The medial prefrontal cortex (mPFC) has been implicated in the processing of emotionally significant stimuli, particularly the inhibition of inappropriate responses. We examined the role of the mPFC in regulation of fear responses using a differential fear conditioning procedure in which the excitatory conditioned stimulus (CS+) was paired with an aversive footshock and intermixed with the inhibitory conditioned stimulus (CS-). In the first experiment, using rats as subjects, muscimol, a gamma-amino-butyric acid type A (GABAA) receptor agonist, or artificial cerebrospinal fluid (aCSF) was infused intracranially into the mPFC across three conditioning sessions. Twenty-four hours after the last conditioning session, freezing response of the rats was tested in a drug-free state. Neither the muscimol nor the aCSF infusion had any effect on differential responding. In the second experiment, the same experimental procedure was used except that the infusion was made before the testing session rather than the conditioning sessions. The results showed that muscimol infusion impaired differential responding: the level of freezing to CS- was indiscriminable from that to CS+. Taken together, these results suggest that the mPFC is responsible for the regulation of fear response by inhibiting inappropriate fear expressions.
Animals ; Freezing ; Muscimol ; Prefrontal Cortex ; Rats

Executive Function ; Humans ; Prefrontal Cortex ; physiology

Attention is a phenomenon hard to define, but can be conceptualized as a mental function ranging from sustaining readiness to perceive stimuli to understanding the nature and value and selecting stimuli that are most relevant to the given situation. Manifestations of attention include vigilance, and focused, directed, selective, divided, and sustained attentions. While basic attentional tone is controlled by the interaction among reticular activating system, thalamus, and prefrontal cortex, direction and selection of attention is controlled by neural circuits of prefrontal, posterior parietal, and limbic cortex. It is expected that understanding of attention and its neural could provide answers to the relationship between pathophysiology and clinical symptoms of some major psychiatric disorders. More effort are required to develop tools to assess more detailed and various aspects of attention in Korea.
Attention ; Korea ; Prefrontal Cortex ; Rabeprazole ; Thalamus

Diagnosing and managing dementia, presenting with compulsions is challenging. Presented are three cases, a possible representative subset of the Donepezil responders. Selective degeneration of dorsolateral prefrontal cortex networking striatum leading to compulsions would be amenable to cholinergic modulation.
Compulsive Behavior* ; Dementia* ; Prefrontal Cortex ; Psychotic Disorders

Analyzing the influence of mixed emotional factors on false memory through brain function network is helpful to further explore the nature of brain memory. In this study, Deese-Roediger-Mc-Dermott (DRM) paradigm electroencephalogram (EEG) experiment was designed with mixed emotional memory materials, and different kinds of music were used to induce positive, calm and negative emotions of three groups of subjects. For the obtained false memory EEG signals, standardized low resolution brain electromagnetic tomography algorithm (sLORETA) was applied in the source localization, and then the functional network of cerebral cortex was built and analyzed. The results show that the positive group has the most false memories [(83.3 ± 6.8)%], the prefrontal lobe and left temporal lobe are activated, and the degree of activation and the density of brain network are significantly larger than those of the calm group and the negative group. In the calm group, the posterior prefrontal lobe and temporal lobe are activated, and the collectivization degree and the information transmission rate of brain network are larger than those of the positive and negative groups. The negative group has the least false memories [(73.3 ± 2.2)%], and the prefrontal lobe and right temporal lobe are activated. The brain network is the sparsest in the negative group, the degree of centralization is significantly larger than that of the calm group, but the collectivization degree and the information transmission rate of brain network are smaller than the positive group. The results show that the brain is stimulated by positive emotions, so more brain resources are used to memorize and associate words, which increases false memory. The activity of the brain is inhibited by negative emotions, which hinders the brain's memory and association of words and reduces false memory.
Electroencephalography ; Emotions ; Humans ; Memory ; Music ; Prefrontal Cortex

