Osamu Mandai

An ERP investigation of emotional processing in European and Japanese individuals

This article examined neural time course differences in the processing of emotional pictures in European and Asian individuals. Event-related potentials (ERPs) were recorded in 15 French and 15 Japanese volunteers during the presentation of neutral and emotional pictures in their own country. ERPs were analyzed by means of spatio-temporal Principal Component Analysis (PCA) and allow to evaluate cultural influences on emotional processing along three temporal windows: 105 to 140 ms, 176 to 230 ms and 255 to 455 ms. Main results highlight that (1) early ERP components coded emotional charge but were not modulated by cultural background, (2) later components showed a significant decrease of amplitudes at parieto-occipital areas for Japanese participants compared to French ones in emotional condition. These findings suggest that, in both populations, similar neurocognitive processes are involved in the early stage of the emotional stimuli processing and effects observed on later components may reflect a poorer engagement of parietal areas, known to be involved in emotional arousal dimension. Considering that cognitive judgments were similar in both populations, electrophysiological findings suggest that cultural influences on later stage of emotional processing could be related to the known lower level of emotionally expressive behavior in Japanese than in Caucasians.

Diurnal Emotional States Impact the Sleep Course.

Background Diurnal emotional experiences seem to affect several characteristics of sleep architecture. However, this influence remains unclear, especially for positive emotions. In addition, electrodermal activity (EDA), a sympathetic robust indicator of emotional arousal, differs depending on the sleep stage. The present research has a double aim: to identify the specific effects of pre-sleep emotional states on the architecture of the subsequent sleep period; to relate such states to the sympathetic activation during the same sleep period. Methods Twelve healthy volunteers (20.1 ± 1.0 yo.) participated in the experiment and each one slept 9 nights at the laboratory, divided into 3 sessions, one per week. Each session was organized over three nights. A reference night, allowing baseline pre-sleep and sleep recordings, preceded an experimental night before which participants watched a negative, neutral, or positive movie. The third and last night was devoted to analyzing the potential recovery or persistence of emotional effects induced before the experimental night. Standard polysomnography and EDA were recorded during all the nights. Results Firstly, we found that experimental pre-sleep emotional induction increased the Rapid Eye Movement (REM) sleep rate following both negative and positive movies. While this increase was spread over the whole night for positive induction, it was limited to the second half of the sleep period for negative induction. Secondly, the valence of the pre-sleep movie also impacted the sympathetic activation during Non-REM stage 3 sleep, which increased after negative induction and decreased after positive induction. Conclusion Pre-sleep controlled emotional states impacted the subsequent REM sleep rate and modulated the sympathetic activity during the sleep period. The outcomes of this study offer interesting perspectives related to the effect of diurnal emotional influences on sleep regulation and open new avenues for potential practices designed to alleviate sleep disturbances.

Pre-sleep emotional induction affects REM rate and sympathetic activity during sleep

Background: Insufficient sleep is linked to enhanced risk of developing hypertension; however, the mechanism by which this occurs is currently unknown. In this study we sought to evaluate the effects of experimental sleep restriction on spontaneous baroreflex sensitivity. Methods: Five healthy subjects (4 female; age 23 ± 1 years) underwent a 4-day period of acclimation followed by 9 days of experimental sleep restriction (4 hours of sleep per night – from 12:30 AM to 4:30 AM). Beat-by-beat heart rate (HR, ECG) and blood pressure (BP, Finometer) were measured during 15 minutes of quiet rest. Spontaneous cardiac baroreflex (BRS) sensitivity was determined using spectrum analysis. Subjects were studied on Day 2 (Acclimation) and Day 13 (Restriction). Results: Resting BP and HR were not different between acclimation and experimental sleep restriction (SBP: 127 ± 5 vs 133 ±3 mmHg, p = 0.13; DBP: 79 ± 2 vs 80 ± 4 mmHg, p = 0.21; HR: 68 ±3 vs 73± 4 BPM, p = 0.8). BRS gain was significantly blunted during sleep restriction when compared to the acclimation period (18 ± 2 vs 13 ± 2%, p b 0.01). Conclusion: Acute experimental sleep restriction in young healthy adults results in a reduction of cardiac baroreflex sensitivity prior to obvious/overt changes in resting BP. These data suggest that impaired baroreflex function may be an early contributing factor to the high prevalence of hypertension and cardiovascular diseases in the sleep deprived general population.