The EEG microstate topography is predominantly determined by intracortical sources in the alpha band.

Human brain electric activity can be measured at high temporal and fairly good spatial resolution via electroencephalography (EEG). The EEG microstate analysis is an increasingly popular method used to investigate this activity at a millisecond resolution by segmenting it into quasi-stable states of approximately 100 ms duration. These so-called EEG microstates were postulated to represent atoms of thoughts and emotions and can be classified into four classes of topographies A through D, which explain up to 90% of the variance of continuous EEG. The present study investigated whether these topographies are primarily driven by alpha activity originating from the posterior cingulate cortex (all topographies), left and right posterior cortices, and the anterior cingulate cortex (topographies A, B, and C, respectively). We analyzed two 64-channel resting state EEG datasets (N = 61 and N = 78) of healthy participants. Sources of head-surface signals were determined via exact low resolution electromagnetic tomography (eLORETA). The Hilbert transformation was applied to identify instantaneous source strength of four EEG frequency bands (delta through beta). These source strength values were averaged for each participant across time periods belonging to a particular microstate. For each dataset, these averages of the different microstate classes were compared for each voxel. Consistent differences across datasets were identified via a conjunction analysis. The intracortical strength and spatial distribution of alpha band activity mainly determined whether a head-surface topography of EEG microstate class A, B, C, or D was induced. EEG microstate class C was characterized by stronger alpha activity compared to all other classes in large portions of the cortex. Class A was associated with stronger left posterior alpha activity than classes B and D, and class B was associated with stronger right posterior alpha activity than A and D. Previous results indicated that EEG microstate dynamics reflect a fundamental mechanism of the human brain that is altered in different mental states in health and disease. They are characterized by systematic transitions between four head-surface topographies, the EEG microstate classes. Our results show that intra-cortical alpha oscillations, which likely reflect decreased cortical excitability, primarily account for the emergence of these classes. We suggest that microstate class dynamics reflect transitions between four global attractor states that are characterized by selective inhibition of specific intra-cortical regions.

The functional significance of EEG microstates--Associations with modalities of thinking.

The momentary, global functional state of the brain is reflected by its electric field configuration. Cluster analytical approaches consistently extracted four head-surface brain electric field configurations that optimally explain the variance of their changes across time in spontaneous EEG recordings. These four configurations are referred to as EEG microstate classes A, B, C, and D and have been associated with verbal/phonological, visual, subjective interoceptive-autonomic processing, and attention reorientation, respectively. The present study tested these associations via an intra-individual and inter-individual analysis approach. The intra-individual approach tested the effect of task-induced increased modality-specific processing on EEG microstate parameters. The inter-individual approach tested the effect of personal modality-specific parameters on EEG microstate parameters. We obtained multichannel EEG from 61 healthy, right-handed, male students during four eyes-closed conditions: object-visualization, spatial-visualization, verbalization (6 runs each), and resting (7 runs). After each run, we assessed participants' degrees of object-visual, spatial-visual, and verbal thinking using subjective reports. Before and after the recording, we assessed modality-specific cognitive abilities and styles using nine cognitive tests and two questionnaires. The EEG of all participants, conditions, and runs was clustered into four classes of EEG microstates (A, B, C, and D). RMANOVAs, ANOVAs and post-hoc paired t-tests compared microstate parameters between conditions. TANOVAs compared microstate class topographies between conditions. Differences were localized using eLORETA. Pearson correlations assessed interrelationships between personal modality-specific parameters and EEG microstate parameters during no-task resting. As hypothesized, verbal as opposed to visual conditions consistently affected the duration, occurrence, and coverage of microstate classes A and B. Contrary to associations suggested by previous reports, parameters were increased for class A during visualization, and class B during verbalization. In line with previous reports, microstate D parameters were increased during no-task resting compared to the three internal, goal-directed tasks. Topographic differences between conditions included particular sub-regions of components of the metabolic default mode network. Modality-specific personal parameters did not consistently correlate with microstate parameters except verbal cognitive style which correlated negatively with microstate class A duration and positively with class C occurrence. This is the first study that aimed to induce EEG microstate class parameter changes based on their hypothesized functional significance. Beyond the associations of microstate classes A and B with visual and verbal processing, respectively, our results suggest that a finely-tuned interplay between all four EEG microstate classes is necessary for the continuous formation of visual and verbal thoughts. Our results point to the possibility that the EEG microstate classes may represent the head-surface measured activity of intra-cortical sources primarily exhibiting inhibitory functions. However, additional studies are needed to verify and elaborate on this hypothesis.

