• Clinical Psychopharmacology and Neuroscience
• /
• v.16 no.4
• /
• pp.449-460
• /
• 2018

Objective: Prior functional magnetic resonance imaging (fMRI) work has revealed that children/adolescents with disruptive behavior disorders (DBDs) show dysfunctional reward/non-reward processing of non-social reinforcements in the context of instrumental learning tasks. Neural responsiveness to social reinforcements during instrumental learning, despite the importance of this for socialization, has not yet been previously investigated. Methods: Twenty-nine healthy children/adolescents and 19 children/adolescents with DBDs performed the fMRI social/non-social reinforcement learning task. Participants responded to random fractal image stimuli and received social and non-social rewards/non-rewards according to their accuracy. Results: Children/adolescents with DBDs showed significantly reduced responses within the caudate and posterior cingulate cortex (PCC) to non-social (financial) rewards and social non-rewards (the distress of others). Connectivity analyses revealed that children/adolescents with DBDs have decreased positive functional connectivity between the ventral striatum (VST) and the ventromedial prefrontal cortex (vmPFC) seeds and the lateral frontal cortex in response to reward relative to non-reward, irrespective of its sociality. In addition, they showed decreased positive connectivity between the vmPFC seed and the amygdala in response to non-reward relative to reward. Conclusion: These data indicate compromised reinforcement processing of both non-social rewards and social non-rewards in children/adolescents with DBDs within core regions for instrumental learning and reinforcement-based decision-making (caudate and PCC). In addition, children/adolescents with DBDs show dysfunctional interactions between the VST, vmPFC, and lateral frontal cortex in response to rewarded instrumental actions potentially reflecting disruptions in attention to rewarded stimuli.

• Biomolecules & Therapeutics
• /
• v.28 no.3
• /
• pp.230-239
• /
• 2020

Previous studies have shown disrupted synaptic plasticity and neural activity in depression. Such alteration is strongly associated with disrupted synaptic structures. Chronic stress has been known to induce changes in dendritic structure in the basolateral amygdala (BLA) and medial prefrontal cortex (mPFC), but antidepressant effect on structure of these brain areas has been unclear. Here, the effects of imipramine on dendritic spine density and morphology in BLA and mPFC subregions of stressed mice were examined. Chronic restraint stress caused depressive-like behaviors such as enhanced social avoidance and despair level coincident with differential changes in dendritic spine structure. Chronic stress enhanced dendritic spine density in the lateral nucleus of BLA with no significant change in the basal nucleus of BLA, and altered the proportion of stubby or mushroom spines in both subregions. Conversely, in the apical and basal mPFC, chronic stress caused a significant reduction in spine density. The proportion of stubby or mushroom spines in these subregions overall reduced while the proportion of thin spines increased after repeated stress. Interestingly, most of these structural alterations by chronic stress were reversed by imipramine. In addition, structural changes caused by stress and blocking the changes by imipramine were corelated well with altered activation and expression of synaptic plasticity-promoting molecules such as phospho-CREB, phospho-CAMKII, and PSD-95. Collectively, our data suggest that imipramine modulates stress-induced changes in synaptic structure and synaptic plasticity-promoting molecules in a coordinated manner although structural and molecular alterations induced by stress are distinct in the BLA and mPFC.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1745-1748
• /
• 2005

