• PNF and Movement
• /
• v.14 no.3
• /
• pp.209-217
• /
• 2016

Purpose: Treatments using a mirror neuron system, such as 3D virtual reality therapy, are used in stroke rehabilitation, but they need to be constructed according to a detailed procedure. The aims of this study were to analyze electroencephalograms (EEG) during relaxation and action while observing first person perspective (1AE) and third person perspective (3AE) videos of the right hand for 20's. Methods: Thirty participants (Male=4, Female=26) were recruited for this study. Participants were selected by a vividness of movement imagery questionnaire (VMIQ). EEG was measured during relaxxation and during action with 1AE and 3AE videos, focusing on the supination and pronation actions of participants' right hands. An absolute mu rhythm, a relatively high alpha power, and a relative beta power were identified. In each group, one-way repeated measures ANOVA was used for statistical analysis. Results: Measurement of absolute mu rhythms was significantly suppressed for both 1AE and 3AE compared with relaxation in C3 and C4 regions. High alpha wave measurements were significantly suppressed for both 1AE and 3AE in all regions, while beta wave measurements were significantly increased only for 3AE in F3 and F4 regions. Conclusion: Based on this study, we suggest that the mirror neuron system is activated during actions accompanied by action observation, especially actions with 3AE video observation, which can be a great therapeutic mathod in stroke rehabilitation.

• Proceedings of the Korean Society for Cognitive Science Conference
• /
• 2010.05a
• /
• pp.37-41
• /
• 2010

The previous investigations of electroencephalogram (EEG) activity in the memory retrieval tasks demonstrated that event-related potentials (ERP) during recollection showed different durations and the peak levels from those without recollection. However, it has been unknown that recollection in memory retrieval also modulates high-frequency brain rhythms as well as establishes large-scale synchronization across different cortical areas. In this study, we examined the spectral components of the EEG signals, especially the gamma bands (20-80Hz), measured during the memory retrieval tasks. Specifically, we focused on two major spectral components: first, we evaluated the temporal patterns of the power spectral density before and after the onset of the memory retrieval task; second, we estimated phase synchrony between all possible pairs of EEG channels to evaluate large-scale synchronization. Fourteen healthy subjects performed the memory retrieval task in the virtual reality environment where they selected whether or not t he present item was seen in the previous training period. When the subjects viewed the unseen items, the middle gamma power (40-60Hz) appeared to increase 200-500ms after stimulus onset while the low gamma power (20Hz) was suppressed all the way through the post-stimulus period 150ms after onset. The degree of phase synchronization in this low gamma level, however, increased when the subjects fetched the item from memory. This suggests that phase synchrony analysis might reveal different aspects of the memory retrieval process than the gamma power, providing additional information to the inference on the brain dynamics during memory retrieval.

• Journal of Biomedical Engineering Research
• /
• v.26 no.4
• /
• pp.223-230
• /
• 2005

This paper presents a new approach to investigate spatial correlation between independent components of brain alpha activity in functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). To avoid potential problems of simultaneous fMRI and EEG acquisitions in imaging pure alpha activity, data from each modality were acquired separately under a 'three conditions' setup where one of the conditions involved closing eyes and relaxing, thus making it conducive to generation of alpha activity. The other two conditions -- eyes open in a lighted room or engaged in a mental arithmetic task, were designed to attenuate alpha activity. Using a Mixture Density Independent Component Analysis (MD-ICA) that incorporates flexible non-linearity functions into the conventional ICA framework, we could identify the spatiotemporal components of fMRI activations and EEG activities associated with the alpha rhythm. Then, the sources of the individual EEG alpha activity component were localized by a Maximum Entropy (ME) method that is specially designed to find the most probable dipole distribution minimizing the localization error in sense of LMSE. The resulting active dipoles were spatially transformed to 3D MRls of the subject and compared to fMRI alpha activity maps. A good spatial correlation was found in the spatial distribution of alpha sources derived independently from fMRI and EEG, suggesting the proposed method can localize the cortical areas responsible for generating alpha activity successfully in either fMRI or EEG. Finally a functional connectivity analysis was applied to show that alpha activity sources of both modalities were also functionally connected to each other, implying that they are involved in performing a common function: 'the generation of alpha rhythms'.