Global, regional, and local measures of complexity of multichannel electroencephalography in acute, neuroleptic-naive, first-break schizophrenics.

BACKGROUND: Schizophrenic symptoms commonly are felt to indicate a loosened coordination, i.e. a decreased connectivity of brain processes. METHODS: To address this hypothesis directly, global and regional multichannel electroencephalographic (EEG) complexities (omega complexity and dimensional complexity) and single channel EEG dimensional complexities were calculated from 19-channel EEG data from 9 neuroleptic-naive, first-break, acute schizophrenics and 9 age- and sex-matched controls. Twenty artifact-free 2 second EEG epochs during resting with closed eyes were analyzed (2-30 Hz bandpass, average reference for global and regional complexities, local EEG gradient time series for single channels). RESULTS: Anterior regional Omega-Complexity was significantly increased in schizophrenics compared with controls (p < 0.001) and anterior regional Dimensional Complexity showed a trend for increase. Single channel Dimensional Complexity of local gradient waveshapes was prominently increased in the schizophrenics at the right precentral location (p = 0.003). CONCLUSIONS: The results indicate a loosened cooperativity or coordination (vice versa: an increased independence) of the active brain processes in the anterior brain regions of the schizophrenics.

Stent-grafting to descending thoracic aorta during coronary artery bypass grafting.

We report on 2 patients who underwent successful concomitant operation of coronary artery bypass grafting and stent grafting to descending thoracic aortic aneurysms. The device was inserted through a small linear incision on the anterior wall of the aortic arch. Intraoperative stent grafting to descending thoracic aortic aneurysms is an alternative therapeutic option for patients who require concomitant coronary artery bypass grafting and descending aortic replacement.

Multichannel EEG fields during and without visual input: frequency domain model source locations and dimensional complexities.

27-Channel EEG potential map series were recorded from 12 normals with closed and open eyes. Intracerebral dipole model source locations in the frequency domain were computed. Eye opening (visual input) caused centralization (convergence and elevation) of the source locations of the seven frequency bands, indicative of generalized activity; especially, there was clear anteriorization of alpha-2 (10.5-12 Hz) and beta-2 (18.5-21 Hz) sources (alpha-2 also to the left). Complexity of the map series' trajectories in state space (assessed by Global Dimensional Complexity and Global OMEGA Complexity) increased significantly with eye opening, indicative of more independent, parallel, active processes. Contrary to PET and fMRI, these results suggest that brain activity is more distributed and independent during visual input than after eye closing (when it is more localized and more posterior).

Low resolution brain electromagnetic tomography (LORETA) functional imaging in acute, neuroleptic-naive, first-episode, productive schizophrenia.

Functional imaging of brain electrical activity was performed in nine acute, neuroleptic-naive, first-episode, productive patients with schizophrenia and 36 control subjects. Low-resolution electromagnetic tomography (LORETA, three-dimensional images of cortical current density) was computed from 19-channel electroencephalographic (EEG) activity obtained under resting conditions, separately for the different EEG frequencies. Three patterns of activity were evident in the patients: (1) an anterior, near-bilateral excess of delta frequency activity; (2) an anterior-inferior deficit of theta frequency activity coupled with an anterior-inferior left-sided deficit of alpha-1 and alpha-2 frequency activity; and (3) a posterior-superior right-sided excess of beta-1, beta-2 and beta-3 frequency activity. Patients showed deviations from normal brain activity as evidenced by LORETA along an anterior-left-to-posterior-right spatial axis. The high temporal resolution of EEG makes it possible to specify the deviations not only as excess or deficit, but also as inhibitory, normal and excitatory. The patients showed a dis-coordinated brain functional state consisting of inhibited prefrontal/frontal areas and simultaneously overexcited right parietal areas, while left anterior, left temporal and left central areas lacked normal routine activity. Since all information processing is brain-state dependent, this dis-coordinated state must result in inadequate treatment of (externally or internally generated) information.

