Biomedical subjects

J Urata

Publications and source records attributed to J Urata.

At least 37 records · Page 2Linked to original sources

PubMed1998

Melatonin treatment for circadian rhythm sleep disorders.

We administered 1-3 mg melatonin to 11 patients (eight men, three women, aged 16-46 years) with circadian rhythm sleep disorders; nine with delayed sleep phase syndrome and two with non-24-hour sleep-wake syndrome. Sleep logs were recorded throughout the study periods and actigraph and rectal temperature were monitored during treatment periods. Melatonin was administered 1-2 h before the desirable bedtime for expected phase-shifting, or 0.5-1 h before habitual bedtime for gradual advance expecting an hypnotic effect of the melatonin. Melatonin treatments were successful in 6/11 patients. Timing and dose of melatonin administration, together with its pharmacological properties for circadian rhythm sleep disorders, should be further studied.

Adolescent↗

PubMed1998

Trials of bright light exposure and melatonin administration in a patient with non-24 hour sleep-wake syndrome.

We report a patient with non-24 h sleep-wake syndrome (non-24) whose free-running sleep-wake cycle was successfully treated with both scheduled bright light exposure and melatonin treatment. In the present study, morning bright light as well as evening melatonin phase-advanced sleep-wake cycles and melatonin rhythm. Both these procedures achieved appropriate entrainment to a 24 h day. However, the patient did not continue morning bright light therapy after the discharge. Rising at appropriate times in the morning for bright light therapy was difficult for him to continue. Melatonin treatment was better tolerated because of its ease of application.

Adult↗

PubMed1998

Mucin-producing tumor of the pancreas: diagnostic value of diffusion-weighted echo-planar MR imaging.

PURPOSE: To determine whether diffusion-weighted echo-planar magnetic resonance (MR) imaging can help differentiate mucin-producing tumors of the pancreas from other cystic lesions. MATERIALS AND METHODS: Diffusion-weighted echo-planar 1.5-T MR imaging was performed in patients with mucin-producing tumor (n = 15), pseudocyst (n = 15), or serous microcystic tumor (n = 2). Images were obtained with diffusion-sensitizing gradients of 30 and 300 sec/mm2. The apparent diffusion coefficient (ADC) was calculated. RESULTS: At 30 sec/mm2, all cystic lesions had very high signal intensity. The dilated main pancreatic duct was depicted in eight patients with mucin-producing tumor and in six with pseudocyst. The mean (+/- standard deviation) ADCs of mucin-producing tumors (2.7 x 10(-3) mm2/sec +/- 0.9 x 10(-3)) and pseudocysts (3.2 x 10(-3) mm2/sec +/- 1.0 x 10(-3) were significantly lower (P < .01) than those of serous cysts or cerebrospinal fluid (5.8 x 10(-3) mm2/sec +/- 2.0 x 10(-3)). At 300 sec/mm2, cysts and the main pancreatic ducts had high signal intensity in cases of mucin-producing tumor, indicative of the presence of mucinous products in both the cystic cavity and the main pancreatic duct. The signal intensity of cystic fluid in pseudocysts was high on diffusion-weighted images, but that of the pancreatic duct was decreased (ADC = 5.1 x 10(-3) mm2/sec +/- 1.7 x 10(-3)). CONCLUSION: Diffusion-weighted MR imaging can help characterize cystic lesions of the pancreas. Findings-suggestive of viscous fluid in mucin-producing tumors are present on such images.

Adenocarcinoma, Mucinous↗

PubMed1997

Percutaneous microwave coagulation therapy in liver tumors. A 3-year experience.