• Clinical and Experimental Pediatrics
• /
• v.54 no.1
• /
• pp.22-28
• /
• 2011

Purpose: To investigate the clinical characteristics of late-onset epilepsy combined with autism spectrum disorder (ASD), and the relationship between certain types of electroencephalography (EEG) abnormalities in ASD and associated neuropsychological problems. Methods: Thirty patients diagnosed with ASD in early childhood and later developed clinical seizures were reviewed retrospectively. First, the clinical characteristics, language and behavioral regression, and EEG findings of these late-onset epilepsy patients with ASD were investigated. The patients were then classified into 2 groups according to the severity of the EEG abnormalities in the background rhythm and paroxysmal discharges. In the severe group, EEG showed persistent asymmetry, slow and disorganized background rhythms, and continuous sharp and slow waves during slow sleep (CSWS). Results: Between the two groups, there was no statistically significant difference in mean age (P=0.259), age of epilepsy diagnosis (P=0.237), associated family history (P=0.074), and positive abnormal magnetic resonance image (MRI) findings (P=0.084). The severe EEG group tended to have more neuropsychological problems (P=0.074). The severe group statistically showed more electrographic seizures in EEG (P=0.000). Rett syndrome was correlated with more severe EEG abnormalities (P=0.002). Although formal cognitive function tests were not performed, the parents reported an improvement in neuropsychological function on the follow up checkup according to a parent's questionnaire. Conclusion: Although some ASD patients with late-onset epilepsy showed severe EEG abnormalities, including CSWS, they generally showed an improvement in EEG and clinical symptoms in the longterm follow up. In addition, severe EEG abnormalities tended to be related to the neuropsychological function.

• Development and Reproduction
• /
• v.16 no.1
• /
• pp.53-58
• /
• 2012

Circadian rhythmicity (e.g. secretory pattern of hormones) plays an important role in the control of reproductive function. We hypothesized that the alteration of feeding pattern via meal time shift/restriction might disrupt circadian rhythms in energy balance, and induce changes in reproductive activities. To test this hypothesis, we employed simple animal model that not allowing $ad$ $libitum$ feeding but daytime only feeding. The animals of $ad$ $libitum$ feeding group (Control) have free access to food for 4 weeks. The day feeding (=reverse feeding, RF) animals (RF group) have restricted access to food during daytime (0900-1800) for 4 weeks. After completing the feeding schedules, body weights, testis and epididymis weights of animals from both group were not significantly different. However, the weights of seminal vesicle (control : RF group = $0.233{\pm}0.014g$ : $0.188{\pm}0.009g$, $p$<0.01) and prostate (control : RF group = $0.358{\pm}0.015g$ : $0.259{\pm}0.015g$, $p$<0.001) were significantly lower in RF group animals. The mRNA levels of pituitary common alpha subunit ($C{\alpha}$; control : RF group = $1.0{\pm}0.0699$ AU : $0.1923{\pm}0.0270$ AU, $p$<0.001) and $FSH{\beta}$ (control : RF group = $1.0{\pm}0.1489$ AU : $0.5237{\pm}0.1088$ AU, $p$<0.05) were significantly decreased in RF group. The mRNA levels of ACTH were not significantly different. We were unable to find any prominent difference in the microstructures of epididymis, and there were slight alterations in those of seminal vesicles after 4 weeks of reversed feeding when compared to control samples. The present study demonstrates that the shift and/or restriction of feeding time could alter the pituitary gonadotropin expression and the weights of seminal vesicle and prostate in rats. These data suggest the lowered gonadotropin inputs may decrease androgen secretion form testis, and consequently results in poor response of androgen-dependent tissues such as seminal vesicle and prostate.

• Sleep Medicine and Psychophysiology
• /
• v.27 no.1
• /
• pp.1-7
• /
• 2020

Mobile digital devices are very familiar and useful devices in the daily life of modern people, and are used for various tasks such as communication, reading, writing, and playing media. As the use of mobile digital devices has become more prevalent, user time has also been increasing. In particular, the number of people who use digital devices before sleep is growing. The light pollution associated with these devices is classified into four categories: urban sky glow, glare, light trespass, and clutter. The pattern in which modern people use digital devices corresponds to light pollution caused by light trespass and clutter from light exposure to artificial light at night. The light pollution caused by digital devices can cause melatonin secretion suppression, delayed sleep onset, reduction of sleepiness before bedtime, and periodic rhythm and cognitive function disturbances. In addition, a study of children and adolescents showed there may be disturbances in the sleep-wake cycle and circadian rhythm, deterioration of sleep quality, and daytime fatigue due to light pollution caused by artificial light at night from mobile digital devices. A multi-faceted research effort is also necessary to investigate the healthy use of mobile digital devices based on research evidence and insights with an accurate evaluation of the influence of mobile digital devices as a form of light pollution.

