Lexical/semantic processing in dorsal left inferior frontal gyrus.

Previous studies have not determined whether the dorsal left inferior frontal gyrus has a lexical or semantic function. This study conducted an event-related functional MRI experiment to explore its function using Japanese words and nonsense words in a syllable counting task. The word task activated a dorsal area (BA6/44) and a ventral area (BA45/47) more extensively than did the nonsense word task. The results indicate that the dorsal area also has lexical or semantic functions, despite that it has been related to phonological processing from studies using written stimuli. The more extensive activation by the word task might result from the same level of effort during phonological processing of Japanese words and nonsense words.

Function segregation in the left inferior frontal gyrus: a listening functional magnetic resonance imaging study.

Function segregation in the left inferior frontal gyrus was investigated in a functional magnetic resonance imaging experiment using a passive listening task, in which Japanese volunteers were required to passively listen to words and nonsense words in Japanese and English. The statistical analysis results showed that the dorsal part of the left inferior frontal gyrus was more extensively activated by listening to English words and nonsense words than to those of Japanese, respectively, which suggests automatic articulatory representation access for non-native stimuli perception, and that the ventral part was more extensively activated by listening to English and Japanese words than to nonsense words in either language, which suggests a lexical or semantic processing function.

Plasma adrenomedullin and carotid atherosclerosis in atherothrombotic ischemic stroke.

OBJECTIVE: Adrenomedullin is known to exert anti-atherosclerotic actions by inhibiting proliferation and migration of smooth muscle cells in vitro. Here we examine the relationship between the plasma concentration of adrenomedullin and ultrasonographic characteristics of carotid arteries both in ischemic stroke and in the absence of cerebrovascular disease. METHODS: We studied 61 patients with atherothrombotic ischemic stroke in the chronic phase and 50 patients without any cerebrovascular disease. Intima-media thickness and vascular lumen diameters were evaluated by carotid ultrasonography. Plasma mature-adrenomedullin was determined by radioimmunoassay. RESULTS: Plasma mature-adrenomedullin in the patients with atherothrombotic ischemic stroke in the chronic phase (2.01 +/- 0.58 fmol/ml) was significantly higher than that in the patients without any cerebrovascular disease (1.24 +/- 0.18 fmol/ml, P < 0.001). With multiple regression analysis, plasma mature-adrenomedullin was found to be predicted by: stroke status (atherothrombotic ischemic stroke versus no cerebrovascular disease), diabetes status (yes/no), left ventricular ejection fraction, internal carotid artery intima-media thickness, and common carotid artery pressure strain elastic modulus (R = 0.79; F5,105 = 85.39, P < 0.0001). CONCLUSION: Plasma mature-adrenomedullin showed significantly positive associations with carotid atherosclerosis and atherothrombotic ischemic stroke, independent of systolic blood pressure.

Comparison of magnetic resonance imaging and transesophageal echocardiography in detection of thrombus in the left atrial appendage.

BACKGROUND AND PURPOSE: A noninvasive technique of visualizing the left atrial appendage (LAA) and its thrombus in patients with atrial fibrillation would be of great interest. This study examined the utility of MRI for the assessment of thrombus in the LAA. METHODS: We evaluated 50 subjects with nonrheumatic continuous atrial fibrillation and a history of cardioembolic stroke. Each patient received an MRI and a transesophageal echocardiography (TEE) on the same day for thrombus detection in the LAA. Both double- and triple-inversion recovery sequences were used for the MRI evaluations. RESULTS: In all subjects, the LAA was readily visualized with MRI. High-intensity masses in the LAA were clearly distinguishable from the LAA wall in the triple-inversion recovery sequences. Concordance between detection of high-intensity mass with MRI and thrombus with TEE was high: no mass (MRI), no thrombus (TEE), 31 patients; mass (MRI), thrombus (TEE), 16 patients; and mass (MRI), no thrombus (TEE), 3 patients (overall kappa=0.876, SE=0.068). CONCLUSIONS: MRI is a noninvasive and reproducible modality for thrombus detection in the LAA of patients with nonrheumatic continuous atrial fibrillation and previous cardioembolic stroke.