Mediating Effect of Internet Addiction on the Association between Resilience and Depression among Korean University Students: A Structural Equation Modeling Approach

OBJECTIVE: This study examined the mediating role of internet addiction in the association between psychological resilience and depressive symptoms. METHODS: 837 Korean university students completed a survey with items of demographic information, Connor-Davidson Resilience Scale (CD-RISC), Internet Addiction Test (IAT), and Patient Health Questionnaire (PHQ-9) in 2015. The complex associations among psychological resilience, internet addiction, and depressive symptoms were delineated using structural equation models. RESULTS: In the most parsimonious model, the total effect and indirect effect of resilience on depressive symptoms via internet addiction, were statistically significant. The goodness of fit of the measurement model was satisfactory with fit indices, normed fit index (NFI) of 0.990, non-normed fit index (NNFI) of 0.997, comparative fit index (CFI) of 0.998, root mean square error (RMSEA) of 0.018 (90%CI=0.001–0.034); and Akaike Information Criterion (AIC) of -21.049. CONCLUSION: The association between psychological resilience and depressive symptoms was mediated by internet addiction in Korean university students. Enhancement of resilience programs could help prevent internet addiction and reduce the related depression risks.

The Sex-Related Differences of EEG Coherences between Patients with Bipolar Disorder and Controls

OBJECTIVES: Sex hormones exposure during the prenatal period has an effect on cerebral lateralization. Male brains are thought to be more lateralized than female brains. Bipolar disorder was known to show abnormalities in cerebral laterality whose characteristics could be estimated by electroencephalography (EEG) coherences. We studied sex-related differences of EEG coherences between healthy controls and patients with bipolar disorder to examine the sex effects in the genesis of bipolar disorder. METHODS: Participants were 25 patients with bipolar disorder (11 male, 14 female) and 46 healthy controls (23 male, 23 female). EEG was recorded in the eyes closed resting state. To examine dominant EEG coherence associated with sex differences in both groups within five frequency bands (delta, theta, alpha, beta, and gamma) across several brain regions, statistical analyses were performed using analysis of covariance. RESULTS: Though statistically meaningful results were not found, some remarkable findings were noted. Healthy control females showed more increased interhemispheric coherences than control males in gamma frequency band. There were no differences in the intrahemispheric coherences between the healthy control males and females. In patients with bipolar disorder, female dominant pattern in interhemispheric coherences was attenuated compared with healthy control. CONCLUSIONS: Sex differences of EEG coherences, which could be a marker for cerebral laterality, were attenuated in patients with bipolar disorder compared with healthy controls. These results imply that abnormal sex hormone exposure during early development might play some role in the pathogenesis of bipolar disorder.

The Sex-Related Differences of Relationships between 2D : 4D Ratio and Electroencephalographic Coherence in Patients with Schizophrenia Compared with Controls

OBJECTIVES: Prenatal testosterone is known to influence both cerebral laterality and 2nd to 4th digit ratio (2D : 4D). Epigenetic changes are thought to play some role in it. We studied sex-related differences between 2D : 4D and cerebral laterality in patients with schizophrenia and controls to examine the effects of prenatal testosterone in the development of schizophrenia. METHODS: Forty one men (18 schizophrenic patients and 23 controls) and 40 women (17 schizophrenic patients and 23 controls) were recruited from one psychiatric hospital in Korea. The 2D : 4D and electroencephalographic (EEG) coherence in 19 channels (66 pairs of interhemispheric coherence and 54 pairs of intrahemispheric coherence) were measured. The sex-related statistical analyses between 2D : 4D and EEG coherence in controls and patients with schizophrenia were performed using multiple regression. RESULTS: In male patients, the relationship between 2D : 4D and right intrahemispheric EEG coherence showed mainly positive correlation in delta and theta frequency bands, while it showed negative correlation in male controls. In female patients, the relationship between 2D : 4D and interhemispheric EEG coherence showed stronger positive correlation in alpha and beta frequency bands, while it showed weaker positive correlation in female controls. CONCLUSIONS: Low prenatal testosterone may play certain roles in altered correlation between 2D : 4D and cerebral laterality in schizophrenia and the development of schizophrenia by epigenetic mechanism.

Erratum: A Study of the Relationships between the Ratio of 2nd to 4th Digit Length and Cerebral Laterality

We would like to correct the degree for the 2nd author.

Sex-Related Differences of EEG Coherences between Patients with Schizophrenia and Healthy Controls

