1. Eosu Kim, Jeonghun Ku, Young-Chul Jung, Hyeongrae Lee, SunI.Kim, Jae-Jin Kim, Kee Nam Koong, Dong-Ho Song, Restoration of mammilothalamic functional connectivity through thiamine replacement therapy in Wernicke's encephalopathy, Neuroscience,(in press)
5. Kim JJ, Ku J, Lee H, Choi SH, Kim IY. Distinct neural responses used to gain insight into hallucinatory perception in patients with schizophrenia. J Psychiatr Res. 2012 Oct;46(10):1318-25.
Most patients with schizophrenia suffer from various types of hallucinations, which commonly produce distress, functional disability or behavioral dyscontrol. The neural process of adapting to hallucinations in patients with schizophrenia remains unknown.
Functional magnetic resonance imaging (MRI) responses to an unusual threatening visual stimulus designed to simulate a hallucinatory experience were compared between 16 patients with schizophrenia and 17 healthy controls. Linear and quadratic repetition-variant as well as repetition-invariant responses to the stimulus were compared between the two groups.
Repetition-invariant responses were similar between patients with schizophrenia and healthy controls. Patients with schizophrenia exhibited a linear activation pattern in the anterior cingulate, whereas healthy controls exhibited a parabolic activation pattern in the anterior prefrontal cortex, occipito-temporal junction and amygdala.
These results provide us with a better understanding of the neural processes involved in gaining insight into unreality. Patients with schizophrenia may use a salience-related region instead of reality monitoring-related regions to react to the unusual stimuli, and this peculiarity of the neural processes may be related to vulnerability to psychosis.
4. Kim K, Roh D, Kim CH, Cha KR, Rosenthal MZ, Kim SI. Comparison of checking behavior in adults with or without checking symptom of obsessive-compulsive disorder using a novel computer-based measure. Comput Methods Programs Biomed. 2012 Oct;108(1):434-41.
Easy to administer behavioral measures of checking are needed to improve the assessment of this hallmark feature of OCD. We recently developed a new computer-based behavioral assessment of OCD in a previous study. As a follow-up experiment for this method, the goal of this study was to examine whether the new computer-based behavioral assessment would be capable of differentiating behaviors in adults with OCD characterized by checking behavior from those without checking behavior. We compared 22 OCD patients with compulsive checking behaviors (OCD checkers), 17 OCD controls without checking behavior (OCD controls), and 31 healthy controls (HCs) on a novel computer-based behavioral measure of checking behavior. Despite similar levels of successfully completed tasks, OCD checkers demonstrated longer duration of checking behaviors than OCD controls or HCs. Interestingly, no differences were found between OCD controls and HCs in any of the dependent variables. Our new behavioral measure offers a novel, objective, and ecologically valid measure of checking behaviors in a sample of adults with OCD.
3. Han K, Heo JK, Seo SO, Hong MY, Lee JS, Shin YS, Ku J, Kim SI, Kim JJ. The effect of simulated auditory hallucinations on daily activities in schizophrenia patients. Psychopathology. 2012;45(6):352-60.
Background: Auditory hallucinations often influence schizophrenia patients in many aspects. In order to develop effective behavioral interventions for overcoming enduring auditory hallucinations, it is necessary to understand how the annoying symptom affects the daily lives of the patients. This study evaluated the effect of hearing unusual voices on performing the activities of daily life in schizophrenia patients. Methods: Eighteen hallucinating patients, 18 nonhallucinating patients and 20 normal controls performed the virtual daily-life task of packing 8 items for travel under 3 conditions: (1) without unusual voices and without avatars, (2) with unusual voices and without avatars and (3) with unusual voices and with avatars. Task completion time and the number of times the packing list was checked were recorded as a measure of the task performance. Results: When exposed to unusual voices without avatars, hallucinating patients checked the packing list fewer times than nonhallucinating patients, and they required longer to complete the task, as positive and negative symptoms were worse. Subjective responses to unusual voices were stronger in hallucinating patients than in nonhallucinating patients. Conclusions: Daily-life activities of hallucinating patients may be less easily influenced by odd auditory stimuli in a nonsocial situation than those of nonhallucinating patients; however, hallucinating patients may feel more strongly affected by unusual voices. To better evaluate and thereby understand the difficulties faced by hallucinating patients in their daily life, the discrepancies between objective and subjective measures as well as social situations should be taken into consideration.