Source localization of EEG activity during hypnotically induced anxiety and relaxation.

The engagement of different brain regions which implement subjectively experienced emotional states in normals is not completely clarified. Emotional states can conveniently be induced by hypnosis-based suggestions. We studied brain electric activity during hypnotically induced anxiety and relaxation in 11 right-handed normals (5 males, 6 females, mean age 26.5+/-7.6 years). After induction of light hypnosis, anxiety and then relaxation was suggested using a standardized text (reverse sequence in half of the subjects). Nineteen-channel, eyes-closed EEG (20 artifact-free s/subject) was analyzed (source localization using FFT approximation and low resolution electromagnetic tomography, LORETA). Global tests revealed the strongest difference (P<0.005) between EEG source gravity center locations during the two emotional states in the excitatory beta-2 EEG frequency band (18.5-21 Hz). Post hoc tests showed that the sources were located more right during anxiety than during relaxation (P=0.01). LORETA specified that anxiety showed maximally stronger activity than relaxation in right Brodmann area 10, and relaxation showed maximally stronger activity than anxiety in left Brodmann area 22. Clearly, the two induced emotional states were associated with activity of different neural populations. Our results agree with reports on brain activity shifted to the right (especially fronto-temporal) during negative compared with positive emotions, and support the role of beta-2 EEG frequency in emotional states.

Functional imaging with low-resolution brain electromagnetic tomography (LORETA): a review.

This paper reviews several recent publications that have successfully used the functional brain imaging method known as LORETA. Emphasis is placed on the electrophysiological and neuroanatomical basis of the method, on the localization properties of the method, and on the validation of the method in real experimental human data. Papers that criticize LORETA are briefly discussed. LORETA publications in the 1994-1997 period based localization inference on images of raw electric neuronal activity. In 1998, a series of papers appeared that based localization inference on the statistical parametric mapping methodology applied to high-time resolution LORETA images. Starting in 1999, quantitative neuroanatomy was added to the methodology, based on the digitized Talairach atlas provided by the Brain Imaging Centre, Montreal Neurological Institute. The combination of these methodological developments has placed LORETA at a level that compares favorably to the more classical functional imaging methods, such as PET and fMRI.

[Aortic regurgitation caused by the proximal dissecting flap invagination to the left ventricle].

A 68-year-old male with sudden back pain and cardiogenic shock status transferred to our ward. Transthoracic echocardiography revealed that the abnormal round shape string was in the left ventricular outflow tract. The continuity from the staring to the aortic valve was unclear. Intimal flap could not be detected at the level of the ascending aorta. Color Doppler flow imaging showed that the severe AR jet extended into the round string. TEE showed that the intimal tear and flap was seen just above the left subclavian artery. Preoperative diagnosis was acute Stanford type A dissection and acute severe AR due to the inversion of the proximal intimal flap to the left ventricular outflow tract through the aortic valve. At operation, the proximal intimal flap was dissected circumferentially and was cut all the way around 8 cm above the aortic valve ring and was inverted to the left ventricular outflow tract. The aortic valve was preserved because of its normal character after exclusion of the proximal intimal flap. Ascending and arch replacement was carried out. Postoperative TEE and TTE slowed no findings of AR. The patient's postoperative course was uneventful. To our knowledge, this is the first reported case that severe AR caused by the proximal intimal invagination to the left ventricle.

A case of isolated acute DeBakey II redissection occurring in a postoperative survivor who underwent an arch replacement for acute DeBakey IIIb dissection.

A case of isolated acute DeBakey II redissection which occurred in a postoperative survivor who underwent an arch replacement for acute DeBakey IIIb dissection is reported. The operative findings revealed that there was an intimal tear above the left coronary cusp, that there was a false lumen in the native ascending aorta, and that a residual false lumen caused by the initial operation had not been detected. Redissection caused mainly by the operative procedure, such as the failure to include the site of the intimal tear in the original repair and the formation of a new dissection as a result of anastomotic failure, is frequently seen. However, isolated redissection is a rare condition. In this paper we discuss classification, diagnosis and treatment of redissection.

