Satoru Saito

Contrast-enhanced, wide-band harmonic gray scale imaging of hepatocellular carcinoma correlation with helical computed tomographic findings

We evaluated the usefulness of contrast‐enhanced, wide‐band harmonic gray scale imaging for the diagnosis of hepatocellular carcinoma and compared it with helical computed tomography. Forty‐eight patients with 61 hepatocellular carcinoma lesions were scanned by contrast‐enhanced, wide‐band harmonic gray scale imaging after an intravenous bolus injection of the contrast agent Levovist. Fifty‐seven of the 61 hepatocellular carcinoma lesions showed hypervascular enhancement, and intratumoral vessels could be observed in 40 of the 57 lesions. Helical computed tomography revealed a high‐attenuation area in 54 of the 61 lesions, whereas the other lesions showed an equivocal‐attenuation area. Contrast‐enhanced, wide‐band harmonic gray scale imaging is a useful method for diagnosing the vascularity of hepatocellular carcinoma.

Effect of articulatory suppression on task‐switching performance: Implications for models of working memory

In a series of experiments, we examine some effects of articulatory suppression in task switching. The results from Experiments 1a and 2a showed that switch costs in the articulatory suppression condition were larger than those in the control and tapping conditions when the switching cues were not provided. On the other hand, articulatory suppression did not have any effect on switch costs in Experiments 1b and 2b, where the switching cues were provided. In Experiment 3, using a computer‐assisted experimentation, this pattern of data was replicated in a two‐factor design with articulatory suppression and switching cues factors. The results indicate that a specific component in working memory, the phonological loop, might contribute to the performance in task switching, at least in situations where the external task cues were not available. The data reported here suggest that the phonological loop plays an important role in one of the executive control processes, and challenge the traditional idea that the slave systems are simply governed by the central executive in the working memory.

Direct Exploration of the Role of the Ventral Anterior Temporal Lobe in Semantic Memory: Cortical Stimulation and Local Field Potential Evidence From Subdural Grid Electrodes

Semantic memory is a crucial higher cortical function that codes the meaning of objects and words, and when impaired after neurological damage, patients are left with significant disability. Investigations of semantic dementia have implicated the anterior temporal lobe (ATL) region, in general, as crucial for multimodal semantic memory. The potentially crucial role of the ventral ATL subregion has been emphasized by recent functional neuroimaging studies, but the necessity of this precise area has not been selectively tested. The implantation of subdural electrode grids over this subregion, for the presurgical assessment of patients with partial epilepsy or brain tumor, offers the dual yet rare opportunities to record cortical local field potentials while participants complete semantic tasks and to stimulate the functionally identified regions in the same participants to evaluate the necessity of these areas in semantic processing. Across 6 patients, and utilizing a variety of semantic assessments, we evaluated and confirmed that the anterior fusiform/inferior temporal gyrus is crucial in multimodal, receptive, and expressive, semantic processing.

Disruption of visual feature binding in working memory

In a series of five experiments, we studied the effect of a visual suffix on the retention in short-term visual memory of both individual visual features and objects involving the binding of two features. Experiments 1A, 1B, and 2 involved suffixes consisting of features external to the to-be-remembered set and revealed a modest but equivalent disruption on individual and bound feature conditions. Experiments 3A and 3B involved suffixes comprising features that could potentially have formed part of the to-be-remembered set (but did not on that trial). Both experiments showed greater disruption of retention for objects comprising bound features than for their individual features. The results are interpreted as differentiating two components of suffix interference, one affecting memory for features and bindings equally, the other affecting memory for bindings. The general component is tentatively identified with the attentional cost of operating a filter to prevent the suffix from entering visual working memory, whereas the specific component is attributed to the particular fragility of bound representations when the filter fails.

The phonological loop and memory for rhythms: An individual differences approach

The purpose of the current study was to examine the relationship between short-term memory for rhythm and the phonological loop in working memory. Results showed that digit span scores significantly correlated with the scores on the rhythmic memory task, and that the correlation between the two scores remained significant even after the common variance with reading speed was partialled out. Partial correlation and regression analyses indicated that the relation between memory for rhythm and digit span scores is mediated by the third component in the phonological loop, the component that is responsible for regulation of timing mechanisms in immediate memory tasks.

Does test delay eliminate collaborative inhibition

Earlier research has demonstrated that collaborative groups recall more than individuals, but less than nominal groups (pooled performance of individuals), thus exhibiting collaborative inhibition. In two experiments, all participants were first asked to recall story material on their own. Some participants were then assigned to pairs and recalled the material collaboratively. On the other hand, the participants in the individual recall condition were asked to recall the material once again on their own. In Experiment 1, the collaborative pairs recalled less than the nominal pairs in accordance with previous studies. In Experiment 2, the timing of the initial individual recall was manipulated by inserting one week between the learning and the recall. The collaborative inhibition was eliminated in this situation. Sources of the collaborative inhibition in immediate recall and its disappearance in delayed recall are discussed in terms of the effect of cross cueing in collaborative remembering.