Zona Incerta ; Prefrontal Cortex ; Fear ; Neural Pathways

OBJECTIVES: Empathy has been conceptualized as the ability of emotional resonance and perspective-taking. Emotional awareness has been proposed as the basis of empathy. In this study we examined the relationship between empathy and mood awareness and their neural correlates in resting-state activity in normal controls and patients with schizophrenia. METHODS: Empathy and mood awareness scale scores were compared between 29 patients with schizophrenia and 21 normal controls by voxel-based t-tests and voxel-based correlation analyses of resting-state 18F-FDG PET images. RESULTS: Empathy and mood labeling scale scores were significantly decreased in schizophrenic patients. Mood monitoring was positively correlated with empathy score in normal controls, but not in schizophrenic patients. In normal controls, empathy was positively correlated with resting-state activities in the intraparietal sulcus and mood monitoring was positively correlated with the temporal pole, frontopolar cortex, inferior temporal gyrus, entorhinal cortex and the subgenual prefrontal cortex resting activities. The orbitofrontal cortex resting activity was positively correlated with mood monitoring-related subgenual prefrontal cortex activity in the normal controls. Patients with schizophrenia showed decreased orbitofrontal resting activity and loss of its correlations with mood monitoring-related regional activities. CONCLUSION: This study showed that alteration in the resting-state activity in schizophrenia may reflect dysfunctional empathy and distorted characteristic of emotional awareness. However, the resting-state activity may not reflect the relationship between emotional awareness and empathy.
Brain* ; Empathy* ; Entorhinal Cortex ; Fluorodeoxyglucose F18 ; Humans ; Prefrontal Cortex ; Schizophrenia*

In this case study with 2 chronic stroke patients, we investigated the nature of modulation of neural activities during the working memory (WM) task by transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (DLPFC) using functional MRI (fMRI). Two patients with chronic right hemispheric stroke participated. Patients performed the 2-back WM task within the fMRI scanner before and after tDCS application while the response data were recorded. An anodal tDCS of 1 mA over the left DLPFC was applied for 20 min within fMRI scanner. The accuracy and the recognition accuracy of WM task were improved after applying tDCS. In fMRI images, activation was decreased in the left superior temporal areas in both cases which represent increased efficiency of neural resources after applying the tDCS. The results of this study showed that the effective modulation of cortical activity by tDCS might be a determinant for behavioral changes of enhancing WM function in patients with stroke.
Humans ; Magnetic Resonance Imaging ; Memory, Short-Term ; Prefrontal Cortex ; Stroke

OBJECTIVE: In general, it is known that repetitive regular stimuli induce tolerance and repetitive irregular stimuli induce sensitization. We sought to determine the dopamine response in the rat prefrontal cortex under the repetitive regular and repetitive irregular stimuli. METHODS: After giving irregular and regular electrical stimuli repetitively to rats, we measured the dopamine levels of prefrontal cortex. We compared these results with the dopamine levels of prefrontal cortex of rats which were given just one electrical stimulus. Samples were obtained using in vivo brain microdialysis. Dopamine levels in the samples were measured by high pressure liquid chromatography with electrochemical detection. RESULTS: 1) Dopamine levels of prefrontal cortex of both repetitive regular stimuli group and repetitive irregular stimuli group increased after electrical stimuli. 2) Dopamine levels of prefrontal cortex also significantly increased after just one electrical stimulus. 3) Among the repetitive regular stimuli group, repetitive irregular stimuli group and one stimulus group, the dopamine response was most significant in the repetitive irregular stimuli group. CONCLUSIONS: Repetitive irregular electrical stimuli induce sensitization of prefrontal cortex and repetitive regular electrical stimuli don't induce tolerance of prefrontal cortex.
Animals ; Brain ; Chromatography, Liquid ; Dopamine* ; Microdialysis ; Prefrontal Cortex* ; Rats*

Objectives : Recently, several attempts have been made to use repeated transcranial magnetic stimulation (rTMS) with various stimulation frequencies as a novel treatment for patients with obsessive-compulsive disorder (OCD). However, findings about the efficacy of rTMS in treating OCD have been inconsistent. In the present study, we evaluated the clinical effect and safety of low frequency rTMS on the right dorsolateral prefrontal cortex in the treatment of refractory OCD. METHODS : Twenty-four patients with treatment-refractory OCD received a daily treatment of 20 minutes low frequency rTMS (1 Hz) to the right dorsolateral prefrontal cortex with power of 100% of motor threshold, for 15 days. Clinical status was evaluated using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), Hamilton Anxiety Scale (HAMA), and Clinical Global Impression (CGI) at baseline, at the end of the rTMS treatment (3 weeks), and 4 weeks after finishing the rTMS treatment course. RESULTS : After 3 weeks treatment with low frequency rTMS, Y-BOCS, HAMA and CGI-S scores were significantly decreased. CONCLUSION : The present study found that low-frequency rTMS on the right prefrontal cortex for 3 weeks showed significant therapeutic effects in patients with OCD. Further controlled trials are indicated to assess the efficacy of rTMS in the treatment of OCD.
Anxiety ; Humans ; Obsessive-Compulsive Disorder ; Prefrontal Cortex ; Transcranial Magnetic Stimulation