Kichun Nam

MEG study on neural activities associated with syntactic and semantic violations in spoken Korean sentences.

We carried out an magnetoencephalography (MEG) study to record cortical responses elicited in the left hemisphere by ending verb phrases, which had syntactic or semantic anomalies, in Korean sentences of subject-object-verb order. Using the high temporal and spatial resolution of MEG, the study was aimed at identifying neural activities that occur during a latency course associated with the syntactic or semantic process in the spoken sentence. Major responses, distinct from the responses to normal sentences, were observed in two latency periods of about 400 and 600 ms following the onset of the verb phrase. Source localization of the grand average fields indicated separate activities in the inferior frontal region and the vicinity of the auditory cortex for the first 400-ms response to the syntactic anomaly. The region around the auditory cortex was indicated for the response to the semantic anomaly in a similar latency. The second 600-ms response indicated activity around the middle temporal gyrus inferior to the auditory cortex for both syntactic and semantic anomalies. The results are discussed with reference to the ERP components established for Indo-European languages, and the possibility of concurrent processing of syntactic and semantic aspects is suggested.

Impact of lingual gyrus volume on antidepressant response and neurocognitive functions in Major Depressive Disorder: a voxel-based morphometry study.

BACKGROUND Voxel-based morphometry (VBM) has demonstrated structural brain changes between patients with Major Depressive Disorder (MDD) and healthy individuals. The initial response to antidepressants is crucial to predict prognosis in the treatment of MDD. The aim of the present study was to investigate gray matter abnormalities predicting antidepressant responsiveness and the relationships between volumetric differences and clinical/cognitive traits in MDD patients. METHODS Fifty MDD patients who received 8 week period antidepressant treatment and 29 healthy controls participated in this study. VBM was applied to assess structural changes between MDD groups and control group. Neuropsychological tests were conducted on all participants. RESULTS Both treatment responsive and non-responsive patients showed a significant volume reduction of the left insular, but only non-responsive patients had decreased volume in the right superior frontal gyrus compared to healthy controls. The comparison between treatment responsive and non-responsive patient groups demonstrated a significant difference in gray matter volume in the lingual gyrus. The larger volume of lingual gryus predicted early antidepressant response, which was attributable to better performance in neuropsychological tests. LIMITATION This study included a small sample size and the patients received various antidepressants and benzodiazepines. CONCLUSION Our findings suggest that the patients who responded poorly to antidepressants were morphologically and cognitively impaired, whereas the treatment responsive patients showed less structural changes and relatively preserved cognitive functions. The lingual gyrus may be a possible candidate region to predict antidepressant responsiveness and maintained cognition in MDD.

Enhanced saccadic control in young people with Tourette syndrome despite slowed pro-saccades

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by motor and vocal tics. Tics are repetitive and uncontrolled behaviours that have been associated with basal ganglia dysfunction. We investigated saccadic eye movements in a group of young people with TS but without co-morbid ADHD. Participants performed two tasks. One required them to perform only pro-saccade responses (pure pro-saccade task). The other involved shifting, unpredictably, between executing pro- and anti-saccades (mixed saccade task). We show that in the mixing saccade task, the TS group makes significantly fewer errors than an age-matched control group, while responding equally fast. By contrast, on the pure pro-saccade task, the TS group were shown to be significantly slower to initiate and to complete the saccades (longer movement duration and decreased peak velocity) than controls, while movement amplitude and direction accuracy were not different. These findings demonstrate enhanced shifting ability despite slower reflexive responding in TS and are discussed with respect to a disorder-related adaptation for increased cognitive regulation of behaviour.

Differential Reorganization of Fusiform Gyrus in Two Types of Alexia after Stroke

Lesions affecting the left fusiform gyrus (FG) commonly result in dyslexia and recovery largely depends on efficient reorganization of the reading network. We performed a follow-up fMRI study to elucidate the reorganization patterns of the FG according to the recovery of reading ability in two patients (MH with pure alexia and KM with alexia with agraphia) after stroke involving the left FG. Initially, MH was an effortful letter-by-letter (LBL) reader, and she improved to become a proficient LBL reader. The initial fMRI results showed scattered activation on occipital and ventral temporal cortex during reading, which was localized to right FG in the follow-up study. KMs severe alexia with agraphia did not improve, even after 6 months had passed since the onset of the alexia. The initial and follow-up fMRI results showed no significant activation in the bilateral FG or central higher language areas during word reading. Our results suggest that the reorganization of the FG is different according to the type of alexia and the amount of clinical recovery in each patient. Also, the successful reorganization of the visual component of reading in the right FG is responsible for the recovery of LBL reading in pure alexia.

