Neural correlates of bridging inferences and coherence processing.

We explored the neural correlates of bridging inferences and coherence processing during story comprehension using Positron Emission Tomography (PET). Ten healthy right-handed volunteers were visually presented three types of stories (Strong Coherence, Weak Coherence, and Control) consisted of three sentences. The causal connectedness among sentences in the Strong Coherence story was strong that readers would not have to generate bridging inferences, whereas the causal antecedent of the last sentence in the Weak Coherence story was not explicitly stated so that readers should draw bridging inferences to fill the gap between sentences. It was found that the left middle temporal gyrus was activated while participants read the Weak Coherence stories. In contrast, the dorsomedial prefrontal cortex (dmPFC) and posterior cingulate cortex were activated only in the Strong Coherence condition. This suggests that the dmPFC was involved in coherence processing whereas bridging inference was mediated by the left middle temporal gyrus. It was also found that anterior temporal pole and the temporo-parietal junction mediated general semantic processing.

A network analysis of ¹5O-H2O PET reveals deep brain stimulation effects on brain network of Parkinson's disease.

PURPOSE: As Parkinson's disease (PD) can be considered a network abnormality, the effects of deep brain stimulation (DBS) need to be investigated in the aspect of networks. This study aimed to examine how DBS of the bilateral subthalamic nucleus (STN) affects the motor networks of patients with idiopathic PD during motor performance and to show the feasibility of the network analysis using cross-sectional positron emission tomography (PET) images in DBS studies. MATERIALS AND METHODS: We obtained [¹5O]H2O PET images from ten patients with PD during a sequential finger-to-thumb opposition task and during the resting state, with DBS-On and DBS-Off at STN. To identify the alteration of motor networks in PD and their changes due to STN-DBS, we applied independent component analysis (ICA) to all the cross-sectional PET images. We analysed the strength of each component according to DBS effects, task effects and interaction effects. RESULTS: ICA blindly decomposed components of functionally associated distributed clusters, which were comparable to the results of univariate statistical parametric mapping. ICA further revealed that STN-DBS modifies usage-strengths of components corresponding to the basal ganglia-thalamo-cortical circuits in PD patients by increasing the hypoactive basal ganglia and by suppressing the hyperactive cortical motor areas, ventrolateral thalamus and cerebellum. CONCLUSION: Our results suggest that STN-DBS may affect not only the abnormal local activity, but also alter brain networks in patients with PD. This study also demonstrated the usefulness of ICA for cross-sectional PET data to reveal network modifications due to DBS, which was not observable using the subtraction method.

Results of curative radiation therapy with or without chemotherapy for stage III unresectable non-small cell lung cancer.

PURPOSE: We retrospectively analyzed the patients who received curative radiotherapy for unresectable stage III NSCLC to investigate the impact of chemotherapy. MATERIALS AND METHODS: From 1998 to 2001, the records of 224 patients who completed curative radiotherapy for NSCLC were reviewed. There were 210 males and 14 females, and their median age was 64 years (range 38 approximately 83). 54 patients had stage IIIA disease and 170 patients had stage IIIB disease. Conventional radiotherapy was given and the radiation dose ranged from 50 approximately 70 Gy with a median of 60 Gy, and chemotherapy was combined for 116 patients (52%). RESULTS: The median survival, the 2-year, and 5-year actuarial survival rates of all 224 patients were 15 months, 30%, and 7%, respectively. The median survival of the patients with stage IIIA and IIIB disease were 21 months and 13 months, respectively (p=0.14). The median survival of patients who received chemoradiation was 18 months compared to 14 months for the patients who received RT alone (p=0.02). Among the chemoradiation group of patients, the median survival time of the patients who received 1 to 3 cycles of chemotherapy was 16 months and that for the patients who received more than 3 cycles was 22 months (p=0.07). We evaluated the effects of the timing of chemoradiation in 57 patients who received more than 3 cycles of chemotherapy. The median survival of the patients with the concurrent sequence was 25 months and that for the patients with the sequential chemotherapy was 19 months (p=0.81). CONCLUSIONS: For advanced stage III non-small cell lung cancer patients who completed the curative radiotherapy, the addition of chemotherapy improved the survival compared to the patients who received radiotherapy alone.