PURPOSE: Percutaneous microwave coagulation therapy (PMCT) is an interventional alternative for inoperable malignant liver tumors. In this paper, we report the results of our 3-year experience of PMCT in order to establish suitable indications for this treatment. MATERIAL AND METHODS: We studied a total of 27 inoperable liver tumors in 24 patients. Histology of the tumors showed 20 hepatocellular carcinomas (HCCs) (13 well differentiated, 4 moderately differentiated, and 3 poorly differentiated) and 7 metastases. These tumors were treated by PMCT and were followed for 4-40 months (average 18 months). Under US guidance, the tumors were coagulated by microwaves emitted from an electrode. The changes of tumor size after PMCT were evaluated by CT. When the tumors disappeared or were reduced in size after treatment, PMCT was regarded as effective. Complications from PMCT were also evaluated. The patient survival rate was obtained by means of the Kaplan-Meier method. RESULTS: In tumors of 30 mm or less, treatment response was obtained in 70% of cases, while 55% of tumors larger than 30 mm responded. The tumor became smaller or disappeared in 85% of the well differentiated HCCs, and in 25% of the moderately differentiated HCCs, but none of the poorly differentiated HCCs responded. In metastatic tumors, PMCT was effective in 57% of cases. Slight pain (24%), fever (20%) and subcutaneous hematoma (8%) were experienced immediately after PMCT. In 2 poorly differentiated HCCs, needle tract seeding was observed. No case of liver dysfunction was seen after PMCT. The overall survival rate was 83.1% at 1 year and 68.7% at 2 years. CONCLUSION: Good therapeutic results were achieved with PMCT in lesions of 30 mm or less, and in well differentiated HCCs.

Aged↗

PubMed1997

Cavernous hemangioma of the liver: pathologic correlation with dynamic CT findings.

PURPOSE: To correlate the pathologic findings of cavernous hemangiomas with enhancement patterns seen at dynamic computed tomography (CT) performed after injection of contrast material. MATERIALS AND METHODS: Sixteen patients underwent dynamic CT followed by hepatectomy. Resected specimens of 16 cavernous hemangiomas, which ranged from 2 to 15 cm in diameter, were obtained. The average size of vascular spaces in the histologic specimen was correlated with their appearance on dynamic CT scans. RESULTS: In 11 tumors, characteristic progressive fill-in after peripheral contrast enhancement was seen (type 1). In type 1 tumors, three zones were noted within the tumor: areas of peripheral puddling in the arterial-dominant phase, areas of gradual fill-in, and areas of no or minimal enhancement. Vascular spaces in areas of peripheral global enhancement were significantly smaller than those in areas of gradual fill-in (P = .03). In areas of no or minimal enhancement, extensive scar tissue (n = 9) or cystic cavity (n = 3) was seen. In three hemangiomas smaller than 3 cm, enhancement occurred diffusely in the arterial-dominant phase and vascular space was small (type 2). In two tumors, enhancement was seen only in the periphery of the tumor (type 3), and the majority of tumor was occupied by the cystic cavity or scar tissue. CONCLUSION: Dynamic enhancement patterns of cavernous hemangiomas are related to the collective size of their constituent vascular spaces.

Adult↗

PubMed1997

In vitro and clinical studies of image acquisition in breath-hold MR cholangiopancreatography: single-shot projection technique versus multislice technique.

OBJECTIVE: This study was undertaken to compare the in vitro and clinical value of two-dimensional multislice breath-hold MR cholangiopancreatography (MRCP) with a single-shot projection technique using a half-Fourier acquisition single-shot turbo spin-echo sequence. SUBJECTS AND METHODS: We examined 108 patients with pancreaticobiliary diseases, using breath-hold MRCP and a half-Fourier acquisition single-shot turbo spin-echo sequence on a 1.5-T MR unit with a body phased-array coil. Two data acquisition techniques were employed: multislice acquisition postprocessed by maximum intensity projection (MIP) (multislice technique) and single-shot projection with a thick slice (projection technique). In the multislice technique, nine contiguous slices were obtained with a thickness of 5 mm (acquisition time. 18 sec). In the projection technique, a single slice was obtained with a thickness of 30, 50, or 70 mm (acquisition time. 2 sec). Contrast-to-noise ratio (CNR) between the common bile duct and the liver as well as detectability of normal structures and diseases were compared for these two acquisition techniques. In the multislice technique, source images were also evaluated. ERCP or percutaneous transhepatic cholangiography images were used as the gold standard. RESULTS: Most of the pancreatic duct and common bile duct was revealed on 54% and 100% of the projection images, respectively, and on 35% and 98% of the MIP images, respectively, CNR was significantly higher with the multislice technique than with the projection technique (p < .01). With the projection technique, CNR decreased as slice thickness increased. Dilatation and occlusion of the pancreaticobiliary tree were equally well revealed by the two imaging techniques. However, abnormalities in the periampullary region and anomalies in the pancreaticobiliary tree were more clearly seen on projection images than on MIP images (p < .05). Stones in the common bile duct, gallbladder, or intrahepatic bile duct were best seen on source images acquired by the multislice technique (83% sensitivity). CONCLUSION: Because of the absence of misregistration and the speed of image acquisition, breath-hold single-shot MRCP using the projection technique with a slice thickness of 30 or 50 mm consistently revealed the pancreaticobiliary tree and periampullary region with an acceptable CNR. Stones in the bile duct were best seen on the source images acquired by the MIP technique.