A case report of epithelioid leiomyosarcoma of transverse mesocolon: diagnosis and treatment.

A case of epithelioid leiomyosarcoma of the transverse mesocolon in a 45-year-old man was reported. The patient had a rapidly growing mass in the left upper quadrant. Ultrasonography, gastrointestinography, and abdominal computed tomography showed that the mass was separated from the pancreas, the gastrointestinal tract, and the retroperitoneal organs. Preoperatively the primary origin of this tumor was related to the transverse mesocolon. On laparotomy the tumor of 5cm by 6cm by 3cm in size was found in the anterior left of the transverse mesocolon and the mass was resected entirely. The patient is well 18 months after surgical treatment with no evidence of recurrence.

A case of traumatic pseudoaneurysm of the ascending aorta occurring in a postoperative patient who underwent arch replacement and Bentall's operation.

A case of traumatic pseudoaneurysm of the ascending aorta occurring in a postoperative patient who underwent an arch replacement and Bentall's operation was reported. A bleeding point was clear at the graft of the ascending aorta, and a pseudoaneurysmal formation was suspected following an echocardiogram. An aortogram demonstrated the presence of an aneurysm approximately 8 cm by 4 cm in size originating 5 cm above the right coronary ostia. An emergency operation was carried out. A Trans-femoral bypass was established before sternotomy. The Operative findings showed that adhesive connective tissue covered a pseudoaneurysm 8 cm by 4 cm in size, and that there was a tear in the anastomosis of the grafts between the ascending aorta and the arch 5 cm above the coronary ostia. Direct suture was performed, using hypothermic circulatory arrest. In this paper, We discuss the mechanism, classification, and operative strategy of traumatic pseudoaneurysm.

An experience of ischemic limb salvage associated with myositis ossificans of the left thigh.

A case of ischemic limb salvage associated with myositis ossificans of the left thigh in a 66-year-old man was reported. The patient had a medical history of cerebral palsy and a cervical spinal cord injury, and had an operative past history of hip arthroplasty for fracture of the left femoral neck 10 years before. He showed ischemic symptoms such as paleness, coldness, and loss of the left dorsal arterial pulsation in the left toe, and had a rapidly growing mass in the left thigh. Roentgenography and computed tomography showed a mass 10 cm by 10 cm by 8 cm in size with severe calcification in the left quariceps muscle. Occlusion of the left common femoral artery was found in the arteriogram. Surgery was carried out in order to establish an accurate diagnosis and to rescue the left lower limb. The arterial pulsation was recovered as the result of completely resecting the left quariceps muscle tumor. The pathohistological diagnosis was of myositis ossificans in the quariceps muscle of the thigh. Etidronate disodium was administered in order to prevent a recurrence postoperatively. The patient has been well for the 13 months since surgery.

A case report of substernal goiter.

A case of substernal goiter is reported. A 78-year-old female was admitted to our hospital with no symptoms. Chest roentgenography on admission showed that a mass of 3 by 5 cm in size with calcification located in the substernal region. Computed tomography of the chest and aortography revealed that the mass was attached to the trachea, but the connection to the great vessels was not clear. Pathological findings of the incisional biopsy specimen showed thyroid tissue with no evidence of malignancy. Our clinical diagnosis was substernal goiter. Surgery was not carried out in this case, based on the literature. Surgery is indicated in case of malignancy or in cases with severe illness such as respiratory disorder and superior vena cava syndrome.

[The effect of milrinone for the shock patients after cardiac surgery].