• Phonetics and Speech Sciences
• /
• v.4 no.2
• /
• pp.61-70
• /
• 2012

The current study observes the durational interaction of tautosyllabic consonants and vowels in the word-initial position of English and Korean child-directed speech (CDS). The effect of phonological laryngeal contrasts in stops on the following vowel duration, and the effect of the intrinsic vowel duration on the release duration of preceding stops in addition to the acoustic realization of the contrastive segments are explored in different prosodic contexts - phrase-initial/medial, focal accented/non-focused - in a marked speech style of CDS. A trade-off relationship between Voice Onset Time (VOT), as consonant release duration, and voicing phonation time, as vowel duration, reported from adult-to-adult speech, and patterns of durational variability are investigated in CDS of two languages with different linguistic rhythms, under systematically controlled prosodic contexts. Speech data were collected from four native English mothers and four native Korean mothers who were talking to their one-word staged infants. In addition to the acoustic measurements, the transformed delta measure is employed as a variability index of individual tokens. Results confirm the durational correlation between prevocalic consonants and following vowels. The interaction is revealed in a compensatory pattern such as longer VOTs followed by shorter vowel durations in both languages. An asymmetry is found in CV interaction in that the effect of consonant on vowel duration is greater than the VOT differences induced by the vowel. Prosodic effects are found such that the acoustic difference is enhanced between the contrastive segments under focal accent, supporting the paradigmatic strengthening effect. Positional variation, however, does not show any systematic effects on the variations of the measured acoustic quantities. Overall vowel duration and syllable duration are longer in English tokens but involve less variability across the prosodic variations. The constancy of syllable duration, therefore, is not found to be more strongly sustained in Korean CDS. The stylistic variation is discussed in relation to the listener under linguistic development in CDS.

• Safety and Health at Work
• /
• v.9 no.2
• /
• pp.203-209
• /
• 2018

Background: Night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue. This study set out to measure cognitive performance, melatonin rhythms, and sleep after different consecutive night shifts (7 vs. 4) among control room operators (CORs). Methods: The participants included 60 CORs with a mean age of 30.2 years (standard deviation, 2.0) from a petrochemical complex located in Southern Iran. Cognitive performance was assessed using the n-back task and continuous performance test. To evaluate melatonin, saliva was collected and tested by enzyme-linked immunosorbent assay. To assess sleep and sleepiness, the Pittsburgh Sleep Quality Index and Karolinska Sleepiness Scale were used, respectively. Results: Individuals who worked 7 consecutive night shifts had a significantly better cognitive performance and sleep quality than those who worked 4 consecutive night shifts. However, salivary melatonin profile and sleepiness trend were not affected by shift type. Conclusion: The main duty of CORs working night shifts at the studied industry included managing safety-critical processes through complex displays; a responsibility that demands good cognitive performance and alertness. It is suggested that an appropriate number of consecutive night shifts in a rotating shift system should be planned with the ultimate aim of improving CROs performance/alertness and enhancing safety.

• Journal of Veterinary Clinics
• /
• v.27 no.4
• /
• pp.440-444
• /
• 2010

A 7-year-old neutered male Shih Tzu dog weighing 5.2 kg was presented because of severe neurological signs (paddling, unconsciousness, blindness, seizure). ECG revealed accelerated idioventricular rhythm (AIVR) with ~140 bpm ventricular rate. Based on magnetic resonance imaging (MRI) study and cerebrospinal fluid (CSF) analysis, the neurological condition was tentatively diagnosed as disseminated granulomatous meningoencephalomyelitis (GME). The neurological signs were managed with steroids, anticonvulsive drugs, diuretics and antibiotics with 20% mannitol infusion. The rhythm disturbance (AIVR) was managed with oral medication of mexiletine. Because the heart rhythms were unstable without anti-arrhythmic therapy in spite of improvement of clinical signs after emergency treatment for neurological problems, the anti-arrhythmic therapy was maintained till the neurological signs were abolished.

• The Journal of the Korea Contents Association
• /
• v.12 no.11
• /
• pp.527-538
• /
• 2012

The purpose of this study was to suggest a new direction for the development of children's music education and to provide a basis for the development of improved music education program for children through the qualitative investigation of what 'musicing' means to children on the basis of musical experiences - singing, listening, body expression, learning rhythms and time, playing instruments - in the children's comprehensive musical activities. The study was carried out from September $5^{th}$, 2011 to November $25^{th}$, 2011, on 15 4-years-old children in Haetnim-class, in S nursery, in the city of D. The observations were recorded in the field and materialized, and the collected materials were categorized and analyzed. The results of the study suggests that 'doing music' to children means 'making movements,' 'sharing emotions through imitation,' 'fun activity that one can look forward to,' 'musical instruments as playthings,' and 'finding 'the true me'.