Biliary Tract Diseases↗

PubMed1996

Effects of a small dose of triazolam on P300 and resting EEG.

The aim of the present study was to clarify whether cognitive impairments caused by benzodiazepines (BDZs) are a consequence of their specific direct effects on cognitive function or whether they are explained as secondary effects of increased sleepiness. Ten healthy men (mean age, 33.9 years) participated in two experimental sessions in a randomized cross-over, double-blind study: in one session subjects were given a placebo and in the other they were given 0.125 mg triazolam (TRZ). Each experimental session was conducted on 1 day. After a pre-drug EEG recording and an event-related potential (ERP) recording, under an oddball paradigm, subjects took the TRZ or placebo orally at 1000 hours. Thereafter, EEG and ERP recording sessions, following the same procedure as the pre-drug sessions, were conducted at 1, 2, 4, 6 and 8 h after drug administration. The EEG and ERP recordings from Cz and Pz referred to the bilaterally linked ear electrodes were used. We found that P300 latency was significantly prolonged in TRZ condition at 2 h (Pz) and 4 h (Cz and Pz) after TRZ, and that the P300 amplitude was significantly reduced at 2 h (Cz and Pz) and 4 h (Pz) after TRZ, compared to the same times after placebo. The absolute power values for the theta (4-7 Hz), alpha 1 (8-9 Hz), and alpha 2 (10-12 Hz) bands did not differ at any measurement time between the treatments. Only the beta band (13-19 Hz) power value was significantly elevated after the TRZ administration (versus placebo). No significant sedative effects were detected in subjective measurements. These results indicate that a single oral dose of 0.125 mg TRZ caused cortical changes without distinct general sedation or subjective sleepiness.

Adult↗

PubMed1996

Small hepatocellular carcinoma in patients with chronic liver damage: prospective comparison of detection with dynamic MR imaging and helical CT of the whole liver.

PURPOSE: To compare contrast material-enhanced dynamic magnetic resonance (MR) imaging with helical computed tomography (CT) for the detection of small hepatocellular carcinoma (HCC) in patients with chronic liver damage. MATERIALS AND METHODS: Fifty patients with chronic hepatitis or liver cirrhosis underwent dynamic contrast-enhanced fast low-angle shot MR imaging and multiple-phase helical CT. Arterial, portal-venous, and delayed-phase images were compared. Diagnostic ability with both techniques was evaluated by means of receiver operating characteristic (ROC) analysis; images in patients with (n = 27) and those without (n = 15) HCC in whom the same anatomic levels were available for both examinations were assessed. Seventy-two lesions were evaluated, and tumor diameter ranged from 0.5 to 3.0 cm (mean, 1.9 cm). RESULTS: ROC analysis showed that the arterial-phase images obtained with both techniques allowed better detection of HCC. Diagnostic ability was significantly better with arterial-phase MR imaging (mean area under the ROC curve [Az] = 0.96) than arterial-phase CT (Az = 0.87) or with images from any other phase (P < .05). For the delayed phase, diagnostic capability was significantly better with CT (Az = 0.84) than with MR imaging (Az = 0.77) (P < .05). CONCLUSION: Arterial-phase dynamic MR imaging is superior to helical CT for the detection of HCC in patients with chronic liver damage.