Verbal representation in task order control: An examination with transition and task cues in random task switching

Recent task-switching studies in which a predictable task sequence has been used have indicated that verbal representation contributes to the control of task order information. The present study focused on the role of verbal representation in sequential task decisions, which are an important part of task order control, and examined the effects of articulatory suppression in a random-task-cuing paradigm with two different types of cues presented just before the presentation of a stimulus: a transition cue and a task cue. The former cue provided information only about switching or repeating the task, whereas the latter was associated directly with the identity of the task (i.e., indicating a parity or a magnitude task). In Experiment 1, in which transition cues guided task sequences, articulatory suppression impaired performance in both repetition and switch trials, thereby increasing the mixing costs. In Experiment 2, in which a task cue, rather than a transition cue, was presented to examine the influence of a cue-decoding process, articulatory suppression had no specific effect on task performance. Experiment 3, in which the transition cue and the task cue were randomly presented in the same block to equalize the memory load and task strategy for the two types of cues, confirmed that articulatory suppression significantly increased the mixing costs only in transition cue trials. The results from the three experiments indicated that the use of verbal representation is effective in sequential task decision—that is, in selecting a task set on the basis of transient task order information in both repetition and switch trials.

Characterization of Portal Vein Thrombus With the Use of Contrast-Enhanced Sonography

Objectives. To select an appropriate treatment regimen, it is essential to accurately characterize the nature of a thrombus. This study prospectively assessed the ability of contrast‐enhanced sonography to differentiate between benign and malignant portal vein thrombosis in a population of high‐risk patients. Methods. Fifty‐five patients (43 men and 12 women; mean age, 66 years; range, 55–83 years) with thrombi of the portal venous system were examined by power Doppler sonography and contrast‐enhanced sonography with the intravenous contrast agent SH U 508A (Levovist; Schering AG, Berlin, Germany). Of the thrombi, 40 were characterized as malignant and 15 as benign. Pulsatile flow in the thrombus on power Doppler sonography and positive enhancement of the thrombus on contrast‐enhanced sonography were judged as indications of a malignant thrombus. The sensitivity and specificity of both methods in differentiating the nature of the thrombus were evaluated. Results. The detection of pulsatile flow in a portal vein thrombus as the criterion for diagnosing malignant portal vein thrombus yielded overall sensitivity of 82.5% and specificity of 100%, whereas positive enhancement of the portal vein thrombus itself as a criterion for diagnosing malignancy yielded overall sensitivity and specificity of 100% for each. Conclusions. Contrast‐enhanced sonography can be helpful in discriminating between benign and malignant portal vein thrombi.

Soluble CD14 Levels Reflect Liver Inflammation in Patients with Nonalcoholic Steatohepatitis

Background & Aims Liver inflammation is a risk factor for the progression of nonalcoholic fatty liver disease (NAFLD). However, the diagnosis of liver inflammation is very difficult and invasive liver biopsy is still the only method to reliably detect liver inflammation. We previously reported that overexpression of CD14 in Kupffer cells may trigger the progression to nonalcoholic steatohepatitis (NASH) via liver inflammation following hyper-reactivity to low-dose lipopolysaccharide. Therefore, the aim of this study was to investigate the relationship between soluble type of CD14 (sCD14) and histological features in patients with NAFLD. Methods Our cohort consisted of 113 patients with liver biopsy-confirmed NAFLD and 21 age-matched healthy controls. Serum sCD14 levels were measured by an enzyme-linked immunosorbent assay. Results Serum sCD14 levels were significantly associated with diagnosis of NASH and the area under the receiver operator characteristic curve (AUROC) to distinguish between not NASH and NASH was 0.802. Moreover, serum sCD14 levels were significantly associated with the disease activity based on NAFLD activity score and hepatic CD14 mRNA expression, which is correlated with membrane CD14 (mCD14) expression, in patients with NAFLD. In multiple regression analysis, the serum sCD14 levels were independently associated with liver inflammation. The AUROC to distinguish between mild and severe liver inflammation in patients with NAFLD was 0.752. Conclusions We found that serum sCD14 levels increased significantly with increasing liver inflammation grade in patients with NAFLD, reflecting increased hepatic CD14 expression. Serum sCD14 is a promising tool to predict the worsening of liver inflammation, and may offer a potential biomarker for evaluation of therapeutic effects in NAFLD.

Irrelevant sound disrupts speech production: Exploring the relationship between short‐term memory and experimentally induced slips of the tongue

To explore the relationship between short-term memory and speech production, we developed a speech error induction technique. The technique, which was adapted from a Japanese word game, exposed participants to an auditory distractor word immediately before the utterance of a target word. In Experiment 1, the distractor words that were phonologically similar to the target word led to a greater number of errors in speaking the target than did the dissimilar distractor words. Furthermore, the speech error scores were significantly correlated with memory span scores. In Experiment 2, memory span scores were again correlated with the rate of the speech errors that were induced from the task-irrelevant speech sounds. Experiment 3 showed a strong irrelevant-sound effect in the serial recall of nonwords. The magnitude of the irrelevant-sound effects was not affected by phonological similarity between the to-be-remembered nonwords and the irrelevant-sound materials. Analysis of recall errors in Experiment 3 also suggested that there were no essential differences in recall error patterns between the dissimilar and similar irrelevant-sound conditions. Weproposed two different underlying mechanisms in immediate memory, one operating via the phonological short-term memory store and the other via the processes underpinning speech production.