• Animal cells and systems
• /
• 제2권1호
• /
• pp.65-69
• /
• 1998

The hippocampus and prefrontal cortex are regarded as the highest-order association cortices. The hippocampus has been proposed to store "cognitive maps" of external environments, and the prefrontal cortex is known to be involved in the planning of behavior, among other functions. Considering the prominent functional roles played by these structures, it is not surprising to find direct monosynaptic projections from the hippocampus to the prefrontal cortex. Rhythmic stimulation of this projection patterned after the hippocampal EEG theta rhythm induced stable long-term potentiation of field potentials in the prefrontal cortex. Comparison of behavioral correlates of hippocampal and prefrontal cortical neurons during an a-arm radial maze, working memory task shows a striking contrast. Hippocampal neurons exhibit clear place-specific firing patterns, whereas prefrontal cortical neurons do not show spatial selectivity, but are correlated to different stages of the behavioral task. These data lead to the hypothesis that the role of hippocampal projection to the prefrontal cortex is not to impose spatial representations upon prefrontal activity, but to provide a mechanism for learning the spatial context in which particular behaviors are appropriate.propriate.

• 생물정신의학
• /
• 제5권2호
• /
• pp.184-196
• /
• 1998

With a rapid development of neuroscience, the theories related to the pathophysiology of schizophrenia have been changed a lot from a simple hyperdopaminergic one to the various complicated ones. Among these, the theories regarding prefrontal cortex(PFC) pathology as a cause of schizophrenia are gaining more recognition as the results of neuroimaging and neuropsychological tests in schizophrenia consistently report abnormalities in PFC. Therefore, we first reviewed the unique characteristics of PFC in anatomy, neurochemistry and neurophysiology to enhance an understanding of those ones. Secondly, various neurotransmitter, neurodevelopmental and neural network theories of schizophrenia introduced recently were reviewed in terms of PFC pathology.

• Korean Journal of Radiology
• /
• 제1권1호
• /
• pp.19-24
• /
• 2000

Objective: In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed. Materials and Methods: In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p < .001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks. Results: The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere. Conclusion: The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.

• Journal of Korean Neurosurgical Society
• /
• 제54권6호
• /
• pp.484-488
• /
• 2013

Objective : To examine the synergistic effects of both computer-assisted cognitive rehabilitation (CACR) and transcranial direct current stimulation (tDCS) on cognitive function in patients with stroke. Methods : The current double-blind, sham-controlled study enrolled a total of 11 patients who were newly diagnosed with stroke. The patients of the tDCS group (n=6) completed sessions of the Korean computer-assisted cognitive rehabilitation program five times a week for 30 minutes a session during a mean period of 18.5 days concomitantly with the anodal tDCS over the bilateral prefrontal cortex combined with the CACR. The patients of the control group (n=5) also completed sessions of the sham stimulation during a mean period of 17.8 days. Anodal tDCS over bilateral prefrontal cortex (F3 and F4 in 10-20 EEG system) was delivered for 30 minutes at an intensity of 2 mA. Cathode electrodes were applied to the non-dominant arm. All the patients were evaluated using the Seoul Computerized Neuropsychological Test (SCNT) and the Korean Mini-Mental State Examination. Results : Mann-Whitney U test revealed a significant difference between the two groups. The patients of the tDCS group achieved a significant improvement in the post/pre ratio of auditory continuous performance test and visual continuous performance test on the SCNT items. Conclusion : Our results indicate that the concomitant use of the tDCS with CACR to the prefrontal cortex may provide additional beneficial effects in improving the cognitive dysfunction for patients with stroke.