Aged↗

PubMed1996

Gadolinium-enhanced breath-hold three-dimensional MR angiography of the portal vein: value of the magnetization-prepared rapid acquisition gradient-echo sequence.

The authors evaluated magnetic resonance (MR) angiography of the portal vein performed with a breath-hold, gadolinium-enhanced, magnetization-prepared rapid acquisition gradient-echo sequence in five volunteers and 24 patients. The main portal vein and its branches and the liver were depicted clearly in all images. The hepatic vein was clearly depicted in 21 of the 24 patients. MR angiography performed with this sequence allowed high-quality imaging of the portal and hepatic veins.

Adult↗

PubMed1996

Detection of hepatocellular carcinoma by intraarterially enhanced ultrasonography with CO2 microbubbles. Comparison with DSA, dynamic CT, and Lipiodol CT.

PURPOSE: To evaluate the diagnostic value of contrast-enhanced US with CO2 microbubbles (EU) for HCCs. Detectability was compared with DSA, dynamic CT, and Lipiodol CT. MATERIAL AND METHODS: Forty-seven histologically proven HCCs detected with US were evaluated with EU, DSA, and dynamic CT. In 23 patients (35 lesions), Lipiodol CT was also performed. The size of the tumors ranged from 8 to 71 mm (average 28.1 mm); 24 lesions were smaller than 20 mm and 23 lesions were larger than 20 mm. RESULTS: Overall detection was possible in 40 of 47 lesions (85%) by EU, in 32 of 47 (68%) by DSA, in 33 of 47 (74%) by dynamic CT, and in 27 of 35 (77%) by Lipiodol CT. In tumors smaller than 20 mm, detection was possible in 21 of 24 lesions (88%) by EU, 14 of 24 (58%) by DSA, 14 of 24 (58%) by dynamic CT, and 11 of 17 (65%) by Lipiodol CT. CONCLUSION: EU has significant diagnostic value for detection of HCCs, particularly tumors smaller than 20 mm.

Angiography, Digital Subtraction↗

PubMed1996

Detection of pseudocapsule of renal cell carcinoma with MR imaging and CT.

OBJECTIVE: A pseudocapsule surrounding a renal cell carcinoma is a pathologic feature seen frequently in the early stages of this disease. Partial nephrectomy or simple enucleation may be indicated when a pseudocapsule is detected. The purpose of this study is to analyze the roles of MR imaging and CT in showing the pseudocapsule in renal cell carcinomas. SUBJECTS AND METHODS: MR imaging and CT appearances of the kidneys in 52 patients with 54 renal cell carcinomas--and 40 patients with 45 other renal masses for comparison--were prospectively analyzed and correlated with pathologic results. The frequency of a pseudocapsule in renal cell carcinomas and in various renal tumors was analyzed. We compared the detectability of a pseudocapsule in renal cell carcinomas with MR imaging on T1-weighted spin-echo, T2-weighted spin-echo, and contrast-enhanced T1-weighted spin-echo sequences, and on contrast-enhanced CT. RESULTS: At pathologic evaluation, a pseudocapsule was seen in 66% (19 of 29) of tumors 4 cm or less in diameter and in 28% (7 or 25) of tumors larger than 4 cm in diameter. All tumors with a pseudocapsule were low histologic grade. Large renal cell carcinomas and other tumors appeared expansile but not encapsulated. A rim corresponding to the pseudocapsule was seen around the tumor in seven lesions on T1-weighted images, 26 lesions on T2-weighted images, and 11 lesions on postcontrast T1-weighted images. T2-weighted imaging was the most sensitive technique for visualization of the pseudocapsule (sensitivity, 68%; specificity, 91%). All pseudocapsules detected on T1-weighted images or postcontrast T1-weighted images could be detected on T2-weighted images. With postcontrast images, enhancement of the pseudocapsule resulted in poor contrast relative to the surrounding tissue. At contrast-enhanced CT, the pseudocapsule was not visible in any tumors. In all MR imaging sequences and in CT, a pseudocapsule were not found in other pathologic conditions except oncocytoma. CONCLUSION: A pseudocapsule was seen in 66% of renal cell carcinomas 4 cm in diameter or smaller. T2-weighted MR imaging is the most sensitive technique for showing this feature.