Near-infrared spectroscopy (NIRS) can be used to monitor brain activation by measuring changes in the concentration of oxy- and deoxy-hemoglobin (Hb) by their different spectra in the near-infrared range. Because NIRS is a noninvasive, highly flexible and portable device, it is very suitable to study brain activation when a human repeatedly performs a manipulative task, and possibly provides useful information to construct human adaptive mechatronics (HAM). There is some evidence that the dorsolateral prefrontal cortex (DLPFC) plays a major role in working memory and it is proposed that the use of working memory decreases as a human develops manipulative skills. In the present study, we investigated the activation of the dorsolateral prefrontal cortex (DLPFC) of the brain in Brodmann's areas 9 and 46 in drawing tasks to examine whether NIRS can measure the changes of DLPFC activation as a human develops manipulative skills. Subjects performed a mirror image drawing task and a square drawing task by ones' left hands. In the mirror image task the subject drew following a star shape based on a mirror image of it, but square drawing did not involve mirror image and was estimated to be simpler. The changes of the concentration of oxy-Hb was higher in the mirror image drawing than the square drawing in most subjects. The changes of oxy-Hb decreased as the subject repeated the drawing task in most subjects. In conclusion, The activation of DLPFC measured by NIRS can reflect the brain activity in the development of manipulative skills.

• The Korean Journal of Pain
• /
• v.35 no.4
• /
• pp.413-422
• /
• 2022

Background: The neocortex, including the medial prefrontal cortex (mPFC), contains many neurons expressing nitric oxide synthase (NOS). In addition, increasing evidence shows that the nitric oxide (NO) and opioid systems interact in the brain. However, there have been no studies on the interaction of the opioid and NO systems in the mPFC. The objective of this study was to investigate the effects of administrating L-arginine (L-Arg, a precursor of NO) and N(gamma)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of NOS) into the mPFC for neuropathic pain in rats. Also, we used selective opioid receptor antagonists to clarify the possible participation of the opioid mechanism. Methods: Complete transection of the peroneal and tibial branches of the sciatic nerve was applied to induce neuropathic pain, and seven days later, the mPFC was cannulated bilaterally. The paw withdrawal threshold fifty percent (50% PWT) was recorded on the 14th day. Results: Microinjection of L-Arg (2.87, 11.5 and 45.92 nmol per 0.25 µL) increased 50% PWT. L-NAME (17.15 nmol per 0.25 µL) and naloxonazine (an antagonist of mu opioid receptors, 1.54 nmol per 0.25 µL) inhibited anti-allodynia induced by L-Arg (45.92 nmol per 0.25 µL). Naltrindole (a delta opioid receptor antagonist, 2.45 nmol per 0.25 µL) and nor-binaltorphimine (a kappa opioid receptor antagonist, 1.36 nmol per 0.25 µL) were unable to prevent L-Arg (45.92 nmol per 0.25 µL)-induced antiallodynia. Conclusions: Our results indicate that the NO system in the mPFC regulates neuropathic pain. Mu opioid receptors of this area might participate in pain relief caused by L-Arg.

• Journal of the Korean Society of Physical Medicine
• /
• v.18 no.2
• /
• pp.103-114
• /
• 2023

PURPOSE: This study compared the effects of computer-based and virtual reality-based cognitive rehabilitation programs on the cognitive function, upper limb function, activities of daily living, and their impact on the prefrontal cortex in convalescent stroke patients. METHODS: Ten recovering stroke patients were assessed for their cognitive function, upper limb function, and daily living activities using the Neurobehavioral Cognitive Status Examination, the Korean version of the Fugl-Meyer Assessment, and the Korean version of the Modified Barthel Index. The prefrontal cortex activity was measured with functional Near Infrared Spectroscopy. The virtual reality-based cognitive rehabilitation group utilized a program of daily living activities delivered via a laptop and Oculus Rift. The computer-based cognitive rehabilitation group performed various cognitive tasks on an all-in-one PC. Both groups underwent cognitive rehabilitation training for 30 minutes per day, three times a week, for six weeks, with identical conventional rehabilitation therapies in the hospital. RESULTS: Both programs positively impacted the cognitive and physical functions. On the other hand, the virtual reality-based cognitive rehabilitation program had a larger influence on improving the cognitive and physical functions of convalescing stroke patients. CONCLUSION: The virtual reality program suggests its potential to enhance cognitive and physical functions in convalescent stroke patients through increased engagement, focus, real-time feedback, and game elements, making it a promising rehabilitation approach.