The effect of milrinone in the 16 postoperative shock patients of cardiovascular surgery was studied. The preoperative hemodynamic status were 12 of cardiogenic shock, 2 cases of chronic heart failure and 2 cases of unstable angina pectoris. The operative procedure were 8 cases of coronary artery bypass grafting, 4 cases of valvular surgery, 2 cases of closure of ventricular septal perforation, 2 cases of Bentall operation and 1 case of ascending aortic replacement. The postoperative hemodynamic status were 15 cases of cardiogenic shock, 10 cases of hemorrhagic shock and 1 case of septic shock. Continuous intravenous infusion of 0.5 microgram/kg/min without initial bolus loading was administered immediately after the entrance of the intensive care unit. Significant increase in the maximum blood pressure 3 hours after the infusion were observed (84 +/- 17 mmHg vs 94 +/- 12, p = 0.033). The maximum blood pressure was increased gradually until 24 hours after the infusion. Significant increase in the peripheral body temperature 3 hours after the infusion were observed (32.5 +/- 2.0 degrees C vs 35.9 +/- 1.1 degrees C, p = 0.001). The difference between the peripheral temperature and the central body temperature diminished until 24 hours after the infusion. No significant change in the central venous pressure, pulmonary arterial pressure, pulmonary and cardiac index wedge pressure were observed. No significant change in the platelet number was observed until 3 days after the infusion. Twenty patients (75%) were discharged. Four hospital deaths included 1 cardiac and 3 septic cause were seen. These data suggest that the administration of milrinone for the shock patients after cardiac surgery showed safe and that the continuous intravenous infusion of 0.5 microgram/kg/min without bolus loading showed effective for the recovery of the peripheral circulation.

Event-related electric microstates of the brain differ between words with visual and abstract meaning.

The present study shows that different neural activity during mental imagery and abstract mentation can be assigned to well-defined steps of the brain's information-processing. During randomized visual presentation of single, imagery-type and abstract-type words, 27 channel event-related potential (ERP) field maps were obtained from 25 subjects (sequence-divided into a first and second group for statistics). The brain field map series showed a sequence of typical map configurations that were quasi-stable for brief time periods (microstates). The microstates were concatenated by rapid map changes. As different map configurations must result from different spatial patterns of neural activity, each microstate represents different active neural networks. Accordingly, microstates are assumed to correspond to discrete steps of information-processing. Comparing microstate topographies (using centroids) between imagery- and abstract-type words, significantly different microstates were found in both subject groups at 286-354 ms where imagery-type words were more right-lateralized than abstract-type words, and at 550-606 ms and 606-666 ms where anterior-posterior differences occurred. We conclude that language-processing consists of several, well-defined steps and that the brain-states incorporating those steps are altered by the stimuli's capacities to generate mental imagery or abstract mentation in a state-dependent manner.

Event-related potential P300 microstate topography during visual one- and two-dimensional tasks in chronic schizophrenics.

Reports on left-lateralized abnormalities of component P300 of event-related brain potentials (ERP) in schizophrenics typically did not vary task difficulties. We collected 16-channel ERP in 13 chronic, medicated schizophrenics (25 +/- 4.9 years) and 13 matched controls in a visual P300 paradigm with targets defined by one or two stimulus dimensions (C1: color; C2: color and tilt); subjects key-pressed to targets. The mean target-ERP map landscapes were assessed numerically by the locations of the positive and negative map-area centroids. The centroids time-space trajectories were searched for the P300 microstate landscape defined by the positive centroid posterior of the negative centroid. At P300 microstate centre latencies in C1, patients' maps tended to a right shift of the positive centroid (p < 0.10); in C2 the anterior centroid was more posterior (p < 0.07) and the posterior (positive) centroid more anterior (p < 0.03), but without left-right difference. Duration of P300 microstate in C2 was shorter in patients (232 vs 347 ms; p < 0.03) and the latency of maximal strength of P300 microstate increased significantly in patients (C1: 459 vs 376 ms; C2: 585 vs 525 ms). In summary only the one-dimensional task C1 supported left-sided abnormalities; the two-dimensional task C2 produced abnormal P300 microstate map landscapes in schizophrenics, but no abnormal lateralization. Thus, information processing involved clearly aberrant neural populations in schizophrenics, different when processing one and two stimulus dimensions. The lack of lateralization in the two-dimensional task supported the view that left-temporal abnormality in schizophrenics is only one of several task-dependent aberrations.