Spatiotemporal Analysis of Event-related Current Density Reveals Dissociable Effects of Arousal and Valence on Emotional Picture Processing

BACKGROUND: The processing of emotional visual stimulation involves the processing of emotional and visuoperceptual information. It is not completely revealed how the valence and arousal affect these two aspects. The objective was to investigate the effects of valence and arousal on spatiotemporal characteristics of cortical information processing using distributed source imaging of event-related current density (ERCD). METHODS: Electroencephalograms (64 channels) were recorded from 19 healthy men while presenting affective pictures. Distributed source localization analysis was adopted to obtain the spatiotemporal pattern of ERCD on cortical surface in response to emotional visual stimulation. A nonparametric cluster-based permutation test was used to find meaningful time and space without prior knowledge. RESULTS: Significant changes of ERCD in 400–800 ms among positive, negative, and neutral emotional conditions were found in left posterior cingulate cortex (PCC) and right inferior temporal cortex (ITC). In the PCC, the stimuli with higher arousal levels showed more negative ERCD than neutral stimuli. In the ITC, the ERCD for negative stimuli was significantly more negative than those of positive and neutral ones. CONCLUSION: Arousal and valence had strong influence on memory encoding and visual analysis at late period. The location and time showing significant change in neural activity according to arousal and valence would provide valuable information for understanding the changes of cortical function by neuropsychiatric disorders.

Cardiac Activation Associated with Non-Periodic Leg Movements in Comparison to Periodic Leg Movements during Sleep in Patients with Restless Legs Syndrome and Healthy Subjects

OBJECTIVES: Periodic leg movements in sleep (PLMS) are associated with arousals and autonomic activation, which may contribute to higher cardiovascular disease risk in patients with restless legs syndrome (RLS). Non-periodic leg movements in sleep (NPLM) are leg jerks in sleep that does not satisfy standard criteria of PLMS. The aim of this study was to evaluate impact of short-interval leg movements in sleep (SILMS) and isolated leg movements in sleep (ILMS) in comparison to PLMS on heart rate in both patients with RLS and healthy controls. METHODS: Seven idiopathic RLS patients and 9 controls were enrolled in this study. Polysomnographic studies were analyzed and leg movements (LM) were automatically detected. NPLM can be classified as SILMS and ILMS. SILMS are LM separated by an inter-movement interval (IMI) shorter than 10 s, and ILMS are LM with IMI longer than 90 s. Frequency and heart rate associated with SILMS, ILMS, and PLMS in RLS patients were compared to those in controls. Heart rate change associated with LM were determined for a fixed time window. RESULTS: Frequencies of SILMS and ILMS of patients with RLS were not significantly different to those of controls. RLS patients presented higher heart rate change associated with SILMS than PLMS before movement onset, while heart rate change associated with SILMS, ILMS, and PLMS were not different in the controls. CONCLUSIONS: Although the number of SILMS is not higher than PLMS, SILMS may have closely associated with higher cardiac activation of RLS than PLMS. Therefore, SILMS might be an important treatment target for patients with RLS to reduce long-term cardiovascular risk. Long-term prospective studies are needed to evaluate the relationship between NPLM and cardiovascular disease in patients with RLS.

Abnormal Sleep Delta Rhythm and Interregional Phase Synchrony in Patients with Restless Legs Syndrome and Their Reversal by Dopamine Agonist Treatment

BACKGROUND AND PURPOSE: The purpose of this study was to characterize abnormal cortical activity during sleep in restless legs syndrome (RLS) patients and to determine the effects of treatment with a dopamine agonist. Based on whole-brain electroencephalograms, we attempted to verify alterations in the functional network as well as the spectral power of neural activities during sleep in RLS patients and to determine whether the changes are reversed by treatment with pramipexole. METHODS: Twelve drug-naïve RLS patients participated in the study. Overnight polysomnography was performed before and after treatment: the first recording was made immediately prior to administering the first dose of pramipexole, and the second recording was made 12–16 weeks after commencing pramipexole administration. Sixteen age-matched healthy participants served as a control group. The spectral power and interregional phase synchrony were analyzed in 30-s epochs. The functional characteristics of the cortical network were quantified using graph-theory measures. RESULTS: The delta-band power was significantly increased and the small-world network characteristics in the delta band were disrupted in RLS patients compared to the healthy controls. These abnormalities were successfully treated by dopaminergic medication. The delta-band power was significantly correlated with the RLS severity score in the RLS patients prior to treatment. CONCLUSIONS: Our findings suggest that the spectral and functional network characteristics of neural activities during sleep become abnormal in RLS patients, and these abnormalities can be successfully treated by a dopamine agonist.

