Frequency-following response effect according to gender using a 10-Hz binaural beat stimulation.

BACKGROUND: Several studies have continuously investigated FFRs using binaural beat (BB) stimulations and their related effects. However, only a few studies have investigated the differences in BB stimulation effects according to basic demographic characteristics, such as gender and age. OBJECTIVE: This study aimed to determine the alpha wave activity after a 10-Hz BB stimulation and subsequently identify differences according to gender across all brain areas (frontal, central, parietal, temporal, and occipital areas). METHODS: A total of 23 healthy adults (11 male and 12 female), aged 20-29, participated in the study. For the 10-Hz BB stimulation, pure tone auditory stimuli of 250 and 260 Hz were given to the left and right ear, respectively. Through a power spectrum analysis of the phase-excluding BBs (non-BBs) and phase-including 10-Hz BBs (α-BBs), the alpha power at each brain area was estimated. These values were compared using a mixed-design ANOVA. RESULTS: With the exception of the temporal area, all other brain areas showed a significant increase in alpha power for α-BBs compared to those of non-BBs. However, the difference according to gender was not significant. CONCLUSION: The results indicated the lack of gender effects in alpha wave generation through a 10-Hz BB stimulation.

Increase in brain activation due to sub-tasks during driving: fMRI study using new MR-compatible driving simulator.

BACKGROUND: Several studies have used functional magnetic resonance imaging (fMRI) to show that neural activity is associated with driving. fMRI studies have also elucidated the brain responses associated with driving while performing sub-tasks. It is important to note that these studies used computer mouses, trackballs, or joysticks to simulate driving and, thus, were not comparable to real driving situations. In order to overcome these limitations, we used a driving wheel and pedal equipped with an MR-compatible driving simulator (80 km/h). The subjects drove while performing sub-tasks, and we attempted to observe differences in neuronal activation. METHODS: The experiments consisted of three blocks and each block consisted of both a control phase (1 min) and a driving phase (2 min). During the control phase, the drivers were instructed to look at the stop screen and to not perform driving tasks. During the driving phase, the drivers either drove (driving only condition) or drove while performing an additional sub-task (driving with sub-task condition) at 80 km/h. RESULTS: Compared to when the drivers were focused only on driving, when the drivers drove while performing a sub-task, the number of activation voxels greatly decreased in the parietal area, which is responsible for spatial perception. Task-performing areas, such as the inferior frontal gyrus and the superior temporal gyrus, showed increased activation. Performing a sub-task simultaneously while driving had affected the driver's driving. The cingulate gyrus and the sub-lobar region (lentiform nucleus, caudate, insula, and thalamus), which are responsible for error monitoring and control of unnecessary movements (e.g., wheel and pedal movements), showed increased activation during driving with sub-task condition compared to driving only condition. CONCLUSIONS: Unlike simple driving simulators (joysticks, computer mouses, or trackballs) used in previous research, the addition of a driving wheel and pedals (accelerator and brake) to the driving simulator used in this study closely represents real driving. Thus, the number of processed movements was increased, which led to an increased number of unnecessary movements that needed to be controlled. This in turn increased activation in the corresponding brain regions.

Differences in driving performance due to headway distances and gender: the application of jerk cost function.

Driving is directly controlled by the driver's movement. This study tried to compare differences in gender and headway distances between the DRIVING phase and the SUDDEN STOP phase by using subjects' movement during driving in the simulator. To quantify subjects' movement, the jerk cost function (JC) was used, and conventional vehicle control parameters such as the coefficient of variation of the mediolateral trajectory (MLCV) for lane keeping and the brake time (BT) were also used. As the headway distance increased, MLCV and JC decreased significantly in the DRIVING phase. In the SUDDEN STOP phase, BT was increased and, MLCV and JC were decreased. Differences between genders were detected for both MLCV (males < females) and JC (males > females). The results of this study demonstrate that JC may be used as a variable in evaluating driving performance as influenced by driving conditions and gender.

Effects of three levels of arousal on 3-back working memory task performance.

This study investigated how three levels of arousal affected performance of a 3-back working memory task. Ten female and ten male university students participated in this experiment. With pictures selected from a group test, three levels of arousal were induced--i.e., tense, neutral, and relaxed emotions. Each subject was run through the procedure three times, once for each arousal level. The procedure consisted of six phases for each arousal condition: (1) Rest 1 (2 min), (2) Picture 1 (presenting emotion arousing photos for 2 min), (3) 3-back working memory task 1 (2 min), (4) Picture 2 (presenting emotion-arousing photos for 2 min), (5) 3-back working memory task 2 (2 min), and (6) Rest 2 (2 min). The skin conductance level of electrodermal activity was also measured during all phases of the experiment. The accuracy rate of 3-back working memory task performance was the highest at a neutral emotional state, followed by relaxed and then tense emotional states. There were no significant differences in reaction time.