• Journal of Ginseng Research
• /
• v.47 no.4
• /
• pp.552-560
• /
• 2023

Background: Ginseng Radix (Panax ginseng Meyer, Araliaceae) has been used medicinally to treat the brain and nervous system problems worldwide. Recent studies have revealed physiological effects that could potentially benefit cognitive performance or mood. The present study aimed to investigate the antidepressant effects of Korean red ginseng water extract (KGE) and its active component in an unpredictable chronic mild stress (UCMS)-induced animal model and elucidate the underlying mechanisms. Methods: The antidepressant potential of the UCMS model was evaluated using the sucrose preference test and open field tests. The behavioral findings were further corroborated by the assessment of neurotransmitters and their metabolites from the prefrontal cortex and hippocampus of rats. Three doses of KGE (50, 100, and 200 mg/kg) were orally administered during the experiment. Furthermore, the mechanism underlying the antidepressant-like action of KGE was examined by measuring the levels of brain-derived neurotrophic factor (BDNF)/CREB, nuclear factor erythroid 2-related factor 2 (Nrf2), and Kelch-like ECH-associated protein 1 (Keap1) proteins in the prefrontal cortex of UCMS-exposed rats. Results: KGE treatment normalized UCMS-induced depression-related behaviors. Neurotransmitter studies conducted after completing behavioral experiments demonstrated that KGE caused a reduction in the ratio of serotonin and dopamine, indicating a decrease in serotonin and dopamine turnover. Moreover, the expression of BDNF, Nrf2, Keap1 and AKT were markedly increased by KGE in the prefrontal cortex of depressed rats. Conclusion: Our results provide evidence that KGE and its constituents exert antidepressant effects that mediate the dopaminergic and serotonergic systems and expression of BDNF protein in an animal model.

• Korean Journal of Biological Psychiatry
• /
• v.5 no.1
• /
• pp.83-94
• /
• 1998

Objectives : Phencyclidine(PCP) or PCP-like substances such as ketamine have been known to rekindle the cognitive dysfunction in schizophrenia. The aims of this study were to identify whether PCP-like substances can produce cognitive deficit in schizophrenia, to discuss relation with aging process, and finally to speculate underlying neurochemical mecha-nisms by various drug responses. Methods : In experiment I, radial maze tests were done in 24 Sprague-Dawley rats for 3 days to get baseline data. Being divided into 4 groups(6 rats respectively) of normal aged, normal adult controls, atropine-treated and ketamine-treated, the radial maze tests were repeated on every week for 6 weeks, and then the rats were sacrificed by intracardiac perfusion with phosphate-buffered 10% formaldehyde solution for histology. The brain specimen was stained with hematoxylin-eosin to count cells in the prefrontal cortex and hippocampus. In experiment II, radial maze tests were done for 48 rats before any drug treatment and only after ketamine administration. Thereafter, haloperidol, bromocriptine, clonidine, nimodipine, tacrine, valproic acid, naloxone and fluoxetine were intramuscularly injected on every other day in addition to ketamine. Radial maze tests were repeated on every week for 6 weeks, and then rats were prepared by the same procedure for histology. Results : 1) Reaction times of radial maze tests of atropine-treated rats were significantly prolonged than those of normal aged(p<0.05) or normal adult controls(p<0.05). Cell numbers of prefrontal cortex & hippocampus in ketamine-treated rats were significantly reduced than those in normal aged (p<0.05) or normal adult controls(p<0.005). 2) Reduced cell numbers by ketamine became significantly raised by tacrine administration in prefrontal cortex & hippocampus(p<0.05), while there were no significant changes on radial maze tests. Cell numbers also tended to be raised by nimodipine, fluoxetine and haloperidol administration. Conclusions : In conclusion, the visuospatial memory disorders in ketamine-induced psychotic rats might be partly asso-ciated with aging process. Furthermore, the responses to the various drugs suggested cholinergic system might have an important role in the neurochemical mechanism of the cognitive dysfunction in ketamine-induced psychosis. Otherwise, calcium metabolism as well as serotonergic and dopaminergic systems seemed to be possibly related.