OBJECTIVES: Alteration of epigenetic effects of testosterone during early development was suggested as an ancillary mechanism for the genesis of schizophrenia. EEG coherence was thought to be a marker for cerebral laterality of which important determinant was testosterone during early development. We studied sex-related differences of EEG coherences between patients with schizophrenia and controls to examine the sex effects in the genesis of schizophrenia. METHODS: EEG was recorded in 35 patients with schizophrenia and 46 healthy controls in the eyes closed resting state. Pair-wise EEG coherences were calculated over delta, theta, alpha, beta and gamma frequency bands. To examine the differences of EEG coherence according to sex in each group, ANCOVA was performed using Statistical Analysis system (SAS, Ver 9.3) and R (Ver 2.15.2). RESULTS: Healthy control males showed more increased right intrahemispheric coherences than healthy control females in delta, theta, alpha and beta frequency bands. In patients with schizophrenia, this male dominant pattern in right intrahemispheric coherences was attenuated especially in alpha and beta bands. Healthy control females showed more increased interhemispheric coherences than healthy control males in delta, theta, beta and gamma frequency bands. In patients with schizophrenia, these female dominant patterns in interhemispheric coherences were attenuated especially in delta, theta, and beta bands, which were commonly observed in frontal to central areas. CONCLUSION: Sex differences in resting EEG coherences were attenuated in schizophrenia patients. These results imply that sex-related aberrant cerebral lateralization might exist in patients with schizophrenia, which are partly due to sex hormones via epigenetic mechanisms.

Potential Significance of Eyeblinks as a Behavior Marker of Neuropsychiatric Disorders

The primary purpose of this review is to present an overview of relationship between human spontaneous eyeblinking and internal cognitive processes. The second purpose is to address the neural substrates of human eyeblinking based on recent studies focusing on the central dopaminergic system and to explore the significance of spontaneous eyeblinks in neuropsychiatric disorders. We reviewed recent and previous studies on eyeblink patterns under various cognitive tasks. We also reviewed neural substrates of eyeblinking, particularly based on the central dopaminergic system. This paper suggests that spontaneous eyeblinks are highly correlated with various cognitive processes and the activity of central dopaminergic system. Various neuropsychiatric disorders are related to the alteration of the occurrence of eyeblinking. Spontaneous eyeblinking is the unique human behavior that occurs regularly without conscious effort. It is known that the rate of eyeblinking is modulated by internal cognitive processes and dopamine-related neuropsychiatric disorders. Further research is required to how the temporal dynamics of spontaneous eyeblinking is correlated with the disease activity and progression.

A Study of the Relationships between the Ratio of 2nd to 4th Digit Length and Cerebral Laterality

OBJECTIVES: Cerebral laterality is thought to be an important marker for neurodevelopment. Prenatal testosterone could influence both cerebral laterality and 2nd to 4th finger length ratio(2D:4D). EEG coherence and 2D:4D were examined to investigate the relationship between prenatal testosterone level and cerebral laterality. METHODS: EEG was recorded in 24 healthy subjects in the eyes closed resting state. Differences in 2D:4D finger ratio were used to discriminate "masculine finger type" and "feminine finger type" groups. The 2D:4D ratio was lower and greater than one for the "masculine finger type" group and "feminine finger type" group, respectively. We used coherence analysis to estimate the cortical functional connectivity. RESULTS: There were statistically meaningful relationships among cerebral functional connectivity, sex and finger ratio. Man and masculine finger type group showed higher intra-hemispheric coherence than those of woman and feminine finger type group. Woman and feminine finger type group showed higher inter-hemispheric coherence than those of man and masculine finger type group. CONCLUSIONS: These results imply that prenatal testosterone might act as important determinants of cerebral laterality. Further examination of the relationship between 2D:4D and EEG coherence in schizophrenia could give some clues for the neurodevelopmental hypothesis of schizophrenia genesis.

Temporal Changes in Functional Magnetic Resonance Imaging Activation of Heterosexual Couples for Visual Stimuli of Loved Partners

OBJECTIVE: Previous neuroimaging studies on romantic love have focused on determining how the visual stimuli that serve as a representation of loved ones induce the neural activation patterns of romantic love. The purpose of this study was to investigate the temporal changes in romantic love over a period of 6 months and their correlated neurophysiological changes. METHODS: Five heterosexual couples (n=10, mean age 21.1+/-1.97) who started dating not less than 100 days previously were recruited to measure their blood oxygen level dependent (BOLD) signals using functional magnetic resonance imaging (fMRI) while showing them pictures of their loved ones and their previously identified, opposite-sex friends. Subsequently, the subjects were scanned under the same experimental conditions to assess possible changes in their brain activities after 180 days. RESULTS: We found that their Passionate Love Score (PLS) values (M: 118.6+/-9.1, F: 120.2+/-7.0) were significantly reduced after 6 months (M: 110.8+/-4.0, F: 106.2+/-3.0). Furthermore, significantly increased activations were found in the cingulate gyri, inferior frontal gyri, supramarginal gyri, etc., after 6 months, whereas the head and tail of the right caudate nucleus were deactivated, which is indicative of the inhibition of expression and sensory neglect. CONCLUSION: These findings suggest that dynamic neural processes in the cortical-subcortical regions are involved in temporal changes in romantic love.

Neural Substrates of Fear Based on Animal and Human Studies

OBJECTIVES: The neural substrate of fear is thought to be highly conserved among species including human. The purpose of this review was to address the neural substrates of fear based on recent findings obtained from animal and human studies. METHODS: Recent studies on brain regions related to fear, particularly fear conditioning in rodents and humans, were extensively reviewed. RESULTS: This paper suggests high consistency in anatomical structure and physiological mechanisms for fear perception, response, learning and modulation in animals and humans. CONCLUSIONS: Fear is manifested and modulated by well conserved neural circuits among species interconnected with the amygdala, such as the hippocampus and the ventromedial prefrontal cortex. Further research is required to incorporate findings from animal studies into a better understanding of neural circuitry of fear in human in a translational approach.