Differential Effect of Light Emitting Diode Light on Electroencephalographic Oscillations in Young and Old Healthy Subjects

OBJECTIVES: To investigate brain oscillatory characteristics according to brightness and color temperature of light emitting diode (LED) light in young and elderly subjects. METHODS: We analyzed 22 young (age, 29.0±5.2 years) and 23 elderly (age, 64.8±4.5 years) healthy subjects. A LED light source was used with a combination of two color temperature (6,500 K vs. 3,000 K) and two brightness (700 lx vs. 300 lx) conditions. Participants were exposed to each light condition in relaxed wakefulness. Then, we analyzed power spectral density and functional connectivity from eye-open electroencephalography. RESULTS: A main effect of brightness on delta (p=0.044) and theta (p=0.038) power was significant in the elderly subjects. Bright light enhanced delta and theta power in the frontal region. By contrast, power spectral density of young subjects was affected by color temperature; high color temperature significantly increased beta-band power of the central region (p=0.034). Regarding functional connectivity, a significant effect of color temperature was observed in delta (p=0.006) and beta (p=0.046) frequencies. High color temperature light enhanced beta connectivity of young subjects (p=0.007), while not affecting that of elderly subjects (p=0.979). CONCLUSIONS: The present study demonstrated that spectral power and functional connectivity as well as subjective feelings are affected by the brightness and color temperature of LED light. These results might help us to understand the neurophysiological effects of light and identify the optimal indoor lighting conditions for an individual's environment.

Evaluation of the Efficacy and Tolerability of Isradipine in the Treatment of Mild to Moderate Hypertension

An open clinical trial was conducted to evaluate the efficacy and tolerability of isradipine in 30 cases (male 16, female 14 cases, average age 52.6+/-7.94) of mild to moderate essential hypertension using 1.25-2.5mg twice a day for 8 weeks of active treatment. Blood pressure was significantly reduced from 168.5+/-14.33/108.3+/-6.37mmHg, 163.7+/-9.74/105.5+/-7.1mmHg to 141.0+/-13.69/92.0+/-9.27mmHg, 138.8+/-13.46/92.3+/-11.16mmHg in sitting and standing position respectively. The extent of reduction was 27.5/16.3mmHg in sitting position and 29.9/13.2mmHg in standing position. This comprised the mean response rate in terms of reduction of DBP of 10mmHg or more being 90% and the normalization rate, deficed as DBP lowering to 90mmHg or below, being 70%. Heart rate, hematology and blood chemistry including blood sugar and lipids were not changed significantly after treatment with isradipine. No significantl side effect was observed except 2 cases of mild transient facial flushing and nausea during the treatment, so could proceed the trial without drug discontinuation in all 30 cases. The results suggest that isradipine is one of the useful and safe drugs in the treatment of mild to moderate essential hypertension.

Clinical Effects of Isosorbide 5-Mononitrate(Elantan(R)) on Angina Pectoris

An open trial was carried out to investigate the efficacy and tolerance of isosorbide 5-mononitrate(Elantan(R)) in 30 patients diagnosed as angina pectoris at Pusan national university hospital. Drugs were given 20mg two times daily for 2 to 3 weeks and the results were assessed in terms of effects on anginal pain and untoward side effects experienced during administration of medication. Treament resulted in an overall improvement in 25 patients(83.4%), complete abolition of anginal attacks in 17 patients(56.7%) and reduction in frequency of attacks in 8 patients(26.7%). So called "Nitrated headache" was observed in 5 patients(16.6%) but improved with proceeding of administration in 3 patients. This trial indicates that isosorbide 5-mononitrate should be efficacious as well as tolerated in patients with coronary heart disease.