The effects of disruption in attention on driving performance patterns: analysis of jerk-cost function and vehicle control data.

This study analyzes the effects of attention disruption factors, such as sending text messages (STM) and performing searching navigation (SN) on driving performance patterns while actively driving, centering on motion signals. To this end, it analyzes not only data on control of the vehicle including the Anterior-Posterior Coefficient of Variation (APCV), Medial-Lateral Coefficient of Variation (MLCV), and Deviation of Vehicle Speed but also motion data such as the Jerk-Cost function (JC). A total of 55 drivers including 28 males (age: 24.1 ± 1.5, driving experience: 1.8 years ± 1.7 years) and 27 females (age: 23.8 ± 2.6, driving experience: 1.5 ± 1.0) participated in this study. All subjects were instructed to drive at a constant speed (90 km/h) for 2 min while keeping a distance of 30 m from the front car also running at a speed of 90 km/h. They were requested to drive for the first 1 min and then drive only (Driving Only) or conduct tasks while driving for the subsequent 1 min (Driving + STM or Driving + SN). The information on APCV, MLCV, and deviation of speed were delivered by a driving simulator. Furthermore, the motion signal was measured using 4 high-speed infrared cameras and based on the measurement results, JCs in a total of 6 parts including left shoulder (L.shoulder), left elbow (L.elbow), left hand (L.hand), right knee (R.knee), right ankle (R.ankle), and right toe (R.toe) were calculated. Differences among the results of 3 conditions of experiment, Driving Only, Driving + STM, and Driving + SN, were compared and analyzed in terms of APCV, MLCV, Deviation of Vehicle Speed, and JC. APCV and Deviation of Vehicle Speed increased in Driving + SN, rather than in Driving Only. MLCV increased in Driving + STM and Driving + SN, rather than in Driving Only. In the case of most JCs except that of L.hand, the values increased in Driving + SN, compared to Driving Only. This study indicated that JC could be a reliable parameter for the evaluation of driving performance patterns. In addition, it was discovered that additional tasks under driving, such as STM and SN, impaired smoothness or proficiency in driving motion, thereby increasing anterior-posterior and medio-lateral variability and deviation of speed.

Attitudes toward Olfaction: A Cross-regional Study.

This study aimed to determine whether there are regional influences on attitudes toward olfaction. A total of 1082 participants aged 21-50 years from 4 different regions (Mexican, Korean, Czech, and German) were asked to rate general attitudes toward olfaction in everyday life. To examine affective attitudes to odors (i.e., pleasantness), participants were also asked to list 3 odors as being the most pleasant or unpleasant, respectively. Next, the mentioned odor names were attributed to 1 of 4 main categories: "Food & Drink," "Social relationship," "Nature," and "Civilization" and the distribution of these categories was compared across regions. Mexicans were significantly different to the other regions in their general attitudes toward olfaction. In addition, in all regions, in comparison with men, women indicated a higher interest in the sense of smell. Moreover, a significant positive correlation was present between individuals' self-rating of olfactory sensitivity and general attitudes toward olfaction. Finally, there were significant cross-regional differences in affective attitudes toward specific categories of odors. In conclusion, our findings support and extend the notion that regions affect attitudes toward the olfactory world.

Activation of the limbic system under 30% oxygen during a visuospatial task: an fMRI study.

The purpose of this study was to observe activation of the limbic system during the performance of visuospatial tasks under 21% O(2) or 30% O(2). Eight right-handed male college students were selected as subjects for this study. A visuospatial task was presented while brain images were scanned by a 3T fMRI system. The experiment consisted of the following two runs: a visuospatial task under normal air (21% O(2)) and a visuospatial task under hyperoxia (30% O(2)). The accuracy rate on the visuospatial task was enhanced during 30% O(2) compared to 21% O(2). The neural activation areas of the limbic system were similar in the cingulate gyrus, thalamus, limbic lobe and parahippocampal gyrus. Increased neural activation was observed in the cingulate gyrus and thalamus under 30% O(2) compared to 21% O(2). Under 30% O(2), the improvement in visuospatial task performance was related to an increase in neural activation of subcortical structures, such as the thalamus and cingulate gyrus, as well as the cerebral cortex.

Influences of olfactory impairment on depression, cognitive performance, and quality of life in Korean elderly.

