• Annals of Clinical Neurophysiology
• /
• 제23권2호
• /
• pp.69-81
• /
• 2021

Cortico-cortical evoked potential (CCEP) mapping is a rapidly developing method for visualizing the brain network and estimating cortical excitability. The CCEP comprises the early N1 component the occurs at 10-30 ms poststimulation, indicating anatomic connectivity, and the late N2 component that appears at < 200 ms poststimulation, suggesting long-lasting effective connectivity. A later component at 200-1,000 ms poststimulation can also appear as a delayed response in some studied areas. Such delayed responses occur in areas with changed excitability, such as an epileptogenic zone. CCEP mapping has been used to examine the brain connections causally in functional systems such as the language, auditory, and visual systems as well as in anatomic regions including the frontoparietal neocortices and hippocampal limbic areas. Task-based CCEPs can be used to measure behavior. In addition to evaluations of the brain connectome, single-pulse electrical stimulation (SPES) can reflect cortical excitability, and so it could be used to predict a seizure onset zone. CCEP brain mapping and SPES investigations could be applied both extraoperatively and intraoperatively. These underused electrophysiologic tools in basic and clinical neuroscience might be powerful methods for providing insight into measures of brain connectivity and dynamics. Analyses of CCEPs might enable us to identify causal relationships between brain areas during cortical processing, and to develop a new paradigm of effective therapeutic neuromodulation in the future.

• The Journal of Korean Physical Therapy
• /
• 제24권4호
• /
• pp.262-267
• /
• 2012

Purpose: This study was designed to analyze the differences in cerebral cortex activity of the elderly after extracting the movement related cortical potentials (MRCPs) from electroencephalogram (EEG) during a concentric and eccentric contraction of the elbow joint flexors, and entering them into the brain-mapping program to make the images. Methods: Right-dominant normal elderly people were divided into an eccentric contraction group and a concentric contraction group. Then, their MRCPs were measured using EEG and sEMG, during an eccentric and concentric contraction. Then, they were converted into images using the brain-mapping program. Results: Eccentric contraction group's $C_3$ and Cz showed statistically higher mean values of MRCP positive potential than the concentric contraction group. Conclusion: Researching a cerebral cortex activity, using MRCP, would provide basic data for clinical neuro-physiological researches on aging or neural plasticity of patients with a central nervous system injury.

• 대한의용생체공학회:의공학회지
• /
• 제27권2호
• /
• pp.64-72
• /
• 2006

The present study introduces a new cortical patch-based source model for EEG/MEG cortical source imaging to consider anatomical constraints more precisely. Conventional source models for EEG/MEG cortical source imaging have used coarse cortical surface mesh or sampled small number of vertices from fine surface mesh, and thus they failed to utilize full anatomical information which nowadays we can get with sub-millimeter modeling accuracy. Conventional ones placed a single dipolar source on each cortical patch and estimated its intensity by means of various inverse algorithms; whereas the suggested cortical patch-based model integrates whole cortical area to construct lead field matrix and estimates current density that is assumed to be constant in each cortical patch. We applied the proposed and conventional models to realistic EEG data and compared the results quantitatively. The quantitative comparisons showed that the proposed model can provide more precise spatial descriptions of neuronal source distribution.

• Journal of Korean Neurosurgical Society
• /
• 제29권7호
• /
• pp.954-958
• /
• 2000

In the removal of small subcortical lesion in the eloquent area like sensory-motor cortex, the prevention of neurologic deficit is important. We present our technique of identification of M-1, S-1 cortex in a case of subcortical granuloma located in sensorymotor cortex. To accurately localize mass, stereotactic craniotomy was planned. At the beginning of procedure, functional MRI of motor cortex was done with stereotactic headframe in place. Next, the stereotactic craniotomy about 4 cm was done under propofol anesthesia for cortical mapping. After reflection of dura, central sulcus was identified with phase-reversal response of intraoperative SEP(somatosensory evoked potential) of contralateral median nerve. Then the patient was awakened, and direct cortical stimulation was done. We observed the muscle contractions of elbow, hand and fingers and the paresthesia over forearm, hand, fingers on the M-1 and S-1 cortex. Through cortical mapping and stereotactic guidance, we concluded that the mass lie immediately posterior to central sulcus, then the mass was carefully removed through small transsulcal approach, opening about 1 cm of rolandic sulcus.

