Jae-Woong Yang

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.

Difference between smokers and non-smokers in the corpus callosum volume.

The purpose of this study was to analyze the effects of smoking on corpus callosum volume. In addition, the relationships between smoking duration, smoking frequency, and corpus callosum volume were analyzed. Magnetic resonance brain images were acquired for 58 normal Korean men (30 smokers (age 32.82±14.12 years) and 28 non-smokers (age 35.49±13.11 years)). The corpus callosum volume was measured using Brain Voyager 2000S/W and was normalized by intracranical volume, which was calculated using cerebral sizes. The corpus callosum volume for smokers was significantly smaller than that for non-smokers. Also, there was a negative correlation between corpus callosum volume and smoking duration. The change of white matter volume (e.g., corpus callosum) might be a primary factor for characterizing the effects of smoking.

Changes in Cognitive Performance Due to Three Types of Emotional Tension

The purpose of this study was to investigate how three types of emotional tension levels affect performance of a cognitive task. Ten university male (age 25.7 ±1.5) and ten female (age 24.5 ±1.8) students participated in this experiment. We used a 3-back task as a cognitive task. Using pictures selected from a group test, three types of tension levels, i.e. tensed, neutral, and relaxed emotions, were induced. The experimental design consisted of six phases; Rest 1 (2 min), Picture 1 (presenting emotion tensioning photos for 2 min), 3-back Task 1 (2 min), Picture 2 (presenting emotion tensioning photos for 2 min), 3-back Task 2 (2 min), and Rest 2 (2 min). Galvanic skin response (GSR) was also measured during all phases of the experiment. The accuracy rate of 3-back task performance was the highest at a neutral emotional state, followed by relaxed and then tensed emotional state. Through this study it could be inferred that tension, induced by stimuli unrelated to cognitive tasks, decreases the performance of cognitive tasks.

Long-term study of simulator sickness: Differences in psychophysiological responses due to individual sensitivity

The purpose of the present study was to clear the differences of psychophysiological responses due to individual sensitivity of simulator sickness. The present experiment tried to investigate the simulator sickness objectively by observing the change of the simulator sickness for the different level of sickness groups (sick and non-sick group). The subjective evaluations using Simulator Sickness Questionnaire (SSQ) and physiological responses were measured every five minutes when they were driving as 60km/h in the driving graphic simulator. Response level of the subjective evaluation for all subjects on the simulator sickness was linearly increased with time for every item, and the response level of sick group was bigger than that of non-sick group. When the analysis on central nervous system was done separately on the sick and the non-sick group, there was significant difference in the parameter θ/total at Fz and Cz. Although the analysis on autonomic nervous system for all subjects showed the increased activation of sympathetic nervous system, there was no significant difference between the sick and non-sick group. In summary, the parameters to distinguish between the sick and non-sick group were the change on θ/total and subjective evaluation using SSQ.

Prioritizing problem features in Korean patients with senile dementia for implementation of monitoring technologies

The purpose of this study was to investigate the central problem features of Korean patients with senile dementia and to prioritize the features according to risk to the patient with a view to the implementation of remote monitoring technologies. Twenty central problem features were extracted using factorial analysis. The frequency of violent language and confabulation, gathering, and repetition was significantly greater in female than in male patients with senile dementia. All central features, with the exception of abnormal sexual behavior and audiovisual deficits, differed in frequency between the normal elderly and the senile dementia patients and between patients with dementias of different severity. Judgment disorder was the greatest differentiating factor between the normal elderly and the patients with senile dementia. For dementia severity, memory disorder was the greatest differentiating factor of severe versus mild dementia. When risk to the patient was analyzed, problems of perception were identified as the problem features of highest priority.

Effects of Secondary Tasks on Vehicle Speed and Distance during Driving and Brake Response Time during Unexpected Situation

The purpose of this study was to investigate the effects of the secondary tasks such as sending text message(STM) and searching navigation(SN) on vehicle speed and distance during driving and brake response time during unexpected situation using a driving simulator. The participants included 19 college students; 9 males aged 25.2±1.0 with 2.4±2.0years of driving experiences and 10 females aged 21.4±0.5 with 1.3±0.5years of driving experiences. All subjects were instructed to keep a certain distance(30m) from the car ahead and a constant speed(100㎞/h). Average speed and average following distance were measured during 10 seconds before unexpected situation. Also, brake response time after unexpected situation was measured. Average speed was more decreased and average following distance was more increased during the driving with secondary tasks than driving only. Male maintained the assigned speed and distance better than female. The brake response time was faster during driving only than the driving with secondary tasks. And the brake response time of male was shorter than that of female.