Cortical Information Transmission during Tic Suppression in Boys with Tourette's Disorder / 신경정신의학

OBJECTIVES: Tourette's Disorder (TD) is a chronic neuropsychiatric disorder characterized by multiple motor and vocal tics with onset in childhood. The aim of this study was to ascertain the increased cortical information transmission in frontal area during tic suppression in drug naive boys with TD using new nonlinear analysis of EEGs, be called Transfer Entropy (TE) which can detect the directed exchange of information between two systems. METHODS: Subjects were 11 drug naive boys with DSM-IV diagnosis of TD and 10 control boys. Clinical assessments were performed, and EEGs were recorded from 19 scalp loci of the international 10-20 systems. TE was estimated by EEG timeseries data after noise reduction. TE difference between TD and control during resting state and between tic suppression and resting state in TD were investigated. RESULTS: Elevated TE was found in extensive channels, including frontal, central and temporal channels (F7, Fz, F8,Cz, C3, P3, T3, and T4) in resting state of Tourette's disorder compared to normal controls. During tic suppression elevated TE was found in more extensive and asymmetrical channels especially prefrontal area (Fp1, Fp2, F3, Fz, F7, F8, Cz, C4, C5, T3, and T4). CONCLUSION: These findings suggest that pathogenesis of Tourette's disorder involve impaired cortical neuronal modulation in subcortical neural circuits. EEG analysis of TE may be a useful tool to investigation of cortical mechanism of psychiatric illness.

Assessment of Cerebrovascular Reserve before and after STA-MCA Bypass Surgery by SPECT and SPM Analysis

OBJECTIVE: The purpose of this study was to objectively assess the efficacy of superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery using Technetium (Tc)-99m-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients who underwent STA-MCA bypass surgery. MATERIALS AND METHODS: Brain perfusion SPECT images obtained at baseline and after the administration of acetazolamide were reconstructed using statistical parametric mapping in 23 patients, both before and after STA-MCA bypass surgery. The clinical outcomes of the surgery were also recorded and compared with the hemodynamic changes. A voxel with an uncorrected p-value of less than 0.001 was considered to be statistically significant. RESULTS: SPECT images of the territory supplied by the bypass graft showed an increase in both cerebrovascular flow and reserve at baseline, and the increase was significantly higher following the administration of acetazolamide. All patients showed improvement of clinical symptoms and increased blood flow to the left temporal, parietal, and frontal cortices as well as the thalamus. CONCLUSION: Brain SPECT effectively and objectively demonstrated the improved outcomes of STA-MCA bypass surgery, and thus may be used in postoperative analyses.

Nonlinear Dynamic Analysis Using Lyapunov Exponent of EEG in Patients with Schizophrenia / 대한정신약물학회지

OBJECT: It seemed worthwhile to estimate nonlinear measures of the electroencephalogram (EEG) in schizophrenic patients, because nonlinear measures might serve as indicators of the specific brain function in schizophrenia. METHOD: Previous studies which estimated the chaoticity in the brain of schizophrenia with nonlinear methods recorded the EEGs at limited electrodes, so we tried to record EEGs from 16 channels for nonlinear analysis in 19 patients with Schizophrenia and 8 healthy control subjects. We employed a new method to calculate the nonlinear invariant measures. For limited noisy data, this algorithm was strikingly faster and more accurate than previous ones. RESULTS: Our results showed that the schizophrenic patients had lower values of the largest positive Lyapunov exponent at the left inferior frontal and anterior temporal head regions compared with normal controls. CONCLUSIONS: These results suggest that the nonlinear analysis of the EEGs such as the estimation of the largest positive Lyapunov exponent seems to be a useful tool in analyzing EEG data to explore the neurodynamics of the brain of schizophrenic patients.

Nonlinear Dynamic Analysis in EEG of Alzheimer's Dementia: A Preliminary Report Using Correlation Dimension

The changes of electroencephalogram(EEG) in patients with dementia are most commonly studied by analyzing power or magnitude in certain traditionally defined frequency bands. However because of the absence of on identified metric which quantifies the complex amount of information, there are many limitations in using such a linear method. According to chaos theory, irregular signals of EEG cal also result from low dimensional deterministic chaos. Chaotic nonlinear dynamics in the EEG can be studied by calculating the correlation dimension. The authors have analyzed EEG epochs from three patients with dementia of Alzheimer type and three matched control subject. The result showed that patients with dementia of Alzheimer type had significantly lower correlation dimension than non-demented controls on 12 channels. Topographic analysis showed that the correlation dimensions were significantly lower in patients with Alzheimer's disease on frontal, temporal, central, and occipital head regions. These results show that brains of patients with dementia with dementia of Alzheimer type have a decreased complexity of electrophysiological behavior. We conclude that the nonlinear analysis such as calculating correlation dimension can be a promising tool for detecting changes in the complexity of brain dynamics.