• Korean Journal of Radiology
• /
• 제24권6호
• /
• pp.553-563
• /
• 2023

Objective: Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging-derived tractography (DTI-t) contribute to the localization of language areas, but their accuracy remains controversial. This study aimed to investigate the diagnostic performance of preoperative fMRI and DTI-t obtained with a simultaneous multi-slice technique using intraoperative direct cortical stimulation (DCS) or corticocortical evoked potential (CCEP) as reference standards. Materials and Methods: This prospective study included 26 patients (23-74 years; male:female, 13:13) with tumors in the vicinity of Broca's area who underwent preoperative fMRI and DTI-t. A site-by-site comparison between preoperative (fMRI and DTI-t) and intraoperative language mapping (DCS or CCEP) was performed for 226 cortical sites to calculate the sensitivity and specificity of fMRI and DTI-t for mapping Broca's areas. For sites with positive signals on fMRI or DTI-t, the true-positive rate (TPR) was calculated based on the concordance and discordance between fMRI and DTI-t. Results: Among 226 cortical sites, DCS was performed in 100 sites and CCEP was performed in 166 sites. The specificities of fMRI and DTI-t ranged from 72.4% (63/87) to 96.8% (122/126), respectively. The sensitivities of fMRI (except for verb generation) and DTI-t were 69.2% (9/13) to 92.3% (12/13) with DCS as the reference standard, and 40.0% (16/40) or lower with CCEP as the reference standard. For sites with preoperative fMRI or DTI-t positivity (n = 82), the TPR was high when fMRI and DTI-t were concordant (81.2% and 100% using DCS and CCEP, respectively, as the reference standards) and low when fMRI and DTI-t were discordant (≤ 24.2%). Conclusion: fMRI and DTI-t are sensitive and specific for mapping Broca's area compared with DCS and specific but insensitive compared with CCEP. A site with a positive signal on both fMRI and DTI-t represents a high probability of being an essential language area.

• 한방안이비인후피부과학회지
• /
• 제13권2호
• /
• pp.200-210
• /
• 2000

objective to ascertain whether the concept of the therapeutic side is associated with changes in the blind sport mapping that represents the brain function. design Physiological blind spot maps were used as an integer of brain activity before and after acupuncture needling on the meridian point Hapkok(合谷) and Techung(太衝) in the unilateral side decided by double-blind controlled study(20 subjects). setting outpatient clinic participants: adult volunteers intervention twenty subjects were divided into two comparative groups and underwent specific acupuncture therapy on the unilateral side. Blinded examiners obtained reproducible pre and post-acupuncture cortical maps, which were subjected to statistical analysis. main outcome measures Brain activity was demonstrated by reproducible circumferential measurements of cortical hemispheric blind spot maps before and after acupuncture on the unilateral side. in case of acupuncture needling on the ipsilateral side of an enlarged side of bilnd spot, there were reduction of blind spot in 7 cases of 10 subjects, and enlargement in 3 cases. in case of acupuncture needling on the contralateral side of the enlarged side of blind spot, there were enlargement of blind spot in 6 cases of 10 subjects, and reduction in 4 cases. results the significant changes in the blind spots before and after acupuncture were observed Acupuncture needlings on the ipsilateral or contralateral side of an enlarged cortical map were associated with the concept of the therapeutic side traditionally accepted in the oriental medical society. Acupuncture needling on the ipsilateral side of an enlarged blind spot map is associated with the reduction of map, and increaed contralateral cortical activity. Acupuncture needling on the side opposite an enlarged blind spot map is associated with the enlargement of map, and decreased cortical activity. conclusion Reproducible maps of cortical responses can be used to measure the neurological consequences of acupuncture needling. Acupuncture can affect the somatic sensory informations that reach to the contralateral thalamus, and so affect thalamic integration. we found that acupuncture therapy may be associated with an increase or a decrease in brain function depending on the side of acupuncture needling. thus, the traditional concept of the contralateral therapeutic theory in acupuncture approach has the clinical significance in the view of brain function.

• 수면정신생리
• /
• 제4권1호
• /
• pp.96-106
• /
• 1997

The clinical validity of a korean EEG and EP mapping system(Neuronics) was evaluated with schizophrenic patients(n=20), normal controls(n=19), and 10 patients with central nervous system disease(8 patients with cerebrovascular accident, 1 patient with brain mass, and 1 patient with periodic paralysis). In the normal control group, the pattern of resting computerized EEG with eyes closed showed normal parieto-occipital dominance of alpha wave. Compared with normal controls, schizophrenic patients had more delta activity in the frontal region, and less alpha activity especially in the parieto-occipital region. In most cases patients with cortical organic lesions(n=5) revealed increased delta and theta activity and decreased alpha activity on the lesion areas. These findings were compatible with their MRI and clinical findings. However in the cases of subcortical lesions(n=5) EEG showed various findings which suggest diverse influences of subcortical abnormalities on cortical activities. The P300 of schizophrenic group was smaller and more delayed than those of normal controls. These results are generally compatible with the previous studies using other EEG and EP mapping systems consequenty and suggest that the this EEG and EP mapping system(Neuronics) has clinical validity.