• Korean Journal of Biological Psychiatry
• /
• v.24 no.4
• /
• pp.225-234
• /
• 2017

Objectives Local gyrification reflects the early neural development of cortical connectivity, and is regarded as a potential neural endophenotype in psychiatric disorders. Several studies have suggested altered local gyrification in patients with bipolar I disorder (BD-I). The purpose of the present study was to investigate the alterations in the cortical gyrification of whole brain cortices in patients with BD-I. Methods Twenty-two patients with BD-I and age and sex-matched 22 healthy controls (HC) were included in this study. All participants underwent T1-weighted structural magnetic resonance imaging (MRI). The local gyrification index (LGI) of 66 cortical regions were analyzed using the FreeSurfer (Athinoula A. Martinos Center for Biomedical Imaging). One-way analysis of covariance (ANCOVA) was used to analyze the difference of LGI values between two groups adjusting for age and sex as covariates. Results The patients with BD-I showed significant hypogyria in the left pars opercularis (uncorrected-p = 0.049), the left rostral anterior cingulate gyrus (uncorrected-p = 0.012), the left caudal anterior cingulate gyrus (uncorrected-p = 0.033). However, these findings were not significant after applying the multiple comparison correction. Severity or duration of illness were not significantly correlated with LGI in the patients with BD-I. Conclusions Our results of lower LGI in the anterior cingulate cortex and the ventrolateral prefrontal cortex in the BD-I group implicate that altered cortical gyrification in neural circuits involved in emotion-processing may contribute to pathophysiology of BD-I.

• Journal of Biomedical Engineering Research
• /
• v.29 no.4
• /
• pp.272-277
• /
• 2008

Functional MRI technique was used in this study for examining the language switching mechanisms between the first language (L1) and the second language (L2). Language switching mechanism is regarded as a complex task that involves an interaction between L1 and L2. The aim of study is to find out the brain activation patterns during the phonological process of reading real English words and English words written in Korean characters in a bilingual person. Korean-English bilingual subjects were examined while they covertly read four types of words native Korean words, Korean words of a foreign origin, English words written in Korean characters, and English words. The fMRI results reveal that the left hemispheric language-related regions at the brain, such as the left inferior frontal, superior temporal, and parietal cortices, have a greater response to the presentation of English words written in Korean characters than for the other types of words, in addition, a slight difference was observed in the occipital-temporal lobe. These results suggest that a change in the brain circuitry underlying the relational processes of language switching is mainly associated with general executive processing system in the left prefrontal cortex rather than with a similarity-based processing system in the occipital-temporal lobes.

• Korean Journal of Cognitive Science
• /
• v.24 no.1
• /
• pp.1-24
• /
• 2013

The elderly population continues to increase in Korea and there has been a growing interest in understanding normal aging. In response to this public interest, the present paper reviewed human aging research focusing on recently published neuroimaging studies. For the first half of the paper, I reviewed the effects of aging on the brain and cognition. In normal aging, structural changes in the brain include atrophy and volume reduction in the prefrontal and temporal cortices. Functional changes are exhibited in the form of overactivation of the brain. Moreover, age-related cognitive decline is particularly observed in inhibition and memory, which are also associated with the age-related structural changes in the brain. For the second half of the paper, I introduced physical exercise studies showing that exercise played a protective role in the age-related neurocognitive decline. More specifically, engaging in physical exercise (particularly, aerobic exercise) for a relatively long period of time (e. g., > 6 mon.) protected older adults from volume loss in the prefrontal cortex and the hippocampus, and induced better inhibition and memory. These exercise-induced benefits appear to be associated with changes in neuronal levels, indicating that the aging brain is still plastic and this plasticity can be enhanced by physical exercise.