A simple 5-DoF MR-compatible motion signal measurement system

The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and power supply were located in a shielded case, which was made of copper and aluminum. The motion signal was modulated to an optic signal using pulse width modulation, and the modulated optic signal was transmitted outside the MR shield room using a high-intensity light-emitting diode and an optic cable. The motion signal was recorded on a PC by demodulating the transmitted optic signal into an electric signal. Various kinematic variables, such as angle, acceleration, velocity, and jerk, can be measured or calculated by using the motion measurement system developed here. This system also enables motion tracking by extracting the position information from the motion signals. It was verified that MR images and motion signals could reliably be measured simultaneously.

Gender Differences of Heart Rate due to Change of Supply Rate of Highly Concentrated Oxygen

ABSTRACT The purpose of this study was to examine differences between male and female in heart rate due to 93% oxygen administration of the three levels (1L/min, 3L/min, and 5L/min). Ten healthy male (25.0±1.8years) and ten female (23.7±1.9years) college students were selected as the subjects for this study. The experiment consisted of three runs, i.e., the three levels of 93% oxygen administration, respectively. The each run consisted of three phases, i.e., Rest 1 (5min), Hyperoxia (10min), and Rest 2 (5min). Heart rate was measured throughout the three phases. Heart rate was decreased during hyperoxia compared to Rest 1 and 2. By increasing the supply rate of highly concentrated oxygen, △1 (decreasing rate of heart rate during hyperoxia compared to Rest 1) was increased. And △2 (decreasing rate of heart rate during hyperoxia compared to Rest 2) of male was lower than fe male, regardless of supply rate. Keyword: Heart rate, Highly concentrated oxygen, Supply rate, Gender 1. 서 론 인간은 인지 처리를 수행하게 되면 뇌 신경 조직에 글루코스와 산소를 공급하기 위한 다양한 생리 변화가 발생하게 된다[Jonides et al., 1997]. 즉, 인지 처리의 수행은 심박동율, 호흡, 산소 소모의 증가와 같은 생리 변화를 유발한다[Backs and Selihos, 1994]. 외부에서의 산소 공급이 인지 능력에 긍정적인 역할을 한다는 사실이 보고되었다[Moss et a l., 1998; Winder and Borrill, 1998; Scholey et al., 1999; Sung et al., 2002; Chung et al., 2004; Chung et al., 2006, 2007, 2008a, 2008b, 2008c]. 자동차 운전 중 산소 농도가 저하되면 현저한 피로를 느끼게 되나 고농도 산소를 공급하는 경우 피

Analysis of Skin Conductance Level for Cognitional and Emotional Responses associated with Unexpected Situation during Driving

ABSTRACT The purpose of this study was to analyze the skin conductance level (SCL) induced by unexpected situation which reflected the emotional and cognitional responses during driving. The participants included 57 college graduates; 28 males aged 24.5±1.3 with 2.3±1.5 years of driving experiences and 29 females aged 23.6±2.6 with 2.2±1.7 years of driving experience. Reaction time of brake, averaged SCL, maximum SCL, and rising time to maximum amplitude were measured. They were analysed according to condition (crash, non-crash) and gender (male, female). The reaction time of brake was more faster and averaged SCL was greater during non-crash condition than during crash condition. There were no significant differences between male and female drivers in the reaction time of brake and averaged SCL whether or not it crash. There were no significant differences between crash and non-crash conditions in the maximum SCL and rising time to maximum amplitude, but there were significant differences between male and female in them. These results support the hypothesis that averaged SCL is more related to cognitional response and maximum SCL and rising time to maximum amplitude are more related to emotional responses. Keywords: Unexpected situation, Skin conductance level, Cognitional and emotional responses, Crash and non-crash, Gender

Development of a Magnetic Resonance Compatible Motion Signal Measurement System

The purpose of this study was to develop 3-axis Magnetic Resonance (MR) compatible motion measurement system which can measure motion signals without deteriorating MR image. 3-axis accelerometer was used to measure motion signals and velcro was used to attach accelerometer module to finger or wrist. To minimize mutual interference effect between MR imaging system and motion measurement system, amplifier circuit was made of analog devices and amplifier was located at the shielded case which was made of copper and aluminum. Motion signal was modulated to optic signal by using Pulse Width Modulation (PWM) and modulated optic signal was transmitted to outside MR room by using Light Emitting Diode (LED) and optic cable. Measurement of 3-directional acceleration was possible with 3-axis accelerometer. It was verified that functional Magnetic Resonance imaging (fMRI) and motion signals were measured simultaneously and stably.