Adult↗

PubMed1996

MR cholangiopancreatography using HASTE (half-Fourier acquisition single-shot turbo spin-echo) sequences.

OBJECTIVE: Images of breath-hold MR cholangiopancreatography (MRCP) using HASTE (half-Fourier acquisition single-shot turbo spin-echo) sequences were taken in healthy volunteers. The technique was then evaluated as a noninvasive alternative to direct cholangiopancreatography in patients with pancreaticobiliary diseases. SUBJECTS AND METHODS: Forty healthy volunteers and 56 patients with various pancreaticobiliary diseases were examined by MRCP using HASTE with 128 echo train lengths on a 1.5-T MR unit. A body phased-array coll was used for data collection. Imaging times were 2 sec for the single-slice technique with a 20-mm slice thickness and 18 sec for sequential acquisition by the multislice technique with a 5-mm slice thickness (effective TE, 87 msec). We used the healthy volunteers to determine our ability to detect normal structures. The results obtained by HASTE for both patient groups were correlated with imaging by percutaneous transhepatic cholangiography or endoscopic retrograde cholangiopancreatography. RESULTS: In all healthy volunteers, HASTE-MRCP showed both the common bile duct and the main pancreatic duct. Cystic ducts were visualized in 88% of these volunteers by HASTE-MRCP, and branches of pancreatic ducts were visualized in 75% by HASTE-MRCP. The diameter and length of dilated or stenotic ducts seen on HASTE-MRCP were correlated with percutaneous transhepatic cholangiography or endoscopic retrograde cholangiopancreatography images in 56 diseased patients. Not only the position of stenosis or dilatation but also the distal portion of the stenosis was visualized by HASTE-MRCP. CONCLUSION: Breath-hold HASTE-MRCP with a phased-array multicoil consistently allows for high-quality images of both normal and diseased pancreaticobiliary tracts. This technique can be used as a noninvasive screening method for pancreaticobiliary diseases in the majority of patients.

Biliary Tract↗

PubMed1996

Multiple-phase helical CT of the liver for detecting small hepatomas in patients with liver cirrhosis: contrast-injection protocol and optimal timing.

OBJECTIVE: Helical CT scanners allow multiple-phase sequential scans of the entire liver to be obtained during a single bolus injection of contrast material. The purpose of this study was to compare two injection protocols and to establish timing that would optimize detection of hepatomas less than 3 cm in diameter. SUBJECTS AND METHODS: Triple-phase helical CT of the liver was evaluated in 217 patients who had liver cirrhosis and were referred for known or suspected hepatomas. Proof of individual neoplasms was based on biopsy results, surgical findings, or findings of other imaging studies. Sixty percent nonionic contrast material, infused at 2 or 4 ml/sec, was followed by sequential arterial-phase, portal-venous phase, and equilibrium-phase helical scans of the liver. Aortic and hepatic enhancement curves were constructed by measuring CT attenuation. The CT attenuation values of individual tumor lesions were also measured. We compared the degree of enhancement of normal structures and tumors obtained with four scan protocols (injection at 2 ml/sec with a 30-sec scan delay [n = 54], injection at 2 ml/sec with a 35-sec scan delay [n = 47], injection at 4 ml/sec with a 20-sec scan delay [n = 56], and injection at 4 ml/sec with a 25-sec scan delay [n = 60] and determined the optimal injection protocol and timing for CT acquisition. RESULTS: Peak aortic and hepatic enhancement was obtained earlier with the 4-ml/sec protocol (at 24 sec and 61 sec versus 36 sec and 90 sec for the 2-ml/sec protocol). The peak attenuation value of the aorta was higher with the 4-ml/sec protocol (330 H versus 186 H for the 2-ml/sec protocol). However, peak hepatic attenuation was similar for both protocols (98 H for the 4-ml/sec protocol versus 92 H for the 2-ml/sec protocol). Liver-tumor contrast was highest in the arterial phase with both protocols. The next highest contrast was obtained during the equilibrium phase. Liver-tumor contrast in the portal-venous phase was significantly lower than that in the other two phases. Tumor enhancement was significantly higher in scans obtained using the 4-ml/sec protocol with a delay time of 25 sec than those obtained with a delay time of 20 sec. In 109 hepatomas, 35 tumors were only seen or were most conspicuous during the arterial phase, four tumors were most conspicuous during the equilibrium phase, and one tumor was most conspicuous during the portal-venous phase. CONCLUSION: Arterial-phase helical CT of the liver after 4-ml/sec injection of contrast material significantly improves detection of hepatomas less than 3 cm in diameter when performed in addition to delayed scanning. Portal-venous phase helical CT is of limited value in detecting small hepatomas.