• 대한핵의학회지
• /
• 제35권4호
• /
• pp.231-240
• /
• 2001

Purpose: Normal aging results in detectable changes in the brain structure and function. We evaluated the changes of regional cerebral glucose metabolism in the normal aging process with FDG PET. Materials and Methods: Brain PET images were obtained in 44 healthy volunteers (age range 20-69 'y'; M:F = 29:15) who had no history of neuropsychiatric disorders. On 6 representative transaxial images, ROIs were drawn in the cortical and subcortical areas. Regional FDG uptake was normalized using whole brain uptake to adjust for the injection dose and correct for nonspecific declines of glucose metabolism affecting all brain areas equally. Results: In the prefrontal, temporoparietal and primary sensorimotor cortex, the normalized FDG uptake (NFU) reached a peak in subjects in their 30s. The NFU in the prefrontal and primary sensorimotor cortex declined with age after 30s at a rate of 3.15%/decade and 1.93%/decade, respectively. However, the NFU in the temporoparietal cortex did not change significantly with age after 30s. The anterior (prefrontal) posterior (temporoparietal) gradient peaked in subjects in their 30s and declined with age thereafter at a rate of 2.35%/decade. The NFU in the caudate nucleus was decreased with age after 20s at a rate of 2.39%/decade. On the primary visual cortex, putamen, and thalamus, the NFU values did not change significantly throughout the ages covered. These patterns were not significantly different between right and left cerebral hemispheres. Of interest was that the NFU in the left cerebellar cortex was increased with age after 20s at a rate of 2.86%/decade. Conclusion: These data demonstrate regional variation of the age-related changes in the cerebral glucose metabolism, with the most prominent age-related decline of metabolism in the prefrontal cortex. The increase in the cerebellar metabolism with age might reflect a process of neuronal plasticity associated with aging.

• 대한약리학회:학술대회논문집
• /
• 대한약리학회 2006년도 The 6th Congress of the Federation of Asian and Oceanian Physiological Societies
• /
• pp.106.2-106.2
• /
• 2006

• 대한의용생체공학회:의공학회지
• /
• 제36권5호
• /
• pp.177-182
• /
• 2015

The activation of prefrontal cortex of brain during some mental tasks like mental arithmetic induce has been studied using hemodynamic imaging modalities. In this study, we focused on the differentiation of activated area in local prefrontal brain caused by the different mental activities as well as evaluating the classification accuracy of in-house fNIRS system. The study preliminarily validated the device including the signal quality and tightness of contact between detectors and prefrontal area. Experimental results of mental tasks on 5 subjects showed the subject dependent tendencies in correlated prefrontal activation and the area of highest accuracy.

• Animal cells and systems
• /
• 제8권Supplyment
• /
• pp.14-14
• /
• 2004

• Journal of Ginseng Research
• /
• 제42권3호
• /
• pp.298-303
• /
• 2018

Background: Panax ginseng is one of the most commonly used medicinal herbs worldwide for a variety of therapeutic properties including neurocognitive effects. Ginsenoside Rg1 is one of the most abundant active chemical constituents of this herb with known neuroprotective, anxiolytic, and cognition improving effects. Methods: We investigated the effects of Rg1 on the medial prefrontal cortex (mPFC), a key brain region involved in cognition, information processing, working memory, and decision making. In this study, the effects of systemic administration of Rg1 (1 mg/kg, 3 mg/kg, or 10 mg/kg) on (1) spontaneous firing of the medial prefrontal cortical neurons and (2) long-term potentiation (LTP) in the hippocampal-medial prefrontal cortical (HP-mPFC) pathway were investigated in male Sprague-Dawley rats. Results: The spontaneous neuronal activity of approximately 50% the recorded pyramidal cells in the mPFC was suppressed by Rg1. In addition, Rg1 attenuated LTP in the HP-mPFC pathway. These effects were not dose-dependent. Conclusion: This report suggests that acute treatment of Rg1 impairs LTP in the HP-mPFC pathway, perhaps by suppressing the firing of a subset of mPFC neurons that may contribute to the neurocognitive effects of Rg1.

• Clinical Psychopharmacology and Neuroscience
• /
• 제16권4호
• /
• 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.