2. Kang YJ, Park HK, Kim HJ, Im SJ, Ku J, Cho S, Kim SI, Park ES. Upper extremity rehabilitation of stroke: Facilitation of corticospinal excitability using virtual mirror paradigm. J Neuroeng Rehabil. 2012 Oct 4;9(1):71.
BACKGROUND: Several experimental studies in stroke patients suggest that mirror therapy and various virtual reality programs facilitate motor rehabilitation. However, the underlying mechanisms for these therapeutic effects have not been previously described.ObjectivesWe attempted to delineate the changes in corticospinal excitability when individuals were asked to exercise their upper extremity using a real mirror and virtual mirror. Moreover, we attempted to delineate the role of visual modulation within the virtual environment that affected corticospinal excitability in healthy subjects and stroke patients.
A total of 18 healthy subjects and 18 hemiplegic patients were enrolled into the study. Motor evoked potential(MEP)s from transcranial magnetic stimulation were recorded in the flexor carpi radialis of the non-dominant or affected upper extremity using three different conditions: (A) relaxation; (B) real mirror; and (C) virtual mirror. Moreover, we compared the MEPs from the virtual mirror paradigm using continuous visual feedback or intermittent visual feedback.
The rates of amplitude increment and latency decrement of MEPs in both groups were higher during the virtual mirror task than during the real mirror. In healthy subjects and stroke patients, the virtual mirror task with intermittent visual feedback significantly facilitated corticospinal excitability of MEPs compared with continuous visual feedback.
Corticospinal excitability was facilitated to a greater extent in the virtual mirror paradigm than in the real mirror and in intermittent visual feedback than in the continuous visual feedback, in both groups. This provides neurophysiological evidence supporting the application of the virtual mirror paradigm using various visual modulation technologies to upper extremity rehabilitation in stroke patients.
1. Choi SH, Lee H, Chung TS, Park KM, Jung YC, Kim SI, Kim JJ. Neural network functional connectivity during and after an episode of delirium. Am J Psychiatry. 2012 May;169(5):498-507.
Delirium is a common and potentially life-threatening clinical syndrome. The authors investigated resting-state functional connectivity in patients with delirium to elucidate possible neural mechanisms underlying this disorder.
Twenty-two patients underwent initial functional MRI at rest during an episode of delirium. Of these patients, 14 completed follow-up scans after the episode resolved. Twenty-two comparison subjects without delirium also underwent scanning. The authors assessed cortical functional connectivity using the seed region of the posterior cingulate cortex and functional connectivity strengths between a priori subcortical regions related to acetylcholine and dopamine on data from 20 initial and 13 follow-up scans.
Dorsolateral prefrontal cortex activity and posterior cingulate cortex activity were inversely correlated in comparison subjects but strongly correlated in patients during an episode of delirium as indicated by increased functional connectivity between the two regions. Although precuneus activity was positively correlated with posterior cingulate cortex activity in comparison subjects, the correlation was further increased in patients during an episode of delirium, and the increment was associated with less severity and shorter duration of delirium. Functional connectivity strengths of the intralaminar thalamic and caudate nuclei with other subcortical regions were reduced during an episode of delirium but recovered after resolution of the episode.
These findings suggest that the disruption in reciprocity of the dorsolateral prefrontal cortex with the posterior cingulate cortex and reversible reduction of functional connectivity of subcortical regions may underlie the pathophysiology of delirium. In addition, enhanced integration in the posteromedial cortices may account for facilitating the rapid improvement of delirium.