Carcinoma, Hepatocellular↗

PubMed1995

Unresectable hepatocellular carcinoma: analysis of prognostic factors in transcatheter management.

PURPOSE: To evaluate the effect of transcatheter management of hepatocellular carcinoma (HCC) on survival. MATERIALS AND METHODS: A prospective trial of transcatheter arterial embolization (TAE) was performed in patients with unresectable HCC. Three hundred twenty-two patients (265 men, 57 women; age range, 30-83 years) underwent TAE alone: 60 patients underwent TAE with gelatin sponge (GS) that contained anticancer agents (protocol 1); 78, TAE with GS and iodized oil mixed with anticancer agents (protocol 2); and 159, TAE with iodized oil with anticancer agents (protocol 3). A Cox proportional hazard model was used to analyze prognostic factors. RESULTS: In the randomized group (n = 272), survival rates for protocols 1, 2, and 3 were 80.4%, 86.3%, and 65.9%, respectively, at 1 year. Findings of analysis of prognostic factors showed that extrahepatic metastases, ascites, tumor extension, and icterus were the important factors. CONCLUSION: TAE with GS was superior to TAE without GS. Patient characteristics were important factors for survival.

Adult↗

PubMed1995

US-guided liver biopsy: predicting the effect of interventional treatment of hepatocellular carcinoma.

PURPOSE: To analyze the results of ultrasound (US)-guided biopsy as a predictor of the outcome of interventional treatment of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: US-guided biopsy was performed in 125 lesions in 102 high-risk patients, before transcatheter arterial embolization (TAE) (82 lesions) or before percutaneous ethanol injection (PEI) therapy (25 lesions, including 14 lesions previously treated with TAE). Pathologic results were correlated with treatment effects. RESULTS: Results of biopsy confirmed 107 HCCs, which were classified as early (n = 17), frank (n = 67), sclerosing (n = 12), or poorly differentiated or undifferentiated (n = 11). Hypervascularity was observed in most frank HCCs, with a good response to TAE. Tumor vascularity in early or sclerosing HCCs was slight and did not respond to TAE. Sclerosing and poorly differentiated or undifferentiated HCCs enlarged after treatment, whereas early HCCs did not. Early HCCs were treated successfully with PEI therapy; sclerosing HCCs responded poorly to PEI therapy. CONCLUSION: Evaluation of histologic subtype of HCC by means of US-guided biopsy is essential, because subtype may affect treatment planning.

Adult↗

PubMed1995

Early detection of pancreatic glucagonoma.

Glucagonoma is a rare islet cell tumor of pancreas. Only 122 proven cases have been reported in the English literature so far. Diagnosis of glucagonoma has usually been delayed. The average size of clinically detected glucagonomas was 5.8 cm, and 54.7% of them exhibited metastasis. We describe the case of a 0.7-cm asymptomatic pancreatic glucagonoma. A 45-yr-old female was demonstrated to have a demarcated, small, low echoic mass in the pancreatic head by routine ultrasonography. Table incremental dynamic computed tomography showed a small well-enhanced mass recognized only in an early phase. A 0.7 x 0.7 cm firm nodule on the pancreatic head was excised at operation. Immunohistochemical and ultrastructural studies revealed that this tumor was a glucagon-producing adenoma. This may be the smallest glucagonoma detected by image diagnostics that has been reported in the English literature. Possible early detection of glucagonoma was discussed in this report.

