• Journal of Biomedical Engineering Research
• /
• v.16 no.4
• /
• pp.425-430
• /
• 1995

The correlation technique has been widely used in ctRl data processing. The proposed CLT (clus- tering threshold) technique is a modified CCT (correlation coefficient threshold) technique and has many advantages compared with the conventional CCT technique. The CLT technique is explained by the following two steps. First, once the correlation coefficient map above the proper TH value is obtained using the CCT technique which is discrete and includes splash noise data, then the spurious pixels are rejected and the real neural activity pixels extracted using an nxn matrix box. Second, a clustering operation is performed by the two correction rules. The real neuronal activated pixels can be clustered and the false spurious pixels can be suppressed by the proposed CLT technique. The proposed CLT technique used in the post processing in ctRl has advantages over other existing techniques. It is especially proved to be robust in noisy environment.

• Korean Journal of Biological Psychiatry
• /
• v.29 no.1
• /
• pp.15-21
• /
• 2022

Objectives Maltreatment experiences can alter brain function related to emotion regulation, such as cognitive reappraisal. While dysregulation of emotion is an important risk factor to mental health problems in maltreated people, studies reported alterations in brain networks related to cognitive reappraisal are still lacking. Methods Twenty-seven healthy subjects were recruited in this study. The maltreatment experiences and positive reappraisal abilities were measured using the Childhood Trauma Questionnaire-Short Form and the Cognitive Emotion Regulation Questionnaire, respectively. Twelve subjects reported one or more moderate maltreatment experiences. Subjects were re-exposed to pictures after the cognitive reappraisal task using the International Affective Picture System during fMRI scan. Results The maltreatment group reported more negative feelings on negative pictures which tried cognitive reappraisal than the no-maltreatment group (p < 0.05). Activities in the right superior marginal gyrus and right middle temporal gyrus were higher in the maltreatment group (uncorrected p < 0.001, cluster size > 20). Conclusions We found that paradoxical activities in semantic networks were shown in the victims of maltreatment. Further study might be needed to clarify these aberrant functions in semantic networks related to maltreatment experiences.

• Progress in Medical Physics
• /
• v.16 no.1
• /
• pp.32-38
• /
• 2005

Impaired processing of facial information is one of the broad ranges of cognitive deficits seen in patients with schizophrenia. The purpose of this study was to elucidate the differences in brain activities involved in the process of facial working memory between schizophrenic patients and healthy comparison subjects. Ten patients with schizophrenia were recruited along with matched healthy volunteers as a comparison group. Functional magnetic resonance imaging (fMRI) was used to assess cortical activities during the performance of a 1-back working memory paradigm using images of neutral faces as mnemonic content. The patient group performed the tasks with reduced accuracy. Group analysis revealed that left fusiform gyrus, right superior frontal gyrus, bilateral middle frontal gyri/insula, left middle temporal gyrus, precuneus and vermis of cerebellum and showed decreased cortical activities in the patient group. On the other hand, an increased level of activation in lateral prefrontal cortex and parietal lobule was observed from the patient group, all in the right hemisphere. A decreased level of activity in the left fusiform gyrus among the patient group implicates inefficient processing of facial information. An increased level of activation in prefrontal and parietal neural networks from the patient group confirms earlier findings on the impaired working memory of patients with schizophrenia.

• Sleep Medicine and Psychophysiology
• /
• v.27 no.1
• /
• pp.24-31
• /
• 2020

Objectives: Subjective-objective discrepancy of sleep (SODS) is a common symptom and one of the major phenotypes of insomnia. A distorted perception of sleep deficit might be related to abnormal brain reactivity to insomnia-related stimuli. We aimed to investigate differences in brain activation to insomnia-related stimuli vs. general anxiety-inducing stimuli among insomnia patients with SODS, insomnia patients without SODS, and healthy controls (HCs). Methods: All participants were evaluated for subjective sleep status using a sleep diary and questionnaires; occult sleep disorders and objective sleep status were assessed using polysomnography and actigraphy. Task functional magnetic resonance imaging was performed during insomnia-related stimuli (Ins) and general anxiety-inducing stimuli (Gen). Brain reactivity to Ins versus Gen was compared among insomnia with SODS, insomnia without SODS, and HC groups, and a combined insomnia disorder group (ID, insomnia with and without SODS) was also compared with HCs. Results: In the insomnia with SODS group compared to the insomnia without SODS group, the right precuneus and right supplementary motor areas showed significantly increased BOLD signals in response to Ins versus Gen. In the ID group compared to the HC group, the left anterior cingulate cortex showed significantly increased BOLD signals in response to Ins versus Gen. Conclusion: The insomnia with SODS and ID groups showed higher brain activity in response to Ins versus Gen, while this was not observed in the insomnia without SODS and HC groups, respectively. These results suggest that insomnia patients with sleep misperception are more sensitive to sleep-related threats than general anxiety-inducing threats.

• Korean Journal of Cognitive Science
• /
• v.18 no.2
• /
• pp.159-178
• /
• 2007

Lee & Kang (2002) showed that simultaneous phonological rehearsal significantly delayed the performance of multiplication but not subtraction, whereas holding an image in the memory delayed subtraction but not multiplication. This result indicated that arithmetic function is related to working memory in a subsystem-specific manner. The aim of the current study was to examine the neural correlates of previous finding using fMRI. For this goal, dual task conditions that required suppression or no suppression were manipulated. In general, several areas were more activated in the interference conditions than in the less interference conditions, although both conditions were dual condition. More important finding is that the specific areas activated in the phonological suppression rendition were right inferior frontal gyrus, left angular, and inferior parietal lobule, while the areas activated in the other condition were mainly in the right superior temporal gyrus and anterior cingulate gyrus. Furthermore, the areas activated in the phonological or visual less suppression condition were right medial frontal gyrus, left middle frontal gyrus, and bilateral medial frontal gyri, anterior cingulate cortices, and parahippocampal gyri, respectively. These results revealed that sharing the processing code invokes interference, and its neural basis.