a sustained attention task. Such a bottom-up effect by stimulus salience seemed to overwhelm a prestimulus top-down effect reflected in prestimulus alpha power during the bright background condition. This finding might imply a dynamic competition between prestimulus top-down and poststimulus bottom-up processes. Our findings provide compelling evidence that the illumination condition substantially modulates our attentional processing. Further refinement of the illumination parameters and subsequent exploration of cognitive-modulation are necessary to facilitate our cognitive performance.

Validation of the Korean Version of the Eating Disorder Inventory-2: Psychometric Properties and Cross-Cultural Comparison

Purpose The purpose of the present study was to examine the validity and reliability of the Korean version of the Eating Disorder Inventory-2 (EDI-2) in Korean patients with eating disorders and healthy controls, and to investigate cultural differences of EDI-2 between a Korean group and a North American standardization sample. Materials and Methods The Korean version of the EDI-2 was prepared after comprehensive clinical assessment of Korean patients with eating disorders (n=327) as well as female undergraduates (n=176). Results were compared between eating disorder subgroups (anorexia nervosa, bulimia nervosa and eating disorders not otherwise specified) and those of a North American standardization sample and healthy controls. Results The results showed that the Korean EDI-2 had adequate internal consistency (0.77-0.93) and discriminated well between patients with eating disorders and healthy controls on all subscales. Significant differences in EDI-2 subscale scores between the eating disorder groups and the healthy control group were observed; however, there was no discernible difference among the eating disorder subgroups. When compared with a North American standardization sample, the Korean control group showed significantly higher scores for drive for thinness and asceticism. When patient groups were compared, the Korean group showed significantly lower scores for perfectionism. Conclusion As expected, the results accurately reflected psychometric properties of the Korean version of EDI-2 for eating disorder patients in Korea. These findings also suggest that common characteristics for the eating disorder exist as a whole rather than with significant difference between each subgroup. In addition, significant differences between the Korean and the North American groups for both patients and controls also demonstrated specific cultural differences.

Illumination influences working memory: An EEG study

Illumination conditions appear to influence working efficacy in everyday life. In the present study, we obtained electroencephalogram (EEG) correlates of working-memory load, and investigated how these waveforms are modulated by illumination conditions. We hypothesized that illumination conditions may affect cognitive performance. We designed an EEG study to monitor and record participants EEG during the Sternberg working memory task under four different illumination conditions. Illumination conditions were generated with a factorial design of two color-temperatures (3000 and 7100 K) by two illuminance levels (150 and 700 lx). During a working memory task, we observed that high illuminance led to significantly lower frontal EEG theta activity than did low illuminance. These differences persisted despite no significant difference in task performance between illumination conditions. We found that the latency of an early event-related potential component, such as N1, was significantly modulated by the illumination condition. The fact that the illumination condition affects brain activity but not behavioral performance suggests that the lighting conditions used in the present study did not influence the performance stage of behavioral processing. Nevertheless, our findings provide objective evidence that illumination conditions modulate brain activity. Further studies are necessary to refine the optimal lighting parameters for facilitating working memory.