Despite high prevalence of olfactory loss in the elderly, this is typically overlooked. The aim of this study was to examine the impact of olfactory loss on depression, cognitive performance, and quality of life (QoL) in the general population of South Korea, and also to investigate the association between the above variables. A total of 127 Korean elderly aged from 65 to 89 years participated in this study. Olfactory sensitivity, depression, cognitive performance, and QoL were assessed with T&T olfactometry, the Geriatric Depression Scale, Mini-Mental State Examination, and a questionnaire for Geriatric Quality of Life, respectively. Subjects with severely impaired olfactory function showed a significantly higher degree of depression, lower cognitive performance, and decreased QoL compared to subjects with normal to moderately impaired olfaction. However, when controlling for cognitive performance, the olfactory sensitivity was not correlated with degrees of depression and QoL. In conclusion, our findings confirm the relationships of olfactory loss with depression, cognitive performance, and QoL; they also indicate that tests of olfactory function could be used in the screening for cognitive impairment.

A study on the cerebral sizes of Koreans in their 20S and 40S.

The purpose of this study was to measure the cerebral sizes of Korean adults in their third (20s) and fifth decades (40s) of life using Talairach-Nowinski reference points to determine the effect of sex and age on cerebral size and asymmetry. Magnetic resonance images of the brain of 94 adults between 20 and 29 years of age (43 males and 51 females) and 99 adults between 40 and 49 years of age (38 males and 61 females) were measured. The distance between reference points and cerebral size of males was greater than those of females. Cerebral width and the size of the left cerebrum of those in their 40s decreased more than those in their 20s. The effect of age on left cerebral atrophy of males was greater than that of females. Left cerebral size was greater than right cerebral size. There was no difference in cerebral asymmetry between the genders. Cerebral asymmetry of those in their 40s was smaller than of those in their 20s and the decrease of cerebral asymmetry of males due to age was greater than that of females. A positive relationship existed between cerebral height, and body height and weight for males in their 20s.

Cerebral lateralization index based on intensity of bold signal of FMRI.

This study proposes a new cerebral lateralization index (LI) on the basis of neural activation intensity. Eight right-handed male college students (mean age 23.5 years) and 10 right-handed male college students (the mean age 25.1 years) participated in this study of visuospatial and verbal tasks, respectively. Functional brain images were taken from 3T MRI using the single-shot EPI method. A cerebral LI based on neural activation area (i.e., number of activated voxels) and another based on neural activation intensity (i.e., intensity of BOLD (blood oxygen level dependent)) were calculated for both cognition tasks. The result of calculating a cerebral LI based on neural activation area suggested that the right hemisphere is dominant during visuospatial tasks and the left hemisphere is dominant during verbal tasks. When a cerebral LI was computed on the basis of the neural activation intensity, it was shown that the area of cerebral lateralization closely related to visuospatial tasks is the superior parietal lobe, and the area of cerebral lateralization closely related to verbal tasks is the inferior and middle frontal lobe. Since the proposed method can determine the dominance of the cerebrum by each area, it can be helpful to determine cerebral lateralization accurately and easily.

Development of the Real-Time Subjective Emotionality Assessment (RTSEA) system.

A new Real-Time Subjective Emotionality Assessment (RTSEA) system was developed for this study. The system is composed of two parts: an emotionality input and evaluation parts. An experiment was conducted in order to investigate the effectiveness of the RTSEA system. The present study compared Galvanic Skin Response (GSR) with the RTSEA by presenting 28 subjects with pictures that aroused either positive or negative emotion. Following the experiment, a subjective assessment using a questionnaire was given to the same subjects. According to the correlation coefficients, changes of the RTSEA had strong correlations with the changes of the GSR. Also, the questionnaire results showed marked similarity to the average responses of the RTSEA. In conclusion, the most remarkable characteristic of the present system is that it not only assesses the average emotionality when stimuli are presented, but also shows the trend of change in emotionality over time.

Young adult drivers' sensitivity to changes in speed and driving mode in a simple vehicle simulator.

The study was done to check replication of changes in sensitivity with a simple simulator as had been obtained in an experiment using the real road situation. Another purpose was to control simulator sickness which could have confounded data from testing with a simulator or in actual driving. Sensitivity of the drivers (72 healthy young adults, M age = 24 yr., SD = 5) while performing the driving task was measured in terms of subjective ratings of simulator sickness and affect, and physiological measures (i.e., galvanic skin responses and skin temperature) at different driving speeds and in driving mode conditions, using a simple vehicle simulator. Analysis showed measures of drivers' state, including simulator sickness, physiological indices, and subjective reports, increased with driving speed (30 --> 90 -->120 km/hr.) and driving mode change from the regular speed to sudden increasing to sudden decreasing speeds. Particularly, the results suggest that the increased autonomic nervous activation induces increase of rated simulator sickness. Based upon the same tendency in change of the simulator sickness and physiological state with driving speed and driving mode conditions, it was concluded that, if the results obtained from the simulator experiment can be generalized to the real situation, the simulator sickness must be considered a confounding factor. The results also suggest that the changes in human sensitivity are dependent upon aspects related to speed of a vehicle and driving mode.