• 대한의용생체공학회:의공학회지
• /
• 제28권2호
• /
• pp.258-264
• /
• 2007

Spatiotemporal changes of brain rhythmic activity at a certain frequency have been usually monitored in real time using scalp potential maps of multi-channel electroencephalography(EEG) or magnetic field maps of magnetoencephalography(MEG). In the present study, we investigate if it is possible to implement a real-time brain activity monitoring system which can monitor spatiotemporal changes of cortical rhythmic activity on a subject's cortical surface, neither on a sensor plane nor on a standard brain model, with a high temporal resolution. In the suggested system, a frequency domain inverse operator is preliminarily constructed, considering the individual subject's anatomical information, noise level, and sensor configurations. Spectral current power at each cortical vertex is then calculated for the Fourier transforms of successive sections of continuous data, when a single frequency or particular frequency band is given. An offline study which perfectly simulated the suggested system demonstrates that cortical rhythmic source changes can be monitored at the cortical level with a maximal delay time of about 200 ms, when 18 channel EEG data are analyzed under Pentium4 3.4GHz environment. Two sets of artifact-free, eye closed, resting EEG data acquired from a dementia patient and a normal male subject were used to show the feasibility of the suggested system. Factors influencing the computational delay are investigated and possible applications of the system are discussed as well.

• Korean Journal of Radiology
• /
• 제24권11호
• /
• pp.1131-1141
• /
• 2023

Objective: Cortical iron deposition has recently been shown to occur in Alzheimer's disease (AD). In this study, we aimed to evaluate how cortical gray matter iron, measured using quantitative susceptibility mapping (QSM), differs in the clinical cognitive impairment spectrum. Materials and Methods: This retrospective study evaluated 73 participants (mean age ± standard deviation, 66.7 ± 7.6 years; 52 females and 21 males) with normal cognition (NC), 158 patients with mild cognitive impairment (MCI), and 48 patients with AD dementia. The participants underwent brain magnetic resonance imaging using a three-dimensional multi-dynamic multi-echo sequence on a 3-T scanner. We employed a deep neural network (QSMnet+) and used automatic segmentation software based on FreeSurfer v6.0 to extract anatomical labels and volumes of interest in the cortex. We used analysis of covariance to investigate the differences in susceptibility among the clinical diagnostic groups in each brain region. Multivariable linear regression analysis was performed to study the association between susceptibility values and cognitive scores including the Mini-Mental State Examination (MMSE). Results: Among the three groups, the frontal (P < 0.001), temporal (P = 0.004), parietal (P = 0.001), occipital (P < 0.001), and cingulate cortices (P < 0.001) showed a higher mean susceptibility in patients with MCI and AD than in NC subjects. In the combined MCI and AD group, the mean susceptibility in the cingulate cortex (β = -216.21, P = 0.019) and insular cortex (β = -276.65, P = 0.001) were significant independent predictors of MMSE scores after correcting for age, sex, education, regional volume, and APOE4 carrier status. Conclusion: Iron deposition in the cortex, as measured by QSMnet+, was higher in patients with AD and MCI than in NC participants. Iron deposition in the cingulate and insular cortices may be an early imaging marker of cognitive impairment related neurodegeneration.

• Applied Microscopy
• /
• 제46권4호
• /
• pp.179-183
• /
• 2016

Mapping brain structural and functional connections through the whole brain is essential for understanding brain mechanisms and the physiological bases of brain diseases. Although region specific structural or functional deficits cause brain diseases, the changes of interregional connections could also be important factors of brain diseases. This review will introduce common neuroimaging modalities, including structural magnetic resonance imaging (MRI), functional MRI (fMRI), diffusion tensor imaging, and other recent neuroimaging analyses methods, such as voxel-based morphometry, cortical thickness analysis, local gyrification index, and shape analysis for structural imaging. Tract-Based Spatial Statistics, TRActs Constrained by UnderLying Anatomy for diffusion MRI, and independent component analysis for fMRI also will also be introduced.