A Personalized English vocabulary learning system based on cognitive abilities related to foreign language proficiency

This paper proposes a novel of a personalized Computer Assisted Language Learning (CALL) system based on learner’s cognitive abilities related to foreign language proficiency. In this CALL system, a strategy of retrieval learning, a method of learning memory cycle, and a method of repeated learning are applied for effective vocabulary memorization. The system is designed to offer personalized learning based on cognitive abilities related to the human language process. For this, the proposed CALL system has a cognitive diagnosis module which can measure five types of cognitive abilities. The results of this diagnosis are used to create dynamic learning scenarios for personalized learning and to evaluate user performance in the learning. This system is also designed in order to have users be able to create learning word lists and to share them simply with various functions based on open APIs. Additionally, through experiments, it has shown that this system helps students to learn English vocabulary effectively and enhances their foreign language skills.

The different P200 effects of phonological and orthographic syllable frequency in visual word recognition in Korean.

The principal purpose of this study was to examine whether event-related potential (ERP) waveform amplitudes at around 200 ms are affected by first-syllable frequency. Another purpose of this study was to investigate whether the source of the amplitude at around 200 ms is phonological syllable frequency or orthographic syllable frequency. The phonological first-syllable frequency and the orthographic first-syllable frequency of Korean pseudo-words were manipulated, and ERPs were collected during a go/no-go lexical decision task. The results of this study showed that the P200 waveform is sensitive to the frequency of the first phonological syllable; specifically, pseudo-words with higher phonological first-syllable frequency produced a lower P200 amplitude than those with lower phonological first-syllable frequency. The orthographic syllable frequency did not affect the P200 waveform. The present result implies that there may be different routes by which phonological syllables and orthographic syllables are processed during the early stage of the visual word recognition process.

Double Dissociation of Hangul and Hanja Reading in Korean Patients with Stroke

The orthographic system of the Korean language consists of both phonogram (Hangul) and ideogram (Hanja). We report 2 patients who revealed selective impairment in reading either of orthographies after the brain damages. YJ, a 67-year-old man, showed Broca’s aphasia and severe apraxia of speech after a stroke in the left inferior parietal lobe. He demonstrated predominant difficulties in reading phonogram. KS, a 51-year-old woman, had an intracerebral hemorrhage in the left parietal lobe. She showed anomic aphasia and a selective impairment on reading ideogram. These findings support the notion that recognition of visual words is processed in different ways depending on the characteristics of orthographic systems.

Mining biometric data to predict programmer expertise and task difficulty

Programming mistakes frequently waste software developers’ time and may lead to the introduction of bugs into their software, causing serious risks for their customers. Using the correlation between various software process metrics and defects, earlier work has traditionally attempted to spot such bug risks. However, this study departs from previous works in examining a more direct method of using psycho-physiological sensors data to detect the difficulty of program comprehension tasks and programmer level of expertise. By conducting a study with 38 expert and novice programmers, we investigated how well an electroencephalography and an eye-tracker can be utilized in predicting programmer expertise (novice/expert) and task difficulty (easy/difficult). Using data from both sensors, we could predict task difficulty and programmer level of expertise with 64.9 and 97.7% precision and 68.6 and 96.4% recall, respectively. The result shows it is possible to predict the perceived difficulty of a task and expertise level for developers using psycho-physiological sensors data. In addition, we found that while using single biometric sensor shows good results, the composition of both sensors lead to the best overall performance.

Developing a cognitive evaluation method for serious game engineers

Serious game is an application that has been recently designed for a specific purpose in areas such as education, healthcare, management, and engineering with the core components in games. There have been recent attempts to evaluate the effects of serious games through cognitive aspects used in empirical research, yet there are struggles for application designers to apply these cognitive neuroscientific principles to validate their proposed programs. In this paper, simple tools in cognitive psychology are introduced for analyzing serious game designs through empirical testing. The experiment is designed to investigate the effects of a tangible walking game on attention, memory, and emotion. Results revealed that the group that directly played the tangible walking game showed a slightly better performance on word recall than the control group that just watched the game. We are proposing, in this paper, an experimental method for validating a tangible walking game that can be potentially applied to other serious games. A cognitive evaluation procedure has been developed showing how to exploit simple empirical testing to validate the effectiveness of the proposed tangible game through the cognitive aspects of information processing.

ERP Index of the Morphological Family Size Effect during Word Recognition.

The purpose of this study was to examine whether the N400 is affected by the semantic richness of associated neighboring word members or by the density of the orthographic syllable neighborhood. Another purpose of this study was to investigate the source of the different LPC in respect to the semantic richness. To do so, the density of the syllable neighborhood and the size of the morphological family of a word were orthogonally manipulated. ERPs from 24 participants were collected during a go/no-go semantic categorization task. The results showed that the N400 effect was mainly influenced by the density of the syllable neighborhood rather than by the morphological family size. The results also showed that words with a larger morphological family size generate significantly larger LPC than words with a smaller morphological family size. The present study did not support the assumption that the main source of the N400 effect is the semantic richness of the associated neighbors. The present results suggest that the N400 is more sensitive to the density of the syllable neighborhood and LPC is sensitive to the density of the semantic neighborhood reflected by the morphological family size.