Physiological evaluation on emotional change induced by imagination.

In this study, emotional changes were induced by four imaginations--pleasantness, unpleasantness, arousal, and relaxation. They were induced using situations or pictures, as stimuli for imagination, selected on the basis of subjective evaluation and were examined by analyses of the physiological signals of the central and autonomic nervous systems whether the intended emotions were appropriately achieved, and whether these emotional changes could be distinguished from the analysis of physiological signals. While participants were asked to recall each situation (for experiment 1--free recall) or picture (experiment 2--forced recall) of the four imaginations, Electroencephalogram (EEG) in the area of Fz and Cz, Electrocardiogram (ECG), Galvanic Skin Response (GSR), Skin Temperature (SKT), and Respiration (RSP) were measured. The analysis of the EEG revealed that three emotional states were classified by values of alpha/(alpha + beta) and beta/(alpha + beta) and the autonomic nervous system responses, particularly the average interval of R-R and RSP. The results suggest that the values of alpha/(alpha + beta) or beta/(alpha + beta) in the areas of Fz and Cz and the average interval of R-R and/or RSP can be reliable parameters to measure some of the emotional states.

Effects of oxygen concentrations on driver fatigue during simulated driving.

Driver fatigue has been the cause of traffic accidents. Despite this, the amount of time that drivers spend within cars has been increasing due to complex city life, traffic congestion, and particular occupational requirements. Consequently, fatigue and stress cannot be avoided. In present study, in order to find out the possibility for reducing fatigue while driving due to the supply of oxygen, driver fatigue resulting from the passage of time when different oxygen concentrations are supplied has been examined through subjective evaluations and reaction times using driving simulator for 10 male subjects. The results revealed the subjective fatigue feeling was highest in the low rate (18%) oxygen condition, while in the high rate (30%), it decreased to a certain extent. The feeling of sleepiness also showed the tendency to decrease somewhat in the case of the driving time having passed over 1h in the high-rate conditions. Also, the reaction time for braking after being instructed to suddenly stop following more than 2h of driving was reduced in the high-rate oxygen conditions compared to the low-rate oxygen condition. From the above results, it was shown that while driving a car, if the oxygen rate is lowered, fatigue is felt severely, and that in the case of supplying a high-rate of oxygen, the feeling of fatigue is lowered to some extent and the reaction time is shortened. It was suggested that the driver's fatigue can be reduced according to the supply of oxygen.

Psychophysiological evaluation of simulator sickness evoked by a graphic simulator.

The present study investigated the effects of simulator sickness, as an important bias factor on evaluation of emotional changes under the controlled condition of driving a car for 60 min at a constant speed (60 km/h) in a graphic simulator. Simulator sickness was measured and analyzed every 5 min using both subjective evaluation and physiological signals. Results of the subjective evaluation showed there was a significant difference between the rest and the driving conditions 10 min after the main experiment started and that the level of difference increased linearly with time. Analysis of the central and the autonomic nervous systems showed the significant differences in delta, theta, alpha and beta bands of an electroencephalogram (EEG), skin temperature, and the R-R interval between the rest and the driving conditions after about 5 min from the start of driving. In particular, there was the highest correlation between parameter of theta and subjective evaluation, and thus theta was considered an effective physiological parameter for numerically evaluating simulator sickness. The results indicate that physiological changes due to simulator sickness can be a bias factor in evaluation of human sensibility.

Analysis of mutual information content for EEG responses to odor stimulation for subjects classified by occupation.

To investigate the changes of cortico-cortical connectivity during odor stimulation of subjects classified by occupation, the mutual information content of EEGs was examined for general workers, perfume salespersons and professional perfume researchers. Analysis of the averaged-cross mutual information content (A-CMI) from the EEGs revealed that among the professional perfume researchers changes in the A-CMI values during odor stimulation were more apparent in the frontal region of the brain, while for the general workers and perfume salespersons such changes were more conspicuous in the overall posterior temporal, parietal and frontal regions. These results indicate that the brains of professional perfume researchers respond to odors mainly in the frontal region, reflecting the function of the orbitofrontal cortex (OFC) due to the occupational requirement of these subjects to discriminate or identify odors. During odor stimulation, the perfume salespersons, although relatively more exposed to odors than the general workers, showed similar changes to the general workers. The A-CMI value is in inverse proportion to psychological preferences of the professional perfume researchers and perfume salespersons, though this is not the case with the general workers. This result suggests that functional coupling for people who are occupationally exposed to odors may be related to psychological preference.