Modulation of human global/local perception by low spatial frequency filtering  

作　　者：HANShihui J.A.Weaver S.O.Murray KANGXiaojian E.W.Yund D.L.Woods 

机构地区：[1]DepartmentofPsychology,CenterforBrainandCognitiveSciences,PekingUniversity,Beijing100871,China [2]DepartmentofNeurology,UniversityofCaliforniaatDavis,VANorthernCaliforniaSystemofClinics,Davis,CA95616,USA

出　　处：《Chinese Science Bulletin》2003年第21期2336-2339,共4页

基　　金：supported by the National Natural Science Foundation of China(Grant No.30225026);the Ministry of Science and Technology of China(Grant No.2002CCA01000);the National Institutes of Mental Health(Grant No.N1MH-41544);the Scientific Research Foundation for the Returned Overseas Chinese Scholars,the Ministry of Education of China,and Peking University.

摘　　要：We investigated the effect of low spatial fre-quency (SF) filtering on neural substrates underlying global and local processing in the peripheral vision by measuring hemodynamic responses with functional magnetic resonance imaging (fMRI). Subjects identified global or local shapes of compound letters that were either broadband in spatial- frequency spectrum or contrast balanced (CB) to removed low SFs and displayed randomly in the left or right visual fields. Attention to both broadband and CB global shapes generated stronger activation over the medial occipital cor-tex relative to local attention. Lateralized activations in association with global processing were observed over the right temporal-parietal junction for broadband stimuli whereas over the right fusiform gyrus for CB stimuli. Atten-tion to CB local shapes resulted in activations in the medial frontal cortex, bilateral inferior frontal and superior tempo-ral cortices. The results were discussed in terms of the competition between global and local information in determining brain activations in association with global/local processing of compound stimuli.We investigated the effect of low spatial fre-quency (SF) filtering on neural substrates underlying global and local processing in the peripheral vision by measuring hemodynamic responses with functional magnetic resonance imaging (fMRI). Subjects identified global or local shapes of compound letters that were either broadband in spatial- frequency spectrum or contrast balanced (CB) to removed low SFs and displayed randomly in the left or right visual fields. Attention to both broadband and CB global shapes generated stronger activation over the medial occipital cor-tex relative to local attention. Lateralized activations in association with global processing were observed over the right temporal-parietal junction for broadband stimuli whereas over the right fusiform gyrus for CB stimuli. Atten-tion to CB local shapes resulted in activations in the medial frontal cortex, bilateral inferior frontal and superior tempo-ral cortices. The results were discussed in terms of the competition between global and local information in determining brain activations in association with global/local processing of compound stimuli.

关 键 词：神经系统 血液动力学 功能磁性共振图 空间频率光谱 

分 类 号：R338[医药卫生—人体生理学]