Female↗

PubMed1992

[Interpeak components of event-related potentials--comparison between normal and schizophrenic groups].

Event-related potentials (ERPs) during a two-tone discrimination task were recorded in 85 normal subjects and 110 schizophrenic subjects. We divided ERPs into 4 interpeak components. We named them A, A', B and B'. A is the component from the stimulus point to n100 peak. A' is the one from n100 peak to p200 peak. B is the one from p200 peak to n200 peak. B' is the one from n200 peak to p300 peak. Their latency was named Al, A'l, Bl, and B'l respectively. Their amplitude was also named Aa, A'a, Ba and B'a respectively. Bl and A'l of the schizophrenic group were both significantly longer than those of the normal group. B'a of the schizophrenic group was significantly smaller than that of the normal group. Interrelations between interpeak components of the normal group were examined statistically. Regarding latency, a significant negative correlation was seen between Al and A'l, and also between Bl and B'l. Regarding amplitude, a significant positive one was seen between Aa and A'a, and also between Ba and B'a. Interrelations between Al and A'l, Bl and B'l, Aa and A'a, and Ba and B'a of the schizophrenic group were the same as those of the normal group. These negative correlations in latency suggest that n100 peaks and n200 peaks have 'jitter'. A combination of interpeak components is supposed to reflect a higher function of the brain. There was a significant negative correlation between (A + A')l and (B + B')l in the normal group, but there was not a significant one between them in the schizophrenic group. The schizophrenic group is supposed to have a certain abnormality in a higher function of the brain. Our result suggests that we may possibly be able to associate an abnormal focus around p200 peak with some symptoms and signs of schizophrenia.

Adult↗

PubMed1992

[Mechanism of attention in sleep--the changes of waveforms of event-related potentials in sleep].

Since attention has such a close correlation with arousal level, the influence of sleep on the waveforms of event related potential (= ERP) must be studied in advance for evaluating attentiveness of human mental activity. ERP, which odd-ball paradigm was used to elicit, was examined in 9 adult and healthy subjects from arousal to sleep. And ERP during a whole night was also examined in 5 of them to study the relation of the waveforms of ERP and sleep stages including a stage of rapid eye movement. As a result, there were some clear differences between the waveforms of the rare and frequent stimuli, and with change of sleep stages the differences also changed. Remarkable increase of amplitude and prolongation of latency of P200 and N200 were found in the waves of target stimuli in stage I. Activities of both components were connected with each other like a complexed component and preceded by the change of P300 activities. The waveforms of target stimuli in stage II had same kind of components with those of arousal stage. There were increased P200, N200, P300 activities and subsequent large negative activity which we called N3. These components were not clear in the waveforms of non-target stimuli. But P300 and N3 components were disappeared gradually during stage III. The averaged waveforms in stage III accompanied with 14-16 Hz fast wave suggested that they were identical with K-complex of sleep EEG. Add to this result, the habituation usually observed on P200 and N200 of nontarget stimuli in arousal let us to think that they are also identical with orienting reflex by rare and novel stimuli of external events (Sokolov). According to the result of examination changing the probability of target stimuli (20%----50%----80%), the waves of target stimuli in stage II were dependent on the probability of rare stimuli as well as in arousal stage. The dependence on probability was thought to reflect an automatic processing of selecting stimuli by orienting reflex in sleep. Another 3 subjects were examined of auditory evoked response in sleep with the same stimuli and without a task of counting numbers of rare stimuli. In stage II, however, they showed the waveforms by rare stimuli just like those by rare and target stimuli of 9 subjects. Then, it was supposed that attentiveness for external stimuli might be existent in sleep and changeable with sleep stages.

Adult↗